**

Research Branch
Technical Bulletin 1993-3E

Fertilizer

management

for forage

crops in

central

Alberta

Canada

Cover illustration

The images represent the Researeh Branch's objective:

to improve the long-term competitiveness of the Canadian

agri-food sector through the development and transferor new

technologies.

Designed by Research Program Service.

Illustration de la couverture

Les dessins iljustrent I'objectif de la Direction generate de la
recherche : ameliorer la competitivite a long terme du secteur
agro-alimentaire canadien grace a la mise au point et an transfert
de nouvelles technologies.
( 'onception par le Service au\ programmes de recherches.

®

Fertilizer

management for

forage crops in

central Alberta

S.S.MALHI

Agriculture Canada

Research Station

Lacombe, Alberta

D.H. LAVERTY

Star Quality Samplers
Edmonton, Alberta

J.T. HARAPIAK
Western Co-operative Fertilizers Limited

Calgary, Alberta

L.M. KRYZANOWSKI, D.C. PENNEY

Soils Branch
Alberta Agriculture
Edmonton, Alberta

Technical Bulletin 1993-3E

Research Branch

Agriculture Canada

1993

Copies of this publication are available from

Director

Research Station

Research Branch, Agriculture Canada

Bag Service 5000

58th St at the C & E Trail

Lacombe, Alberta

T0C1S0

© Minister of Supply and Services Canada 1993
Cat. No. A54-8/1993-3E
ISBN 0-662-20365-8

CONTENTS

ACKNOWLEDGEMENTS V

SUMMARY /RESUME VI

INTRODUCTION 1

PURPOSE 1

FORAGE NUTRIENTS 2

Nutrient Requirement and Removal 2

Fertilizer Nutrients and Climate 3

FORAGE YIELD RESPONSE TO APPLIED FERTILIZER 5

Grass Forage for Hay 5

Effect of N fertilizers 5

Rate ofN application 6

Single initial vs annual N applications 7

Annual single vs split N applications 7

Source and time ofN application 7

Effect of P fertilizer 11

Effects of K and S fertilizers 13

Economics of N fertilizers 13

Legume Forage for Hay 14

Effect of N fertilizer and N-fixing bacteria 17

Effect of P fertilizer 17

Effect of K fertilizer 19

Effect of S fertilizer 19

Effect of S fertilizer on selenium (Se) concentration of forage .... 20

Grass-Legume Mixtures for Hay 21

Effect of N fertilizer 21

Effect of P, K and S fertilizers 23

Tame Pasture Forage 25

Sources, times and methods of N application 25

Effect of forage fertilization on animal performance 27

SOIL ACIDITY 28

Reasons for Soil Acidity 30

Acidification of Soil by N Fertilizers 30

Longevity of Liming for Neutralizing Soil Acidity 33

CONCLUSIONS 34

in

RECOMMENDATIONS .... 35

REFERENCES 36

APPENDICES 38

IV

ACKNOWLEDGMENTS

The authors wish to thank the Alberta Agriculture Research Institute (Farming for the
Future Program) for financial support to conduct N fertilization research on meadow bromegrass
grown as simulated pasture. Acknowledgment is given to Alberta Agriculture Soils and Animal
Nutrition Laboratory for various chemical analyses, M. Bjorge and Ann de St. Remy for
reviewing the bulletin, K. Heier for technical assistance, and Pierre LePage for french translation.
The authors are endebted to Western Co-operative Fertilizers Limited (WESTCO) for providing
research data from long-term fertilizer application trials on grass and mixed forage stands this
organization maintains in south-central Alberta.

SUMMARY

Land for forage production in Alberta represents approximately 50% of the total
agricultural land of the province, however, only 25% of the improved pasture and hay land
receives fertilizer nutrient applications. Efficient forage fertilization is dependent upon the
producer deciding on the type, timing and amount of fertilizer needed for optimum production.
One or more of the four major nutrients, nitrogen (N), phosphorus (P), potassium (K) and sulphur
(S) may be limiting for optimum forage production.

Grass forage crops have a high N requirement and respond well to N fertilizer application,
while responses to P, K and S fertilizer are moderate and variable. Rates, times and methods of N
fertilizer application have a strong influence on forage yield response and the effectiveness of the
N fertilizer used. In moist areas of the province good yield response will occur up to 200 kg
N/ha, while for dry areas maximum N rates are closer to 100 kg N/ha. Smaller annual N
applications will produce higher and more consistent yields of dry matter than will an equivalent
single large N application made every 3 or 4 years. Annual split applications of N fertilizer may
produce more uniform forage production in moist areas and under irrigation, whereas in the drier
areas split applications are not recommended. Of the N sources available, ammonium nitrate
produces higher dry matter and protein yield than urea when broadcast on surface, but the
effectiveness of urea can be improved by disc-banding below the soil surface. Early spring applied
N is generally more effective than N applied in fall or late spring. Economic analysis suggests that
relatively high rates of N fertilizer can be economical but the benefits are greatly affected by
climate. For P-deficient soils, P fertilizer that is broadcast and incorporated into the soil prior to
establishment of a grass forage stand will remain available to the crop for several years but it is
not as effective as annual broadcast applications of P. Applying moderate annual rates of P early
in spring ensures adequate P levels for the entire growing season. Potassium and S fertilizers are
essential for forage production on K- and S-deficient soils.

Legume forages have the ability to form a symbiotic relationship with N-fixing bacteria,
which allows the legume crop to obtain its N needs through fixation of N from the atmosphere.
Proper inoculation with N-fixing bacteria is critical for successful establishment of legume
forages. As a result N fertilizer is usually not required by legume forages, however, P, K and S
fertilizers may be essential to correct deficiencies. In general, legume forages will produce higher
yields and use P more effectively where P is applied annually rather than from a single large
application made at time of establishment that is intended to last several years. Annual surface
applications of P to established forage stands may not become completely available in the year of
application due to poor mobility of P. Adequate supplies of K are essential to ensure proper
nodulation, regrowth and stronger winter hardiness. Under K-deficient soil conditions, legumes
show yield benefit from annual broadcast applications of K fertilizer. Legume forages have a high
S requirement for N-fixation, yield and protein content. On S-deficient soils, marked increases in
yield and forage quality can be obtained from small annual applications of S.

Fertilizer management for mixed grass-legume forages is much more difficult than in the
case with pure grass or legume stands. In general, stands with more than 80% grass should be

VI

fertilized as a pure grass and stands with more than 80% legume should be managed as a pure
legume forage. To maintain mixtures between 40 to 60% legume and thereby receive the benefits
from N-fixing capabilities of the legume, limited amounts of N fertilizer should be applied but
adequate levels of P, K and S must be maintained. Application of N fertilizer will stimulate grass
production but can reduce the legume content of the stand. Small annual applications of P, K and
S fertilizers will correct deficiencies and produce higher and more consistent yields than an equal
amount of single initial application intended to last several years.

The amounts of tame pasture forage production can have a direct effect on animal
performance. Fertilizer application to forage pastures shows substantial increases in animal gain
and carrying capacity compared to pastures that receive no fertilizer.

Soil acidification can occur from the application of fertilizers to forage stands. Nitrogen
application has a significant acidifying effect on the soil. The greatest effect occurs near the
surface (0-5 cm), where both acidity and extractable aluminum (Al) increase with higher N rates.
Ammonium nitrate is more acidifying than urea, while ammonium sulphate is the most acidifying
N fertilizer. A single application of lime can effectively neutralize the excess acidity and improve
forage yields for many years.

Soil testing is an effective tool for evaluating soil fertility status, diagnosing nutrient
deficiencies, identifying potential soil salinity and acidity problems and providing the basis for
fertilizer recommendations. Climate and soil type have a significant influence on the response of
forage to fertilizer application. Recommendations for fertilizer application are affected by agro-
climatic areas and forage type.

vu

RESUME

En Alberta, le sol disponible pour la croissance des fourrages represente environ 50% du territoire
agricole de la province. De cette superficie, seulement 25% des paturages et terres a foin amendes
sont fertilises. Pour que la fertilisation des fourrages soit efficace, pour obtenir une production
optimale, et pour contrer des carences nutritionnelles en elements essentiels tels que l'azote (N), le
phosphate (P), le potassium (K) et le soufre (S), le producteur doit tout d'abord decider du type et
de la quantite de fertilisant a utiliser ainsi que de la periode appropriee pour l'epandage.

La culture des graminees fourrageres necessite un apport eleve en azote et reagi bien a 1'utilisation
de fertilisants azotes. Par contre la reaction aux fertilisants P, K et S est variable et moderee. La
methode, la periode et le taux d'application du fertilisant azote ont une influence importante sur le
rendement des fourrages et l'efficacite du fertilisant azote utilise. Dans les regions humides de la
province, on obtient un bon rendement en utilisant jusqu'a 200 kg d'azote/ha, alors que dans les
regions plus seches, la teneur maximale en azote serait de l'ordre de 100 kg/ha. Plusieurs
applications annuelles d'azote produiront un rendement plus eleve et plus constant en matiere
seche qu'une seule application equivalente faite a toutes les 3 ou 4 ann6es. L'application annuelle
fractionnee de l'azote peut produire un fourrage plus uniforme en regions humides et sous
irrigation, mais n'est pas recommendee dans les regions seches. Parmis les sources d'azote
disponibles, l'emploi du nitrate d'ammonium epandu en surface est preferable a celle de l'uree et
ce, pour un rendement eleve en matiere seche et en proteines. Mais l'efficacite de l'uree peut-etre
amelior^e grace a l'epandage en bandes par disque sous la surface du sol. De plus, l'application
d'azote tot au printemps est habituellement plus efficace qu'en automne ou tard au printemps. Des
6tudes suggerent qu'un taux eleve de fertilisant azote" peut-etre economiquement rentable mais
que les effets bdn6fiques dependent du climat Pour les sols pauvres en phosphate, l'engrais
phosphate epandu en nappes et incorpore dans le sol avant l'etablissement d'un peuplement de
graminees fourrageres demeurera disponible pour les plantes pendant plusieurs annees, mais n'est
pas aussi efficace que l'epandage annuel de phosphate. L'application annuelle moderee de P tot au
printemps assurera une disponibilite de phosphate pour toute la saison de croissance. Les
fertilisants potasses et soufres sont essentiels pour la production de fourrages sur sols pauvres en
KetS.

Les legumineuses fourrageres ont la particularity de former une symbiose avec des bacteries
fixatrices d'azote, et ce phenomene permet aux plantes d'obtenir l'azote directement de
l'atmosphere par fixation. L'inoculation efficace de bacteries fixatrices d'azote est importante pour
l'etablissement des legumineuses. Meme si aucun engrais azote est necessaire, les fertilisants P, K
et S peuvent s'averer essentiels pour corriger certaines carences. En general les legumineuses
fourrageres ont un meilleur rendement et utilisent P plus efficacement la ou il est applique
annuellement plutot qu'une seule application faite au moment de l'ensemencement et destinee a
durer plusieurs anndes. L'epandage phosphatee annuelle en surface, pour l'etablissement du
peuplement fourrager, peut ne pas etre completement accessible durant l'annee d'application due a
la pauvre mobilite du phosphate dans le sol. Une quantite adequate de potassium est necessaire
pour assurer une bonne nodulation, un redemarrage et une resistance a l'hiver adequats. Les
legumineuses sur sol pauvre en K ont un meilleur rendement lorsqu'elles beneficient d'un epandage

vru

en nappes annuel de fertilisant potasse. Les legumineuses ont de plus besoin de soufre pour fixer
l'azote, pour un bon rendement et une bonne teneur en proteines. On peut accroitre le rendement
et la quality des fourrages sur sols pauvres en soufre par de petites applications annuelles de
soufre.

La gestion des fertilisants pour les fourrages mixtes de graminees-legumineuses est plus complexe
qu'avec ces cultures prises sepanSment. En general les cultures qui possedent plus de 80% de
plantes legumineuses sont considerees legumineuses pures. Pour maintenir des melanges en
legumineuses entre 40 et 60% et pour aussi beneficier de la capacite de fixation de ces plantes, de
petites quantites de fertilisant azote devraient etre appliquees tout en s'assurant de maintenir des
taux appropries en P, K et S. L'emploi d'engrais azote stimule la production de graminees, mais
peut rdduire la quantity de legumineuses du peuplement. De legeres applications annuelles
d'engrais P, K et S corrigeront les carences et produiront un rendement plus eleve et plus
consistant que de plus grandes applications concues pour durer plusieurs ann6es.

La production de prairie fourragere artificielle peut avoir un effet direct sur la performance des
animaux. En effet, la fertilisation des prairies fourrageres se caracterise par un gain du poids et
une augmentation du chargement chez les animaux lorsque comparee aux prairies n'ayant recues
aucun engrais.

L'acidification du sol peut apparaitre lorsque Ton applique du fertilisant sur les peuplements
fourragers. Cette acidification est particulierement causee par l'apport d'azote au sol. et est surtout
importante en superficie (0-5 cm) ou l'acidite et l'aluminium extractible augmentent avec la
concentration d'azote. Le nitrate d'ammonium est plus acidifiant que l'uree, alors que le sulfate
d'ammonium est le fertilisant azote le plus acidifiant. Une seule application de chaux peut
neutraliser effectivement l'exces d'acidite et ameliorer le rendement du fourrage pour plusieurs
annees.

L'analyse du sol est un outil efficace pour evaluer la fertilite, les carences nutritionnelles, les
problemes de salinite et d'acidite et pour determiner les besoins en fertilisants. De plus, le type de
sol et le climat ont une influence marquee sur la maniere dont le fourrage reagi a l'application
d'engrais. Les recommendations sur la fa9on d'appliquer le fertilisant sont soumises aux variations
agro-climatiques et au type de fourrage.

IX

INTRODUCTION

The current importance of forages in Alberta is demonstrated by the fact that
approximately 50% of the agricultural land base produces forages (Table 1) and forages are the
major source of food for beef cattle, dairy cattle, sheep, horses, and ruminant wild life.
Furthermore, sales from domestic ruminant Livestock generate over 40% of total on-farm income
for Alberta farmers.

Table 1. Forage land area in Alberta.

Types of forages Hectares ( 1 ,000's)

Unimproved pasture 6,674

Improved pasture 1 , 742

Perennial hay and silage 1,723

Annual hay and silage 741

Seed 93

Total forage land 10,273

Total agricultural land 20,811

Source: Statistics Canada 1991 Census (numbers do not include Crown lands).

Forages are also an important component of many sustainable agriculture cropping
systems in Alberta. Well managed forage crops can significantly reduce wind and water erosion
on land and can also help to improve soil tilth and fertility.

Despite the importance of forage crops for livestock production and the on-going
maintenance of the agricultural soil resource, forage crops are often managed poorly. A strong,
productive forage stand that will last for several years is the desired objective of most producers.
To maintain strong annual crop production, fertilizer nutrients must be applied regularly.
However, surveys have shown that less than 25% of the improved pasture and hay land in Alberta
receives fertilizer nutrient applications. Therefore, it would appear that there is considerable
room for improvement in forage production with the effective use of fertilizer nutrients.

PURPOSE

Forage crops, like most other agricultural crops grown in Alberta, respond well to the
application of fertilizer nutrients when soils are deficient in those nutrients. Research has shown
that properly fertilized forage crops, grown under a wide range of climatic conditions, will
produce higher yields of more nutritious forage than unfertilized crops will. Improved production
of forage crops through better use of fertilizers requires a greater understanding of some basic
interactions between soil, climate, and the forage crop.

The purpose of this publication is to provide fertilizer management information for
improved production of quality hay and pasture. Nutrient requirements and soil deficiencies are
discussed for grasses, legumes, and grass-legume mixtures. Research information is summarized
to demonstrate how fertilizers can be applied effectively to improve forage yield and quality.
Different fertilizer materials, and times, rates and methods of fertilizer applications are discussed
and evaluated. Some information is also given regarding soil acidity and liming, forage quality,
and economics.

FORAGE NUTRIENTS

Nutrient Requirement and Removal

Forages require 16 or more essential nutrient elements from soil for normal healthy
growth (nitrogen, phosphorus, potassium, sulphur, calcium, magnesium, copper, zinc, iron,
manganese, boron, sodium, molybdenum, chloride, cobalt, vanadium and silicon). The amounts
of these nutrients vary considerably among forage species. Nutrient requirements are quite
different for forages compared to annual cereal grains.

In Alberta, one or more of the four main nutrients may be limiting for maximum forage
production; N and P are the most commonly deficient nutrients, while K and S may also be
deficient for certain crop and soil conditions. Deficiencies of other nutrients have seldom been
identified in forage crops in Alberta, but more research is needed.

Large amounts of N, P, K and S are required for high forage yields (Table 2). When
forages are harvested as hay or silage, these amounts of nutrients are removed from the field and
these nutrients are not returned to the soil unless manure is reapplied to each field from which the
forage was removed. This differs from cereal grain production where lesser amounts of nutrients
are generally required and only the grain portion of the crop is removed from the field. Variations
in crop nutrient requirements between forages and cereals are greatest for N and K.
Requirements for these nutrients are higher for forages than for cereals and highest for legume
forages.

Table 2. Plant nutrients used by three types of forage crops compared to barley grain (kg/ha).

Crop Yield (t/ha) N P K S

Grass hay

6.7

125

15

130

10

Legume hay

9.0

270

20

180

20

Cereal silage

6.7

120

13

100

10

Cereal grain (barley)

4.3

90

15

25

15

Source: Plant Nutrients Use by Crops. Compiled by Western Canada Fertilizer Association, October, 1978.

Without adequate fertilizer, three to five years of continuous forage production can
deplete soil nutrient reserves and cause a soil nutrient deficiency more quickly than continuous
annual grain production. The lack of tillage when perennial forages are grown also slows the rate
of nutrient release from the soil. With the exception of N for legume forages, fertilizer nutrients
required for forage production generally need to be applied at higher rates than for grain
production.

Fertilizer Nutrients and Climate

Nutrients contained in fertilizers are applied to make up the deficiency between the
nutrients needed for optimum forage growth and the nutrients available from the soil. Although
the soil can supply most of the nutrients needed for optimum growth, N and P are usually lacking.
Forage yield is always reduced when soil nutrients are lacking.

Large amounts of N are needed by forage crops to produce maximum growth. As grass
forage yields increase, greater amounts of N are required. The importance of N fertilizer for
balancing N requirements is apparent when the amounts of N needed for increased forage yields
are compared to N released from the soil (Figure 1). The N released from the soil is small in
relation to the amount of N needed for maximum forage production. If the difference between
plant needs and soil supply is recognized and balanced with fertilizer N, the maximum growth
potential can be achieved.

As in the case of N, the needs of a forage crop for P, K and S must be balanced with
fertilizers to meet maximum crop yield when the soil supply is deficient in these nutrients. Also,
when more than one nutrient is deficient in soil and only one is supplied by fertilization, crop yield
will still be limited by the nutrient not provided. For example, if both N and S are deficient in the
soil, adding only N or only S will not produce the full yield response that would result from the
addition of both N and S.

Although N is required in large quantities by forages, only those crops with high
percentage of grasses need N fertilizer. Legume forage crops can obtain most of their N
requirements directly from the air through a process called N fixation. Nitrogen fixation is
discussed in more detail in the section, "Legume Forage for Hay".

Adequate moisture is a critical factor affecting forage crop production, nutrient
requirements, and the effectiveness of fertilizer application. Forage crop response to fertilizer
application is directly related to the amounts and distribution of growing season precipitation and
the ability of the soil to store water. In the drier areas of the province and on some sandy soils,
response from fertilizers will be quite low because of limited available water. Fertilizers applied
on established forages need to be leached into the soil before they can be used by the forage.
Therefore, information regarding times and methods of application that will increase movement of
fertilizer to crop roots is important to improve forage response to fertilizer. Even in the wetter
areas of the province, variations in the amounts and times of seasonal precipitation can cause
erratic responses to fertilizer application. However, in both dry and wet areas, strong

Figure 1. Nitrogen required for various yields of grass forage

150

140

130

120 h

110

100

90
80

i

bp

w

SP

.2

U
(DO

.o

* 70

§

s

u

3

c

so
o

.5 30

60
50
40

20

10 h
0

1

4.0 6.0 8.0

i

i

Additional N required
as fertilizer

N released during
growing season

N available in soil
in spring

i

o

00

Dry matter yield of grass forage (t/ha)

responses occur when fertilizers are applied on nutrient-deficient soils. Residual effect of
fertilizers can last for three or more years after the year of application. For these reasons,
economic returns from forage fertilization need to be measured over a period of several years.

FORAGE YIELD RESPONSE TO APPLIED FERTILIZER

Three factors must be considered when determining what rate and kind of fertilizer to use
on forage crops. These factors include:

- which nutrients are deficient and how severe are the deficiencies;

- what are the yield responses when various rates of fertilizer nutrients are applied; and

- what are the net returns from increased yield when crop prices, and fertilizer and application
costs are taken into consideration.

The more accurately these three factors can be determined, the greater the potential for
profitable returns from forage fertilization. Methods of estimating nutrient requirements and crop
yield response are discussed separately for grass, legume and mixed grass-legume forages.

Grass Forage for Hay

Perennial grass forage has a high N requirement and will respond very well to fertilizer N
particularly in the moist regions of Alberta. Responses to P, K and S fertilizers are more
moderate and variable on most soils. Dramatic responses can occur, however, where soils are
very deficient in only one of these nutrients.

Effect of N fertilizers

Grass forage crops obtain N from two main sources: (1) available N stored in the soil and
mineralized during the growing season (released from soil organic matter, manure, and crop
residues), and (2) fertilizer N. Nitrogen released from the soil is generally not sufficient to
produce high yields of forage. Mineralization of soil N is slow in established forage stands. Only
about one-quarter of the total N required for high yielding forages can be supplied from soil N
during the early growing season. Soil tests of available soil N on established grass fields have
shown that very little N is carried over from one growing season to the next. It appears that
under forage cropping conditions, almost all available N released from soil organic reserves
during the growing season is consumed immediately by the forage stand for production of new
growth. Thus, there is no build up of available soil N for initial spring growth as may be expected
under annual cropping conditions. Therefore, the N supplied by fertilizer becomes very important
for achieving maximum yield of grass forage. Rates, sources, times and methods of N fertilizer
application are factors that have a strong influence on how effectively forage crops respond and
use the N fertilizer that is applied.

Rate of N application

Field research in central Alberta has shown that grass forage yields will increase with
increasing rates of early spring applied N (Table 3). Although average dry matter yield (DMY)
varied considerably where no N fertilizer was applied, yield consistently increased with N
application for all three areas in central Alberta. With moderate rates of 100 kg N/ha, DMY
increased by 2.74, 3.68 and 4.07 t/ha, respectively, for north-central, central, and south-central
areas.

Table 3. Dry matter yield and protein content of bromegrass hay, fertilized annually in the spring of the year with
six or seven levels of ammonium nitrate at locations in north-central, central and south-central Alberta totalling 41
site years.

Locations in

]

Parameters

Levels of ai

?plied

N (kg N/ha)

Alberta

0

50

100

150

200

300

North-central
(Ave. 3 yr - 2
locations)

Central

(Ave. 4 yr - 4
locations)

DMY§

pet

PY*

DMY
PC

PY

DMY
PC
PY

1.37
12.5
171

3.86
11.2

432

2.99
10.3
308

5.98
11.6
694

4.11
12.1
497

7.54
13.0
980

5.16
13.7
707

8.49
14.4

1223

5.82
14.6
850

8.70
15.2
1322

7.09
16.3
1156

8.73
15.8
1379

Levels of a]

jplied

N (kg N/ha)

0

56

112

168

224

280

336

South-central
(Ave. 19 yr - 1
location)

1.17
7.3

84

3.63

7.2
247

5.24
8.5
425

5.41
9.6
496

5.69
11.0

582

5.62
10.9
576

5.45
11.6
598

§DMY = dry matter yield (t/ha).
tPC = protein content (%).
tPY = protein yield (kg/ha).

Protein content in forage is important to livestock nutrition. As the rate of N
increased, protein content increased up to the maximum rate of N applied (Table 3). At the
lower rates of N {i.e. 50 and 100 kg N/ha) where DMY response to N was greatest, the
increase in protein content from N application was the smallest. At high N rates the DMY
response decreases and protein content in the forage increases more rapidly. This is
understandable since N is required for plant growth and where DMY is small, N will
accumulate as extra protein. High DMY and protein content will occur at N rates that
approach maximum yield. Protein yield (PY), which is the result of DMY and protein content,
also increases with increasing rates of applied N, but at a faster rate. Thus, more protein will
be produced per hectare at an N rate of 150 kg N/ha than at 100 kg N/ha because both DMY
and protein content are greater.

Single initial vs annual N applications

Often a high initial N application is suggested on the assumption it will last for several
years of grass forage production. Such a practice would reduce labor costs and might allow
producers to take advantage of favorable fertilizer prices and years with above-average rainfall.
Studies in central and north-central Alberta compared high single N application with smaller
annual applications for 3 to 4 years. Single initial application produced the greatest effect on
DMY in the first year, but the effect did not persist beyond the third year and yields dropped
significantly after the second year (Table 4).

When individual treatments were summed and averaged for the 3 or 4 years of the studies,
it was possible to compare the responses to equal rates of N (e.g. 50 kg N/ha annually for 3 years
vs 150 kg N/ha single initial). In the north-central and central Alberta trials, annual applications
generally produced greater DMY and PY than single initial application (Table 5). These results
indicate that smaller annual N applications will produce higher and more consistent yields of dry
matter than will equivalent single N application made every three or four years.

Annual single vs split N applications

Grass forage gives a strong yield response to early spring applied N. Split N application
during the growing season has been successfully used in areas where two or more cuts of hay
are regularly harvested. In drier areas of the province, where total yields of forage are relatively
low and only one cut of hay is usually harvested, splitting the N application during the growing
season is not recommended. In many areas of Alberta, the growing season rainfall is irregular
and unpredictable, particularly in July and August. So, split N application gives variable results.
In areas with higher rainfall or with irrigation and where two or more cuts of hay are regularly
harvested, applying N in two or more increments may be beneficial.

Source and time ofN application

Several N sources are available for forage fertilization and the majority of forage
fertilization is done with granular fertilizer . The N source for granular fertilizer is heavily
dominated by urea. Nitrogen fertilizers are usually applied to forage stands in early spring. Farm
workload and weather conditions may cause producers to consider other times of N application.
Experiments conducted in south-central Alberta have shown that some application times and N
sources produce more consistent DMY and PY responses than other times and sources (Table 6).
In this study, DMY was measured over a period of 15 years at four locations in response to
annual applications of 1 12 kg N/ha using two N sources, ammonium nitrate and urea, at two dates
in the fall and two dates in the spring. Strong DMY increases occurred at all locations from both
fall and spring applications for each N source. For all dates of applications, urea produced lower
DMY increases than ammonium nitrate. Average DMY for fall and spring applied N were
consistently higher for ammonium nitrate compared to those for urea (4.36 vs 3.82 t/ha for fall

Table 4. Total dry matter yield of smooth bromegrass managed as hay, treated with three rates of a single
application of ammonium nitrate during the initial year at four locations in central Alberta and two locations in
north-central Alberta.

Levels of applied N (kg N/ha)

Locations

Lacombe

Joffre

Botha

Rocky

Mountain

House

Ellerslie

Vimy

Year

0

200

400

t/ha - -

1975§

9.52

10.66

9.92

1976

5.78

9.51

11.71

1977

2.85

2.97

4.54

1978

3.56

4.36

3.11

1979

3.12

3.53

3.12

1975§

7.16

7.79

8.78

1976

3.13

5.54

7.09

1977

2.88

3.97

6.32

1978

4.51

5.52

6.15

1979

2.97

2.90

2.96

1975§

4.75

6.76

7.93

1976

2.34

3.37

4.96

1977

2.15

2.43

3.13

1978

4.23

3.94

6.61

1979

3.36

2.92

3.93

1976§

8.77

15.36

13.76

1977

4.09

5.72

10.66

1978

4.86

5.45

5.27

1979

3.12

4.01
Levels of applied N (kg N/ha)

4.16

0

150

300

1975§

0.89

4.28

4.88

1976

0.26

0.53

2.33

1977

0.69

0.72

0.69

1976§

1.73

4.76

6.64

1977

2.18

3.14

4.11

1978

2.47

3.10

2.12

§ Year of application.

Table 5. Dry matter yield of smooth bromegrass hay (t/ha) summed over three or four years and averaged for N
fertilizer in single initial or annual applications at locations in north-central and central Alberta.

Locations
in Alberta

Level of applied N fertilizer (kg N/ha)

Single
150

Annual
3x50

Single
300

Annual
3x100

North-central
(3 yr - 2 locations)

4.11

Central
(4 yr - 4 locations)

18.43

8.27

8.97

10.39

Level of applied N fertilizer (kg N/ha)

Single
200

Annual
4x50

Single
400

24.34

27.04

28.53

12.33

Annual
4x100

32.09

and 4.40 vs 3.98 t/ha for spring). Early spring applied N gave the highest DMY for both urea and
ammonium nitrate. The lowest yield response for urea occurred when applied in early fall, while
for ammonium nitrate the lowest yield response occurred when applied in the late spring.

Urea was a less effective N source for increasing protein yield and content than ammonium
nitrate (Table 6). Average protein yields were 445, 376 and 167 kg/ha, respectively, for
ammonium nitrate, urea, and no fertilizer N treatments. In the same order, average protein
contents were 10.4, 9.9 and 8.7%. Ammonium nitrate gave protein contents that were similar for
fall and early spring applications. However, for urea, fall applications resulted in lower forage
protein contents than when applied in spring. Late spring application gave the highest protein yield
and content for both N sources. The higher protein yield with late spring application than early
spring application suggests that the applied N became available to plants later in the growing
season. The N use efficiency and % N recovery were lower when urea was the N source compared
to ammonium nitrate at all dates of application (Table 6). The percent recovery of applied N was
greatest when N was applied in the late spring and early fall application gave the lowest N
recovery.

In another study in north-central Alberta, N sources were compared when two rates of N
were applied in early spring on established bromegrass (Table 7). Dry matter yield increased
markedly with N applications in this study. Ammonium nitrate was slightly superior to urea in
increasing dry matter yield, protein yield, protein content, N use efficiency, and recovery of applied
N at application rates of 50 and 100 kg N/ha.

In summary, ammonium nitrate produced greater dry matter and protein yield than urea.
This is likely due to the well established fact that urea is more vulnerable to ammonia volatilization
loss than similarly applied ammonium nitrate. Although, ammonium nitrate outperforms urea, it
must be emphasized that urea is still a good source of N for forage crops when considering its cost
and availability.

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Table 7. Dry matter yield (DMY), protein yield (PY), protein content (PC), N use efficiency (NUE), and recovery
of applied N (NR) with smooth bromegrass managed as hay and fertilized annually with ammonium nitrate and
urea at 50 and 100 kg N/ha applied in early spring for three years at two locations in north-central Alberta.

N rate and source

Check

50

kg

N/ha

100 kg N/ha

A.N.§

Urea

A.N. Urea

DMY (t/ha)

1.37

2.99

2.79

4.11 3.81

PY (kg/ha)

171

308

286

497 441

PC(%)

12.6

10.3

10.3

12.1 11.6

NUE (kg DM/ha/kg N)

32.3

28.4

27.4 24.4

NR(%)

43.5

36.6

52.0 43.0

§ Ammonium nitrate.

Effect of P fertilizer

Unlike nitrate-N (NO3-N) and sulphate-S (SO4-S) which move relatively freely with
water in the soil, P is quite immobile. For this reason, placement of P fertilizer in the soil
where it will be directly intercepted by roots is very important. To place the P below the soil
surface in established forage stands has been difficult and often impractical due to the stand
damage that can result from attempting this practice. Hence, for P-deficient soils, P fertilizer is
usually broadcast and incorporated at high rates prior to forage establishment, and/or
broadcast on the soil surface for established stands.

A field experiment was conducted over a five-year period to compare the effects of
prior P incorporation with annual P applications in central Alberta using smooth bromegrass as
the test crop (Tables 8 and 9). Rates for annual spring broadcast P application were 0, 10, 20,
30, 40, and 60 kg P/ha (Table 8). Single initial P application rates of 60, 120, and 180 kg P/ha
were broadcast and incorporated in the soil just prior to seeding bromegrass (Table 9). On this
P-deficient soil, the greatest DMY increase resulted from the first 10 kg P/ha, but DMY
continued to increase up to the 60 kg P/ha rate. The reported results also show that single
initial application as low as 60 kg P/ha produced increase in DMY in the fifth year. This would
indicate that P broadcast and incorporated in the soil prior to the establishment of grass forage
will remain available to the crop for several years.

In this same study, two cuttings of hay were harvested in four of the five years that
results were collected. In all years, P fertilizer application increased the DMY of the second
cut for all rates of P application. At the 60 kg P/ha rate, the average DMY for the second cut
was 1.35 t/ha higher than where no P was applied. This indicates that a good supply of
available P in the soil will contribute to stronger plant growth throughout the growing season.
Thus, by simply applying moderate annual rates of P early in spring, marked increases in late
season DMY can be obtained. This would be most significant for pasture and for hay in areas
where consistent second cut hay harvests are possible.

11

Table 8. Dry matter yield (t/ha) of first and second cuts of smooth bromegrass hay, treated annually with six levels
of phosphorus for four years at Lacombe in central Alberta.

Cut

Levels of applied

P (kg P/ha)

Year

0

10

20

30

40

60

1976

1

7.75

8.80

7.99

8.96

8.83

8.62

2

3.04

3.81

4.31

4.62

4.50

4.83

Total

10.79

12.61

12.30

13.58

13.33

13.45

1977

1

6.82

7.29

7.64

7.56

7.77

7.88

2

2.57

3.42

3.41

3.38

3.49

3.94

Total

9.39

10.71

11.05

10.94

11.26

11.82

1978

1

7.25

7.83

8.26

7.88

7.59

8.54

2

0.82

1.77

1.54

1.72

2.03

2.31

Total

8.07

9.60

9.80

9.60

9.62

10.85

1979

1

5.25

6.60

6.98

6.84

6.46

7.20

2

1.44

2.00

2.23

2.00

2.07

2.20

Total

6.69

8.60

9.21

8.84

8.53

9.40

Mean

1

6.77

7.63

7.72

7.81

7.66

8.06

(1976-79)

2

1.97

2.75

2.87

3.08

3.02

3.32

Total

8.74

10.38

10.59

10.89

10.68

11.38

Table 9. Total dry matter yield (t/ha) of smooth bromegrass hay, treated with four levels of phosphorus
incorporated into soil in the establishment year (1974) and harvested from 1975 until 1979 at Lacombe in central
Alberta.

Levels of

applied P (kg P/ha)

Year

0

60

120

180

1975

10.06

11.47

11.02

12.24

1976

10.79

. 11.66

13.42

12.38

1977

9.39

10.42

10.87

10.32

1978

8.07

10.90

9.72

9.25

1979

6.69

7.74

7.82

7.74

Mean (1975-79)

9.00

10.44

10.57

10.39

To determine the amount of P fertilizer that moved into the soil profile, extractable P
was measured in soil samples taken from experimental sites where P had been surface
broadcast on established forage for several years. On a sandy loam soil at Lacombe, annual P
applications on a creeping red fescue stand for seven years totalled 67 to 536 kg P/ha. At the
end of this period, extractable P in soil samples taken from the 0-5, 5-15, 15-30 cm depth
showed that the majority of fertilizer P recovered as extractable P was present in the 0-5 cm
depth (Table 10). There was some increase in extractable P in the 5-15 and 15-30 cm depths,

12

but only at the two highest rates of P application. At the two lowest rates, little of the applied
P moved below the 5 cm depth. Similar results were found in other experiments on different
soils showing that most of the applied P remained near the surface and greater P movement in
the soil occurred with higher rates of application and on the coarse textured soils. Although
some fertilizer P moves into the upper part of the soil, most remains very near the surface and
this P will be available to plants only as long as the surface soil is moist and roots are active in
the zone of P concentration.

Table 10. Extractable P in soil after application of P fertilizer to creeping red fescue over seven years on a Black
chernozem soil at Lacombe in central Alberta.

P applied in seven Extractable P in soil (ppm)t

years (kg P/ha) 0-5 cm 5-15 cm 15-30 cm

0 17 10 6

67 48 12 9

134 87 13 8

268 145 25 10

536 258 72 19

t Miller and Axley extractable P (parts per million).

Effects of K and S fertilizers

Like P, the need for applying K or S on grass forage is not as great as is the need for N
fertilizer. However, on deficient soils, these nutrients must be applied in order to obtain high
yields of forage grass. Regular soil tests are the best means of determining if K and S are likely
to be limiting for forage production. Large amounts of nutrients are used by grass forage and as
these nutrients are removed from the field in harvested product, the available supplies of P, K
and S in the soil may be rapidly reduced. Thus, nutrients may become deficient after 2 or 3
years of forage production on fields where the soil tests showed nutrient supplies to be marginal
to adequate at the time of forage establishment.

Deficiencies of P, K and S have also been associated with reduced forage quality,
particularly protein content. More research is needed to establish this relationship for grass
forage.

Economics of N fertilizers

Grass forages such as smooth bromegrass respond well to N fertilizer application on
most soils in central Alberta. Dry matter yield, however, varies considerably with annual
weather fluctuations between different soil zones and with different soil types. The economics
of forage fertilization will, therefore, also vary with climate and soil differences as well as with
the price of hay and fertilizer N. Results from field experiments have been used to calculate the
returns above fertilizer costs and the most economical rates of N on the basis of soil-climate

13

zone, hay price and N fertilizer cost.

One study involved two locations in central Alberta (Lacombe, and Rocky Mountain
House) and one location in east-central Alberta (Botha) over four years and with six annual rates
(0 to 300 kg N/ha) of ammonium nitrate fertilizer applied to bromegrass. A close relationship
was found, at each location, between total dry matter yield (TDMY) and the rate of annually
appplied N. The TDMY increased more slowly as the rate of N fertilizer increased (Table 11).
The TDMY response to fertilizer N varied with the location, Lacombe showing the highest and
Botha showing the lowest increase. Botha was a relatively dry area and therefore produced
lower TDMY than the other locations which were in relatively wetter areas.

The economic returns above fertilizer costs changed with location and were influenced
by TDMY, yield response to applied N, cost of N fertilizer, and the value of hay (Table 11).
Returns above fertilizer costs increased with increasing rates of N fertilizer, with the maximum
occuring at the most economical N rate and decreasing thereafter. At $60/t of hay and $500/t of
N, maximum returns above fertilizer costs were $375, $166 and $98/ha at N rates of 200, 150
and 100 kg N/ha, respectively, at Lacombe, Rocky Mountain House and Botha. Lower net
returns at Botha were due to the low rainfall common to the area. Differences among the other
locations were due to soil type.

In another experiment in south-central Alberta, seven levels (0-336 kg N/ha) of am-
monium nitrate were applied early in the spring for 19 years on established bromegrass at one
location. The DMY increased with N application to a maximum at 224 kg N/ha. The increase
in DMY per unit N from fertilization, however, was greatest with rates of 56 and 1 12 kg N/ha.
The economic returns above fertilizer costs maximized at N rates close to 1 12 kg N/ha.

Many central Alberta producers apply only 30 to 60 kg N/ha when they are fertilizing
hay and pasture fields. These N levels are considerably lower than the most economical rates of
N fertilizer calculated for even the drier areas and years in these long-term studies. Often a
wider risk or uncertainty factor, such as 1.5 to 2.0, is desired for capital input for hay
production. Table 12 shows the dollar returns per dollar invested on N fertilizer for the
locations studied in central, east-central and south-central Alberta. More intensive N
fertilization can be economically practised, particularly in the moister areas in central Alberta.
In addition to the increase in DMY resulting from N fertilization, it must also be recognized that
there is an increase in protein content and improved soil tilth.

Legume Forage for Hay

High yielding legume crops that may produce two to three cuts per year remove large
amounts of the four major plant nutrients (N, P, K, S). Compared to cereal grain crops, legumes
may remove three times as much N and K and two times as much P and S (Table 12). These
large nutrient removals by legume crops make it essential to monitor the soil fertility status and
forage nutrient composition annually in order to manage fertilizer inputs for maximum economic
production of quality legume forage.

14

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16

Effect of N fertilizer and N-fixing bacteria

Alfalfa, like other legume crops, co-exists with nodulating bacteria that can take large
quantities of N from the atmosphere and change it to a form that is available to plants.
Consequently, no N fertilizer is required for properly inoculated legume forages which are
utilizing atmospheric N. Large amounts of N fertilizer may cause the nodulating bacteria to
reduce fixing of atmospheric N.

Adequate soil fertility and the proper inoculation of legume seed with specific bacteria
suited to the legume crop are critical factors for transfer of sufficient N from the bacteria to the
growing legume. For more details regarding legume bacteria and how to inoculate legumes, the
reader is referred to Agdex No. 100/23-1, "Inoculation of Legume Crops", available from Alberta
Agriculture. Legumes should be checked occasionally for the presence of effective nodules on the
roots. The presence of large nodules that are bright pink in color, when cut open, is a good
indication that the legume crop is being supplied with N. Legume bacteria are growing organisms
that require nutrients to function. When soils are deficient in nutrients, the bacteria function less
effectively in fixing and transferring N to the plant. Sulphur deficiency is the most common
nutrient limiting the activity of these bacteria. Soil pH is also important. Nodule formation and
functioning is severely limited by acid soil conditions (pH < 6.0).

Effect of P fertilizer

Phosphorus is commonly deficient in Alberta soils. Therefore, annual applications of P are
usually required to maintain high legume yields. Generally, legume forages will produce higher
yields and use P more effectively with annual applications of P than from a single large application
made at seeding that is intended to last for several years of production. On very P-deficient soils,
the full benefit of annual applications of P may not be realized for two to three years. Therefore,
it is important to apply P fertilizer prior to seeding for establishing legume stands, followed by
annual applications of P.

Field experiments have been conducted to determine legume response to P fertilizer when
applied annually compared to single initial application broadcast and incorporated prior to
establishment (Tables 13, 14 and 15). Response varied between the two locations, partly due to
climatic conditions and level of available P in the soil. Lacombe, located in a higher rainfall area,
had a greater DMY potential. However, the available P in the soil was relatively low (Table 13).
At the drier site (Botha), soil available P was medium. Average alfalfa DMY increased at both
locations with P application. On the soil where available P was low and moisture was adequate
(Lacombe), average alfalfa DMY was increased by 1.73 t/ha with an annual application of only 10
kg P/ha. Similarly, at the 20 kg P/ha rate, average DMY increased by 2.97 t/ha. Average DMY
increases at the drier location with a medium soil available P supply were smaller but consistently
showed a response to applied P in dry and wet years.

Results of first and second cut of alfalfa DMY taken at Site 1 are reported in Table 14.
Yield of both first and second cuts of alfalfa increased with P application. At the rate of

17

Table 13. Average total dry matter yield (t/ha) with six rates of P fertilizer applied annually to alfalfa forage
managed as hay for three or four years at two locations in central Alberta.

Soil test P
(kg P/ha)

Rate of applied

P (kg P/ha)

Site

0

10

20

30

40

60

Lacombe

18

4.53

6.26

7.50

7.47

7.64

7.65

(3 yrs)

Botha

27

4.07

4.32

4.73

4.98

5.55

4.89

(4 yrs)

Table 14. Average dry matter yield (t/ha) of first and second cuts of alfalfa forage managed as hay with six rates of
P fertilizer applied annually for three years at Lacombe in central Alberta.

Soil test P
(kg P/ha)

Rate of applied

P (kg P/ha)

Cut No.

0

10

20

30

40

60

1
2

18

3.21
1.32

4.24
2.02

4.72
2.78

4.91
2.56

4.80
2.84

4.86
2.79

Table 15. Average total dry matter yield (t/ha) with four rates of P fertilizer broadcast and incorporated in a single
initial application prior to establishment of alfalfa managed as hay for three or four years at two locations in central
Alberta.

Soil test P
(kg P/ha)

Rate of

applied

P (kg P/ha)

Site

0

60

120

180

Lacombe
(3 yrs)
Botha

(4 yrs)

18

27

4.53
4.07

6.86

4.47

7.78
5.07

7.58
5.07

20 kg P/ha, DMY for the first cut was 1.5 times greater than the DMY where no P was applied
and was 2.1 times greater for the second cut. Thus, DMY of alfalfa can be increased substantially
with relatively small (20 to 40 kg P/ha) annual P fertilizer applications, particularly when soils test
low in available P. Also, these responses are extended later into the growing season where this
may be an advantage for second cutting of hay or for extended pasture production.

Single initial application of P incorporated before alfalfa was established resulted in DMY
increase from rates of 60 and 120 kg P/ha (Table 15). No further increase in average DMY
resulted at the rate of 180 kg P/ha. The residual effect of large single P application lasted at least
for four years but DMY diminished with time.

18

Phosphorus applied at low rates on the surface of forage stands may not become
completely available in the year of application because sufficient P does not move downward into
the soil to the rooting zone of the crop. At higher rates, more P is moved into the soil and some
is carried over for use by crops in subsequent years. Some P carryover is desirable to ensure there
is always an adequate supply of P to meet early growth needs. One should also recognize that at
low rates of P fertilization on P-deficient soils, a large part of the plant requirement for P will be
removed from the soil.

Effect of K fertilizer

Potassium is a nutrient that is used in large quantities by legumes. Although the majority
of Alberta soils contain adequate K for legume production, there are some soils in the central and
north-east regions that will benefit from K fertilization. Coarse textured soils (loamy sand and
sandy loam) and organic soils are most likely to be K deficient. Both yield, and protein content,
will be increased by the application of K on low K soils. On such soils, research has shown that
an adequate supply of K will stimulate fixation of N by nodule bacteria and the regrowth of
legumes following harvest. Potassium has also been shown to decrease the incidence of winter
injury in legume stands because adequate K increases the accumulation of carbohydrates in the
root system of legumes. On marginal and K-deficient soils, legumes may produce well in the first
year of establishment or for the first cuts in subsequent years. However, after several harvests the
soil K supply will not maintain high yields of legumes. Thus, under K-deficient conditions, the
stand of legume is reduced and the quality of forage decreases significantly. Annual applications
of K fertilizer can avoid these problems and will ensure the legume crop will be able to take full
advantage of favorable climatic conditions for maximum growth.

Effect of S fertilizer

Sulphur is deficient in many soils in west-central and northern Alberta. Soils most
commonly deficient in S are Gray Wooded (Gray Luvisol) and coarse textured Black and Thin
Black Chernozem soils. Many years of experiments on these soils have shown that over 50%
contain insufficient S for producing high yields of legume forage. Sulphur is an essential nutrient
for N-fixing bacteria in legume crops. Therefore, S affects both yield and protein content of
legumes. Because S deficiency reduces N fixation, S-deficient legumes are stunted, appear pale
green in color and have low protein content. However, both yield and forage quality can be
decreased by S deficiencies long before visual symptoms appear. On S-deficient soils, marked
increases in yield and forage quality have resulted from relatively small (20 to 25 kg S/ha) annual
applications of S. Soils growing legumes should be tested regularly to insure an adequate supply
of S is available in the soil.

19

Effect of S fertilizer on selenium (Se) concentration of forage

Although Se is not needed as a plant nutrient, it is needed for animals and low Se (<200
parts per billion) levels in livestock rations have been associated with white muscle disease in beef
cattle and sheep. High incidence of this disease has been found in west-central Alberta and
farmers suspect S fertilizers applied on pasture and hay crops increases white muscle desease.

To determine the effect of S fertilizer on Se levels in forage, yield response trials and plant
analyses were conducted on forage from 59 sites over two years. Soils were all Gray Wooded,
ranging in texture from sandy loam to clay loam and in pH from 5.1 to 6.9. At 40 sites, the soil
was S-deflcient.

Generally, the results showed that Se concentrations in the forage grown in the test region
were low (Table 16). Concentrations were less than 100 ppb (parts per billion) Se in all samples
of bromegrass, alsike and red clover, and less than 20 ppb Se in timothy hay. Average Se levels
for alfalfa were higher than for other species; however, two-thirds of the samples still contained
less than 100 ppb Se. When S fertilizer was applied, average Se concentration decreased in all
forage species. This decrease, however, was most pronounced where the S fertilizer increased
forage production and where Se levels without fertilizer were greater than 100 ppb Se.
Therefore, the reduction in Se content in forage seems to be caused by dilution resulting from
increased forage production.

Table 16. Selenium in top growth of forage species sampled at the early flowering stage of growth in west-central
Alberta.

Yield

response to S

fertilizer

No. of
samples

Selenium in 1

top growth (ppb)§

Without S

fertilizer

With S fertilizer

Species

Ave.

Range

Ave.

Range

Alfalfa

Yes

10

242

10-1005

112

12-470

No

13

113

10-560

79

13-217

Alsike clover

Yes

31

18

3-59

13

2-27

No

7

24

7-68

15

6-22

Red Clover

Yes

26

19

7-56

11

4-23

No

4

8

6-9

7

4-8

Bromegrass

Yes

7

28

12-58

22

4-33

No

8

31

12-86

26

12-43

Timothy

Yes

19

12

4-19

11

5-26

No

6

12

6-19

9

4-17

§ Parts per billion (109).

Where possible, direct comparison of Se content was made between forage species grown
at the same site. Alfalfa had a much higher content than other species. This indicated that for
some unidentified reason, alfalfa is able to take up more Se from soils than other common forage
species. Other legumes were generally slightly higher in Se content than grasses.

20

These results indicate that much of the forage grown in west-central and some other areas
of Alberta is deficient in Se for good animal health. Forage Se concentrations were often reduced
when S fertilizer was applied, particularly on S-deficient soils. When forages are suspected of
being low in Se, samples should be analyzed and mineral supplements be used in livestock ration
as required.

Grass-Legume Mixtures for Hay

Managing soil fertility for mixed grass-legume forages is much more difficult than for
pure grass or legume stands. It is not possible to provide an ideal combination of nutrients for
both crops grown in mixed stands. If too much N is applied to a grass-legume mixture, the
grass will be stimulated and become dominant and the N fixation activity of the legume nodule
bacteria will be decreased. Applying adequate P, K and S fertilizers to mixed stands is important
for maintenance of the legume component and may cause legumes to become dominant.

Effect of N fertilizer

In experiments at eight sites, there appears to have been a general relationship between the
initial nitrate-N in the soil or the percentage of alfalfa in forage stands and the DMY response to
applied N or the net returns above fertilizer costs (Table 17). If either soil test N or percent
legume is high, the yield response to applied N is low. On the Black Chernozem soils, DMY
without N fertilizer were quite high and DMY increases from applied N were generally small.
With the exception of one site, Gray Wooded soils produced much lower DMY when not
fertilized. Soil at that site had a higher organic matter content and did not appear strongly
eluviated. The results also indicated that the sites with greater than 50% alfalfa in the stands
produced high yields when not fertilized and were less responsive to applied N.

The economic appraisal of DMY indicated that returns above fertilizer costs were
influenced by soil type, initial soil nitrate-N level and the percentage of alfalfa in forage stands.
On Black Chernozem soils, there were no net returns from N application (Table 17). The net
returns from applied N were greater on soils with low levels of nitrate-N. The net returns and the
N rate which produced the highest DMY were lower on soils with more than 50% alfalfa in the
stands. At two Gray Wooded sites which had approximately 50% alfalfa in the stands, the soils
gave DMY response to applied N and produced net returns with N application up to 45 or 90 kg
N/ha. The Gray Wooded soils (which are inherently low in organic matter and have low N
supplying power during the growing season) gave yield responses to applied N and produced
more economic returns from N application than did the mixed forage trials located on Black
Chernozem soils. Soils with high initial nitrate-N and with alfalfa greater than 50% produced
small yield responses and no economic benefit from N application. The results also indicated that
DMY increased with applied N, but the high N rates in many instances produced low or negative
net returns. This emphasizes that an evaluation of DMY response to applied N is not sufficient in
itself and should be accompanied by economic appraisal.

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22

When managing mixed forage stands, knowledge of the legume percentage and the
fertility status of the soil are most important. Generally, stands with more than 80% grass
should be fertilized as pure grass and those with more than 80% legume should be treated as
pure legume. A common mixture that one might attempt to maintain is 40 to 60% legume.
Regular soil testing is an essential tool for decisions regarding the fertilizer nutrients required to
balance and maintain a desired mixture. To maintain approximately 50% legume in the mixture
and thereby receive the benefit of the N-fixing power of legume bacteria, little or no N should be
applied and adequate levels of P, K and S must be maintained. Although large responses to N
have been reported for mixed forages, it is the grass component that is stimulated while the
legume component is sharply reduced. Furthermore, there is a risk that N fertilizer will reduce
the ability of the legume component to survive and to contribute to yield in future years.

Often the legume content can be reduced to less than 25% within three or four years
when relatively small (50 to 100 kg N/ha) amounts of N are applied annually. However, when
P, K and S are applied on an annual basis, the legume percentage and the forage quality can be
maintained at a more stable level.

Effect of P, K and S fertilizers

Research has shown that small annual broadcast applications of P, K and S fertilizers will
correct deficiencies and produce more consistent yields than will large initial application
intended to last several years. Potassium requirements are more critical in mixed stands than in
pure stands. This appears to be due to stronger competition for available K by grasses in the
mixture. Therefore, on coarse textured soils and those with relatively low available K, fertilizer
K should be applied to help maintain the legume component.

Because of the large amounts of nutrients required by a vigorously growing mixed
forage and the fact that most of these nutrients are removed annually in the harvested forage,
nutrient draw down from the soil is more rapid than with annual crops. As a result, nutrient
supply in the soil should be monitored regularly by soil tests and noted deficiencies should be
corrected with annual broadcast applications. The benefits of such treatments will usually be
very obvious after 3 to 4 years by mamtaining a more consistent grass-legume composition and
by increased yield and forage quality.

The effect of N and P fertilizers on yield and forage composition was measured in a
study of grass-legume forages in south-central Alberta. Experiments were established on
existing stands at 16 locations where three rates of N (0, 28, 56 kg N/ha) and four rates of P (0,
12, 24, 36 kg P/ha) were applied annually in the spring for four years. Average DMY are shown
in Table 18. Although N responses were consistent, yield increases tended to be small and were
significant at only 25% of the experimental sites when no P was added. At several sites, yield
response to added P was minimal in the first year of the study; however, yield increases became
more apparent by the final year. The average yield response to N only exceeded the response to

P in the first year. Addition of 12 kg P/ha resulted in an average yield increase of 0.75 t/ha in
the first year (Table 19). Further average yield responses were evident at P rates of 24 and 36
kg P/ha. The contribution of P to yield increase became larger with each successive year of
fertilizer application. This study showed that yield response to P fertilizer was closely related to
the supply of available P in the soil and the amount of precipitation in the year of application.
On P-deficient sites, response increased with time, rate of P application and precipitation.

Table 18. Average annual dry matter yield (DMY) of smooth bromegrass-alfalfa stands in unfertilized check and
with N or P application.

DMY (t/ha)

DMY

increase

(t/ha;

Year

Check

28 N§

56 N

24 P§

28 N

56 N

24 P

1979

4.57

5.09

5.36

4.99

0.52

1.79

0.42

1980

5.84

6.57

7.05

7.17

0.73

1.21

1.33

1981

5.71

6.72

7.13

7.21

1.01

1.42

1.50

1982

3.80

4.39

4.94

5.63

0.59

1.14

1.83

§ Kg/ha of Nor P.

Table 19. Yearly increase in dry matter yield (DMY) of smooth bromegrass-alfalfa mixed stands from application
of N or N plus P from 1979 to 1982.

DMY increase (t/ha)§

Year OPf 12 P 24 P 36 P

1979 0.66 (14)* 0.75 (16) 0.85(19) 0.93 (20)

1980 0.97(17) 1.55(27) 1.86(32) 2.08(36)

1981 1.22(21) 2.16(38) 2.29(40) 2.59(45)

1982 0.87(23) 1.82(48) 2.37(62) 2.63(69)

§ Based on average of treatments to which N was applied at 28 and 56 kg N/ha.
Kg P/ha.
Numbers in brackets are percent yield increases.

Results from this study also show that application of N stimulates the grass component
of a grass-legume mixture (data not shown). This was particularly evident at the 56 kg N/ha
rate where the grass/legume ratio was consistently higher than at the 28 kg N/ha rate. Annual P
application stabilized or lowered the grass/legume ratios by stimulating the legume component in
the mixture. Therefore, the temptation to apply high rates of N to mixed stands should be
resisted because application of N can result in a weakening of the legume component with an
associated decline in the contribution of the legume to future yield. After the initial year of
fertilizer application, the most economic response may be achieved with the application of P in
combination with modest amounts of N (i.e. usually no more than 20-25 kg N/ha, but the
research information on N fertilizer requirements of various grass-legume compositions at a

24

given site is lacking in Alberta).
Tame Pasture Forage

Nitrogen (N) fertilizer application has been shown to produce dramatic DMY increases
with bromegrass hay. Similar responses could be expected on grass stands that are pastured. In
the past, N fertilizer was most commonly applied on forage land in the early spring. More
recentiy, to overcome spring workload pressure and to try to ensure ample available N supply for
early spring forage growth, fertilizer N has been applied in the fall.

Sources, times and methods of N application

Urea and ammonium nitrate are the primary fertilizer N sources used for application on
grass pasture. Urea is the dominant form of granular N fertilizer available to farmers in western
Canada. Surface broadcasting is the usual method of N application; however, under this
condition urea is vulnerable to ammonia volatilization loss. Clearly, it is important to study ways
for effective and efficient use of fertilizer N because of DMY and quality increases and the
quantities of N required for high forage yields. Experiments conducted in central Alberta using
urea and ammonium nitrate applied on established meadow bromegrass grown as simulated
pasture compared N rates and determined the most effective time and method of N application
(Tables 20, 21 and 22). Meadow bromegrass is a preferred grass species for pasturing.

As N fertilizer rate increased, DMY also increased to the maximum rate applied (300 kg
N/ha) with both urea and ammonium nitrate (Table 20). Where no N was applied, DMY was low
at both locations and when moderate and high rates of N were applied, DMY response was
strong. At the 100 and 300 kg N/ha rates, average DMY with urea N at the Lacombe site was
2.27 and 3.43 times higher than the check and with ammonium nitrate as the N source it was 2.34
and 3.65 times higher. Similarly, at the Eckville site, average DMY with urea was 2.25 and 3.25
times greater than the check and the yield with ammonium nitrate was 2.45 and 3.47 times
greater. At both locations and at all N rates, ammonium nitrate in spring applications produced
larger DMY than urea did.

Effectiveness of N fertilizer applied in the spring and fall was determined on established
meadow bromegrass (Table 21). When 100 Kg N/ha was applied at five different times in the fall,
winter and spring, average DMY was highest for N applied in early fall and early spring for urea
and ammonium nitrate at both locations. Average DMY was greater for ammonium nitrate than
for urea for all times of application and at both locations. The least effective time of application
was early winter for urea and late fall for ammonium nitrate. The relative average DMY response
to N fertilizer compared with no N fertilizer was greatest at the Eckville location and was highest
for ammonium nitrate at both locations (relative DMY: Lacombe, urea = 1.89, A.N. = 2.02;
Eckville, urea = 2.36, A.N. = 2.79).

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26

Table 21. Dry matter yield (DMY) and protein yield (PY) of meadow bromegrass managed as simulated pasture by
cutting four times, treated annually with 100 kg N/ha of urea and ammonium nitrate applied at different times in
fall and spring at two locations in central Alberta (average of three years).

DMY (t/ha)

PY (kg/ha)

Fertilizer treatment

Lacombe

Eckville

Lacombe

Eckville

Check (Zero N)

2.77

2.17

276

178

Urea early fall

5.57

5.11

614

602

Urea late fall

4.93

5.09

538

590

Urea early winter

4.93

5.01

538

625

Urea early spring

5.47

5.22

637

663

Urea late spring

5.13

5.21

629

639

Average

5.21

5.13

591

624

A.N.S early fall

5.86

6.16

648

785

A.N. late fall

5.20

5.71

589

681

A.N. early winter

5.66

5.84

672

647

A.N. early spring

5.75

6.55

695

928

A.N. late spring

5.54

5.98

714

874

Average

5.60

6.05

664

783

» Ammonium nitrate.

In experiments to improve the effectiveness of urea N, several methods of N application
were studied for treatments made in fall and spring. All N treatments were applied at a rate of 80
kg N/ha to a crop of established meadow bromegrass. Based on average DMY, the most
effective method of urea application was disc-banding (bands 22.5 cm apart) in the fall or spring
at both locations (Table 22). The surface-broadcast application method was least effective. No
method of urea application was equivalent to ammonium nitrate broadcast in the spring.
Ammonium nitrate when disc-banded in the spring produced slightly lower DMY than broadcast
application. This may be due to fertilizer N in bands not becoming equally available to all plants
early in the growing season, possibly because the band spacing was wider than optimum.

Effect of forage fertilization on animal performance

In a six-year field experiment (1956-1961) in central Alberta, the beef production potential
of yearling Hereford steers was measured on three pasture crops (bromegrass-alfalfa mixture,
bromegrass, and creeping red fescue) under three fertilizer treatments. Fertilizer application
resulted in substantial increases in dry matter yield, animal weight gain and carrying capacity on all
pasture types (Table 23). Average beef production on all pasture types in the first three years for
the no fertilizer, N, and N plus P treatments was 209, 247, and 283 kg/ha, respectively. Similarly,
the respective values for carrying capacity were 97, 1 17, and 126 days/ha/yr. Responses were even
greater in the last three years when N and P application rates were considerably higher than for
years one to three. Both animal weight gain and carrying capacity increased with the N and P

27

treatments, and the differences between treatments were greater in the last three years than in the
first three years. On the pastures that received no fertilizer, animal weight gains were considerably
lower in the last three years than in the first three years. Also, carrying capacity on the unfertilized
grass pastures dropped markedly.

Table 22. Dry matter yield (DMY) and protein yield (PY) of meadow bromegrass managed as simulated pasture by
cutting four times, treated annually with 80 kg N/ha of urea and ammonium nitrate using different methods of
placement for fall and spring applications at two locations in central Alberta (average of two years).

DMY (t/ha)

PY (kg/ha)

Fertilizer treatment

Lacombe

Eckville

Lacombx

; Eckville

Check (Zero N)

2.18

2.31

203

229

Urea broadcast early October
Urea band (disc) early October

4.58
5.50

4.63
5.11

435
573

469

558

Urea broadcast mid April
Urea band (disc) mid April

5.37
5.59

4.60
4.76

593
637

514

550

A.N.§ broadcast mid April
A.N. band (disc) mid April

5.76
5.37

5.20
5.09

663
605

611
598

§ Ammonium nitrate.

Results from this intensive study have demonstrated that N and P fertilizer applications on
grass and mixed grass-legume pastures will produce substantial increases in beef gain and animal
carrying capacity. The study also showed that when adequate plant nutrients are not supplied, the
productivity of pastures declines quickly in terms of both plant and animal yield.

SOIL ACIDITY

Acidity in soil is determined by the measurement of the soil reaction (pH). Soil reaction is
acid when pH is below 7.0; neutral at 7.0; and alkaline above 7.0. Soil reaction affects soil fertility
and plant growth. For practical purpose, soils with reactions between pH 6.5 and 7.5 are
considered neutral. Soils in the range of 5.6 to 6.0 are moderately acid and below 5.5 are strongly
acid. Poor growth of an acid- sensitive crop, such as alfalfa, may indicate an acid soil condition.

28

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Reasons for Soil Acidity

There are two main reasons for soil acidification. Soils may be naturally acid due to the
materials or processes involved in their formation. Thus, some soils become acid through time as a
result of natural chemical and biological processes that are active in the soil all the time. The
second way soils become acid is through man's activities which tend to speed up the natural
acidification processes. Conversion of ammonium-N to nitrate -N by soil bacteria is an acidifying
process. Therefore, the addition of ammonium N fertilizers can make soils more acid. Similarly,
conversion of elemental S to sulphate by soil bacteria is also an acidifying process. The acidity
equivalents of common N and S fertilizers are shown in Table 24. The theoretical values for N
fertilizers may not necessarily be in agreement with results obtained in actual forage field
experiments.

Table 24. Equivalent acidity of some N and S fertilizers.

Fertilizer Equivalent acidity §

21-0-0 ammonium sulphate 5 .4

34-0-0 ammonium nitrate 1.8

34-0-0 (11) "N plus S" 3.6

46-0-0 urea 1.8

82-0-0 anhydrous ammonia 1.8

0-0-0 (95) elemental sulphur 3.1

§ Equivalent acidity = kg lime (CaCC>3) to neutralize the acidity produced by 1 kg of N or S.

Source: Tisdale, S.L. and Nelson, W.L. 1966. Soil Fertility and Fertilizers. Macmillan Publishing Co., Inc. New

York, NY.

Acidification of Soil by N Fertilizers

Application of N fertilizer to grass forage is essential in Alberta for the production of high
yields of quality hay. However, concern exists that use of N fertilizer on forage will become a
major factor causing further acidification of soils. This could cause problems with some forage
crops.

Several long-term (5 to 16 years) experiments have been conducted in Alberta to
determine the soil acidification from the application of various rates and sources of N fertilizer on
bromegrass. In these experiments, soil samples were collected at various depths to determine the
extent and depth of acidification. Annual application of 100 kg N/ha of ammonium nitrate for five
years at two locations lowered the pH of the soil in the 0-7.5 cm depth and this effect was greater
as the rate of N increased (Table 25). At the higher N rate, the pH tended to be influenced at the
7.5-15 cm depth, but there was no effect in deeper layers.

In a longer term experiment where ammonium nitrate was annually applied over a 16- year
period, N had marked effect on soil acidification (Table 26). There was a close relationship

30

between the decrease in soil pH and the increase in N rate. Acidification was most pronounced in
the 0-5 cm depth. Soil pH did not show a drop in the 5-10 cm layer until the N rate was 224 kg
N/ha or more. During the period of this study, there was little effect on soil pH in the 10-15 cm
layer or in deeper layers.

Table 25. Soil pH in N fertilized and unfertilized smooth bromegrass plots sampled after five years of ammonium
nitrate application at Lacombe in central Alberta and Botha in east-central Alberta.

pH

of soil

depths

(cm)

Rate of N

Lacombe

Botha

(kg N/ha)

0-7.5

7.5-15

0-7.5

7.5-15

0

100

200

6.20
5.87
5.65

6.32
6.30
6.17

5.77
5.52
4.87

5.90
6.10
5.62

Table 26. The pH of soil layers after 16 years of ammonium nitrate application at seven rates to smooth
bromegrass at Crossfield in south-central Alberta.

Levels ol

applied N

(kgNha"1)

Depth (cm)

0

56

112

168

224

280

336

7.07
7.12
7.30

-Soil nH -

0-5
5-10
0-15

6.47
7.25
7.15

5.62
7.32
6.98

4.87
7.12
6.37

4.32
6.50
6.20

4.32
6.03
5.40

4.27
5.05
5.25

Extractable aluminum (Al) is another component associated with soil acididty that can
impact crop growth. High levels of soluble Al in soil are toxic to growing plants and solubility of
Al often increases with increasing soil acidity. Therefore, extractable Al levels were determined in
the above study and were found to increase in the 0-5 cm layer with higher N rates to the highest
rate of 336 kg N/ha (data not shown). The Al concentration in the soil increased from 0.1 to 23.7
mg/kg when N rate increased from 112 to 336 kg N/ha. Soluble Al concentrations in the soil as
low as 1-2 mg/kg are considered harmful to the growth of some crops such as alfalfa.
Fortunately, there was no increase in Al concentration below the 5 cm level even at the highest N
rate.

In another related study, urea and ammonium nitrate were annually applied at 1 12 kg N/ha
in spring or fall for 1 1 years (Table 27). Both N sources caused the soil pH in the 0-5 cm depth
to decrease. Urea tended to decrease pH more when spring applied than fall applied. Ammonium
nitrate had a greater acidifying effect than urea.

A five-year experiment utilizing four different N fertilizers showed that the acidifying
effect of N fertilizer varied with the source (Table 28). Soil pH was lowest in plots where
ammonium sulphate was applied and the next lowest pH resulted with ammonium nitrate. Urea
had less influence on soil pH of the surface layer than ammonium nitrate, while calcium nitrate
slightly increased soil pH. Soil acidification only occurred in the 0-15 cm depth and was greater
at the rate of 336 kg N/ha than at 168 kg N/ha. Also, at the higher rate, urea and ammonium
nitrate lowered the soil pH at both the 0-5 and 5-10 cm depths and ammonium sulphate affected
the soil pH in all depths to 15 cm.

Table 27. The pH of soil layers after 1 1 years of urea and ammonium nitrate application at 1 12 kg N/ha to smooth
bromegrass at Crossfield in south-central Alberta.

Time of Source pH of soil

application of N (0-5 cm)

Check 7.08

Fall A.N.§ 5.87

Urea 6.51

Spring A.N. 5.85

Urea 6.32

§ Ammonium nitrate.

Table 28. The pH of soil layers after five years of ammonium nitrate, urea, calcium nitrate and ammonium
sulphate application at 168 and 336 kg N/ha to smooth bromegrass at Crossfield in south-central Alberta.

Check

168 kg

N/ha

336 kg N/ha

Depth (cm)

A.N.§

Urea

C.N.

A.S.

AN.

Urea

C.N.

A.S.

- Soil nt-T - - ■

0-5

6.55

5.85

6.17

6.67

5.18

5.07

5.45

6.65

4.75

5-10

6.80

7.00

6.82

7.08

6.55

6.55

6.38

7.08

5.31

10-15

7.10

7.28

7.18

7.27

6.92

7.00

6.90

7.22

6.58

0-15

7.00

6.85

6.92

7.20

6.33

6.30

6.53

7.13

5.70

§ A.N., C.N. and A.S. refer to ammonium nitrate, calcium nitrate and ammonium sulphate, respectively.

The experiments show that N application on established bromegrass has a significant
acidifying effect on the surface soil (0-15 cm). The greatest effect occurs near the surface (0-5
cm) where both acidity and extractable Al increased with higher N rates. Results of these studies
indicate that long-term application of fertilizer N to bromegrass may require liming to counteract
the soil acidification. This is particularly true if ammonium sulphate and ammonium nitrate are the
primary N sources.

32

Longevity of Liming for Neutralizing Soil Acidity

Acid soils (pH 6.0 or lower) are less suitable for crop production than are neutral (pH 6.5-
7.5) or slightly alkaline (pH 7.5-8.0) soils. Moderately acid soils can seriously reduce the yield of
certain forage crops such as alfalfa. Lime (CaCC^) may be applied to acid soils to neutralize the
excess acidity. Lime, unlike most fertilizers, has a long term effect and therefore one application
can correct the acidity and improve yields for many years.

Field experiments have been conducted in central Alberta to determine how long the
liming effects last and how much crop yields are improved. Finely ground limestone was applied
at rates ranging from 0 to 11 t/ha on soils at two locations in 1965 and 1967. Samples of surface
(0-15 cm) soil were taken in various years to determine changes in soil acidity (Table 29). Results
from these tests show that liming has an effect on soil pH within a year after application. Even at
the lowest rates (2.2 and 4.4 t/ha), the pH was increased in the first year and that increase
persisted through seven to nine years at both locations and up to 16 years at one location. Higher
rates of lime had a greater influence on increasing soil pH levels.

Table 29. Effect of lime application in 1965 or 1967 on soil pH (0-15 cm depth) at two locations in central Alberta.

SoilpH

Rate of lime

Rocky

Mountain House

Pendryl

(t/ha)

1966

1974

1981

1968

1974

0

5.4

5.3

5.7

5.1

5.4

2.2

5.8

5.8

5.9

5.6

5.8

4.4

5.8

6.0

5.9

6.2

6.2

6.6

6.2

6.3

6.2

6.4

6.4

8.8

6.2

6.2

~

6.7

6.6

11.0

6.4

7.0

6.5

6.9

6.9

Alfalfa grown periodically at these experimental locations showed marked response to the
lime applications (Table 30). Again, the lowest rate of lime application resulted in substantial
yield increases (1.9 and 1.5 t/ha) at both locations shortly after application. Also, the gready
improved production persisted for 16 years at the location where alfalfa was grown.

These results show that production of alfalfa can benefit greatly from lime applied to
reduce acidity. In addition, the results demonstrate that a single application of lime, made at a
rate sufficient to raise the soil pH to 6.0 or more, will have a neutralizing effect lasting 10 to 16
years. Because of this long-lasting effect, the cost of applying lime to acid soils should be
considered a capital investment cost that is amortized over several years.

33

Table 30. Effect of lime application in 1965 or 1967 to acid soil on alfalfa hay yields at two locations in central
Alberta.

Yield of hay (t/ha)

Rate of lime

Rocky

Mountain House

Pendryl

(t/ha)

1966

1974

1981

1969

0

0.7

2.4

1.1

0.9

2.2

2.6

4.4

2.4

2.4

4.4

2.6

4.4

2.6

2.9

6.6

2.6

4.4

3.3

2.6

8.8

2.4

4.2

4.0

2.6

11.0

2.9

4.2

4.2

2.9

CONCLUSIONS

Forage acreage represents a significant proportion of the agricultural land base in Alberta.
However, proper fertilization is a low priority. Effective forage management must include proper
fertilization based on soil tests and efficient fertilizer application.

Soil testing is critical for proper forage establishment and maintenance of the stand. Soil
testing can identify nutrient deficiencies and other soil restrictions prior to establishing the forage.
To maintain a productive forage stand, soil testing is an effective and essential tool to monitor
nutrient levels and for developing proper fertilizer recommendations.

Effective fertilizer application is greatly influenced by forage type, time of application,
method of application and fertilizer source. The legume content of the mixed forage will have a
major impact on the N fertilizer requirements but will also have impact on P, K and S
requirements. With proper inoculation, forages with a high proportion of legumes (greater than
80%) require no N fertilizer. Mixed forage stands with 40 to 60% legume require little N
fertilizer. Forages with low or no legume content will require larger amounts of N fertilizer.
Phosphorus, potassium and sulphur fertilizer requirements will also vary with the forage type.
Fertilization prior to seeding a forage is critical for establishing a forage stand especially for less
mobile nutrients such as P and K. For an established stand, broadcast application is currently the
most practical method of applying fertilizers, however, timing and source of fertilizer will have a
significant effect on fertilizer use efficiency and stand productivity. In general, fertilizers are more
effective when applied in early spring than fall or late spring. In high moisture areas and under
irrigation, N fertilizer can be split into two applications, (i.e. early spring and after the first cut).
For sources of N fertilizer, ammonium nitrate is more effective than urea when broadcast on an
established stand. However, supplies of ammonium nitrate are limited and it is more expensive.
Effectiveness of urea can be improved by disc-banding the fertilizer below the soil surface, but
more research is needed to properly identify conditions that may affect urea efficiency.

34

Across Alberta, forage response to fertilizer application will vary due to climatic
conditions and soil types. Moisture has a major impact on forage growth and nutrient
requirements. In drier regions forage response will be low and more variable, while in wetter
regions forage response will be consistently higher and more uniform. With proper fertilizer
management, forage productivity can be greatly enhanced by promoting maximum dry matter
production, extending the longevity of the stand and producing high quality feed material for
livestock.

RECOMMENDATIONS

Climate and soil type have a significant effect on forage response to fertilizer application,
while forage composition will affect the overall nutrient requirements. Fertilizer requirements for
pure stands of grasses or legumes are very straight forward, however, it is much more difficult to
develop an effective fertilizer program for mixed grass-legume stands.

Fertilizing to Establish a Forage Stand

A critical factor in forage stand management is proper establishment. This includes:

1. Soil sampling and testing prior to establishment to properly assess the nutrient status of
the soil and to identify any possible soil limitations, i.e. acidity and salinity.

2. Selection of the best forage species and variety for the intended use, soil type and climate.

3. Application of the required fertilizers prior to seeding, particularly on very deficient soils.

4. Proper inoculation and handling of legume forage seed.

5. Proper timing, rates and methods for seeding.
Fertilizing to Maintain a Forage Stand

Fertilizer application to an established forage stand is essential to maintain the productivity and
longevity of the stand. This includes:

1. Regular soil sampling and soil testing to determine the type and amount of fertilizer to
apply.

2. Soil sampling and tissue sampling to diagnose problem situations and to monitor changes
that may occur in soils and crops.

3. Annual fertilizer applications are usually more effective than large initial single application
made at the time of establishment for all forage types.

4. Early spring fertilizer application is generally more effective than fall or late spring
application for all forage types, but the effectiveness of fall-applied N can be improved by
disc-banding the fertilizer below the soil surface.

5. Split applications of N fertilizer as opposed to one time annual application for grass or low
legume forages should be used only in high moisture areas and under irrigation.

6. Urea is less effective than ammonium nitrate as a source of N fertilizer for established
grass forages, but its effectiveness can be improved by disc-banding the fertilizer below
the soil surface. Even though urea may be less effective than ammonium nitrate, it is still a
very good source of N for fertilizing forage crops.

7. Liming acid soil will increase forage production and the life of the forage stand.

REFERENCES

Harapiak, IT. and Flore, N.A. 1984. Behaviour of fertilized mixed forage stands. Pages 256-
263 in Proceedings of Alberta Soil Science Workshop, 21-22 February, 1984, Edmonton,
Alberta (Available from Faculty of Extension, University of Alberta, Edmonton, Alberta).

Harapiak, J.T., Malhi, S.S., Nyborg, M. and Flore, N.A. 1992. Dry matter yield, protein
concentration, N use efficiency and N recovery of bromegrass in south-central Alberta:
Effect of N rate. Commun. Soil Sci. Plant Anal, (in press).

Malhi, S.S. and Dew, D. 1987. Effect of fertilization of peat soils on hay yields. Canadex
(Forage Crops - Soil Fertility and Improvement) 120-530. March, 1987.

Malhi, S.S. and McBeath, D.K. 1987. Long-term effect of liming on soil pH and crop
production on acid soils. Canadex (Soil Acidity). 534. March, 1987.

Malhi, S.S. and Ukrainetz, D. 1990. Effect of band spacing of urea on yield and quality of
bromegrass. Fert. Res. 21: 185-187.

Malhi, S.S., Baron, V.S. and McBeath, D.K. 1986. Nitrogen fertilization of bromegrass.
Canadex (Forage Grasses - Fertilizer Trials) 127-543. October, 1986.

Malhi, S.S., Baron, V.S. and McBeath, D.K. 1987. Economics of N fertilization of bromegrass
for hay in central Alberta. Can. J. Plant Sci. 67: 1 105-1 109.

Malhi, S.S., Baron, V.S. and McBeath, D.K. 1990. Economics of nitrogen fertilization of
bromegrass. Canadex (Forage - Fertilization). 120-543.

Malhi, S.S., Harapiak, J.T., Nyborg, M. and Flore, N.A. 1992. Dry matter yield, protein
concentration, N use efficiency and N recovery of bromegrass in south-central Alberta:

36

Effect of time and source of N application. Commun. Soil Sci. Plant Anal. 238: 953-964.

Malhi, S.S., McBeath, D.K. and Baron, V.S. 1986. Effects of nitrogen application on yield and
quality of bromegrass hay in central Alberta. Can. J. Plant Sci. 66: 609-616.

Malhi, S.S., McBeath, D.K., Walker, D.R. and Robertson, J.A. 1988. Fate of surface applied P
on established forage stands. Canadex - Forages (Fertilizer Application). 120-542. May,
1988.

Malhi, S.S., McBeath, D.K. and Nyborg, M. 1992. Effect of phosphorus fertilization on
bromegrass hay yield. Commun. Soil Sci. Plant Anal. 23: 113-122.

Malhi, S.S., McBeath, D.K., Arshad, M.A. and Gill, K.S. 1992. Effect of phosphorus
fertilization on alfalfa hay yield. Commun. Soil Sci. Plant Anal. 23: 717-724.

Malhi, S.S., Nyborg, M., Harapiak, J.T. and Flore, N. 1991. Acidification of soil in Alberta by
nitrogen fertilizers applied to bromegrass. Pages 547-553 in R.J. Wright et al. eds. Plant-
Soil Interactions at Low pH. Kluwer Academic Publishers, Dordrecht, The Netherlands.

Malhi, S.S., Walker, D.R., Doran, W.J. and Bowman, G.H. 1987. Relative productivity of a
fertilized and unfertilized pasture. Canadex (Pasture Crops - Cultural Practices). 130-21.
July, 1987.

Penney, D.C., Malhi, S.S. and Kryzanowski, L. 1990. Effect of rate and source of N fertilizer on
yield, quality and N recovery of bromegrass grown for hay. Fert. Res. 25: 159-166.

Rice, W.A. and Rennie, R.J. 1985. Inoculation of legume crops. Agdex 100/23-1, Alberta
Agriculture.

Webster, G.R., McBeath, D.K., Heapy, L.A., Lore, H.C., Von Maydell, U.M. and Robertson,
J.A. 1976. Influence of fertilizers, soil nutrients and weather on forage yield and quality in
central Alberta. Alberta Institute of Pedology, University of Alberta, Edmonton, Alberta.
Publication No. M-76-10. p. 145.

37

APPENDICES

Table 1 General range of fertilizer requirements for forage crops in Alberta (kg/ha) *.

Forage

Nutrient

Brown

Dark
Brown

Thin
Black

Black

Gray
Wooded

Irrigated

Legume
(80-100%)

N
P205

0
20-40

0
20-40

0
20-50

0
20-60

0
20-60

0-40
20-60

KjO

0

0

0

0-40

0-40

0

s

0-20

0-20

0-25

0-30

0-30

0-30

Grass-legume
(60-80% legume)

N
P205

0
20-40

0
20-40

0
20-50

0
20-60

0
20-60

0-40
20-60

K^O

0

0

0

0-40

0-40

0

S

0-20

0-20

0-25

0-30

0-30

0-30

Grass-legume
(40-60% legume)

N

p2o5

0
20-40

0
20-40

0-10
20-50

0-30
20-60

0-20
20-60

0-40
20-60

10,0

0

0

0

0-40

0-40

0

s

0-20

0-20

0-25

0-30

0-30

0-30

Grass-legume
(20-40% legume)

N

p2o5

20-40
20-40

30-50
20-40

40-70
20-50

50-90
20-50

40-80
20-50

70-150
20-50

iqo

0

0

0

0-40

0-40

0

s

0-15

0-15

0-20

0-20

0-20

0-20

Grass
(80-100%)

N

p2o5

40-80
20-40

40-80
20-40

80-120
20-50

90-140
20-50

80-130
20-50

120-200
20-50

K^O

0

0

0

0-40

0-40

0

S

0-15

0-15

0-20

0-20

0-20

0-20

* Specific fertilizer requirements should be based on soil test recommendations.
Source: Alberta Agriculture Soils and Animal Nutrition Laboratory, Edmonton, Alberta.

38

AGRICULTURE

SOIL ZONES

SOLONETZIC SOILS

ADAPTED FROM ALBERT4 INSTITUTE Of PEOOLOGY SOU GROUP MAP
Of ALBERTA

PROOUCEO BY THE RESOURCE EVALUATION ANO PLANNING OIVISION ALBERTA ENERGY ANO NATURAL RESOURCES 1986

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Mi'co,

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