— — — , , -, . 7A 7 - . _ — — — ,, 7 i — if i, — — —'IU1_L I004> (1)0001 EFFECT OF FERTILIZERS ON PHOSPHORUS AVAILABILITY AND EXCHANGEABLE CALCIUM. POTASSIUM. AND MAGNESIUH IN SOIL FERTILITY PLOTS ON HILLSDALI SANDY LOAM Them for the Degree of M. i. MICHIGAN STATE COLLEGE Bennie Arthur Perry I942 / THESIS ‘ EF ECT CF FERTILIZEno OH? HOS IE”? ..u) \/ LUL) AV LII“ AL: IT 7 ATS LAC.£”GEAZLE CALCIUI: , POTAQSTL AXE IAGIESIUM 9 IE SCIL FERTILITY PLOTS CH EILL’TJA E SAFD’ LCAI by Effie“? 1': “m7? I: 13‘ 4.114144" L: .‘ i'AIAJF. BELL! m A TLESIS Submitted to the Gracluate School of Ifiich igan State College of Agriculture and Applied Science in partial fulfilment of the requirem.ents for the deg roe of LASTER OF SCIENCE Department of Soil Science 1942 7er31$ ‘1"?1', 1' n? "TTVM LIXL‘I U'rLEDuLuJJl'i The writer wishes to express his sincere gratitude to Dr. C. H. Spurway, under whose general supervision the work was done. The writer is also indebted to Dr. C. E. Hillar, Mr. A. G. Weidemann, and Mr. Kirk Lawton for their helpful suggestions and constructive criti- cisms throughout the course of this study. Sincere appreciation is also expressed to H .‘J. F. Davis for the photographs used in the manuscript. Acknowledgments are due and are gratefully rendered to other members of the Soils Department for their helpful suggestions which contributed greatly in the development and preparation of the manuscript. 4- _\ I ya. @- I13 4 .7“; C." EFFECT OF FERTILIZERS Oh AID EXCEAYGT‘ELE CALCILX, I: SCIL FERTILITY FLCCS KOSPECELS AVAILABILITY » m (3017:}. 1 1 ~ ws-C‘aw— - IJClifiLAJ04LaIL, .55.-:D LAUIIUDJLL . CY LILLSBA E SANDY LOAN TATLE O1? CCITTEITTS IIITRCDL'CTIOE.’ RE . IE1”: C1 LITETAT RE DESCRI PTICII CE SOIL PLOTS STUDIED EXPER II.-TEI=ITI1L WORK ALA ‘ " AL Pi ZCCEDLPES “IZIZEIIEITTAL TLTA DISCLS SIGN OF “TS‘IT” ILlJOU .4; D SL' MARY A? ID CCITCLLSIOITS IN RODUCTION It has been long recognized that soils are often unproductive because the amount of available phosphorus is inadequate for Optimum growth of the crop. Numerous investigations have revealed that cer- tain soils have the power to fix relatively large quantities of phos- phorus and hold it comparatively unavailable for higher plant nutrition. Farmers being confronted with this problem, have endeavored to al- leviate these conditions by treating their soils with varying amounts of phosphate fertilizers. Some treatments have given satisfactory crOp response, others gave no significant increase in yield. If the soil is deficient in available phosphorus, why is there no crop response to phos- phate fertilizer treatments on some soils? This is the problem that pre- sented itself and during the past few years has been under almost con- tinuous study by numerous investigators. The writer is aware of the numerous reciprocal effects caused by fertilizer materials on both the solubility in the soil and absorption in plants. In this study, it has been the effort of the writer to show 'the relations of these reciprocal effects produced by continuous ferti- lization on the available phosphorus, and replaceablet potassium, cal- cium, and magnesium in the soil. The use of fertilizers to increase the mineral content of soils and plants as discussed in the United States Department of Agriculture Year Book (48) reveals that the mineral com- position of crOps can be affected only within certain limits. An in- crease of one constituent is offset by the decrease of another. Too *The terms "exchangeable" and "replaceable" have been used inter- changeably throughout this study. -2- great an excess, as well as too great a deficiency, of a particular nutritive element brings with it an injury to the crOp which is re- flected in lowered vitality and diminished yield. Somewhere between the limits of excess and deficiency for the different essential ele- ments-~nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, iron, etc.--is the Optimum range of the well-balanced or harmonious mixture of nutrients which will be found to vary according to the na- ture of the soil, variety of crOp, supply of water, amount of sunshine, and numerous other environmental conditions. This chemical equilibrium in soils between the available nutrients is the determining factor for a productive or unproductive crOp. The median between the limits of excess and deficiency has been established by Spurway* in his studies on plant nutrients in greenhouses. In this study, both the direct and indirect reciprocal effects have been considered in an effort to explain the reasons for increase and de- crease in the replaceable cations of the soil and the consequent cr0p response. Any factors which cause a change in the cation equilibrium; in- creased or decreased absorption of cations by plants; efficient or in- efficient utilization of cations within the plant; or increased liber- ation from or fixation of cations in the difficult available form tend to effect the amounts of replaceable bases in the soil and the conse- quent crOp response. It was from this point of view that this study was conducted. *Department of Soil Science, Michigan Agricultural Experiment Station, East Lansing, Michigan -3- REVIEW OF LITERATURE During the past few years a number of workers have studied the relationships between soil reaction and fertilizer needs. This work has been confined in many cases to European soils. Niklas and Hock (32), using the Neubauer method, found that only 25 per cent of the soils havin" a pH below 4.5 gave a phosphoric acid value above 8 mgms. and nearly 50 per cent were below 4 mgms. In the alkaline soil regions, however, nearly 50 per cent of the soils showed values above 8 mgms. and only 21 per cent less than 4 mgms. Sekara (41) found that, in general, both very acid and very alka- line soil were more deficient in phosphorus than neutral soils. For potassium, acid soils were found to be more deficient than neutral soils while alkaline soils were relatively well supplied. Schmitt (40) obtained Neubauer results for phosphorus that were lower on both acid and alkaline soils than on neutral soils. Larger amounts of available potash were found in neutral and alkaline soils. Goy (17), using the Neubauer method, found that in general potash deficiency increased with increase of soil acidity. Kling and Engels (23) tested 166 soils by means of the Neubauer method and found that either very acid or very alkaline soils were much more likely to be deficient in available phosphoric acid and very acid soils in available potash. Gourley and Smock (16) in a survey of Ohio orchard soils found a low available phosphorus supply in the acid soils of eastern and cen- tral Ohio and a relatively large supply in the less acid soils of north- western Ohio. -4- Recent studies have been made in relation to the available phos- phorus and potassium contents of surface soils and subsoils and the conseqeunt cr0p productivity. Much of the work on this problem in re- cent years has been confined largely to pot test and field observations. Because of the large amount of work involved in such tests only a re- latively few soils have been investigated. Millar (28, 29, 50), from work with several soil types, concluded that the poor growth of corn in soil from A2 and B horizons is due very largely to a lack of available nutrients and that very large quantities, particularly of phosphorus, must be added to satisfy the adsorptive cap- acity of the soil and make plant growth commensurate with that obtained when surface soil is used. McMiller (27) used alfalfa in pot tests to show that certain Min- nesota subsoils which previously had been found "raw" towards innocu- lated legumes were rendered as productive as the corresponding surface soils when soluble phosphorus and potassium fertilizers were added. Lipman (24) questioned the existence of humid subsoils which were sterile towards inoculated legumes and denied that lack of phosphoric acid or potash could be the cause of such unproductivity. In order to determine the efficiency of added phOSphorus and pot- assium fertilizers to soils, many investigations have been conducted to obtain data concerning the fixation capacities of soils. Recent work has shown that a number of factors are important in determining the fix- ation capacities of soils. Probably the most important of these are soil reaction, amount and composition of soil colloids and the amounts of organic matter, active silicon and iron and aluminum compounds pres- ent. -5- In general, for phosphorus, it appears that increased fixation capacity of the soil accompanies very acid soil reactions, the presence of large amounts of soil colloids, low silica-sesquioxide ratios of the soil colloids and the presence of large quantities of active iron and aluminum compounds. Decrease in fixation capacity may be expected with neutral or slightly acid soil reactions, low colloidal contents, high silica-sesquioxide ratios, and the presence of only small amounts of ac- tive iron and aluminum compounds and relatively large amounts of active silica and organic matter. For potassium fixation much less information is available regarding either its prevalence or the mechanism through which it takes place. Even the effect of lime, which has been intensively studied, is still a disputed question. However, it is generally agreed that when potassium in solution is added to soils it readily and rapidly combines with the exchange material of the soil and is held in less soluble but exchange- able and plant available forms. It has been suggested that in time a part of this exchangeable potassium is changed to non-exchangeable and available forms, the rapidity and completeness of the change varying greatly with different soils. In these processes, the reaction of the soil and the amount and composition of the colloidal material present appear to be important factors. Davis (6), on the basis of his work with Hawaiian soils, stated that phosphate fixation in soils may occur through three processes: 1. Formation of insoluble phOSphates through reaction with soluble bases, such as calcium, magnesium, iron, aluminum and manganese. -5- 2. Adsorption on colloidal surfaces. 3. Slow diffusion out of the soil solution and into some of the amorphous solids of the soil where it combines with substances such as hydrated oxides of iron and aluminum to form complex compounds. Davis found, that, even after removal of the readily soluble sub- stances, the soil possessed high phosphorus fixing power and believed that little phosphorus is fixed in Hawaiian soils as insoluble phos- phates or by absorption by soil colloids. Beck (19) states that, if the ratio of active calcium to active iron and aluminum is high, phosphorus fixation will be largely in the form of calcium phOSphates and so readily available to plants. If the reverse is true, fixation will be largely as iron and aluminum compounds which are difficultly available. On the basis of solubility, it was found that phosphorus was fixed in a Miami silt loam largely as calcium phosPhates, in a more acid Carrington silt loam less as calcium phos- phate and more as iron and aluminum phosphates, and in two Hawaiian laterites largely as basic forms of iron and aluminum phosphates. Al- though reaction and the presence of active calcium are ordinarily im- portant factors, in the laterites they are overshadowed by the presence of large quantities of hydrated oxides of iron and aluminum. Ayres (3), in a study of phosphorus fixation in Hawaiian soils found that the degree of fixation was characteristic for a given local- ity. In general, lowland soils showed a lower phosphate fixing capac- ity than upland soils and surface soils lower than subsoils. A general correlation existed between the degree to which fixation occurred in -7- soils and the availability therein of applied phosphates. weiser (50) found relatively high phosphorus fixation capacities for Vermont soils. Fixation was increased by exposure of the ferti- lizer to large amounts of soil. It was considered as due chiefly to compounds of iron and aluminum. Certain hydrated oxides and precipi- tated salts fixed especially large amounts of phosphorus. On the other hand certain silicates, minerals and organic matter reduced fixation. Lime likewise increased the ability of creps to recover applied phos- phorus . Scarseth and Tidmore (39) studied phosphorus fixation by soil col- loids. Availability of the native phosph rus in the four types of soil colloids used varied directly as the silica-sesquioxide ratio, being less available in soils with red colloids than in soils with grey col- loids. Phosphate fixation capacity of the colloid was inversely pro- portional to the silica-sesquioxide ratio. The lower the silica- sesquioxide ratio, the smaller was the influence of the degree of cal- cium saturation on the amount of phOSphorus fixed by the colloid. The more acid the soil colloid the greater was the recovery of added phos- phorus. Gile (15) studied the effect of different colloidal soil materials on the efficiency of superphosphate. he concluded that the degree to which the colloid was saturated with phOSphorus, the silica-sesquioxide ratio, effect of colloid on the pH f the medium and the content of or- ganic matter seemed important in determining relative efficiency of superphosphate. Volk (48), in an extensive study of potash fixation in soils, found -8- that rapid fixation in a non-replaceable form was caused by alternate wetting and drying. For the four soils investigated, the ultra-clay fraction contained the lowest percentage of potash but was by far the most active in fixation. Fixation was influenced by the nature as well as the amount of soil colloids present. Sodium carbonate and calcium hydroxide both increased fixation. SLnthetic mixtures of al- umnia gel, silica gel, calcium hydroxide and sand did not fix potash. Mineralogical, chemical and X—ray analyses of hagerstown silt loam soil, a part of which had received 5,000 lbs. f muriate of potash over a period of 50 years, led to the conclusion that a portion of the added potash became fixed in the soil in the form of muscovite. KcGeorge (26), in a comparison of calcareous and non-calcareous soils having the same amount of replaceable potassium, found higher values for water soluble potassium with the non-calcareous soils while Neubauer values were higher with the calcareous soil. calcareous soils were found to contain a larger part of their potassium adsorbed by non- crystalline colloids, either in the form of synthetic zeolite-like com- pounds or iso-clectric precipitates. Many investigators have attempted to correlate the size of par- ticles to the availability of phosphorus in rock phosphates. DeTurk and Sears (10) found no marked differences with material of different fineness used on soil in greenhouse cultures. Ames and Kitsuta (1) obtained increased phosphorus absorption by plants from the more finely ground rock phosphate. Rauscher (36), using the Neubauer method and several different types of rock phosphate, found it necessary to consider each type sep- arately. 'With certain types of material particle size exerted an -9- important influence on the phosphorus absorption, this being especially true with the hard phosphates. With the soft phosphates, phosphorus absorption was greater but much less influenced by differences in par- ticle size than with the hard phosphates. There appears to be no pronounced or consistent increase in avail- ability with decrease in particle size. Early investigations revealed evidence of reciprocal effects of nitrogen, phosphorus, and potassium additions on the absorption of phos- phorus and potassium. In addition to its direct effects on plant growth and development, any nutrient added to the soil may have important in- direct effects on the utilization of the other nutrients present. Oc- casionally these indirect effects are fully as important as the direct ones. In explanation of the effect of one nutrient on the utilization of another several possibilities are suggested: 1. Changes in solubility relationships in the medium upon which the plant is growing. \ 2. Influence on absorption by the plant. 3. Effects on efficiency of utilization within the plant. Soil reaction and concentration and nature of the cations in the soil solution an the exchange complex of the soil have been suggested as the principal factors determining the availability of phosphorus and potassium. From this it is to be expected that any treatment that influences either of these factors will affect the availability of these two plant foods. Thomas (43, 44) studied the reciprocal effects of a number of materials on both solubility in soils and absorption by-plants. Addition -10- of monocalcium phosphate to Hagerstown silty clay loam soil increased the amounts of iron and aluminum in the soil solution, addition of sodium nitrate and potassium sulfate increased the amount of phosphorus in solution and both monocalcium phosphate and potassium sulfate in- creased the concentration of sodium in solution. Potassium additions increased absorption of both nitrOgen and phosphorus by apple trees. In fact, a significant increase in the absorption of phosphorus oc- curred only after the addition of nitrogen or potassium or both. This was true whether or not phosphorus was added. Fudge (14) investigated the effect of a number of nitrogenous fertilizers on phosphorus and potassium availability. Such material may affect both soil reactions and nature and concentration of cations present in the soil complex. Acid-forming materials, such as ammonium sulfate, ammonium nitrate, Leuna-saltpeter and urea, increase soil acidity and the concentration of hydrogen ions. Acid forming ferti- lizers caused a marked decrease in phCSphate availability. For po- tassium, their effect was to increase the water soluble forms but to decrease the potentially available supply. Thornton (45), in his observation on phosphorus absorption by corn and potato plants found that potassium additions increased the absorption of both nitrogen and phOSphorus. A higher concentration of inorganic phosphorus within the plant often was found where re- latively large applications of muriate of potash had been made. This was true whether or not growth responses to the potash additions could be observed and regardless of the initial phOSphate level in the plant. In many cases the phosphorus values were increased more by the addition -11- of potassium alone than by the addition of phOSphorus alone. The ability of soils to supply potassium to crops is a result of many processes. The total replaceable potassium content of a soil is so closely correlated with crOp reSponse to added potassium that its measure can be used in estimating the potassium needs of crops. Re- placeable potassium is in equilibrium with a form of non-replaceable potassium or "difficultly replaceable" potassium which in turn is as- sumed to be in equilibrium with the potassium minerals. Reducing the replaceable potassium induces release of potassium from the "difficultly replaceable" form while increasing it induces "fixation" in this form. Bray (4), in his study of the equilibrium between the replaceable bases and the soil water has found that the ability of a given plant under field conditions to secure replaceable potassium is conditioned by the extent and nature of its rooting system, the amount of replace- able bases present, the degree of saturation with bases, their relative ease of replacement, the electrolyte concentration of the soil water and numerous other factors. He has devised the equation below in order to show the relationship of these factors to the equilibrium of the re- placeable bases in the soil water. 813’ ' Cm ' r2132 + £713 1}}?- + r B \\EL+ E2 +12-" + BL o 5 n n Where B13 : the amount of El in solution. B1, B2, etc. a replaceable bases. f1, f2, etc. = factors for relative ease of replacement for B, B1, etc. E : Base-exchange capacity. CBl . constant for El for the given conditions. -12- All expressed in milliequivalents per 100 grams of soil. For dilute H01 (0.005N) good constants were obtained as follows: CK a 1.7; Chg = 1.0; Ca 8 0.7. Applied to Hoagland and Hartin's data (21) for potassium removed in a 2:1 soil-water extraction the equation gave a CK of 0.12 for their conditions. Factors for ease of replacement were calculated by assuming calcium to have a value of one. The percentages of the replaceable magnesium and replaceable potassium released were then divided by the percentage of the replaceable calcium released, giving factors as follows: fK = 2.3; fMg : 1.7; and fCa = 1.0 for the experiment. The equilibrium expressed by this equation controls the release and movement of the replaceable potassium (and other bases) thru the soil. Any increase in calcium or magnesium will give two opposite ef- fects. It will tend to decrease the potassium in solution in that the potassium in solution is inversely prOportional to the sum of the other replaceable bases times their ease of replacement factors. At the same time it will tend to increase the release of potassium by increasing the degree of saturation with bases. Since the latter is a square root function, the actual result is a decrease in K release. This is con- trary to the conclusion of Jenny and Ayers (22) who believe that po- tassium release will be greater when the replaceable calcium is in- creased by liming. The relatively slow rate of movement of the strongly adsorbed ions, such as K, P04, Ca, Mg, Mn, through the soil is in striking con- trast to the mobility of the relatively unadsorbed ions, notably ni- trates. This situation gives rise to two distinct types of zones from -13- which plants feed or absorb nutrients. The one, for the strongly ad- sorbed ions has a relatively short radius immediately around the roots or root hairs, with untapped areas occurring between these "root sur- face feeding zones" within the root system of the plant. When these "root surface zones" interpenetrate, competition for the adsorbed ions occurs between the individual root hair surfaces of the same or different plants. Spurway (42), in his study of the factors influencing the solu- bility of soil-superphOSphate mixtures found that additions of potas- sium fertilizers increased the solubility of phosphorus. Owens (53) has reported increased absorption of phosphorus with the omission of potassium fertilization. Hess (20) has reported increased solubility of phosphorus upon ad- ditions of potassium. Willis, Et. At. (52), in their study with soybeans found that with an abundance of calcium a deficiency of magnesium does not limit absorp- tion of phosphates. Their data do not indicate whether the phosphate absorbed under these conditions is efficiently utilized, but collateral evidence indicates that magnesium deficiency and phosphate deficiency have no mutual relationship. Dunkle (12) in his studies of potash availability concluded that surface soils were definitely higher than subsoils in replaceable po- tassium and loss of tOp soil by erosion is a factor in increasing the need of applied potassium. The amount of replaceable potassium is re- lated to the organic matter content of the soil. The rapid method for determining replaceable potassium compared favorably with the quantitative -14- cobalti-nitrite method and is satisfactory for determining the general level of soil potassium. His analyses of leaves did not correlate with the replaceable soil potassium but in some cases gave indications of the effects of potash application which could not be detected by ex- change analyses. Richer and White (37) made extensive studies on available phosphorus and crOp yields. As a result of these studies no correlation was found between the available phosphorus and cr0p yields in the comparison of plats receiving various carriers of phOSphorus, such as superphosphate, rock phosphate, basic slag, and bone meal. Plats receiving double or triple amounts of superphOSphate showed only small increases in the available phOSphorus extracted. The available phosphorus of rock phos- phate—treated plats was directly prOportional to the amount applied, but it was many times higher than that of plats receiving superphosphate in equivalent amounts. After long continued use of phosphorus ferti- lizers the soil tends to approach a phosphorus equilibrium. When this equilibrium is approached, available phosphorus has a tendency to show an excellent correlation with crOp yield. Daniels and harper (8), in their studies of the relationships be- tween total calcium and phosphorus in mature prairie grass in Oklahoma found that these grasses make a good growth on both acid and basic soils and often on soils very low in easily soluble phosphorus, base exchange calcium, and organic matter. The correlation coefficient for the comparison between total cal- ciUm in the grass and the exchangeable calcium in the soil was 0.50 i .09 and the correlation between the available phosphorus in the soil -12- U and the total phosphorus in the grass was 0.35 f .11. It was found that a slight positive correlation existed between the total calcium in the plant and exchangeable calcium in high calcium soils. ho data were obtained that would indicate that plants growing in soil low in base exchange calcium would also be low in this element. A slight positive correlation occurred between the total phosPhorus in the grass and the easily soluble phosphorus. A slight negative correlation oc- curred when the plants were collected from soils containing less than 10 p.p.m. of available phosphorus. From their data, they concluded that a single plant food element in the soil will not give an accurate indication as to the amount of that element which will be found in the plant. Dorman and Coleman (11) made greenhouse studies of available phosphorus using cotton and sagrain. They found that cotton and sagrain failed to reSpond to phosphate application on soils containing 15 p.p.m. or more available phosphorus, which indicated that under southern con- ditions creps do not require large quantities of phosphorus. host southern soils do not contain 15 p.p.m. available phosphorus and re- quire phosphorus, but application should be made without determining the available phOSphorus present. It is believed that when nitrogen and potassium are limited and phosphorus fixation is at a minimum, phosphate recommendations for cotton and sorghum may be made on the following basis: Soils containing less than 6 p.p.m. available phos- phorus require liberal applications, those containing from 6 to 15 p.p.m. require light applications, but those containing more than 15 p.p.m. require very little or no phosphorus. -15- Parker and Truog (34) concluded from their compilation of analyses secured from different sources that a rather close relationship existed between the calcium and nitrogen content of plants, while potassium, phosphorus and magnesium do not bear this close relationship. Daniel (7), in his studies on magnesium content of grasses and le- gumes found that the calcium-magnesium ratios varied in mature grasses and legumes from 1.10 to 5.46, the phosphorus-magnesium ratios from 0.09 to 2.42, and the nitrogen-magnesium ratios from 2.09 to 22.06. He found that the magnesium content of legumes decreased as plants matured. Mitchell, Werner, and Morrow (31) found that phosphorus in ferti- lizers decreased the calcium and magnesium content of oats and increased the phosphorus content of oats, grass hay, and soybean hay. Wide vari- ation in phosphorus content of feeds was found in different parts of the country. Ames, Boltz, and Stenius (l), in their investigation on composi- tion of wheat, found that the character of wheat is changed more by seasonal influences than by the differences in soils or fertilizer treatments. Their investigations revealed that a high starch content was associated with a high phosphorus content and a low protein con- tent and that the ratio of phosphorus to nitrogen in wheat stands in the same order as that of phOSphorus to nitrogen in the soil. Lockett (25), in his study on nitrOgen and phosphorus changes in the decomposition of rye and clover at different stages of growth found that the soil microbes engulf a considerable amount of organic and in- organic phosphorus in their microbial cells. He has pointed out that this fixation of phosphorus is important from the point of view of -17- supplying available phosphorus for plant nutrition. If the phosphorus , were liberated immediately in the soil, a large portion might become fixed in forms which are unavailable to higher plants. Eschenhagen (13) applied the Neubauer's method for the study of the nutrient contents of the soil and found that with increasing amounts of potassium the dry weight of plants follows the action law of the growth factors. he concluded the amount of potassium absorbed by plants, depends not only on the amount of potassium available in the soil but also on all other growth factors. It is pointed out that the absorp- tion of potassium is controlled by the concentration of the potassium solution in the soil and does not depend on the lack of available po— tassium. He showed that the Neubauer method can be used only within certain limits. Densch and Hunnius (9), in their extensive investigation of the in- fluence of the soil-water content on the yield, on the grain—straw ratio, and on the phosphorus nutrition of oats at various tires in growth period, have concluded the following: 1. A long period of drought caused a decrease in straw yield but did not show the bad effect on grain formation until early part of July. 2. Phosphoric acid is taken up by the oats until the panicles appear and under favorable moisture condition the whole amount is available for grain formation. 5. Even if the period of drought ends during the stretching period, the plant is able until the panicle formation to take up as much potassium as when under continual favorable moisture conditions. -18- 4. Oats take up nitrogen even after the panicle formation, under favorable moisture conditions, and thenitrogen nutrition lasts until near their ripening. The minimum supply of readily available phosphorus which suffices for plant growth varies depending upon the crop, climate, and soil in- volved. Crops with a long growing period can get along with a lower supply than those with a shorter growing period, because the long growing period makes possible the utilization of a greater amount of the diffi- cultly available phosphorus. A climate which makes possible a long growing period has a similar effect. As a consequence, fairly good crOps of corn can apparently be produced in the South on soils whose readily available phosphorus supply would be entirely inadequate in the North. Unquestionably, a higher amount of readily available phosphorus than 75 to 85 pounds per acre in the plowed layer for the heavier, and better soils, and 50 pounds for the sandy soils will further tend to in- crease yields in many cases. All biological activities of soils are greatly stimulated by a liberal supply of readily available phosphorus. The economics involved must, however, be taken into consideration. Where land values and crOp prices are relatively high, it will be econ- omical to farm with higher amounts of readily available phosphorus than where the reverse conditions hold. In sections when the land is devoted to the production of vegetable and truck crOp production, it is often desirable to have 150 pounds or more per acre of readily available phos- phorus in the plowed layer. In most cases it is not practical and of no avail to supply the soil with readily available phosphorus beyong the point where climatic conditions, such as amount or distribution of rainfall, limit the yield. DESCRIPTION 0' *1" (J) (3 r4 t" "d D *3 U) C!) 5—3 C U H t J O This eXperiment was conducted on a Killsdale sandy loam. The whole area involved was exceptionally level and uniform for that type of soil. The pH determinations on the soil samples ranged from 5.2 to 6.4. The plow layer consisted of a grayish-brown sandy loam, underlain by a 20-inch layer of pale-yellOW'fine-granular friable clay loam ranging from 18 to 24 inches in thickness. The substratum had a pervious sandy clay, which was moderately stony and gravelly in places with separate layers and pockets of sand, clay, and gravel. The humus content was not very high but the amount was sufficient to impart a light-brown color. The subsurface layer was moderately retentive of moisture and is permeable and penetrable to a depth of several feet. Diagrammatic Layout of Plats 7A 8A 9A V 10A 11A 12A 7 8 9 10 ll 12 1A 2A 3A 4A 5A 6A 1 I 2 3 4 5 6 -20- Plate 1 A View of the Phosphorus Series Seeded to Alfalfa and Brome Plate 2 A View of the Phosphorus Series Seeded to Alfalfa and Brome -21- Plate III Iheat and Barley on the Phosphorus Series Plate IV A View of the Phosphorus Series EXPERILTEIEAL “1'0? x The soil on which this experiment was conducted is classified as Hillsdale sandy loam and the whole area involved was exceptionally level and uniform for that type of soil. There are 24 duplicate plats comprising 0.0409 acres each. The soil being acid in reaction, was given a uniform application of 2 tons of limestone per acre. In each set of duplicates there was one plat which received lime only. All other plats got a uniform application of urea, KCl, and Ca804. Only the phosphorus treatments varied and the acre application of this ele- ment is given in Table 1 . During the years of 1933, 1934, 1935, 1936, 1937, and 1939, the plats grew barley, timothy, wheat, oats, barley, timothy, and wheat respectively. Regular fertilizer applications were made in spring for barley and in September for wheat. The first samp- ling after phosphorus applications was made in 1933, 1934, and again in 1937 and 1939. Soil samples were taken in late October or early November each year after time for applying fertilizer for wheat. Twenty borings 1.5 inches in diameter and 6.5 inches deep were taken from as many spots uniformly distributed over the plat. These were put together, dried, sifted through a 20-mesh screen, thoroughly mixed, and stored for analysis. It is quite probable that some of the differences might be due to inaccuracy in sampling, but it is also quite likely that many of them are due to soil differences despite the fact that the soil seemed very uniform. Enough samples were not taken to calculate the error due to method of sampling. -23- The A plots were not started until 1933. Each original plot was divided in half and the new division was given the symbol of A. To each of these A plots a uniform treatment of Urea, K01, and CaSO4 was applied. In each set of duplicates there was only one plot which re- ceived lime only. AEALYTICAL PROCEDURES The soil samples which were analyzed had been previously dried, sifted through a 20-mesh screen, thoroughly mixed and stored for anal- ysis. The soil samples were oven-dried at 1050 C. for several days before beginning the analysis. The samples were then placed in a des- sicator to cool and later weighed accurately to two decimal places. The soil samples were placed in percolator tubes and leached ac- cording to the method recommended by Russel (38). The percolation was allowed to continue 8 to 10 hours with the leachate passing drOp- wise into an Erlenmeyer flask. ////// , //////// / ‘, / Porcelain Plate Quartz Sand Soil ,,,_ Erlenmeyer 'fjf-‘ it? Flask to Quartz Sand flyyju Filter Paper Ammonium Acetate Solutio DISPLACEI. El? CE 3.. SE Twenty-five grams of the oven-dried soil (weighed out to two deci- mal places) was placed in the percolation tubes and firm y packed so that the leaching solution came ir nto contact with the entire sample. The soil was leached for about 8 hours with normal ammonium acetate ad- justed to a pH of 7.0. After the 500 ml. of normal ammonium acetate had percolated through tle soil, the excess armonium acetate was re- moved by passing 300 ml. of a 50 per cent methanol through the sample. The ammonia that remained in the soil after this treatment was in the exchangeable form. The ammonium.acetate leachate was then reserved for the determination of calcium magnesium and :otassium. J L. J 1“"nZIIT TICK OF EX lid GEAZ LE CALCILE After treating the soil with the neutral ammonium acetate solution, calcium, magnesium, and potassium ions were brought into solution as acetates. The ammonium acetate leachate'was then transferred to a 600 ml. beaker and evaporated to dryness on the steam bat h. 10 ml. of aqua regia was added and the evaporation continued until dry again. (This procedure was to remove any organic matter present in the leachate.) The acetates were then destroyed by beneral ignition. This was accom- plished in the pyrex beal {er in which the sample was evaporated to dry- ness, the rim of beaker being held and the lower portion exposed to the flame of a bunsen burner. The residue in it turned black at first, but became white as the ignition continued. The beaker and contents was then cooled to room tenre rature and 10 m1. of (1:1) HCl and 10 ml. of distilled water added. The beaker was then heated until the residue was completely dissolved. The solution was filtered through a Flatman m1 J. Io. 41 filter paper into a 250 ml. beaker. 'ne ’ilter paper was waszed P4» with hot water until 150 ml. of filtrate was obtained. At this point, the filter paper was discarded. To the filtrate, was added 1 gram of ammonirm chloride and 10 m1. of a saturated solution of ammonium oxalate. A few drOps of methyl orange was added and the solution heated to boiling on a hot plate with a drOpwise addition of concentrated ammonium hydroxide, while stirring until the solution became alkaline to methyl orange. The beaker was then placed on the steam bath and digested for 1 hour. This allowed the calcium oxalate to settle and solution to become clear. This sol- ution was then filtered through a Whatman E0. 40 filter paper. The beaker and filter paper was thoroughly washed with hot water until free of oxalates. The filtrate and washings was reserved for magnesium deter- mination. The filter paper and contents was returned to the beaker carefully. 100 ml. of boiling water and 10 ml. of 1:1 112804 added to the beaker and the solution titrated with standardized KMnO4 while still hot. The normality of Khn04 x 0.002004 = Ems. Ca in 25 gms. of soil. BET JRE-LlIIATIOEI 01" EXCILAEEGEALLE L'Adhhs IDLE Concentrated hCI was added drOp by drOp to the filtrate from the calcium determination until the solution became slightly acid. Then 10 ml. of a 10% solution of dibasic ammonium phosphate was added and we beaker cooled to 15° C. Then 30 m1. of concentrated hh4OE with vigorous stirring, special care being taken not to touch sides of beaker with P3 4 ‘TI' glass rod. The addition of the nn4OH was added very slowly and with much care. The beaker was placed in a cool place to allow the precipi- tate to settle out. The solution was filtered after all the precipitate had settled and then washed with a dilute solution of ammonia (1 part of concen. HE4CH in 8 parts of water). hush care was taken to remove all precipi- tate from beaker by use of policeman. The titration method of J. 0. Randy (J. Amer. Chem. 300., 1900, 22, pp. 31-39) was used to determine the magnesium ion present. After the precipitate was thoroughly washed and allowed to drain, the filter paper was Opened and as much of the moisture as possible was removed by placing it on another dry filter paper. This process repeated sev- eral times removed most of the moisture. The filter paper was then dried in the air for 45 minutes to remove the free ammonia. The filter paper and precipitate was then placed in a dry beaker and 5 ml. of N/EO H2804 and 3 drOps of methyl orange added to the beaker also. Th whole contents of the beaker was then diluted to 100 ml. with water and titrated with N/lO NaCH solution to a clear yellow color. 1 ml. x u/io H2804 = 0.001216 gm. of magnesium. Darsarirxsicw or REPLACEAELE FOT.33IUE The replaceable potassium in the soil was determined by the volumetric cobaltinitrite method described by C. s. Piper (J. 30. Chem. Ind., 1934, 53, pp. saz-sssT). The following reagents were used in making the determinations: Glacial Acetic Acid Sodium Chloride Solution.--A filtered saturated solution. Sodium Nitrite Solution.--35 gm. f sodium nitrite was dissolved in water, and made up to 100 ml. and filtered. Cobalt Nitrate Solution.--20 gm. of cobalt nitrate, C0(K03)2-6 K20, was dissolved in'water and then made up to 100 m1. and filtered. For washing the precipitate a saturated solution of potassium sodium cobaltinitre was used. This was previously prepared by adding about 0.3 gm. of potassium sodium cobaltinitrite to a liter of dis— tilled water and shaking at intervals for an hour, and then filtering through an 11 cm. Buchner funnel of unglazed porcelain. Since this filtrate is somewhat unstable, it was always used within % to 1 hour. The color decreases noticeably in 1 hour and disappears completely within 2-3 hours. The supply of potassium sodium cobaltinitrite was prepared by precipitating a potassium chloride solution with sodium cobaltinitrite in the presence of sodium chloride. The precipitate was then collected, washed several times with water and dried by washing with alcohol and ether. The filtrate and washings from the magnesium determination was made just acid by adding a few drOps of H01 and then evaporated to dry- ness on a steam bath. The hCl acted as an agent in destroying any sub- stances present other than the potassium salt. After the filtrate had reached dryness, the residue was dissolved in 1.5 ml. of glacial ace- tic acid and 10 ml. of saturated sodium chloride which was added to the beaker in that order, and, after 10 minutes, 5 ml. of sodium nit- rite solution was added. The contents of the beaker was stirred thor- oughly until all soluble substances were dissolved. After a further 5 to 10 minutes, but not longer, 5 ml. of cobalt nitrate solution was -29- added, the addition was made very rapidly, with constant stirring from a pipette with an extra large jet. After a thorough stirring for 40- 60 seconds the beaker was covered and left over night in-a cool place. The supernatant liquid was then decanted through a 10 ml. Gooch crucible charged with asbestos. The asbestos was previously digested with acidified permanganate and then with an excess of oxalic acid; it was then transferred to the crucible, using a rubber-tipped stirring rod, and washed five times with 10 ml. portions of a freshly prepared saturated solution of potassium sodium cobaltinitrite. A measured volume of standard KMnO4, N/TO, about 5 ml. in excess of the quantity required, was pipetted into a beaker, diluted to 150 ml., and 5 ml. of concentrated £2804 added. The crucible and precipi- tate was then added, the solution stirred, and heated just to the boiling point. It was then removed from the flame, and after 5 minutes a small excess of N/20 oxalic acid solution was added. The beaker and contents was then reheated nearly to the boiling point, and the titration com— .pleted with N/TO KKnO4 until a stable pink color first appeared. Blank determinations were carried out to correct for the small amounts of potassium invariably present in the reagents used. The reagents used were considered satisfactory since the blank titration did not exceed 0.5 ml. of N/QO KLEnO4 solution. The presence of ammonium as an impurity in the cobalt nitrate used in the determination leads to a very serious error. Great care was used to eliminate this possible error. The potassium was calculated from the equation: K20 in mgm. - permanganate value x 0.354 4 (permanganate value)2 I 0.000540 -50- The permanganate value being the amount of potassium permanganate, expressed as ml. of N/éO solution, required to oxidize the precipitate. This equation takes into consideration the change in composition of the precipitate as the quantity of potassium increases. DETERNIRATIOH OP READILY AVAILABLE PICSFECRUS The determinations of readily available phosphorus in these soil samples were made by use of the Truog laboratory method. Truog (46) has suggested the designations readily available and difficultly avail- able be used rather than available and unavailable in speaking of the phosphorus of the soil in relation to its availability to plants. The following reagents were used in making the phosphorus deter- minations: Ammonium molybdate-sulfuric acid solution.--25 grams of ammonium molybdate was dissolved in 200 ml. of water and heated to 60°C. and filtered. 280 ml. of arsenic-and phosphorus-free concentrated sulfuric acid (approximately 36 K) was diluted to 800 ml. After both solutions had cooled, ammonium molybdate solution was added to the sulfuric acid solution slowly with shaking. This solution was diluted to exactly 1,000 m1. after cooling to room temperature. This produced a 10 N sulfuric acid solution containing 2.5 grams of ammonium molybdate per 100 ml. Stannous chloride solution.--25 grams of SnClZ°2H20 was dissolved in 1,000 m1. of dilute (10% by volume) H01 solution. The solution was then filtered and stored in a bottle with a side Opening near the bot- tom, arrarved with a glass stepcock for delivering the solution in drOps. -51- The solution was protected from the air by floating a layer of white mineral oil about 5mm. thick over the surface. Sulfuric acid solution for extraction.--A stock solution of exactly N/10 H2804 was prepared by titrating against a standard alkali. Con— venient volumes of 0.002 N H2804 were prepared from the stock solution by dilution. In order to buffer the solution, 3 grams of (NE)ZSO4 per liter was added to the solution to produce a pH of 3 in the final solu- tion. Standard phOSphate solution.--0.2195 gm. of recrystallized potas- sium-dihydrogen-phosphate was dissolved and diluted to 1,000 ml.v This solution contained 50 p.p.m. of phosphorus which was too concentrated for use directly. A second stock solution was made taking 50 m1. This second stock solution contained 5 p.p.m. and was used in making the standard solution for comparison. To make this standard solution 5 ml. of the second stock solution was diluted to 95 ml. with distilled water and 4 m1. of the ammonium molybdate-sulfuric acid solution added and mixed thoroughly. Six drops of stannous chloride was added with a thorough shaking. The solution was then diluted to 100 ml. with a vigorous shaking the solution was ready for use. It contained 0.25 p.p.m. of phosphorus. After standing 10 to 12 minutes the standard starts to fade, and a drop more of stan- nous chloride would then be added to bring the full color back which would again be permanent for 10 to 12 minutes. In develOping the color it was absolutely necessary to maintain the concentration of acid secured according to the directions, since in a less acid solution ammonium hslphdate itself gives the blue color with stannous chloride, and in a more acid solution phosphate fails to give its full color. w rrt-n mm H i'n T‘M‘T’T-t'“ Yarr ‘..T Y'.‘ 1*“ 7'.“ tr \1“ C‘ LX-.‘.1CL .LO-I $.4I‘J ’A‘;J‘A.i1“4 ICJ.‘ CL TaL PLALS- £.C-LL‘Q From the sample of oven-dried soil, 2 grams of 20 mesh soil was placed in a 750 m1. Erlenmeyer flask together with 400 ml. of H/2000 H2804. The flask and contents was then placed in the shaking apparatus for a 30 minute agitation. At the end of this period, the solution was filtered through a ss. 589 filter paper. The filtrate was discarded until it came through perfectly clear. 50 m1. of this clear filtrate was placed in a 200 m1. Erlenmeyer flask, and 2 ml. of ammonium molyb- date-sulphuric acid solution added with a thorough shaking. A blue color developed after this treatment, the intensity depending on the concentration of phosphorus ion in the solution. A standard PhOS‘ solution was treated similarly. The unknown solution was compared with the standard solution within a few minutes in the colorimeter. Calculation of available phosphorus in pounds per acre in the plowed layer was as follows: The 50 ml. of unknown solution used in the analysis represented 50/h00 x 2/1 or 1/4 gram of soil. If the standard contains 0.25 p.p.m. of phosphorus, and it takes say 40 ml. of standard to match the unknown, the amount of phosphorus in the soil will be equal to: 40 0.25 x 0.25/1 or 40 p.p.m. Since the plowed layer of mineral soils weighs approxi- mately 2,000,000 pounds, the am unt of available phosphorus per acre will be equal to 2 x 40 or 80 pounds per acre. -33- EXPERIMENTAL DATA Table 1.--Rate of fertilizer application, amount of phosphorus per application and amount of available phosphorus in soil at different times. all on the acre basis. Plot Treatment Lbs. available phosphorus No. L in soiloatfigigferent times _g 250 lbs Lbs added per acre per applica- *1955 1954 fl955 1956 1957 1958 1959 tion up 4_ 1 5-8-10 8.75 40.7 42.4 56.0 55.8 5250 54.0 57.5 2 0-0-0 0.00 58.9 59.4 54.7 54.7 29.5 38.8 25.6 5 5-16-10 17.46 55.6 58.9 46.6 45.8 42.8 45.4 59.5 4 5-52-10 54.92 69.6 105.8 77.8 68.0 69.5 85.6 50. 5 5-48-10 52.5 115.9 155.5 125.1 99.8 118.7 156.1 59.1 6 5-0-10 0.00 28.5 26.4 26.2 27.1 22.0 20.2 54.1 10 5-8-10 8.75 47.8 49.4 47.8 45.0 40.1 56.5 56.4 11 0-0-0 0.00 45.4 41.6 40.9 44.5 54.7 52.7 24.6 12 5-16-10 17.46 66.5 79.5 68.5 57.0 58.5 61.1 40.1 7 5-52-10 54.92 61.9 66.5 67.7 85.2 62.7 69.8 41.6 8 5-48—10 52.58 100.7 110.5 117.0 97.7 106.5 115.0 60.1 9 5-0—10 0.00 55.5 54.1 29.2 55.2 28.2 26.9 55.2 1A 6-8-10 8.75 59.8 41.5 55.1 50.5 50.5 26.5 57.0 2A 5-0—0 0.00 59.5 57.7 55.4 52.5 50.2 27.0 56.6 5A 6716-10 17.46 54.4 62.6 57.5 47.6 55.4 49.4 47.8 4A 6—52-10 54.92 77.6 99.9 89.8 58.5 79.5 100.5 57.2 5A 6-48-10 52.58 105.8 144.1 157.9 98.6 128.1 158.0 57.6 6A 6-0-10 0.00 57.5 59.1 54.5 51.2 52.0 26.0 56.9 10A 6—8-10 8.75 55.5 56.6 49.5 44.2 44.6 44.4 55.9 11A 5-0-0 0.00 48.4 51.4 47.5 41.1 45.9 42.9 56.5 12A 6-16-10 17.46 5018 66.5 57.1 42.6 50.7 49.9 44.2 7A 6-52-10 54.92 67.7 90.9 75.5 58.7- 70.5 84.9 59.9 8A 6-48-10 52.58 85.4 117.6 97.5 77.5 95.5 115.5 60.1 9A 6-0-10 0.00 29.1 26.5 25.0 25.1 y21.9 25.1 56.5 * Indicates first samplings after phosphorus applications. Regular fertilizer applications were made in spring for barley and in Sept- Nitrog n only was added for other crops. samples were taken in late October or early November each year after time for applying fertilizer for wheat. ember for wheat. Soil -34.. Table 2.--The replaceable bases in soil samples from soil fertility plots in pounds per acre and milliequivalents per 100 _:1 grams of oven—dry soil. Plot Treatment No. 250 1bs./A Calcium Magnesium Potassium Phosphorous M.e./ Lbs./M.e./ Lbs./ M.e./ Lbs./ M.e./ Lbs./ 100 gm. acre 100 gm. acre 100gm. acre lOOgm. acre soil soil soil soil 1 5-8-10 4.54 1755.0 0.510 124.0 0.254 198.2 0.048 57.5 2 0-0-0 4.41 1765.2 0.296 71.9 0.222 175.6 0.055 25.6 5 5'16710 4.25 1700.0 0.296 71.9 0.285 225.0 0.051 59.5 4 5-52-10 4.56 1745.0 0.210 51.2 0.265 205.8 0.064 50.2 5 5-48—10 4.82 1850.0 0.285 68.9 0.285 225.0 0.075 59.1 6 5-0-10 5.71 1484.0 0.412 100.0 0.265 205.8 0.044 54.1 10 5-8-10 4.82 1950.0 0.496 120.8 0.258 195.5 0.046 56.4 11 0-0-0 4.41 1765.2 0.424 105.2 0.256 184.1 0.052 24.6 12 5-16-10 4.98 1910.1 0.266 64.9 0.290 225.8 0.052 40.1 7 5-52-10 4.51 1720.0 0.296 71.9 0.259 202.1 0.055 41.6 8 5-48—10 5.82 2550.0 0.509 75.2 0.294 229.5 0.078 60.1 9 5-0-10 5.85 1540.0 0.412 100.0 0.261 204.0 0.045 55.2 1A 6-8-10 4.18 1670.0 0.424 105.2 0.224 175.0 0.047 57.0 2A 5-0-0 5.44 1572.0 0.595 145.0 0.254 185.1 0.047 57.0 5A 6-16-10 6.75 2700.0 0.266 64.9 0.246 192.0 0.061 47.8 4A 6-52—10 4.52 1808.0 0.558 82.5 0.242 189.4 0.075 57.5 5A 6-48—10 4.64 1855.0 0.595 145.0 0.509 241.8 0.074 57.6 6A 6-0-10 4.29 1715.0 0.496 121.0 0.277 176.9 0.047 57.0 10A 6-8-10 5.41 1565.0 0.412 100.0 0.282 220.0 0.046 55.9 11A 5-0-0 4.69 1875.0 0.740 180.0 0.226 176.0 0.046 25.9 12A 6-16-10 4.20 1680.0 0.559 151.2 0.246 192.0 0.057 44.2 7A 6-52-10 4.46 1785.0 0.750 177.9 0.244 191.1 0.077 59.9 8A 6-48-10 5.92 1570.0 0.611 148.9 0.276 216.0 0.077 59.9 9A 6-0-10 5.92 1570.0 0.595 145.0 0.264 207.5 0.046 56.5 Table 2a.-—The average replaceable bases in soil samples from deuplicate soil fertility plots in pounds per acre and millieguivalents per 100 grams of even-dry soil. P102 Treatment No. 250 1bs./A. Calcium Magnesium Potassium Phosphorus M.e./ Lbs./M.e./' Lbs./ M.e./1bs./M.e./ 1b./ 100 gm. acre 100 gm. acre 100gm acre 100gm acre _‘ soil soil soil soil 2 & 11 0-0-0 4.41 1765.2 0.560 91.1 0.229 178.8 0.055 24.6 2A & 11A 5-0-0 4.05 1625.6 0.667 162.5 0.250 179.5 0.047 56.4~ 6 & 9 5-0—10 2.78 1512.8 0.412 100.0 0.262 204.9 0.044 56.1 6A & 9A 6-0-10 4.11 1641.2 0.545 155.0 0.271 192.9 0.047 56.6 1 & 10 5-8-10 4.58 1852.8 0.505 122.4 0.246 195.8 0.047 56.8 1A & 10A 6-8-10 5.70 1518.0 0.418 101.6 0.255 197.5 0.047 56.4 5 & 12 5-16-10 4.51 1804.8 0.281 68.4" 0.287 224.4 0.055 59.8 5A & 12A 6-16-10 5.47 2191.2 0.402 98.1 0.246 192.0 0.059 46.0 4A & 7A 6-52-10 4.49 1796.0 0.554 150.2 0.245 190.2 0.075‘58.5 5 a 6 5-48-10 5.52 2150.0 0.296 72.1 0.299 226.2 0.076 59.6 5A & 8A 6-48-10 4.28 1712.8 0.605 146.9 0.292 228.9 0.075 58.8_ -36... Table 5.--Grain yields in pounds per acre on phosphorus series ._ __ from 1955 to 1959 inclusive. Plot Treatment *1955 1954 1955 1956 No. 250 lbs./A garley grain limothy Wheat Oats Bu.of Lbs.of Bu.0f Lbs.of Bu.of Lbs.0f Bu.0f Lbss 0f grain Straw grain Straw grain Straw Grain Straw l "5-8-10 10.89 786 -- -- 26.62 2759 57.60 1058 2 0-0-0 5.85 520 -— -- 17.08 2045 28.14 755 5 5-16-10 8.00 555 —- -- 24.68 2556 52.00 781 4 5-52-10 8.89 655 -- -- 27.17 2455 51.20 950 5 5-48-10 7.11 519' -- —- 25.05 2190“ 51.87 954 6 5-0-10 6.67 526 -— -- 17.98 1991 52.00 879 1A 6-8—10 7.78 580 —- -- 21.25 2255 55.74 956 2A 5-0-0 2.89 258 -- -- 15.97 1754 38.14 806 5A 6-16-10 8.15 655 -- -- 28.49 2771 52.67 845 4A 6-52—10 8.00 655 -- -- 50.01 2765 55.5 959 5A 6-48-10 7.41 540 -- -- 25.72 2586 52.94 1007 6A 6-0-10 7.65 644 -- -- 21.64 2511 52.94 947 10 5.8-10 8.15 569 -- —- 25.65 2526 55.07 977 11 09040 5.85 520 -- -- 17.84 2000 27.47 828 12 5-16—10 8.00 647 —- -- 26.07 2502 52.67 917 7 5-22-10 8.22 558 -- -- 25.44 2414 51.54 852 8 5-48-10 7.56 512 -- -- 28.62 2658 51.87 900 9 5-0-10 6.81 512 -— -- 20.05 2116 50.94 879 10A 6-8-10 4.52 452 -- -- 27.95 2658 52.14 986 11A 5-0—0 2.89 258 —- -- 20.88- 2556 27.07 900 12A 6-16-10 7.11 590 -— -- 50.49 5066 50.54 824 7A 6-52-10 6.22 462 -— -- 26.90 2495 26.40 828 8A 6—48-10 7.56 62 - -- 51.80 2945 51.54 981 9A 6-0-10 4.00 584 -- -- 21.45 2448 52.57 990 -37... Table 582—tGrain yields in pounds per acre on phosphorus series from 1955 to 1959 inclusive. Plot Treatment *1957 1958 *1959 No. 250 1bs./A _* Barley Timothy Wheat By.of Lbs.of Bu. of Lbs. of By. of Lbs. of _¢grain straw .grain straw .grain Straw 1 5-8-10 19.91 768 -- -- 25.16 2529 2 0-0~0 7.29‘ 584 -- -- 19.62 1595 5 5-16-10 12.55 491 -- -- 25.05 1988 4 5-52-10 14.22 574 -- -- 24.45 2159 5 5-48—10 11.11 465 -- -- 22.405 1886 6 5-0-10 15.42 559 —- -- 19.42 1647 1A 6-8-10 18.51 789 -- -- 25.46 2048 2A 5-0-0 8.55 455 -- -- 19.05 1587 5A 6-16-10 16.98 666 -— -- 25.51 1954 4A 6-52-10 16.56 740 -- -— 25.45 2099 5A 6-48—10 15.07 565 -- -- 25.16 2159 6A 6-0-10 20.09 952 -- -- 25.74 2116 10 5-8-10 19.11 841 -- -- 25.51 2065 11 0-0—0 6.58 405 -- -- 19.90 1578 12 5-16—10 16.81 754 -— -- 25.88 2051 7 5-52-10 14.94 625 -- -- 25.59 2048 8 5-48-10 17.87 715 -- -- 26.75 2255 10A 6—8-10 15.81 565 -- -- 25.58 2201 11A 5-0-0 5.96 567 -- -— 22.52 1860 12A 6-16-10 12.71 512 —- -- 25.88 2009 7A 6-52-10 12.18 491 -— —- 25.51 2195 8A 6-48-10 14.67 602 —- -- 26202 2195 9A 6-0-10 14.76 614 -- -- 24.45 2116 -39- Table 4.--Grain yields in pounds per acre on phosphorus series from 1935 to 1959 inclusive.1 510t Treatment No. 250 1bs./A Barley Wheat Oats Barley Wheat 1 5-8-10 525 1597 1205 956 1510 2 0-0-0 185 1025 900 550 1177 5 5-16-10 584 1481 1024 601 1582 4 5-52-10 427 1650 998 685 1467 5 5-48-10 541 1502 1020 555 1556 6 5-0-10 520 1079 1024 644 1169 1A 6-8—10 575 1274 1144 879 1408 2A 5-0-0 159 858 900 409 1145 5A 6-16-10 591 1709 1045 815 1459 4A 6—52-10 584 1801 1067 785 1527 5A 6-48-10 556 1545 1084 627 1510 6A 6-0-10 566 1298 1054 964 1424 10 5-8-10 591 1559 1122 917 1519 11 0-0-0 185 1070 879 516 1194 12 5-16-10 584 1564 1045 802 1555 7 5-52-10 595 1526 1005 717 1555 8 5-48-10 565 1717 1020 858 1604 9 5-0-10 527 1205 990 845 1565 10A 6-8-10 217 1676 1028 648 1555 *11A 5-0-0 159 1255 866 286 1559 12A 6-16-10 541 1829 977 610 1555 7A 6-52-10 299 1614 845 585 1519 8A 6-48—10 565 1908 1005 704 1561 9A 6-0-10 192 1286 1055 708 1467 1Acknowledgement is made to Mr. A. G. Weidemann, Research Assist- ant, for his compilation of tables in this study. *Barley 0n plat 11A was destroyed by pheasants. cate plot was inserted here to facilitate averaging and totaling. Yield of dupli- -39... Table 4a.--The total average yield of wheat, oat, and barley grain and the total yield ofrgrain and straw from duplicate plots of the phosphorus series 1955 to 1959, all on pounds per acre basis. Elot Treatment No. 250 1bs./A Wheat Oat Barley Total Yield Total Yield of grain of straw, 1955-1959 excluding inclusive timothy 1955-1959 inclusive '2 a. 11 0-0-0 1117 889 259 5541 5110 2A &11A 5-0-0 1145 885 243 5656 5261 6 & 9 5—0-10 1204 100 554 4485 5881 6A & 9A 6-0-10 1569 1045 557 4896 6761 1 & 10 5-8-10 1541 1162 696 5658 7529 1A & 10A 6-8—10 1478 1086 524 5100 6757 5 & 12 5-16-10 1495 1054 545 5110 6491 5A & 12A 6-16-10 1657 1011 559 5564 6919 4 & 7 5-52-10 1540 1001 555 5191 6605 4A & 7A 6-52-10 1615 956 515 5215 6821 5 & 8 5-48-10 1545 1020 524 5157 6495 5A & 8A 6-48-10 1651 1028 515 5514 6956 -40.. Table 4b.--The total average yield of wheat, oat, and barley grain; and the total yield of straw and grain fromo plotslgrouped according to per cent P in the treat- ment. Plot Z P in Total yield Total yeild No. fertili,er Wheat Oat Barley of grain of staaw treatment 1955-1959 excluding 250 lbs./A inclusive timothy 1955-1959 inclusive 2.11.5. "’ 2A,11A checked 1208 956 598 4096 5605 1 10 . 9 11,10A 61 1509 1124 610 556 7055 5 12 1 51,121 165 1566 1022 541 5257 6705 4.7. 4A,7A 525 1577 978 554 5202 6712 5,8 , 51,61 46% 1588 1024 518 5255 6665 1The fertilizer treatment was applied at the rate of 850 pounds per acre. -41- Table 5.--Fertilizer treatment and the total average yield per treatment from 1955 to 1959 inclusive, all on the acre basis. Plot Treatment Yields (1955-1959 inclusive7 N0. ‘= :_ 4_ ._ 250 lbs. Lbs. of P Total lbs Total lbs per acre added per Total lbs of straw of grain application of grain (excluding and straw Timothy) 1 5-8-10 8.75 5789 7700 15489 2 0-0-0 0.00 5657 5099 8756 5 5-16—10 17.46 4872 6151 11025 4 5-52-10 54.92 5205 6751 11956 5 5-48-10 52.58 4752 5992 10744 6 5-0-10 0.00 4256 5602 ”98381- 101 5-8—10 8.75 5488 6978 12466 11 0-0—0 0.00 5644 5151 8775 12 5-16-10 17.46 5548 6851 12179 7 5-52-10 54.92 5176 6475 11651 8 5—48-10 52.5 5562 6998 12569 9 5-0-10 0.00 4750 6161 10891 1A 6-8-10 8.75 5078 6626 11704 2A 5-0-0 0.00 5429 4800 8229 5A 6-16-10 17.46 5419 6869 12288 4A 6-52-10 54.92 5564 7174 12758 5A 6-48-10 52.58 5090 6625 11715 6A 6-0-10 0.00 5106 6970 12076 10A 6-8-10 8.75 5122 6840 11962 11A 5—0-0 0.00 5885 5721 9604 12A 6-16-10 17.46 5510 7001 12511 7A 6-52-10 54.92 4862 6467 11529 8A 6-48-10 52.58 5559 7247 12785 9A 6-0-10 0.00 4686 6552 11258 -43- Table 6.--Replaceable bases in pounds per acre in plowed layer and the total average yield of wheat, oat, and barley grain in pounds per acre from 1955-1959 inclusive. Yield(1955-1959 incl.) in total pounds per 8. ilot Treatment NO. 250 1bS./$ Pounds per acre in plowed layer 9 K Ca Mg Wheat Oats Barley 2 0-0-0 25.6 175.6 1765.2 79.1 1105 900 267 11 0-0-0 24.6 184.1 1765.2 105.2 1152 679 251 21 2—0.0 56.6 185.1 1574.4 145.0 991 900 274 11A 5-0-07 56.5 176.0 1672.6 160.0 1296 1666 21s 6 5-0-10 54.1 205.6 1484.8 100.0 1124 1024 562 9 5-0-10 55.2 204.0 1540.8 100.0 1284 1990 566 6A 6-0-10 56.9 176.9 1712.6 121.0 1561 1054 655 9A 6-0-10 56.5 207.5 1569.6 145.0 1577 1055 450 1 5-8-10 57.5 197.2 1755.2 126.0 1554 1205 759 10 5—8-10 56.4 195.5 1950.4 120.6 1529 1122 654 1A 6-8-10 57.00 175.0 1676.0 105.2 1541 1144 626 10A 6-8-10 55.9 220.0 1564.0 100.0 1615 1026 455 5 5-15-10 59.5 225.0 1698.4 71.9 1452 1024 495 12 5-16-10 40.1 225.8 1910.2 64.9 1559 1045 595 51 6-16-10 47.8 192.0 2702.4 64.9 1584 1045 605 121 6-16-10 44.2 192.0 1660.0 151.2 1691 977 476 4 5—52-10 50.0 205.6 1744.8 51.2 1549 996 555 7 5-52-10 41.6 202.1 1725.6 71.9 1551 1005 556 4A 6—52-10 57.2 189.4 1606.0 62.5 1664 1067 585 7A 6-52-10 59.9 191.1 1784.0 177.9 1567 845 442 5 5-48-10 59.1 225.0 1950.4 66.9 1429 1020 457 6 5-48-10 60.1 229.5 252926 75.2 1661 1020 611 51 6-48-10 57.6 241.8 1656.0 145.0 1527 1054 492 8A 6—48-10 60.1 216.0 1569.6 148.9 1755 1005 554 I -llu- T"! '1 ‘TC‘ \\_' ”:1 "rwfir‘v Tn.” 12.1.»; LUQICH C.’ l‘LQL/LJAQ The tables given in the appendix of this study give the results obtained by weidemann (50) in his studies with the phoSphorus series at hichigan AgriCthural Experiment Station, East Lansing, hichigan. ' ‘1 The same results are presented by graphs (figure 1 to figure 8 inclus- ive) unde the discussion of results. Results With Wheat From the data in Table 4a, the increase in average yield of plots 2A and 11A over plots 2 and 11 which were total check plots is not con- sidered significant. It is quite apparent, however, that the 3-0-0 treatment caused a marked rise in the replaceable magnesium as show- by figure 6, and table 2a. The increase in yield on plots 6 and 9 over check plots 2 and 11 becores significant with the 3-0-10 treat- ment. This treatment gave a marked increase in replaceable potassium accompanied by a decrease in replaceable calcium and magnesium. Treat- ment G-O-lO on plots 6A and 95 gave a further increase in yield but here, too, the increase of percentage nitrogen in treatment caused an increase in replaceable magnesium and a decrease in the amount of re- placeable potassium. Plots 1 and 10 which received the 3-8-10 treatment gave a sisnif- icant increase in yield over all plots receiving no phOSphorus in their treatments. The 6-8-10 treatment on plots 1A and 105 save a sraller yield than plots 1 and 10. The replaceable macnesium‘was further de- creased with this treatment on plots 11 and 10A. The treatment of lots 3 and 12 with 6 3-16-10 did not five a si'nificant increase in P 1. 0H. «6 07%.... 3.5.1.5 c Lain 3de 3-31.. 3-6-6 c 1.-.... 3-6-6 dime a H.125. mHe... aoHeH 3.3 «6.3; . a e