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 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; 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 *< , Cram elevators and (Irani storati'i drain storage on farms ........ 27-)!l influence of on time of sale... ...................... :;_':: I. ;;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 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!) 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