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Full text of "A field test for available phosphorus in soils"

LIBRARY OF THE 
UNIVERSITY OF ILLINOIS 
AT URBANA-CHAMPAIGN 




N.QN CIRCULATING 

CHECK FOR UNBOUND 
CIRCULATING COPY 



UNIVERSITY OF ILLINOIS 

Agricultural Experiment Station 



BULLETIN No. :7 



A FIELD TEST FOR AVAILABLE 
PHOSPHORUS IN SOILS 



BY R. II. BKAY 




URBANA, ILLINOIS, AI'(,r>T. 1929 



CONTENTS 

PAGE 

DEVELOPMENT OF THE COLORIMETRIC METHOD OF TESTING 
SOILS FOR PHOSPHORUS 591 

THE ILLINOIS ADAPTATION OF THE COLORIMETRIC TEST 593 

The Reagents Used 593 

Making the Test 593 

Applying the Test in the Field 595 

RESULTS OF THE TEST ON THE ILLINOIS SOIL EXPERIMENT 
FIELDS 595 

Results on Dark-Colored Soils 596 

Results on Light-Colored Soils 598 

Effect of Soil Treatments on Available Phosphorus 600 

Available Phosphorus Found at Various Depths 601 

SUMMARY AND CONCLUSIONS 601 

LITERATURE CITED. . . 602 



A FIELD TFS I FOR AVAILABLE 
PHOSPHORUS IN SOILS 

1U" R. 11. HUAY, First Assistant in Soil Survey An:ily>is 

It is well known that many of the soils: of the Middle \Yest are 
deficient in the phosphorus available for crop growth. After soil acidity 
has been corrected and a proper rotation has been established, phos- 
phorous frequently remains a limiting factor in crop production. Re- 
-ults obtained by Bauer et a I 2 from the soil experiment fields of Illinois 
show that some soils respond highly to phosphate fertilization, while 
others give a very low response or none. Reports from county farm 
advisers and farmers in general are in agreement with these experi- 
mental results. 

A simple field test has been devised at the Illinois Station which 
will distinguish soils having a high amount of available phosphorus 
from those having a low amount. It is the purpose of this bulletin to 
describe this test and to show its agreement with soil productivity, and 
with crop response to phosphate fertilizers. 

Since this test uses the common colorimetric method for phos- 
phorus, a review of the- application of the latter to soil research by 
other investigators is given. 

DEVELOPMENT OF THE COLORIMETRIC METHOD OF 
TESTING SOILS FOR PHOSPHORUS 

In 1920 Bell and I)oisy ! in America, and Deniges 1 in France, pub- 
lished methods for the colorimetric determination of small amounts 
of phosphorus present as phosphate, by means of the blue color pro- 
duced when a. reducing agent is added to an acid solution of ammoni- 
um molybdate containing inorganic phosphates. 

In 1924 Atkins' applied the Deniges method as slightly modified 
by FlorentilV to soil extracts. His application consisted in shaking 10 
grams of 100-mesh soil for three to four hours in 50 cc. of conductivity 
water, Five cubic centimeters of the cent rifuged extract were made 
up to 100 cc. with the proper amount of molybdate reagent and the 
developed color was then compared with a standard phosphate solu- 
tion. His 1:5 extract showed less than two parts per million of phos- 
phorus with most soils, unless the soil had been enriched artificially. 
The Ohio Station is using a modification of Atkin's method in a port- 
able field laboratory. 1 '' 

Parker and Fudge" have studied the Deniges method, applying it 



592 BUU.KTIN Xo. 337 

to the determination of small amounts of phosphorus in soil extracts 
and in the displaced soil solution. a 

Spunvay'-' has also modified this method and obtained an indication 
of the available phosphorus in the field by extracting a small sample 
of soil in a folded wax paper with very dilute nitric acid. To two 
drops of the extract are added two drops of a nitric acid-ammonium 
molybdatc solution and the color developed after stirring with a tin 
rod. The color obtained this way fades rapidly. When the Spunvay 
method was applied at the Illinois Station to soils of the various ex- 
periment fields, it was found that in general a blue color was obtained 
only on soils which had been treated with phosphate fertilizers. In the 
case of soils testing "high" by the method devised at this Station, it 
was possible to get a blue color but in most cases only after consider- 
ably more prolonged contact of soil with the extracting solution than 
is recommended by Spunvay. Xo test color was obtained with the 
Spunvay test with any soils testing either "medium" or "doubtful" by 
the Illinois test regardless of the responsiveness of such soils to phos- 
phate fertilization. That is to say. the range in available phosphorus 
concentration within which differences were observable appeared to be 
confined to soils which had received phosphate applications and to 
soils which, tho untreated, were extremely high in available phos- 
phorus. 

The term "high" in available phosphorus is used in this bulletin 
to mean high amounts with respect to adequacy in grain farming as in- 
dicated by lack of response of these crops to phosphate fertilization. It 
is conceivable that a high amount for grain farming may be an inade- 
quate amount for truck crops. The results of a qualitative test of this 
type depend upon several factors, the most important here being the 
time of reaction with the soil and the acid concentration. An increase 
in the time of reaction or in acid concentration up to a certain point 
results in a darker color. It is thus possible to obtain no color, a light 
blue color, or a dark blue color with the same soil sample by varying 
the acid concentration of the extracting solution. Thus it is seen that 
a qualitative test means nothing until it has been standardized by com- 
parison with crop yields and phosphate responses. This Spunvay has 
done with his test with reference to truck crop soils, and he has ob- 
tained satisfactory results. It is obviously incorrect to compare a test 
standardized for truck crop conditions with one standardized for grain 
crops. The above discussion, centering around Spunvay 's test, has 
been given in order to bring out the need of a different test which 
would be applicable to general farming conditions, rather than to show 
or infer any superiority of one test over the other. 




Analvt. Ed.. In.lus. Knsin. Chom. 1, 136. 1929. 



A FIKI.I) TKST FOR AVAII.AI.LI-: Pnnsi'iioiu's ix SOILS o'lo 

THE ILLINOIS ADAPTATION OF THE 
COLORIMETRIC TEST 

The following test. devised at this Station, differs from that of 
Spurway in tat range of available phosphorus detected, ibi method 
of operation, i c i kind of acid used, idi concentration of reagents and 
(el permanency of the blue color. It has proved to be a reliable index 
of the available phosphorus status of the soil and shows promise of 
becoming a serviceable test, not only for the soil chemist, but also for 
the county farm adviser and the farmer. 

The Reagents Used 

The solution with which the test, is made is prepared as follows: 
Dissolve 100 grams of highest purity ammonium molybdate, phos- 
phate free, in 850 ce. of distilled water. Filter the solution and cool it. 
Then add it slowly with constant stirring to a cold mixture of 1.700 cc. 
of concentrated hydrochloric acid (30 percent) and 700 cc. of water. 
This is the stock solution. The solution as used for the test is made 
by diluting 120 cc. of the stock solution to 1.000 cc. with distilled 
water. In addition to the solution a small tin rod as recommended by 
Spurway is required for the lest. A piece of solder wire is quite satis- 
factory altho slower than pure tin in developing the blue color. 

The acid concentration has been carefully worked out. Slight vari- 
ations are permissable but a large increase in the concentration of acid 
used results in a colorless test, even when phosphates are present in 
large amounts. A large decrease in the acid concentration will result 
in the test solution itself giving a blue color when stirred with the tin 
rod even tho phosphates may be absent. However, the slight dilution 
caused by the water in wet soils has no effect on the results. The solu- 
tion alone when freshly prepared should give no color when stirred 
with the tin rod. After standing for a few weeks it will develop a 
slight blue color upon being stirred with the tin rod. This does not in- 
terfere with its use since 1 the small quantity of the material giving 
the blue color is absorbed by the soil in making the test, so that soils 
which would give a "low" test will .-till give a "low" test with the aged 
solution. If more than a slight blue appears in the solution when it is 
stirred, that is an indication that the solution has been contaminated 
with phosphorus and should not be used. Arsenic, which may be pres- 
ent in the -oils of orchards >prayed with arsenic sprays, gives a blue 
test color. 

Making the Test 

The test is made by shaking 1 part of soil with about 3 parts of 
the solution in a small test tube or vial. Only enough shaking to mix 
the soil and solution is required. "When settled, after about live minutes, 
the soil should occupy about one-third of the tube and the solution 
two-thirds. The clear solution is then stirred gently with a tin rod 
and without disturbing the settled soil until maximum intensity of 



594 BULLETIN No. 337 [August, 

color develops. This requires from 10 to 20 seconds, depending upon 
the amount of phosphate present. The tin dissolves in the acid solution 
and brings about the reducing action necessary for the production of 
the blue color. The varying amounts of phosphate present are indi- 
cated by a series of increasing color intensities and shades. These 
range from very light green thru light greenish blue to a deep blue. 
The color chart presented here shows only four color variations. The 
first is colorless; the second, light green; the third, greenish blue; and 
the fourth, medium blue. 

To simplify the recording of the color readings, any test which is 
colorless or nearly so is called "low.'' A test color which approximates 
the second color shown is recorded as '''doubtful." One varying around 
the third color is called "medium.'' while one giving a color as deep as. 
or deeper than, the last is "high." Since the amount of the blue com- 
pound is directly dependent upon the amount of phosphorus extracted 
from the soil by the acid solution, these colors have also been desig- 
nated to mean "low."' "doubtful/' ''medium," and '"'high" amounts of 
available phosphorus: 1 The color gradually fades upon standing, altho 
contrasts between different samples may often be observed after an 
hour. Some "high" test- have retained a good blue color even after 
24 hours. Clear solutions containing phosphates but without the pres- 
ence of soil show only a slight decrease in color after standing for 
three days. If desired, the faded color may be redeveloped by stirring 
again with the tin rod. altho if allowed to stand over night the re- 
developed color is usually darker than the original. 

The determination of the color range with its corresponding signi- 
ficance in regard to available phosphorus has been based entirely upon 
what is known about the response of grain and legume crops to phos- 
phate fertilization in the field. Xo attempt has been made to correlate 
the results of this test with the response to phosphate fertilization of 
truck or other special crops, and for the present its use should there- 
fore be restricted to general farms growing the usual grain and hay 
crops. 

Effect of Carbonates. Free carbonates in small amounts influence 
this test by producing a bluish green to green color rather than blue 
thruout the entire range of intensities. This, however, does not inter- 
fere with the use of the test, since the depth of color, whether green or 
blue, is the indicator of the relative amounts of available phosphorus. 
If, however, they arc present in large amounts, so that a continuous 
effervescence results the test cannot be relied upon. The resulting de- 
crease in the acid concentration makes the solution useless and for the 
present no means of overcoming this difficulty is known. 






Doubtful 





COLOR CHART OF TEST FOR AVAILABLE PHOSPHORUS 

"Low" indicates a deficiency of available phosphorus for average 
crop growth. 

"Doubtful" indicates that phosphorus is present in somewhat larger 
amount but it is uncertain whether the supply is sufficient for average 
yields. 

"Medium" and "High" represent still larger amounts of available 
phosphorus amounts that in general will be adequate for average 
to high yields. 



_//)-?.''] A FIKLD 'I'KST i-'cm AVAIL. \HI.K PiHisi'iioKrs ix SOILS r>9f> 

Effect of Moisture. Tin' test ni:iy be used on wet soils taken di- 
rectly from the field or on dried samples. The dried samples are prefer- 
able -hire they settle more quickly in the test tube and give a clearer 
solution. The soil may be ground or unground and the amount used 
may vary as much as 25 percent in proportion to the volume of re- 
agents used without' producing an appreciable difference in the re- 
sult s. 

Applying the Test in the Field 

A number of individual soil samples should be obtained from points 
we'd di-iributed over the field and te-ted separately. The plan of sam- 
pling a field as recommended by Linsley and Bauer 7 for the acidity 
te-t i- very -ati-factory. Such a plan of systematic testing makes pos- 
sible mapping of the soil of a. given field with respect to the relative 
abundance of available phosphorus. Obviously, a test of a single sam- 
ple or of a composite -ample made by mixing the samples obtained at 
various point- fails to give an accurate picture of the available phos- 
phorus status of the field. 

The surface samples .-hould be collected at a depth of an inch or 
t \\ o in order to avoid surface litter, using care that they are not taken 
from under manure or decaying organic matter, because of the local 
accumulation of available phosphorus from these materials by leach- 
ing. 

In addition to the surface soil, samples from lower depths should 
also be tested. This is particularly desirable in case the surface soil is 
found to he deficient in available phosphorus, since there is the possi- 
bility of encountering available phosphorus within the feeding range 
of the crop roots. As a matter of fact, most of the soils tested thu- far 
showing negative result-' in the surface have been found to give a 
medium TO high te-t at Mime depth. This depth has varied from 10 to 
more than 40 inches. 



-ome of the uncertainty irom phos- 
phate fertilization. No ie-t can he expected to eliminate all such un- 
certainty. because 1 -ome field- which are deficient in available phos- 
phoru- may not re-pond profitably to plmsphale applications due to 
the lack of potassium oi 1 to -ome other limiting factor. This ie-t i- only 
recommended as a mean- oi determining whether a -oil i- already -uf- 
ficiently high in available phosphorus that phosphates may be elim- 
inated for (he present, a' !ea-t. imm the -oil improvement program. 

RESULTS OF THE TEST ON THE ILLINOIS SOIL 
EXPERIMENT FIELDS 



590 BI-LLETIX Xii. ,337 

used on more than 500 samples from the check plots of 31 experiment 
fields located in different parts of the state and also on samples from 
farms and demonstration plots. The results of these tests have been 
found to be in good accord not only with response to phosphate fertili- 
zation, but also with the productivity of the untreated soil. 

A summary of these results, together with the ranking of the dif- 
ferent fields as to the productivity of the untreated soils on which the 
tests were made, and also with the most profitable system of soil treat- 
ment on the respective fields is shown in Table 1. The ranking in 
productivity is determined from the value of the crops harvested from 
the untreated plots. It is necessary to use crop values rather than 
yields in order to express the average of all crops by a single figure. 
Average December 1 crop values on the farm for the last four years 
are used. The determination of the most profitable system of soil treat- 
ment is based upon the results of 13 to 30 years of cropping on these 
fields under the various treatments. The table is divided into two parts 
representing, respectively, the dark-colored soils of the northern two- 
thirds of the state and the light-colored soils of the southern third. 

Results on Dark-Colored Soils 

Considering the dark-colored soils, the average annual acre crop 
values on untreated land, based upon the rotation period ending in 
1927, are as follows: those giving a "high" phosphorus test, 833.88; 
those testing ''medium," 828.24; and those testing "low," 824.26. This 
is an increase of 39 percent on the field- testing 'high" above those 
testing "low." 

The first six fields (Table 1) whose check plots test "high" or 
"medium'' are highest in order of productivity. In no case was phos- 
phate included in the most profitable system of soil treatment. While 
the Lebanon field is much lower in productiveness than the above six 
fields, the most profitable treatment does not include phosphate. The 
"medium" test shows this soil to be fairly well supplied with available 
phosphorus. 

On the next three fields. Sidell. Carthage, and Carlinville. about 
half of the check plots show a "medium" to ''high" test, while the re- 
mainder are "low." These fields are in the intermediate group so far 
as response to phosphate fertilization is concerned. They are also lower 
in natural productiveness than some of the fields. This is due in part 
apparently to a deficiency in available potassium, since these fields 
lead those on dark-colored soils in response to potassium fertilization. 

Starting with the Kewanee field, the rest of the fields on dark- 
colored soils give a "low" test and with the exception of Mt. Morris 
and Dixon. these fields all include phosphates in the most profitable 
system of soil treatment. 



A FIKI.I) TKST rou AVAII.AHI.K Pnosi'iioin s i\ Son. 



TAHI.K 1. RKSCI.TS OF AVAII.AHI.K PIIOSPIIOUUS TKST. HANK ix Piin 

AND M()ST PliOFITAlil.K Soil. TliKATMKXT OX Jl.I.IXOIS Soil, 
KN T l'"l KI.DS 







Kaiik in Annual acre 


Most profit 


Field 


Predominating soil type 


Phosphorus produc- ."up values 


able soil 






test tiviiv lor untreated 


treatment 






land 


system 1 




Dark-colored soils 




McXabb 


Brown Silt Loam 








I, Muscatine silt loam) 


High 1 


$39 91 


None 


\ledo 


Brown Silt Loam On Clay 








vGrundy silt loam) Medium 2 


34.05 


KL 


1 -iMoille 


Black Clav Loam, poorly drained phase 








(.Loessial clyde clay loam) High 








3 32.90 


KL 




Brown Silt Loam 


Medium 






( Muscatine silt loam) 


to low J 






Hartsburu 


Black Clay Loam 










i Grundy clay loam) 


High 4 31.lt 


K 


Minonk 


Black Clay Loam, poorly drained phase 








(.Loessial clyde clay loam) 


High 5 


31.19 


K 


Spring Valley 


Brownish Yellow Gray Silt Loam 








(Clinton silt loam) 


Medium 


31.11 


K 


1 ebanon 


Grayish Brown Silt Loam On Tight day 








(.Grundy silt loam, grayish phase) Medium 14 


21.58 


KL 


Side!! 


Brown Silt Loam 










iMuscatine silt loam) Low 








10 25 00 


RLPK 




Black Clay Loam, poorly drained phase 






(Loessial clyde clay loam) 


High 






1 'arthage 


Black Silly Clay Loam On Clay 










(Grundy silty clay loam) \ Medium 






12 23.43 


KLl'K 




Grayish Brown Sill Loam On Tight Clay 






(Grundy silt loam, grayish phase) 


Low 






( 'arlinville 


Grayish Brown Silt Loam On Tight Clay 










! Grundy silt loam, grayish phase) 








Series 100 and 20(1 


Medium 






Series 300 and 400 


Low 13 


21.81 


RLPK 


Kewanee 


Brown Silt Loam 










I Muscatine silt loam) 


Low 7 


29.94 


RLP 


Mt. Morris 


Light Brown Silt Loam 










iTama silt loam) 


Low 8 


20.00 


RL 


Urbana 


Brown Silt Loam 










1 Muscatine silt loam) 


Low 9 20 59 


RLP 


Dixon 


Brown Silt Loam 








i Muscatine sill loam) 


Low- 








11 25.07 


RL 




Light Brown Silt Loam 






(Tama silt loam) 


Low 




( 'layton 


Brown Silt Loam On Clav 








'Grundy silt loam) Low 15 21.12 


KLl'K 


Joliet 


Brown Siit Loam On Calcareous Drift 






'Clarion silt loam; Low 10 1!) 53 


RLP 



K = residues, L --limestone, 1' = rock phosphate, and K = potassium. 



59S 



BULLKTIX Xo. 337 



TABLE 1. Concluded 



[August, 



Fiel 



Rank in An!! ' ja! , acre Mo f* P ro .^- 

prcxluc- crop values able soil 

tivitv * or untreated treatment 

land system 





Light-colored soils 




Oquawka 


. . . Dune Sand, Terrace 
(Plainfield sand) . High 

Gray Silt Loam On Tight Clav Low 


1 ill. 87 RL 
2 11.21 RLPK 


Toledo 


. . . Gray Silt Loam On Tieht Clav Low 


3 7.42 RLPK 


Unionville 


. . . Yellow-Gray Silt Loam : Low to 
medium 

Gray Silt Loam On Orange Mottled Tight 


4 7.35 RLPK 


Enfield 


Clay Low 
. . Light Gray Silt Loam On Tight Clay Low 


5 G.45 RLPK 
6 5.08 RLPK 




Gray Silt Loam On Orange Mottled Tight 
Clay Low 

Yellow-Gray Silt Loam On Tight Clav Low 




Odin 


Gray Silt Loam On Orange Mottled Tight 
Clay Low 

Gray Silt Loam On Tight Clay 
Gray Siit Loam On Tight Clav Low 


7 5.91 RLPK 
8 5.77 RLPK 




Gray Silt Loam On Tight Clav Low 






Yellow-Gray Siit Loam On Tight Clay Low 
Grav Silt Loam On Tight Clav Low 


9 5.05 RLPK 
10 4 57 RLPK 


Elizabethtowr. 
Sparta 


. . . Yellow Silt Loam Low 

Yellow-Gray Silt Loam On Medium Plas- 
tic Clay Low 

. . . Light Gray Silt Loam On Tight Clay Medium 


11 4 55 RLPK 
12 3.99 RL 



Results on Light-Colored Soils 

Excluding the Oquawka field, which is dune sand, the light-colored 
-oils are almost uniformly '''low" in available phosphorus and they re- 
spond to phosphate fertilization. The Sparta field shows medium" on 
most of its check plots and does not respond to phosphates. The Union- 
ville field shows a slight color on several plots and the Elizabethtown 
field shows a "medium" color on one check plot. In the above dis- 
cussion, increases indicated for phosphate applications have been based 
on rock phosphate used in a grain system of farming. 

Figure 1 shows the relation between the percentage increases in 
crop yields due to phosphate applications on the various experiment 
fields and the results obtained by the test. The agreement between 
tost color and percentage increase in yield is very good, altho there are 
no sharp breaks between the "high." "medium," and "low" testing 
fields. These figures arc based on the rotation endinc; in 1927. 



A FIKI.D TKST KOU AVAIL. \HI.I-: Pnosi'iioiirs ix Son.* 



PERCENTAGE INCREASE FOR PHOSPHATE 



en 
CD 



ElizabetMown 

West 5alem 

Newton 

Raleigh 

Jol.et 

Enfield 

Ewng 

Urbana 

Union^ille 

Oblong 

Toledo 

Sidell 

Kewanee 

Clayton 

Carlinvilte 

Dixon 

Mt. Morris 

Lebanon 

Hartsburg 

Carthage 

Aledo 

Minonk 

McNabb 

Sparta 

LaMoille 

Spring Valley 

Oquawka 



]TEST LOW ON CHECK PLOTS. 



LOW ON SOME CHECK PLOT5 ; 
MEDIUM TO HIGH ON OTHERS. 

TEST MEDIUM TO HIGH ON CHECK PLOTS. 




GOO 



BULLETIN Xo. 337 



On some experiment fields soil variation with respect to the test 
was very marked, results of '"low," "medium," and "high" being ob- 
tained on the different check plots of the same field. In a number of 
such cases the average yields of corn, oats, and wheat were computed 
separately for these plots and are plotted in Fig. 2. Here again satis- 
factory agreement is observed between the productive level of the soil 



i PHOSPHORUS TEST MEDIUM_TOJIGH. 
D PHOSPHORUS TEST LOW. 



TO 




OflTS CORN WHEflT 

CARTHAGE 



OftTS CORN WHEflT 

MINONK 



OUTS CORN WHEflT BlFfllFfl 

URBANfl " 



FIG. 2. RELATION BETWEEN AVAILABLE PHOSPHORUS TEST AND THE PRO- 
DUCTIVE LEVEL OF UNTREATED SOILS OF THE ILLINOIS SOIL 

EXPERIMENT FIELDS 

Each pair of contiguous bars represents the crop yield of a high 
testing and a low testing check plot in the same series of a given experi- 
ment field. With the exception of the oats crop at Urbana, the high 
testing plot outyielded the corresponding low testing plot. 



and its reaction to the test. For instance, the untreated Check Plot 110 
on the Minonk field tests "low" and the yields of oats, corn, and wheat, 
respectively, are 54.1, 48.5, and 23.7 bushels. Check Plot 101. of the 
same series, likewise untreated, tests "high" and has produced average 
yields of 58.9, 54.7. and 42.5 bushels of the three respective crops. 



Effect of Soil Treatments on Available Phosphorus 

The effect of soil treatments on available phosphorus is readily 
shown by this field test. Plots receiving residues only on the Urbana 
field, for example, showed a "low" but the test color was slightly darker 
than that for the check plot. The manured plots on the above field 
and also on the Joliet field showed still more test color over the check. 
The plots in the northwest rotation of the Urbana South Farm, which 
receives 45 tons of manure every three years, show a "high" while the 



A FIKI.I) TKST KOI; AVAII.AHI.K 1'iiospiiours i\ Son. 



taken immediately beneath fresh manure show a "hiiih" test, altho at 
a depth of two to three indies the soil may test "low." 

All plots receiving phosphate treatment show a ti'ood hhie color. 
l"nevenne-s in distribution of added phosphate is sometime-; indicated 
by lack of uniformity in the depth of the color in individual tests. The 
higher rates of application result in deeper color. Plot 110-W of the 
Davenport Series at Urbana. which has received approximately (10.000 
]uiunds an acre of rock phosphate, i^ives a deep blue-black color. 
Where 13.1200 pounds an acre of rock phosphate had been applied 10 
other parts of this field, the soil <^ave a deep blue, gradually decreasing 
in intensity to a depth of 30 inches, while the adjacent tinphosplmted 
plot showed a colorless test thruout this depth. 

Since any form of phosphate fertilizer, regardless of its chemical 
nature or fineness of division, will pve the blue color when added to 
the soil, it is apparent that this test cannot be used to demonstrate 
the value of any particular form of phosphate fertilizer as compared 
to another, nor to discriminate between various forms of phosphate 
fertilizer. 

Available Phosphorus Found at Various Depths 

Some interesting observations have been made on subsurface and 
subsoil availability. Where a "medium" or ''hiidi'' test is found in the 
surface soil, the color intensity increases in the lower levels unless tin- 
surface color has been caused by phosphate fertilization. 

Where a "low'' test is found on the surface, this ''low" test may 
persist down to 40 inches or more 1 or, attain, there may be a gradual 
increase 1 in color until a "hiu'h" test is secured at some intermediate 
depth. Within any given area which varies with respect to this test, the 
deeper test color on surface soil is usually to be found in lower lyinu' 
land, while the elevations are more likely to uive a "medium" or "low" 
test . 

The existence of variation within a uiiven area emphasizes the 
desirability of mapping the areas of "hiidi." "medium," and ''low'' 
available phosphorus in a iiiven farm or field in order that the need- 
le-- application of phosphate fertilizers may be avoided. 



SUMMARY AND CONCLUSIONS 

1. A field test for available phosphorus has been described which 
is recommended for the use of farm advisers and farmer- because oi 
its simplicity of operation and practical application. 

2. When applied to tin 1 untreated soils of the Illiuoi- Kxperiment 
1'ields a <iood agreement was found between the results of the lest 
and the crop increase- resulting; from the addition of rock phosphate. 



602 BULLETIN Xo. 337 

3. Those soils which tested low in available phosphorus gave 
medium to high crop increases when phosphates were added. In all 
hut two of these fields the phosphate treatment was profitable. On 
these two fields the treatment came within a few cents of paying for 
itself. 

4. The soils which tested medium to high in available phosphorus 
gave little or no crop increase when phosphate was added. In no case 
was the treatment profitable. 

5. The productiveness of untreated soils was generally higher where 
the test showed a good amount of available phosphorus. 

6. All phosphated soils tested high in available phosphorus and 
those to which large amounts of manure had been added also gave 
a blue color. 



LITERATURE CITED 

1. Atkins. W. R. G. The rapid determination of available phosphates in soils by 

the Coeruleo-Molybdate reaction of Deniges. Jour. Agr. Sci. 14. part 2, 
192-197. 1924. 

2. Bauer. F. C.. Smith. R. S.. and Smith. L. H. The Illinois soil experiment 

fields. 111. Agr. Exp. Sta. Bui. 273, 41-327. 1926. 

3. Bell. R. D.. and Doisy, E. A. A rapid colorimetric method for the determina- 

tion of phosphorus in urine and blood. Jour. Biol. Chem. 44, 55-67. 1920. 

4. Deniges. G. Reaction de coloration extremement sensible des phosphates et des 

arseniates. Ses applications. Compt. Rend. Acad. Sci. (Paris), 171, 802-804, 
1920. 

5. Florentin. D. Determination de phosphate dans 1'eau. Ann. Chim. Analyt. 3, 

295-296. 1921. 

6. Jones. Earl. The portable soil laboratory and the Ohio method of testing 

soils for acidity. Jour. Amer. Soc. Agron. 21, 381-384. 1929. 

7. Linsiey. Clyde M.. and Bauer. F. C. Test your soil for acidity. 111. Agr. Exp. 

Sta. Circ. 346. 1929. 

8. Parker. F. W.. and Fudge. F. Soil phosphorus studies: 1. The colorimetric de- 

termination of organic and inorganic phosphorus in soil extracts and the 
soil solution. Soil Sci. 24, 109-117. 1927. 

9. Spurway, C. H. Test soils for water soluble phosphorus. Mich. Quar. Bui. 9, 

64-67. 1926. 



AUTHOU INDEX 



AUTHOR INDEX 



PAGE 

Ashby, R. C. Practices and Prob- 
lems of Cooperative Live- 
stock Shipping Associations 
in Illinois 349-72 

Hauer. F. C. Crop Yields From 
Illinois Soil lOxperiment 
Fields in 1928 209-240 

Herg. H. A.. Case, H. C. M., and 
Wileox. R. II. Organizing the 
Corn-Helt. Farm for Profit- 
able Production 257-332 

Hray. R. H. A Field Test for 
Available Phosphorus in 
Soils 589-604 

Hull. Sleeter, and Longwell, J. H. 
Relative lOconomy of the 
Various Cuts of Pork. .. .333-348 

Case, II. C. M., Mumford, II. W., 
Stewart . C. L., and Johnston, 
1'. F. Developmental Study 
of a Rural-Urban Trade 
Area 129*-208 

Case, IF C. M., Wileox. R. IL, 
and Herg, IL A. Organizing 
(hi 1 Corn-Belt Farm for Prof- 
itable Production 257-332 

Johnston. P. 10., Mumford. II. W., 
Stewart, C. L., and Case, II. 
C. M. Developmental Study 
of a Rural-Urban Trade 
Area 129*-20S 

Kingsley, F. C., and Lehmann, 10. 
W. Fleet ric Power for the 
Farm 373-380 

Knox. John II. , and Snapp, Ros- 
coe R. Summer Rations for 
Fattening Steers 241-256 

Lehmann, 10. W., and Kingsley, 
F. C. Fleet ric Power for the 
Farm 373-380 

Lloyd, J. W., and Newell, II. M. 
Observations on the Refrig- 
eration of Some Illinois 
Fruits in Transit ; .509-544 

Longwell. J. IL, and Hull, Sleeter. 
Relative Feonomy of the 
Various Cuts of Pork ... .333 348 



Mumford, II. W., Stewart. C. L., 
Case, II. C. M., and Johnston, 
P. K. Developmental Study 
of a Rural-Urban Trade 
Area 129+-208 

Newell. II. M., and Lloyd. J. W. 
Observations on the Refng- 
erat ion o I S o m e Illinois 
Fruits in 'Transit 509 544 

Norton, L. J., and Stewart, C. L. 
Seasonal Features of Illinois 
C.rain Marketing 1-4S 

Overmann. O. R., Sanmann, F. P., 
and Wright, K. JO. Studies 
of the Composition of Milk.. 
49-176* 

Ruehe, II. A., and Tracy. P. II. 
Fn/yme Activity of Ice- 
( 'ream Improvers 481- 508 

Sanmann. F. I'., Overmann, O. R., 
and Wright, K. 10. Studies 
of t he Composition of Milk . . 
49-176 

Sayre, C. H. Quality in Celery 

as Related to St met lire . .557- 588 

Snapp, Roscoe, R., and Knox, 
John H. Summer Rations for 
Fat tening Steers 21 1-256 

Stewart, C. L., Mumford, II. W., 
Case. II. C. M.. and Johnston, 
P. 10. Developmental Study 
of a Rural-Urban Trade 
Area 129*-208 

Stewart, C. L.. and Norton. F. J. 
Seasonal Features of Illinois 
(Ira in Marketing 1 48 

Tracy, P. IF, and Ruehe. IF A. 
JOn/yme Activity of Ice- 
Cream Improvers 481 508 

Wilcox, R. IF, Case, II. C. M., 
and Herg. II. A. Organi/ing 
the Corn-Helt, Farm for Prof- 
itable Production 257 332 

Woodworth, C. M. Illini Soy- 
beans 545 516 

Wright. K. F., Overmann. O. R.. 
and Sanmann, F. P. Studies 
of the Composition of Milk 

.. 49-176 



INDEX 



INDEX 



Account intr. sec Farm accounting 
Aledo experiment Hold yields. .213-14 
Alfalfa. place of in farm organi- 
zation 269 

Antiocli experiment field yields. . 214 
Harley, place <>i in farm organi- 
zation 266-67 

Bloomington experiment field 

yields 214 

Carlinville experiment field yields 215 
Carthaee experiment field yields 

. .'...215-16 

Cattle, N( c Steers 

Celery, structure of plant 561-66 

study of quality in as related 

TO structure 559-SS 

effect on quality of fertilizers 569 
of method of blanching. .569-70 
of supplementary irriira- 

tion .' .570-71 

laboratory technic 571-72 

!it( rature cited 5SS 

piwious studies of 559-61 

re.-uhs oi microscopic exami- 

nat ions 573-S5 

summary and conclusions. .5S5-S7 

varioi ies tested 566-67 

comparison of 567-69 

Clayton experiment field yields.. 216 
Clovers, place of m farm organi- 
zation 269 

Corn, marketinu: studies of, see 
C I rain market ing 

production costs of 262-66 

factors affecting 330 

Corn drier, electric 433-36 

( 'urn. elevator, electric 431 33 

Costs of production, factors af- 
fect iiiL r 330 

of grains and hays 262-70 

as afft cted by yield 262-64 

Cre;<m separators, use of elec- 
tricity with 452-51 

Crop diversification, advantages 

of 2s5-s7. 293-96 

Crop yields, factors affecting.... 331 
on experiment fields, 192s. . .210-3S 
possibility for improvement in 

'. 15S-60 |: 

Hairy products, marketinu; of..!79-S2 
study of production and con- 
sumption of 162-67* 

Davi npurl plot yields, 192S 237 



Dixon experiment field yields. .216-17 
Egirs, demand for improvement 

in production of 170-71 

production and consumption of 

167-71* 

Electric plants, farm 472-73 

Electric power for farms, study of 

'377-479 

construction of experimental 

line 3S5-S9 

data from farms on experi- 
mental line 378 So 

discussion of rates 466-71 

energy consumption on each 

farm 3S9-100 

farm production use 429-66 

advantages of portable motor 

for.. 429-30 

cream separating 452-54 

drying grains and SIMM! ... .433-36 

elevating corn 431-33 

incubating and brooding. . .460-61 

milking 447-51 

oat hulling 445-47 

painting, spray 454-57 

poultry house lighting 457-60 

pumping 451 

seed germination 461-66 

seed treatment 466 

household use 401-29 

buttermaking 427 

coffee percolating 419-20 

cooking 415-19 

dishwashing 425-27 

effect of on lime saving 403 

food mixing 419 

ironing 411-15 

lighting and minor appli- 
ances 427-29 

pumping 403-407 

refrigeration 420-25 

washing 409-15 

water heating 407-409 

preliminary survey of equip- 
ment used 2S3-S5 

summary 478-7!) 

HI < nl*n Electric plants, farm 
Eleciric transmission lines in Illi- 
nois 376 

Electricity, energy consumption 

of for various operations. .474-78 
time used in consumption of 
1 kilowatt by various 
pieces of equipment 474 



I NDKX 



F.le\ lit ill's, .s'( i ( iraitl elevaf ors 

Fli/abet htown experiment field 

yields ....................... '_MS 

Knlield experiment tirld yields. 2IS-1!) 
F.quipment costs. regulation of 

farm ..................... 2sl S)> 

F.wintr. experiment field yields.. 210 '20 
Fxperiment field yields. 1928. ..210-38 
Farm accounting. value of ...... 

........... . ....... 2!)l-!>2. )V27 ;]_> 

Farm earnings in east central llli- 

noiH ......................... 32!) 

in noi't hwestern Illinois ..... 1 I!)-")!!* 

Farm labor. M i Labor 

Farm oriram/at ion, da! a from MIC- 

ces>ful ........... I.");!-.")!, M27 ii'2* 

principles of .uood ........... 2C>2 !() 

MI ('onleiils ................ 2.")S 

I''arm ] lower, distribution of t hru- 

0111 year ................. 27S, 2S1 

xi i nixa Labor and Tractois 
Farm products, marketing of.. 17!) S."> 
slii pint 'Ills of in and out of area 

und'T >tud.v ............ 1 i:i 1.")* 

study of production and con- 

sum pi ion of ............ b)7 7!)* 

transportation used for ..... 17!), ISO 

Farm purchases and sales, study 

of .......................... II,")" 

Fanning, planning a profitable 

system of ................ 2!)l-;>27 

.s-( i Contents .................. 2.">S 

r'arminti-type areas of Illinois ... 117* 
r'arms. number of per square mile 

in count n 's .................. l!7!) 

selection and purchase of. . . .)'>2f>-27 

l''armsteads. plannintr of ............. 

................... 2S1 S.'). ;',!!) 2.") 

I'Vuits, market imr of .......... 170-S2 

production and consumption 

of ..................... 171 71 ::: 

refriu'erat ion of in transit ....511-11 

x< c ( 'ontents ................ 510 

(Irain ele\'ators, comjiarat i\'e s(>a- 
sons of purcliase and ship- 
meiit by country ........... )!l-.'!7 

comparison of >ea^onal acti\'iiy 
by farmers' and by private 
..................... )!7. )!!), li'i 

si oraire ca paciiy of I Ilinois 

country ....... ....... 21 27. ;!!) 

(Jrain market imr. >t udy of ...... )!!(') 

corn, distribution of shipments 

.f ................ 12-1)!. I)!. 15 

>ectional differences in.... 11 

seasoiia 1 change- in prices of 1 1 17 
oafs, earnings on hedged and 

un 1 led tred ................ 22 21 

distribution of sliipmetits of 

................ 17-1!). 11, 15 

sect ional differences in . . 1!) 



. 

sea>i>nal chalices ill prict S of 

....................... 1!) 22 

win :i I . disl ribut ion < u .-In j >- 

meiils of .................. ! 5 

Mdioml differences in.... 

................. "> li. 12. 15 

seasonal changes in prices of li 12 
*< , <il.> Cram elevators and 

(Irani storati'i 
drain storage on farms ........ 27-)!l 

influence of on time of sale... 

...................... :;_':: I. ;;<i 

Crams. production costs of ...... 2(>5 

profits from ................. 2d(i d7 

( Irinders, elect i'ic .............. \',\7 !."> 

Hartsbur^- experiment In Id yields 221 
Ha\'s, cost of producing ......... 2(>S 

place of in farm oriranixat ion 

........................ 2(i7 70 

I letiry couniy. Mai i>t ics from . 1H2 207 
llo'j.-s I'ollowiiifi sieei'-. u;iin~- made 

by .......................... 2.">2 

I b >me equipment , d'il a oil ....... 

..................... l.">:)-.)(i. 207 : 

ncc al--> I'llectric po\\'er, house- 

hold u >e of 
Horse labor, crop requirements 

for ...................... '2! I!) ',\()\ 

variations in cost of. .27(>-7X. 27'J SO 
me <ilx<> Labor 
Ice-cream improvers, en/vine ac- 

ti\ ity of ................. I,s2 .Vis 

si'i-. ('onttnis .................. 1S2 

.loliet experiment field yields.... 222 

Ke\vanee experiment field yields. . 22)! 

LaMoille experiment field yields. 22)1 

Labor, adapt imr crop plan to )!())! .'!(),") 

calendar for. . .Fi^. I s . l)i I ween )!()S 

and )',()! 

distribution of in caring lor 

livi Mock .............. :!()."> )H)S 

efficient use of farm ........... 

........... 275 7(1. 2!)<i )!())!. )!OS 

re(|uirenn m- of various crops 

and farm opera I ions. .. .2!)7 )!05 

*' < almi IIor,-e hbor 
t-ebanon experiment lit Id yields 



I.iveMork. adjustments in pro- 

i h ict ion of ................ )!l 7 1M 

amounts and kind- of feeds 

used b\ ................ )!()! 10 

bahnemir oi \\ith crop produc- 

lion .................... )IOs D! 

cooperative shipping of, \< :i<\- 

imr count n-> m ............ '!)! 

et'fecl of on farm earmims. . .270 7)i 
hbor required in carinir for.)!(H'p )!()7 
oppori unit ii s for impro\'em 

in roduction of ........ I do d2* 



COS 



PAGE 

Livestock cooperative shipping 
assoe'iat ions, accomplishments 

ol 352-53 

compel it ion of truck operators 

with 183 

conclusions from study of 371 

location of in Illinois 352 

managers' commissions of 357 

operation and management of 

358-67 

problems of 367-71 

rates charged by 184, 354-57 

summary of study of 371-72 

volume of business done by... 

182-84, 354-58 

McXabb experiment field yields.. 224 

Markets, roadside 184-85 

Milk, studies of composition of.. 

51-174 

sec Contents 50 

Milking machines, electric 447-51 

Minonk experiment iield yields. . 225 
Morrow plots, decline in corn 

yield on 288-89 

yields for, 1928 238 

Mt. Morris experiment field 

yields 226 

Newton experiment field yields.. 

.' 226-28 

Oats, marketing study of, see 

drain marketing 

place of in farm organization.. 266 
Oblong experiment field yields... 229 
Odin experiment field yields. .228, 229 
Oquawka experiment field yields. 230 
Palestine experiment field .yields 

....230-31 

Phosphorus, available', develop- 
ment of colonmetric test for 

591-92 

effect of soil treatments on. 600 601 
Illinois adaptation of colorimet- 

ric test for 593-602 

effect of carbonates a n d 

moisture on 594-95 

field application of 595 

method of making 593-95 

reagents used 593 

results on experiment fields.. 

595-001 

summary and conclusions 001 002 

variation in depth of 001 

Pork, method of calculating 

economy of cuts 34017 

percentages which cuts consti- 
tute of carcass of 337 

physical composition of cuts of 

. 330-10 

prices ol affected by consumer 

preference 335 

relative- costs of edible and e)f 



PACK 

lean meats of 34017 

wholesale' cuts eif 331 

Potatoes, production and e-on- 

sumpt ion of 174-77* 

Poultry prexluets, marketing of.. 

179-82 

ne-eel feir impreive-ment in.... 109-71 
production and cemsumption 

eif 167-69* 

Production costs, see Costs of 

production 

Raleigh e-xpe-riment field yields.. 232 
Refrigeration of fruits, see- Fruits 
Rock Island e'emnty, statistics 

from 192-207 

Scott, county, Iowa, statistics 

from....'.. 192-93, 201 

Seed gcrminators, electric 461-65 

Seed-treating machines, electric.. 466 
Sidell experiment fielel yielels. . . . 233 

Silage emitters, e-Iectrie- 436-37 

Soil experiment lie-Ids, yields on, 

1928 .' 210 38 

Soybeans, place of in farm or- 
ganization 207 

Illini, adaptability of 555-50 

characteristics of 547-52 

oil cemtent eif 554 

origin of 547 

summary of stuely of 546 

yielels of 552-54 

Sparta experiment, fielel yielels. .233-31 
Spring Valley experiment fielel 

yields ..." 23 1 

Ste-ers, summer rations for fat- 
tening 243-55 

amounts of feed consumed. . .245 47 
feeel replacement value of 

pasture; 250-52 

feeels consumed per 100-pound 

gain 249-50 

financial outceime 252-54 

gains maele 24719 

plan of e-xperiment 24315 

summary 251, 255 

Toledo experiment field yie-lds... 235 

Trae-tor costs,' variatiems in 278 

Tractor peiwer use-el feir various 

e'reips 296-97. 299-301, 301 

Trade- ami, stuelv of rural- 
urban ' 130-208* 

see Conte-nts 130 

Truck transportation e)f live- 
stock 182-84 

Fnionville e-xpe-riment field yielels 

'. .. 236-37 

Urbana, experiment fie-ld yields 237-38 

Vegetables, marketing of 179-82 

production and e'onsumption eif 

.. 177 79 



Bulletin 320. 



IM.KK 



PACK 

Wheat. markrtinii Miuly (if. Kit 
( I r,-i in market mil 
lace 1 of in farm t>rir;tni/:tt im . . -(id 



- '9.30 
OF ULlHois 








UNIVERSITY OF ILLINOIS-URBANA 



Q 630.7IL6B C002 

BULLETIN. URBANA 
324-3371929