PHOSPHGRUS UQTAKE BY ALFALFA AS AFFECTED BY fiEPTH OF FERTH..IZER PLACEMENT AND SUPPLEMENTAL ERRIGATION W105i: W: 3210 [399er of M. S. MECi‘iIGAN STATE CGLLEGE Herbert R. Mefzger Hg55 This is to certify that the thesis entitled Phosphorus Uptake by Alfalfa as Affected by Fertilizer Placement and Supplemental Irrigation presented by Herbert H. I‘Tetzger has been accepted towards fulfillment of the requirements for llRStPr'S degree in SCience OHM Major professor PHOSPHORUS UPTAKE BY ALEALFA AS AFFECTED BY DEPTH 0F FERTILIZER PLACER-IBM AND SUPPLEMENTAL IRRIGATION By Herbert R. Metaser AN ABSTRACT Submitted to the School of Graduate Studies of Michigan State College of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Soil Science Year 1955 Approved il- 3. h ui‘ 1 {A .O'.“ , (F I 01 31 the Dho I ABSI‘ FACT Phosphorus uptake by established alfalfa as affected by depth of fertilizer placement and supplemental irrigation was studied. Fertilizer was placed at various depths that ranged from surface appli- cations to depths of twenty four inches. The rates of irrigation tare; none, low irrigation and high irrigation. These tests were conducted on Hillsdale sand;r loan and Brookston clay loam. During the months of July and August the moisture level in the surface six inches of soil drapped to two to four percent available noisture. The percent of fertilizer derived phOSphor'llS in the alfalfa was generally higher for the broadcast and one inch placements on the irrigated plots than from the non-irrigated plots. In addition higher moisture levels increased the uptake of labelled phosphorus placed at the lower soil depths. Feeder roots of alfalfa within the three inch depth of soil on an established alfalfa sod were very active in absorbing fertilizer phosphorus. The activity or number of these feeder roots apparently decreased with an increase in depth as a reduction in the percent of phosphorus in the hay was noted as the depth of fertilizer placement increased. The data presented implies that alfalfa does not derive as large a share of its nutrients from the sub-soil as has been sug- gested by some earlier workers. The idea of a surface pattem of active feeding roots on established alfalfa plants is supported by this work. PHOSPHORUS UPTAKE BY ALFALFA AS AFFECTED BY Dm}! 0F FERTILIZER PLACEI-iENT AND SUPPLEMENTAL IRRIGATION By Herbert H. Metzger L THESIS Submitted to the School of Graduate Studies of Michigan State College of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of mam or SCIENCE Department of Soil Science 1955 AC MIOWLEDG Ell-EMS I would like to express my deep appreciation to Dr. Kirk Lawton.for his help, suggestions, and the interest shown.during the time the research work.was being carried on and while this paper was being written. In addition, the suggestions of Dr. R. L. Cook and Dr. R. M. Swanson in reviewing the manuscript are sincerely appreciated. p.» to *“ Ul g).- C» («’2 “xi v “'2' a - 2‘43- " 7 "use hm u Aé "SIR—oq-Q ‘r .uuu'. J . . $7.": no i..-n‘-‘ 5’3?~ k:‘."IX 6““ INDEX OF FIGURES . . . INDEX OF TABLES. . . . INTRODUCTION . . . . . REVIEW OF LITERATURE . TABLE OF CONTENTS Morphology of Alfalfa Roots. Phosphorus Mbvement and Availability as Related to 8011 I‘IOisture O O O O 0 O O O I O O O I O O O O O 0 Absorption of Surface Applied Phosphate by Alfalfa and Clover . . . . . . . . . . . . EXPERIMENTAL MATERIALS AND METHODS . . . . Description of Experimental Areas. . PlanOfEXPerimen-toeeeeeeee Methods for Soil and Plant Analysis. RESULTS AND DISCUSSION . . . . . . . . . . . . . Soil Moisture and Phosphorus absorption as Normal Precipitation and Irrigation-ExPeriment I. . . Affected by Soil Moisture and Phosphorus Absorption as Affected by Normal Precipitation-~preriment II. . . . . . . . . . Soil Moisture and Phosphorus Absorption as Affected by Normal Precipitation and Irrigation--Experiment III. . Sm‘fl‘mmeeeeeeeeeeeeeoeeeeeeeeeeeee BIBLIOGRAPIHeeeoeeeeeeeeeeeeeeeeeeee ‘Ppmmmeeeeeeeeeeeeeeeeeeeeeeeeee iii iv vi ~10\O\-l=' 12 14 14 25 5O 58 60 hpmz. Figs! 3. “are L. ”an S. Pietro 6 firm 1 Ems 1 Figure lime Figure Figurel. Figure 2. F1831” 30 Figure 1;. Figure 5. Figure 6e Figure 7e Figure 8e F1811" 90 Figure 100 Fight. 11o Figure 12. Figure 13. Figure 11:. Figure 15. um. 16. INDEX OF FIGURES Available soil moisture at the one inch depth, ExpememIeeeeeeeeeeeeeeeeeeoee Available soil moisture at the three inch depth, ExpermentIooooeeeeeeeeeeeeoeeeo Awailable soil moisture at the six inch depth, mement I O C O O O O O O C O O O O O O O O O O O 0 Available soil moisture at the twelve inch depth, men-mam I O O O O O O O O O I O O O O 0 O O O O O 0 Available soil moisture at the twenty four inch depth, Experimentl..................... Available soil moisture under an established alfalfa ”M, memem II 0 O O O O O O O O O O O O O 0 O O O 0 Available soil moisture at the one inch depth, ErperimentIII...._................ Available soil moisture at the three inch depth, ExpeflmentIII.................... Available soil moisture at the six inch depth, ExperimentIII.................... Available soil moisture at the twelve inch depth, ExperimentIII.................... Ayailable soil.moisture at the twenty four'inch depth, ExperimentIII.................... PlotsatExperimentII................ PlotsatExperimentII................ Board that was used to lay out the plots . . . . . . Toolsusedforborings................ Tool used to bore through gravel . . . . . . . . . . . iv 18 19 20 21 22 28 35 36 37 38 39 16 h? 118 1:9 Figure 11: Figure 15 lime 19 limo ZC Finn 21. lien 22. Figure 17 e F1311" 18o Figure 19. Figure 20o Figure 21. Figure 22. Apparatus used to measure the fertilizer . . . . . . . 50 Glass tube and funnel used to place fertilizer atthebottomofthehole . . . . . . . . . . . . . . 51 Funnel used to replace soil in boring holes . . . . . . 52 Equipment used to irrigate the plots . . . . . . . . . 53 One of the plots Just after the first cutting had bGBDMdeeeeeeeeeeeeeeeeeeeeeeee5’4 ViewsoftheplotsinExperimen‘tII......... SS Table 1. Table 2. , . .aale i. Table 3;, Ithle 5. Tibia 5. Table 7. Tible 5. T3513 9. TAble lo. rdble 11. Table 1. Table 2. Table 5. Table he Table 5. Table 6. Table 7. Table 8. Table 9. Table 10. Table 11. INDEX OF TABLES Partial chemical analysis of soils in depth.of fertilizer placement exPeriments. . . . . . . . . . . Rainfall and irrigation data for all experimental areas for the period one week prior to fertilizer application.unti1 final harvest . . . . . . . . . . . The effect of fertilizer placement and irrigation on the absorption of fertilizer phosphorus by an established alfalfa stand on a Hillsdale sandy 103111. (EXPGrimen-tl)eeeeeeeeeeeeeeee The effect of fertilizer placement and irrigation on the phosphorus content of alfalfa cuttings from. a Hillsdale sandy loam. (Experiment I) . . . . . . . The effect of fertilizer placement on the absorption of fertilizer phosphorus by an established alfalfa stand on a Brookston clay loam. (Experiment II). . . The effect of fertilizer placement on the phosphorus content of alfalfa cuttings from a Brookston clay loam. (Experiment II) . . . . . . . The effect of fertilizer placement on the absorption of fertilizer phosphorus by an, established alfalfa stand on a Hillsdale sandy 10w. (EXperimentIII)............... The effect of fertilizer placement and irrigation , on the phosphorus content of alfalfa cuttings from. a Hillsdale sandy loam. (Experiment III) . . . . . . The effect of fertilizer placement and irrigation on the dry weight yield of alfalfa grown on Hillsdale sandy loam. (Experiment I) e e e e e e e e e e e e e The effect of fertilizer placement on the dry weight yield of alfalfa grown on Brookston clay loam. (Experiment II) 0 O O I O O O O O O O O O O O O The effect of fertilizer placement on the dry weight yield of alfalfa grown on Hillsdale sandy loam. (EXPermentIII)eeeeeeeeeeeeeee . vi 15 16 24 25 26 .51 52 55 Table Table Table Table Table Table 12. 15. 14. 15. 16. 17. Data used for calculations. Data used for calculations. Data used for calculations. Data used for calculations. Calculation of standards from labeled fertilizer received in Spring. . . . . . . . . . . . . . . . Calculation of standards from labeled fertilizer received in the summer. . . . . . . . . . . . . . vii (Experiment I) . (mperment 11).. (Experiment III) (Experiment III) 61 62 55 61+ 55 66 the state pmsp'ro r; taint: s \- are able INTRODUCTION Considerable experimental evidence has been obtained in many of the states in the past twenty years indicating surface applications of phosphorus and potassium.are very effective in establishing and mainP taining stands of legumes and grasses. Notably, alfalfa and clovers are able to make effective use of phosphorus applied in bands at plant- ing time and as topdressings of the established legume. Since it is known that phosphorus undergoes very limited downp ward movement in all soils except extremely sandy types, it is logical that absorption of fertilizer phosphate by legumes and grasses occurs largely in the upper layers of soil. Gross morphological studies of alfalfa plants have shown that many small lateral roots are present within the surface six to eight inches. In recent experiments with radioactive phosphate fertilizers, it has been shown that legume and grass roots close to the soil surface are able to absorb relatively large amounts of fertilizer phosphorus. Little information is available concerning the influence of soil moisture on the absorption of fertilizer phosphorus by plants. Since moisture affects root extension and uptake of nutrients as well as movement of phosphorus by diffusion, it is important that such a relationship be better understood. It is the purpose of this paper to study the effect of depth of fertilizer placement and soil moisture levels on the yield and absorption of fertilizer phosphorus by estab- lished alfalfa” REVIEW OF LITERATURE Morphology of Alfalfa Roots The alfalfa plant has both a tap and lateral roots. Although the tap root is the most evident and makes up the largest part of the dry root weight, the smaller lateral roots near the surface are be- lieved to be very important in the absorption of nutrients. Upchurch and Lovvorn (16) noted that approximately fifty percent of all the lateral roots of alfalfa plants grown on.two North.Carolina soils were found to occur within the top three inches of soil. Ruther- more, these workers found that the maximum.depth of tap root penetration was evident by the end of the first year. These roots penetrated to a depth of 24 to 48 inches in a Cecil clay soil and from.#8 to 72 inches in a Norfolk sandy soil. Phosphorus Movement and Availability As Related to Soil Moisture Numerous studies have shown that because of chemical reactions resulting in fixation of soluble phosphorus, the movement of phosphate ions from.source concentrations is greatly retarded. The results of 'topdressed superphosphate experiments by Stanford and NbAuliffe (14) indicated that with.few exceptions ninety percent or more of the applied phosphorus remained within an inch of the point of application even after long periods of contact. They concluded that high rainfall should zmake for somewhat greater downward penetration of the phosphorus dissolve plain slave: g U81 to show i 11:1: . ‘ tent was I'i‘ active s; Hoosier, 01’ the a; three 203‘. Penetmte “Ward my been f’O‘ulfi: the Boil I d“ to th list: soluble 33 Ares t 3.113 C dissolved in the soil solution. These workers were not able to fully explain the high utilization of broadcast phosphate by alfalfa and clover grown under semi-drought conditions. Using granular superphosphate, Lawton and Vomocil (8) were able to show that phosphorus migration away from the granules was very limited. One of the factors having the greatest effect on this move- ment was soil moisture. MbAuliffe, Bradfield and Stanford (9) found that by mixing radio active superphosphate in the l to 5 inch layer of Ontario loam and Wooster, Erie and Canfield silt loams, about twenty to thirty percent of the applied phosphate moved out of the zone of incorporation within three months. However, only a small proportion of this phosphorus penetrated more than two inches below the zone of application. Some upward movement of phosphate was also noted. For some soils it has been found by McAuliffe et a1. (9) that the phosphorus concentration in the soil solutidn is nearly independent of the quantity of water present due to the comparatively low solubility of phosphorus compounds. Motzger (10) in 1940 found that a large proportion of the easily soluble phosphorus, which accumulated in the soil following the top- dressing of various phosphates on alfalfa for twenty-seven years, re- mained in the surface four inches of soil. Experiments by Jordan et.al. (6) showed that the amount of water influences the downward movement of fertilizer phosphorus in the soil. The more supplemental water applied, the greater was the movement of tagged phosphate ions. However, these workers found that potatoes absorbed more fertilizer ans soil phosphorus at low moisture tensions than when soil moisture contents were high. Satchell (12) studied the movement of phosphates in soil systems. His work showed that phosphate movement was predominately upward from the fertilizer band in the Norfolk soil in a dry season. In a Bladen soil the phosphate movement was predominately downward with some lateral movement during a wet season. Phosphate movement was increased when the rate of application was increased. Analysis of samples taken from the Bladen soil fifty-one days after placement indicated considerably more movement of phosphates than.did samples taken thirty days after placement. There was also greater movement of phosphate in a soil with.a low phosphorus content than in soils high in available phosphorus. Satchell's work indicated that the phosphorus from.superphosphate exhibited the greatest move- ment when compared with di-calcium phosphate, calcium.metaphosphate, and fused rock phosphate. However, the mobility in soils varied and in some soils the movement was negligible. Absorption of Surface Applied Phosphate by Alfalfa and Clovers With the use of P$2 labeled fertilizers, it has recently been possible to determine the relative amounts of soil and fertilizer phosphorus taken.up by plants from different fertilizer sources and placements. Stanford and Nelson (15) found that from.twenty to fifty percent of the phosphorus in alfalfa, ladino clover, and orchard grass was de- rived from topdressed phosphate. They concluded that this high utilization of fertilizer phosphorus was due to a large number of active roots near the surface. More than one half of the total root growth of these forage plants was found in the surface eight inches of soil. The utilization of applied phosphorus was much the same for the three crops despite marked differences in the general characteristics of their root systems. Simdlar experiments by Blasser and Mckuliffe (l) with radio- active fertilizer have proven that Ladino clover and orchard grass have very active feeding roots in the surface six inches of soil. Llflton, Tesar, and Kawin (7) also obtained relatively high absorption of fertilizer phosphorus by alfalfa and alfalfa-bromegrass crops from.topdressed superphosphate. Depth placement with P52 studies by these workers have shown that the absorption of applied phosphate falls off rapidly with depth. With placements below six inches for bromegrass and below twelve inches for alfalfa, little fer- tilizer phosphorus was taken up by these plants. EXPERIMENTAL MATERIAIS AND METHODS Description of Experimental Areas Experiment I This experiment was located in the SW l/h of SW 1A; of Section 25, Lansing township, Ingham County, Michigan. The soil was Hillsdale sandy loan, which is a well drained glacial till soil. The area chosen had third year alfalfa. This field was seeded with cats in 1951. The alfalfa stand in the field was good containing 95 percent alfalfa and 5 percent weeds and grasses. Soil samples were collected at various depths prior to laying out the experiment. Values for soil reaction, phosphorus and potassium extractable in 0.13 N H31 according to Spunay and Lawton (l3) and exchangeable calcium by the method of Chang and Bray (2) of these samples are reported in Table I. Rainfall records for this area which were obtained from a weather station about a mile distant are presented in Table 2. Experiment II This experimental area was located in the NI l/h of Section 33, Saginaw County, Michigan. The soil was a Brookston clay loan, a naturally poorly drained soil, which was well tiled. The field had first year alfalfa which had been seeded with oats in 1953. There was a good stand of alfalfa with ninety percent alfalfa and ten percent weeds and grasses. Before fertilizers were applied, soil samples were collected at different depths up to. 18 inches for analysis of soil reaction, available phOSphorus and potassium, and exchangeable calcium. These results are presented in Table I. Rainfall figures for this experiment were obtained from daily records obtained at the farm area, and are listed in Table 2. Experiment III This plot area was also third year alfalfa on Hillsdale sandy loam closely adjacent to that of Experiment I and located in the same field. Soil samples were taken in June for the specific chemical analysis as reported in Table I. The source of rainfall records was the same as for Experiment I. Plan of Experiment Experiment I Plots nine square feet in area were placed in a randomized block design with two replicates of each fertilizer and irrigation treatment, note Figure 12. Concentrated superphosphate (O-h8-O) tagged with P32 and having a specific activity of 0.3 millicures per gram of P205, was broadcast and placed at depths of l, 3, 6, 12 and 21; inches in a grid pattern. The holes were drilled for the fertilizer placement in a 6 inch by 6 inch pattern over the 3 by 3 foot plots by using a 5/8 inch soil auger. To prevent contamination along the sides of the holes, the dry fertilizer was placed at the bottom of the auger holes by using a glass -. .tube and a funnel. These holes were then refilled with dry soil. Fa 23434.qu ,n t .. L. 1.! . . A. .11. 9 Mn .13.... . .45....«41... s Q ,v ("F- TABLE 1. PARTIAL CHEMICAL ANALYSIS OF SOILS IN DEPTH.OF FERTILIZER PLACEMENT EXPERIMENTS rSampling Depth ------- Pounds Per Acre ---...-........ Inches pH P* ' K* Ca** ExPeriment I 0-2 6.11 15 41 214110 2-4 6.1 4 16 2440 5-7 6.2 5 15 2592 11-15 6.6 5 15 2576 22.24 7.4 90 15 3056 Experiment II 0-2 5.9 25 50 5000 2.4 6.2 26 52 6000 5-7 6.5 11 21 4592 11-15 6.8 25 18 5624 16-18 6.9 150 16 5560 Experiment III 0-2 6.1 51 1+2 5968 2-4 6.2 6 16 510%; 5-7 . 6.4 5 20 3-424 11-15 6.6 5 17 5852 22-24 7.7 60 11 5088 * Extracted with 0.15N'HCl solution *‘ Extracted with 25% name; solution TABLE 2. RAINFALL AND IRRIGATION DATA FOR ALL EXPERIMENTAL AREAS FOR THE PERIOD ONE WEEK PRIOR TO FERTILIZER.APPLICATION UNTIL FINAL HAY HARVEST Experiment I Inches of Water ExPeriment II Experiment III Inches of Water Date Rain Irrigation Date Rain Date Rain Irrigation . Low High 4/16 .02 4/27 1.26 6/19 1.10 3/19 .08 5/1 .24 6/20 .61 4/20 .54 5/5 .09 6721 .15 4/24 .25 5/5 .05 6/24 .57 4/26 .15 5/8 .02 6/28 .20 4/27 .20 5/9 .08 7/5 .59 ' .58 5/2 .16 5/11 .05 7/5 .42 5/8 .55 5/51 .118 7/8 .22 5/9 .08 6/1 .80 [7/14 .05 .59 .58 5/19 .08 .77 6/5 .96 7/19 .20 .19 .59 5/25 .16 6/10 .06 7/22 .22 .59 .58 5/24 .77 6/16 .54 7/26 .54 .59 .77 5/27 .07 6/19 1.67 7/28 .14 .59 .96 5/28 .11 .77 6/20 .50 7/50 .10 .19 5/51 .98 6/22 1.01 ' 6/1 .45 6/12 1.15 6/15 .04 Total 4.59 2.51 5.78 5.181.75 5.86 . Fertilizer applied April 17 ** Fertilizer applied may 5 *** Fertilizer applied June 21 3.1 a ‘31P . 1 2312333333 .._1 w .:..._. . , _ . ll [flint III 1]] . . . e e e e e stamina: . . .d . Switéakt 10 The superphosphate was placed in the ground on April 17th. To insure that a potassium deficiency would not affect the results muriate of potash was applied with the superphosphate at the rate of 15l pounds per acre of K20. The triple superphosphate was applied at the rate of 171 pounds of P205 per acre. A gypsum.moisture block was buried at the same depth as the fer- tilizer, but six inches adjacent to each plot. Measurements of percent available moisture were made using a Bouyoucos moisture meter usually twice weekly or 12 hours after precipitation occured. Supplemental water was applied to the irrigated plots over a 5 by 5 foot area in an attempt to maintain a continuous level of about sixty percent available soil moisture. Three samples of alfalfa plants were taken on Kay 29th, June 7th, and June 15th respectively. For each sample three square feet was cut. The plant material was weighed, dried, ground and 2 gram pellets were pressed at 14,000 pounds per square inch for radioactive assay. Phosphorus analysis was made of the pelleted plant material. Experiment II Three feet square (square yard) plots were placed in a randomized block design, using two replicates of each fertilizer depth placement. The P52 labeled concentrated superphosphate (0-48—0) and muriate of potash were applied on.Hay 5th, as described in Experiment I, except that the depths of placement were changed to those of l, 5, 6, 12 and 18 inches. At the start of the experiment gypsum moisture blocks were ll (placed at each of the above depths. No supplemental irrigation was made on these plots. Moisture readings for available soil water were taken about once a week. Plant samples were cut from three square foot areas of each plot on May 28th, June 7th, and on June 26th; in addition the first area was recnt on July 16th. Dry plant weights were recorded and samples prepared for specific activity and total phosphorus analysis as in Experiment I. Experiment III The experimental design used in this mcperiment was a radomized block utilizing two replications of each fertilizer and soil moisture level, note Figures 13 to 22. Triple superphosphate (0-118-0) tagged with P32 and muriate of potash was applied broadcast and at depths of 1, 3, 6, 12, and 211 inch depths on June let. The labeled fertilizer had a specific activity of about 0.3 millicurie per gram of P205 when the material was applied. The rates of application were equivalent to those described in Experiment I. One set of plots was not irrigated, while supplemental water was added to another set in moderate amounts in an attempt to keep the available moisture level at approximately _ forty to sixty percent. In the third group of plots in the experiment using the normal precipitation plus a high level of supplemental water an attupt was made to keep the moisture content of the soil at approxi- mately sixty to eighty percent. I Plant samples were cut on July 9th, July 20th, and August lst and dry weights recorded. The plant material was prepared for radio- I‘ll}! 5 I 7.33341. nae - a. . .I 2.! .e dines. 2. a? e .. cw...” .“I‘v.‘ . e V ,.. . lee-LIME y t in. O\ 12 active and total analyses as in Experiment I and II. Two standards were made from the labeled fertilizer received during the first of the season and two standards were made from the labeled fertilizer received during the middle of the summer. The same pellets used for radioactive assay were used in the total phosphorus analysis. The plant material was wet ashed using nitric, sulfuric and perchloric acids as described by Piper (11). The residue remaining after ashing was taken up in 0.2 N. hydro- chloric acid and.made to volume. Phosphorus in these plant ash solutions was determined as molybdenum.blue using a Coleman Spectro- photometer'with transmission values of unknown and standard solutions compared at 650 millimicrons. Methods for Soil and Plant.Analysis All soil samples used for chemical analyses were air dried and screened through a two mm. sieve. Soil reaction determinations were made on a 1:1 soil to water suSpensions by weight, using a Beckman 3H2 pH meter. Available soil phOSphorus and potassium were extracted and determined according to the reserve procedure by Spurway and Lawton (13) .A Coleman spectrophotometer was used to make comparative transmission.measurements between standards and unknowns for'both elements. Exchangeable calcium.was determined according to the pro- cedure of Cheng and Bray (2) in which exchangeable calcium is extr- acted with a twenty three percent sodium.nitrate solution. An aliquot of this extract is titrated with O.b percent versenate solu- tion(disodium-dihydrogen ethylenediamine tetraacetic acid) using a luretide indicator. 15 Elant material was prepared for specific activity measurements by pressing two grams of dry, ground tissue into a one inch diameter pellet under lh,000 pounds per square inch for one minute. Using a Geigerbmuller tube in conjunction with a Decade Sealer, the activity of the pellet was determined and compared with a standard pellet containing a known amount of radioactive superphosphate. A uniform distribution of P32 in the standard pellet was obtained by dissolving a given quantity of the labeled fertilizer in dilute hydrochloric acid solution and thoroughly moistening a given weight of dry plant material. .After drying at 600 centigrade, two grams of this standard material was pressed into a pellet. “ l|||! .Iiill 1‘ .l Ix v. 1 I I In! “ ’\ I > v E 6."... Jinx»... as L... .. .z. 4,415.31: I . i . [Putt . 'Pl,‘ . a, ,. . . . , . e _ L lllh» 14 RESULTS AND DISCUSSION EXPeriment I From Table 5 it is apparent that irrigation did not influence the percent of phosphorus in the alfalfa cuttings. However, the phos- phorus content of the cuttings declined with the lower depths of fer- tilizer placement. The phosphorus content of the alfalfa was highest for the first sampling and successively lower for the second and third samplings. It is probable that the early spring growth of established alfalfa plants is higher in phosphorus largely because of a dilution of this element with a rapid increase in dry weight production toward the harvest period. The relationship between the depth of the fertilizer placement and the percent of phosphoms derived from the fertilizer is given in Table 4. The percent of plant phosphorus derived from the fertilizer declined with the deeper placement of the labeled superphosphate. There was as shown in Table 4, a slight difference between the irri- gated and the non-irrigated plots for the May 29 and the June 7 cut- tings. The reason the irrigated plots did not show a higher absorption of fertilizer phosphorus when compared with the non-irrigated plots was no doubt due to the high rainfall so that the soil moisture level was similar in both plots. The June 15 cutting showed an appreciable difference in the absorption of phosphorus from the labeled superphos- phate. The amount absorbed from all but the three inch depth was in- creased by irrigation. The moisture might have stimulated more feeder root development. i..Yn\ \ _ final. galw .1”,- mam. J's .zalu-avv M,=.1W$.W..f4}. u... 5 .. a . . v , ., . . Inks-3’“ s. . “a. \ h . . .H La. PS; _ .1..._. l. | | ,n ‘ tray TABLE 5. THE EFFECT OF FERTILIZER PLACE-E'IT AND IRRIGATION ON THE PHOSPHORUS CONTENT OF ALFALFA F R015": A HILISDALE SANDY LOAN. (Experiment I) Depth of Percent phosphorus in alfalfa cuttings fertilizer at sampling dates placement in inches may 29* June 7 June 15 No Irrigation Surface*** 0.46MI 0.54 0.56 1 0.45 0.51 0.50 5 0.44 0.52 0.50 6 0.46 0.55 0.29 12 0.42 0.51 0.28 20 0.44 0.51 0.26 Check --- 0.50 0.55 Irrigated Surface*** 0.46 0.55 0.55 l 0.45 0.52 0.50 5 0.46 0.52 0.50 6 0.58 0.51 0.50 12 0.42 0.50 0.24 24 0.42 0.29 0.26 Check --- 0.55 0.25 * Plots put in April 17th and 18th *‘0' All values are averages of two replicates. *IN' Broadcast application a . L.!_1,..w._.lfi 2.3.7.. 25.11:; a...“ 1.1.4.1 4, . . .0 .a .H..Lrn!... 2:... , . I . ,4 .1. Hi... i . F . 16 TABLE 4. THE EFFECT OF FERTILIZER PLACEMENT AND IRRIGATION ON THE ABSORPTION OE FERTILIZER PHOSPHORUS BY AN ESTABLISHED ALFALFA STAND ON A HILLSDALE SAND! LOAN. (Experiment I) Depth of Percent plant phosphorus derived from. fertilizer fertilizer at sampling dates placement in inches may 29* June 7 June 15 No Irrigation Surface*** l7.9** 52.2 14.7 1 17.2 20.5 14.1 5 10.6 51.0 19.5 6 7.2 15.5 12.7 12 2.5 6.5 5.4 24 1.9 5.5 2.1 Irrigated Surface*** 25.1 56.7 54.6 1 14.7 27.9 25.8 5 8.7 27.4 17.5 6 7.4 24.2 18.8 12 2.5 8.1 10.9 24 0.7 5.7 4.8 :* Plots put in April l7th.and 18th ‘*** Broadcast application; other placements localized Allfvilues are averages of two replicates. 4—“... 'hfla-l ‘1‘; .1 . .r .u. 4 , a. lull, .1 V a mflld anon-.1fluhfl4inmflfil.‘ 4a. . . . .. . ...‘.,. .r» t-..” . .13.». .x I... \ l7 ' In 1955 Lawton et a1. (7) worked with the uptake of fertilizer phosphorus placed at different depths. Their plots were not irrigated. The uptake of fertilizer phosphorus from.the non-irrigated plots was similar to that reported by Lawton and Tesar. However, in the present study the percent of plant phosphorus derived from.the surface applied fertilizer was lower, possibly indicating less contamination of P52 on the plant surfaces. With one exception the percent of fertilizer derived phosphorus in alfalfa from.plots having surface applied or one inch placements was higher where supplemental water was applied. It can also be noted from Table 4 that absorption of fertilizer phosphorus was greater in plants from.the irrigated areas on June 7 and June 15 from plots where fer- tilizer was placed at the 6 and 12 inch depths. No explanation can be given for the reversal of this trend for the 5 inch depth placement. Examination of the available soil moisture data in Figures 1, 2 and 5 show that the surface six inches of the nonpirrigated areas contains less than twenty percent available water from.May 24 to May 50. The very dry period represented here may account for a higher content of plant phosphorus derived from.fertilizer in alfalfa from some of the irrigated plots. It should be noted, however, that plant material from non-irrigated plots receiving fertilizer at the 1, 5, 12 and 24 inch depths was slightly higher in fertilizer phosphorus than alfalfa from. corresponding irrigated plots at the why 29 sampling. A similar instance was noted for alfalfa cut from.5 inch depth fertilizer placement plots on June 7. It is evident from the data in Table 1 that there are some imp portant differences in pH and 'available' phosphorus and potassium.than 18 AH pcmefipoaxmv .COflpmwflsaw new cowhwpwowomsa Hesse: as Umgommmm 4 we now mmammam teamwanwpmo cm amps: xenon socw H mew pm waspwwoe HflOm manwawm>< .H mpsmflm 05:. 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TR ,1 2 his -. 1 . l. _.\.~QHL. a...— . . .n1 A. . 3...?”1 l .. p , ._. {Bull .. . . . , . h 22 AH unmawpoaxmv .cowpmmwssw one cowpmpwowomsa Hesse: an Umpomwmw we now mMHmaHm nmhmenmpmm cm pesos Lemme Locw mm are pm waspmHoa HHom OHpoHHw>¢7 .m mssmHm lullmcg. ‘11 he; .1 .. .u. .Hm.m mHmmHaHHmHHHmN mH o H H A ll HHH COHpmmHsLH Ill 14 ON COHpmpHoHomsm Haemoz J om J 3 I1 0m J om I 2. amps: mo mogoch _ b n h b b— b O a, I O O O O O. I o O O . a Z a»... a. an as u d C/ eansIom 1105;81q9119A9 quasi Jaw—T93, . .31....M4M.’ 2. . ; 1. . 41.3.33 21.51%, TE . 4 .. . . ..1 grin L V. .1... ..H... .. .a. . . 23 samples taken up to twelve inches. In two of these experiments the lowest soil pH was found within the 0—-2 inch soil depth. Samples taken about twentyafour inches deept for Experiment I and III were considerably higher in pH and acid extractable phosphorus. How such effect this high phosphate level in an alkaline medium.has in reducing fertilizer phosphorus absorption from this depth is not known. How— ever, soil test correlation studies by Lawton et a1 (8) on some of the alkaline soils of Michigan show that phosphorus extracted with a strong acid does not correlate too well with response of alfalfa to phosphate fertilizer. At final harvest on June 15 the dry weight of alfalfa listed in Table 5 did not vary appreciably between the irrigated and non-irri- gated areas when plots of similar depth.were compared. It should be emphasized that significant differences for yield figures based on three square feet are likely to be quite high. Experiment II In Table 6 data for the phosphorus content of alfalfa are given :for three samplings of first growth and one sampling of second growth hay on a Brookston clay loam soil. Again as in Experiment 1, these values decreased with depth.of fertilizer placement, especially at the June 7 and the June 26 samplings. The absorption of fertilizer phosphorus by alfalfa as affected by depth of fertilizer placement is listed in Table 7. The highest absorption of fertilizer phosphorus was from the labeled phosphate placed on the surface and at depths of one and three inches. It is . . I o e . . 1!..Wa...—...v}.,_w .2): .‘a... non-.5. ,.!m_o-_1.I_i $.1flL1? a... .11.. V a, .4 .. .. .: nhbtt 24 TABLE 5. THE EFFECT OF FERTILIZER PLACER-{KIT AND IRRIGATION ON THE DRY WEIGHT YIELD 0F.ALEALFA GROWN ON HILLSDALE SANDY LOAN. (Experiment I) Depth of Grams of air dry hay per three square feet at fertilizer sampling dates placement b in inches may 29 June 7 June 15 N0 Irrigation Surface** 74.5* 140.1 124.4 1 59.0 121.1 154.4 5 75.0 155.6 151.9 6 68.0 128.1 171.4 12 58.5 125.1 179.4 24 60.5 119.1 159.4 Average*** 65.6 127.8 146.8 Check, 51.5 119.6 141.4 Irrigated Surface** 70.5 185.1 142.9 1 68.0 141.1 159.9 5 70.5 116.6 157.4 6 59.0 104.6 125.4 12 70.0 156.6 155.4 24 69.5 155.1 109.4 Average*** 67.9 119.0 154.7 ‘Oheck --- 142.6 100.4 * Values are the averages of two replicates. ** Broadcast application; other placements localized *** Check plots were not included. O l I O O I I O I e O 0 I O O _ L O . 0 e e e o e e I I e I I I I e O D a o o e p e I e e a e o e 0 e v . -h... . .. 1|! you! . <.w.3.........r.:4 .....,.H T ,. 9......m.\w I... .2... I. . .1 To . . . .f . TABLE 6. THE EFFECT OF FERTILIZER PLACER-EFT ON THE PHOSPHORUS comma 0F ALFALFA CUTTINGS FROM A BRDOKSTON CLAY LOAN. (Experiment II) Depth of Percent phosphorus in alfalfa cuttings fertilizer at sampling dates placement in inches lhy'28* June 7 June 26 July 16"".l 1 Surface**** 0.24*** 0.52 0.25 0.51 1 0.24 0.55 0.22 0.27 5 0.25 0.25 0.27 0.55 6 0.20 0.21 0.19 0.24 12 0.25 0.18 0.20 0.27 18 0.22 0.20 0.20 0.25 * Fertilizer put in may 5th ** First area recut *** All values are averages of two replicates. *ttt Broadcast application; others localized .40 1.5 M 1.1%.. :..:...3......m. 1" .I . .. «3...... 41....- 3?, In. L. . h . L. \ I; ‘5. H . .lv . l is \ v s . .A . u . l :I ..... I {All 0 . l 26 TABLE 7. THE EFFECT OF‘ FERTILIZER PLACE'IENT ON THE ABSORPTION OF FERTILIZER PHOSPHORUS BY KN ESTABLISHED ALFALFA STAND ON A BROOKSTON CLAY LOAM. (Experiment II) Depth.of Percent plant phosphorus derived from fertilizer fertilizer at sampling dates* placement in.inches Lhy'28 June 7 June 26 July 16** Surfaoetttt 45.9*** 47.6 82.6 14.8 1 28.0 41.2 69.8 18.8 5 17.5 59.6 48.0 15.0 6 4.9 18.2 47.0 11.6 12 5.6 19.5 20.4 14.8 18 4.2 4.5 15.7 4.0 * Fertilizer applied may 5th ** First area recut *** All values are averages of two replicates. **** Broadcast application; other placements localized 2? interesting to note that the feeder roots in the top soil are more active in the spring than those at the lower levels. However, in the June 7 and June 26 cuttings while the feeder roots in the surface three inches remained active the roots in the 6, 12 and 18 inch depths inp creased their activity. Possibly the latter difference was influenced by the lower moisture levels at the l and 5 inch depths during the last of may as indicated in Figure 6. Although no data were collected on the movement of fertilizer phosphorus in the soil, on the basis of work by Fiskel et a1 (4) and others it is postulated that extensive downward movement of phosphate ions from surface applications was negligible. Fiskel and co-workers concluded that very little of surface applied phosphate penetrated to a depth greater than one inch, and that more than ninety percent of the phosphate that was broadcast remained in the surface one inch of soil. The reasons for such a high proportion of plant phosphorus derived from surface applied or 1, 5 and 6 inch depth placements of fertilizer in the may 29 cutting are not clear. Precipitation.from may 5, the date of the fertilizer application, to may 50 was only 0.18 inches and available soil moisture during the last week in may in the surface six inches was less than twentyafive percent. The moisture levels at the 12 and 18 inch depths of soil were high. During the month of may the moisture blocks at these depths never read lower than.fifty-three per- cent available moisture as indicated on Figure 6. Evidence accumulated over the years has indicated that downward penetration of phosphorus usually is quite limited. The studies of Stanford et a1 (14) indicate that ninety percent or more of the Is: 5... . Jain» .. . . I a. , . . . 11a . LA .. .. I. 2.41:...»1j .......:.H. . 1.x 1 § /~_«I 9 . n1 :4 . H . .. . l .. . ..I. .I L 28 AHH psoswpmaxmv .sowpmpwawooaa Hmshoc an 8882.. we com 82:... 1.918338 as $2.. 9.539.. flow 823?: 6 REE we on mmHNSSHmHSaaM —-II*EFI¢W . .. lwllhfirlhfirlePlhflPIldfl . u a m d d _ I o sowpmpflawomaa HQHFHOZ I II. c), I ~ I ~ / In ~ / s I/ . I I ~ / I \IoJ . , L ’ av / Av I\\\\\\//I / I I. / I1 I \ / - o z .m o I I I I. .klvr .1 //I 1111111 null_I 1‘ b I I I \.\ / 5.“! —y _ p38,: mo monocH §d p . 1 P n b P v. n «a a w w a CH ON on 00 0w ow sandstow {109 etqetpene qusoaea ; pflrrflcfli” :5! HI; ........ I.‘ 5......ewkv. ... .. . .I .. a . , 33...! .1} . I l ., .a H... 5.3:... 5.2.1.... I H 29 applied phosphorus remained within an inch of the point of application even after long periods of contact. These workers also found that a relatively high proportion of the phosphorus absorbed by alfalfa, ladino clover and orchard grass was derived from.surface applications of superphosphate. Utilization of the fertilizer phosphorus was much ; the same for the three crops despite the fact that alfalfa is a rela- rively deep rooted plant while ladino clover is shallow rooted. The work of Stanford et a1 (14) supports the data presented here which indicates the presence of a surface pattern of active feeding roots of z . established alfalfa plants. Another condition which may have resulted in a greater absorption of fertilizer phosphorus by roots within the surface foot is that a min- imum.of fixation of phosphorus probably occurred with the fertilizer placed in soil down to the 12 inch depth. The surface foot of soil was slightly acid in reaction and therefore, the applied phosphorus was somewhat more available to alfalfa than fertilizer phosphorus placed eighteen inches below the surface where the soil was alkaline as in- dicated in Table l. I The percent of fertilizer phosphorus in alfalfa from the first area that was recut on July 16 was quite uniform for all the depth placements except that of eighteen inches. It seems quite notable that the second cutting of alfalfa absorbed approximately fifteen percent of its phosphorus from the fertilizer placed at any depth down to twelve inches two months previously. Since no moisture readings were made after June 8 no relationship between soil moisture and phosphorus up— take can be drawn. 4.283% .15.... ., I. new... I ,IE ,kmk 111. Jule” - ,. “idly... .. .41.: 1 Julia: I I \N O In June the rainfall was low and the available soil moisture in the surface six inches declined rapidly (see Figure 6). During this time increased amounts of fertilizer derived phosphorus were being ab- sorbed from the 12 and 18 inch depths as illustrated by Table 7. This might be explained by the decrease in activity of the feeder roots near the surface and an increase in the activity of the feeder roots at the 12 and 18 inch depths due to the more favorable moisture conditions. From.the data in Table 8 it can be concluded that the depth of fertilizer placement had little or no effect on dry weight yields at any of the sampling dates. Experiment III The values for the phosphorus content and percent of phosphorus derived from fertilizer for the dry plant material are presented in Tables 9 and 10 respectively. In general, little difference was noted between the phosphorus content of alfalfa where fertilizer was placed at different depths. Also, the use of supplemental water seemed to have little effect on the percent of phosphorus in second growth alfalfa. However, one exception should be noted. Alfalfa from the August 1 cutting on the non-irrigated plots was substantially lower than that grown under high irrigation. A higher phosplnrunuptake was also re- corded at this time since the dry weight yield for the high irrigation rate was higher than where no supplemental water was applied. marked differences in absorption of fertilizer phosphorus were noted with variation in depth of fertilizer placement but not for rates of irrigation. As in Experiments I and II, the highest amount of 51 TABLE 8.. THE EFFECT OF FERTILIZER PLAGEEENT ON THE DRY WEIGHT YIELD OF ALEALFE GROWN ON BROOKSTON CLAY LOAM. (Experiment III) Depth of Grams of air dry hay per three aquare feet at fertilizer sampling dates placement in inches may 28 June 7 June 26 July 16* Surface 73.4** 87.4 161.1 57.6 1 70.4 112.4 125.6 40.1 5 69.9 105.4 150.6 42.1 6 52.4 98.4 124.6 49.6 12 70.9 97.4 141.1 45.6 18 76.4 95.9 110.1 51.1 Check ---- 84.4 114.1 -- Average*** 68.9 99.1 151.8 94.0 * First area recut ** Values are averages of two replicates. *** Does not include the check plots I a . I I u D o 0 e a . 6.13%}... .....33.4-1.4....1fininsa... ............L. .. . _ . 4“. i . ..\... ii...» I TABLE 9. THE EFFECT OF FERTILIZER PLACEKEET AND IRRIGATION ON THE PHOSPHORUS CONTENT OF ALFALFA FROM A HILLSDALE SANDY LOAN. (Experiment III) Depth of Percent total phosphorus in alfalfa cuttings fertilizer at sampling date* placement in inches July 9 July 20 August 1 No Irrigation .‘3'ur.face'|"|"|l 0.55** 0.29 0.21 1 0.51 0.25 0.19 5 0.55 0.28 0.18 6 0.52 0.25 0.18 12 0.52 0.24 0.19 24 0.52 0.26 0.18 Check 0.28 0.29 0.16 Low Irrigation Surface*** 0.56** 0.29 0.25 1 0.56 0.50 0.20 5 0.29 0.29 0.20 6 0.55 0.28 0.21 12 0.55 0.28 0.21 24 0.54 0.52 0.24 Check 0.40 0.29 0.25 High Irrigation Surface*** 0.55 0.50 0.25 1 0.55 0.51 0.25 5 0.56 0.29 0.22 6 0.52 0.29 0.22 12 0.55 0.28 0.19 Check 0.26 0.28 0.28 * Fertilizers applied June 21st ** All values are averages of two replications. *** Broadcast application; other placements localized 33 TABLE 10. THE EFFECT OF FERTILIZER PLACEMENT ON THE ABSORPTION OF ' FERTILIZER PHOSPHORUS BY AN ESTABLISHED ALFALFA STAND ON A HILLSDALE SANDY LOAM. (Experiment III) Depth.of Percent plant phosphorus derived from. fertilizer fertilizer at sampling dates* placement in inches July 9 July 20 August 1 No Irrigation Surface*** 27.0** 51.5 55.8 1 10.6 19.9 24.1 5 0.4 19.9 19.9 6 6.1 14.0 17.2 12 2.4 7.5 11.2 24' 1.0 2.0 1.7 Low Irrigation 3urface*** 22.0** 52.0 26.0 1 6.5 10.7 15.7 5 5.2 12-2 25.5 5 5.2 5.5 7.2 12 .9 4.7 5.1 24 .7 1.4 1.8 High Irrigation Surface*** 29.8"".l 15.5 52.2 1 9.4 17.9 25.6 5 9.8 19.5 25.8 6 7.8 16.0 25.5 12 2.6 5.6 8.8 * Fbrtilizer applied June 2lst ** All values are averages of two replicates. *** Broadcast application; other placements localized 4i!‘ 1 ._ . 3...... . i ._ . {LAW-cw .. E... :33 .. a . .2: ”Lid. 3.! i O C I 0 Q Q I O I I a l O I I O a I O I Q I O u o e u 0 0 O C 0 O O O c e O I 0 0 o v U I I l b C Q I I v. .61.... q . ._. ...¢ 311 of labeled phosphate was found in alfalfa from.fertilizer placements at or close to the surface. In the first and second sampling of second growth alfalfa there were no notable differences in fertilizer phosphorus uptake between the non-irrigated and high irrigated areas. This can be explained since the available soil moisture for the several depths presented in Figures 7 through.11 were quite similar at all irrigation rates due to reasonably adequate rainfall. The data presented in these figures show that up to July 8 supplemental water was applied only once. Precipitation of 1.01 inches on July 2, 5 and 4 brought the available water generally up to between sixty-five and seventy-five percent at all depths. During the period of July 15 to July 20 soil moisture values on the non-irrigated plots fell to fifteen percent or less in the surface six inches. It seems probably that a drop in absorption of fertilizer phosphorus fol- lows a very dry period since feeder roots desiccated by lack of moisture would not be capable of absorbing nutrients immediately after soil moisture was again at an adequate level. This would account for a lag in relationship between uptake of fertilizer phosphorus and soil mois- ture level noted for the July 20 sampling. Available soil moisture levels continued to drop until August 1 when readings of less than ten percent available moisture at the 24 inch depth.wers noted. Examination of fertilizer phosphorus absorption data determined on.the second and third samplings from the non-irrigated plots indicate alfalfa continued to remove appreciable amounts of labeled phosphorus at all depths except the 24 inch placement. During the period of July 20 to August 1 when the surface six inches of 8011 contained less than 35 AHHH pcoaHaonmv .sowpwwwhpw vow mowpmpwawomaa Heston hp oopommum mm vow wmfimmaw oommfifinmpmo no sous: me so some H 039 pm waspwwoe aflom oHanHw>d .5 opsmflm unswsil wHow mosh m H R “N .N N mm 8 ... .H NH 0 a m einmIIET - . 11.- . a . soflpmmflssfi SWHW III. cowpwwfisafl EQI Cowpepwmflomsm HNEOZ I l v popes mo momosH Nina __ 1.... 11° -— 6“: :— “0 $0 OH 0w 0: om ow ow eanqspom [p09 quBIIeAB queoled that... jg?! * . . h... .|.. . . . . r a . . .. .. 1.-..r IV. 39 PWSU :AW' “I Om mm 0m 4m mm om wH cH m H AHFH pomswpmcxmv .oowpmawaaw new mowpmnwowomsm Hesse: an Umpommmm me now mmeMHm oommwapwpwo on sound Somme some am one pm osspmwoe Hwom memHflw>¢ .HH whomwm hash. JV. All 0:3. l J- u d 54 6r WJ :H NH OH w w a m om mm mm 4N - u u q u d . u . _ . oOHpmmflssfl Boa mafipmpwmwomsa amenoz hope; wo memosH _. “a 0H 0: om ow on ow elnqspom {Ios etquIEAs quaoaed hO ten percent available water some increase in the percent of plant phosphorus derived from fertilizer was noted in alfalfa from plots receiving surface applications and l and 6 inch depth placements. This trend is similar to that reported by'RbAuliffe at al (9) who found that considerable fertilizer phosphorus was absorbed by legumes from surface or near surface placements of fertilizer under semi- drought conditions. An increase in the fertilizer phosphorus content in alfalfa from. low and high irrigated plots was also noted when the second and thind samplings are compared for each level of supplemental water. A similar trend of a higher fertilizer phosphorus content in alfalfa from low and high irrigated plots was noted in the second and third samplings. The only marked decrease was found in plants from plots where fertilizer was surface applied and a low irrigation rate was used. Comparison of the fertilizer phosphorus contents of alfalfa at the different depth placements for irrigated plots in Table 10 shows that cuttings made on July 9 and July 20 were considerably higher than for non-irrigated plots on which.fertilizer was applied to the surface. By August 1 this trend was less evident, especially at the high irrigation rate. Alfalfa cut on August 1 from.high irrigated plots having the 5 and 6 inch depth placements were higher in percent of plant phosphorus derived from.fer— tilizer than alfalfa from non-irrigated plots. Little or no difference was noted in fertilizer phosphorus content of plants from.plots where fertilizer was surface applied or placed one inch below the surface. This latter condition is difficult to explain since on the nonpirrigated plots no increase in dry weight was found between the July 20 and up... we )I.L‘.Il...l:c yr .11...It.1.. .3..- him hl August 1 samplings and a lower total amount of fertilizer phosphonis was taken up by alfalfa out on August 1. It would seem reasonable to expect the greatest effect of irrigation on absorption of phosphorus from.fertilizer of any placement, since the greateHLspread between the soil moisture levels due to irrigation was evident at this time as noted in Figures 7 to 11. At the final harvest the dry weight yields as presented in Table 11 were quite variable, especially between depth of fertilizer placements within irrigation levels. However, if averages of the dry weights at each sampling date for all fertilizer placements in a given irrigation rate are compared, some interesting points can be noted. There was no important difference between the samplings made on July 9. The high rainfall several weeks prior to this date brought soil moisture contents to adequate levels for all plots. The average weights of the first and second samplings from the low irrigated plots were slightly but probably not significantly lower than those of the non-irrigated areas. most notable is the fact that the dry weight yields of the second and third samplings from.plots receiving high irrigation were considerably greater than for the other irrigation levels. This in- crease was most apparent for the August 1 sampling and is believed to be due to water supplied during the very dry and hot period in the last two weeks of July. There are several possible reasons why a higher percentage of fertilizer phosphorus might be expected in alfalfa where a high level of irrigation was used than in plants receiving less water. First, the higher available soil moisture conditions may have resulted in more . . f - .. it 555...... .. ....w.._.... .. madam. .1. _ . n. _... h2 TABLE 11. THE EFFECT OF FERTILIZER PLACEHENT AND IRRIGATION ON THE DRY WEIGHT YIELD OF ALFALF'A GROWN ON HILLSDAIE SANDY LOAN. (Experiment III) Depth of Grams of air dry hay per three square feet fertilizer at sampling dates placement . in inches July 9 July 20 August 1 No Irrigation Surface** 80.6* 115.6 107.6 1 72.1 99.1 90.6 5 64.1 111.6 151.1 6 78.6 125.6 147.5 12 55.6 86.1 124.6 24 59.6 96.6 152.1 Check 69.1 111.1 108.1 Average*** 68.1 105.1 122.2 Low Irrigation Surface** 76.1 99.1 146.6 1 56.1 112.1 155.6 5 62.6 106.1 159.6 6 61.1 95.1 126.6 12 50.1 94.1 104.6 24 56.1 82.6 115.6 Check 70.1 86.1 115.1 Average*** 60.4 98.1 127.8 High Irrigation Surface** 67.1 150.1 141.1 1 64.1 151.6 154.6 5 68.6 101.1 155.1 6 80.1 119.1 155.1 12 60.1 155.6 172.1 Check 52.1 125.1 156.0 Average*** 68.0 125.5 151.6 * Values are averages of two replications. ** Broadcast application; other placements localized *** Does not include the check plots I: .. ;.u~.—mr~..r...3.:.v .4 .F...Ifl... m. J ”a... tarralt. .. .r. 43 extensive development of small lateral roots and greater absorption of the available fertilizer phosphorus. This conclusion is substantiated in part by yield increases from.high irrigation at the last sampling. However, it is of interest to note that Dean et a1 (5) concluded that the factors that influence growth do not necessarily effect the percentage of plant phosphorus that is derived from.fertilizer applied at the time of planting. Second, a higher irrigation rate may have caused a greater dif- fusion of fertilizer phosphorus from the points of application allowing more root contact with the labeled phosphate. Actually the movement of applied phosphorus in most soils has generally been shown to be very small. However, work by Heslep and Black (5) and Lawton and Vomocil (8) indicated that diffusion of fertilizer phosphorus in soils from a given point source increased with increasing soil moisture content. As previously mentioned, no data of this type taken in the field were ob- tained for this experiment. Consequently, this hypothesis of extensive phosphorus migration to lower soil depths is open to question. Satchell (12) also noted that the longer the phosphate was in the ground the greater was the movement and that there apparently was a direct relationship between the amount of moisture and the movement of the phosphorus. However, even with the leaching effect of water applied as surface irrigation, it is still doubtful whether increased migration could account for a higher utilization of fertilizer phosphorus since a considerable period had elapsed for fixation of phosphate ions to‘ take place between the time of application of fertilizer and the period {Eatflxigfié fim... . .. .. ii... a . was. Ki. 411 of frequent irrigation. In addition, Heslep and Black (5) noted that the diffusion rate of phosphorus in soil was reduced by the addition of nitrogen and potassium in proportions typical of those found in mixed fertilizers. Thus the muriate of potash mixed with the labeled super- phosphate may have reduced phosphate ion migration. T _ ’4 r1: ‘Iw;~m“.mmwyh hS Figure 12. Experiment I, located on Michigan State College farms near Bennett Road. When the plots were put in a white stake was placed on each corner. 46 Figure 15. The plots at hperiment II. The photo- graph was taken just after fertilizers were applied June 21. Emgnliamfiw ........ 3...... . .2 paint. 1.... 47 Figure 14. The board used to lay out the plots. The board was 5 feet by 5 feet which was the size of the plots. A stake was placed in each corner. The fer- tilizer was placed in holes in a 6 by 6 inch grid pattern. The holes in the board were in a 6 by 6 inch grid pattern so the borings were made through each hole. E E. .. mangle... n or is}... .78 118 Figure 15. These are the tools used to make the borings. The soil smple tube on the left was purchased, the soil sanmle tube in the center was made from a 7/8 inch stain- less steel tube. The rod on the right was made from a piece of 5/8 inch drill rod'. immunfigww... I... . pam.1..a..auci . ..-..I.Ll:\..1.‘m I.\.\ 119 Figure 16. Because of small stones the borings around the 24 inch depth were hard to mks. Also small pieces of soil fell down the holes and plugged the glass tube when the fertilizer was poured down. To make a hole through the small pieces of rocks and to eliminate the loose pieces of soil at the bottom: the 5/8 inch drill rod was used. If the rod got stuck between the rocks, the chain and the lever were used to extract it. £43,341... .4122 . . H. . . . ,1». . .1. Cents . ‘\ Figure 17. The fertilizer was measured out in small envelopes preparatory to placing it in the plots. First, the muriate of potash, then the labeled triple superphosphate were placed in the envelopes. The superphosphate was measured out with tongs behind the glass so that protection was offered against the beta rays. 50 Figure 18. The fertilizer was placed at the bottom of the holes by using a glass tube and funnel to avoid contaminating the sides of the holes. 51 .EJ0'-‘T -' I Iggeidfi . , .15. we]. , . .. .W . . .. is... sawflxara . airmail» 14V 52 Figure 19. After the wrists of potash and labeled superphosphate were placed in the holes, they were filled with dry soil. The dry soil was placed in the holes by pouring it through a large funnel. gerMEgV cfiflqadai...‘ |mwfi «tires-l? ‘9‘ Figure 20. 'the plate were irrigated by hauling the water in the cane shown above. When the plots were irrigated, a 5 by 5 foot area was watered. One gallon of water on 25 square feet was equivalent to 0.0615 inches. The water was carried to the plate in three gallon eprinkling cane. 53 I "gnaw”? ‘3‘». new. 3!»! .L. _..,l. uh. ‘nn, [(1.1‘ ‘V Figure 21. A oloee-up of one of the plots. The area on the right had just been out. There were three cuttings made from each plot and 1/3 of the plot or three square feet was out each time. , fl" '. rr: “ '1. . .’I“l O u ‘.. ‘.-I,' ' ' Ya . z "r L)! .I .f‘ * ‘ ‘ “I. :(a’V I ‘ -‘. Figure 22. Views of the plote in Experiment 11. 55 .gnzmflndgwmq an. annex-_... . . 0‘ L rr...r. I 56 SUMMARY The phosphorus uptake by alfalfa as affected by depth of ferti- lizer placement and supplemental irrigation was studied on a Brookston clay loan and a Hillsdale sandy loam. From the data obtained, the following conclusions can be made: 1. Feeder roots of alfalfa within the six inch soil depth of an established alfalfa stand were very effective in absorbing ferti- lizer'phosphorus placed in this depth zone. These data support the concept of a surface pattern ofhactive feeding roots of established alfalfa plants. 2. The ability of alfalfa roots to absorb fertilizer phosphorus decreased with depth of fertilizer placement from the surface to twenty four inches. {Although the highest percentage of fertilizer phosphorus in alfalfa was obtained from a surface application, the absorption of some phosphorus through leaf surfaces and crowns cannot be ruled out. 3. The use of supplemental water during the dry periods in- creased the fertilizer phosphorus content of first cutting alfalfa from.plots receiving surface applied fertilizer and the one inch depth placement. On second growth hay, a high irrigation rate increased the percentage of plant phosphorus derived from fertilizer placed at the six and twelve inch depths. In this respect a low irrigation rate had little effect. The following hypotheses have proposed to account for increased absorption of fertilizer phOSphorus during dry periods, especially at depths up to twelve inches when a high rate of irrigation 1:4 stlIAnBH..: ‘ n! aafiiflwhrnfiwHQGJMWflaz i up;-aitrVV l u .t. 57 was used: (a) the number of lateral roots or their capacity to absorb phosphorus were increased, (b) the root-fertilizer contact was improved by increasing the area of dissolution and the downward movement of fertilizer’phosphorus by a leaching action. h. The continued absorption of phosphorus placed on the soil surb face or'at a depth of one inch when the available soil moisture was very low on non-irrigated plots cannot be adequately explained. 5. In samplings of first growth alfalfa, there was a decrease in percentage of total phosphorus in the dry plant tissue with increas- ing depth of fertilizer’placement. For second growth alfalfa this effect was not evident. The use of supplemental'water’had no influence on the total phosphorus content of alfalfa at any given sampling except the final harvest of the second growth, at which time the phosphorus con- tent was substantially higher where a high irrigation rate was employed. 6. The dry weights of hay at the final sampling of both first and second growth alfalfa'whss quite variable with respect to depth of fertilizer placement. Only in the case of plots on Brookston soil was the yield of hay sampled midway through the second growth higher for the lower depth placements than those closer to the surface. Irrigation had no effect on the average dry weights of three samplings of first growth alfalfa and the first sampling of second growth alfalfa. An appreciable increase in average dry weight of hay due to high irri- gation was noted for two samplings taken during the last two weeks of J 11133 £53.. Mania s33? . , . f: _... Jenna: _.."... ,4 [r sl. (1) (2) (3) (h) (5) (6) (7) (8) (9) 58 BIBLIOGRAPHY Blaser, R., McAulifie, C. Utilization of phOSphorus from various fertiliser ma- terials. I Orchard grass and Iadino Clover in New York. Soil Science 68: 1115-150 (19119) Chang, Xe, Bray, Re Determination of calcium and magnesium in soil and plant material. Soil Science 72: M9458 (1951) M, Le et. 8.1. Application of radioactive tracer technique to studies of phosphate fertilizer utilization by crops. Soil Sci. Soc. Amer. Proc. 12: 107-112 (19148) Fiskel, J., Belong, I., Oliver, I. The uptake by plants of labelled phosphate from neutron irradiated calcium phosphates. III Penetration into soil and uptake by pasture herbage. Canadian Journal of Agri. Sci. 33: 559-565 (1953) Heslep, J., Black, c. Diffusion of fertilizer phosphorus in soils. Soil Science 78: 289-301 (1951;) Jordan, J., et. a1. Uptake and movement of fertilizer phosphorus. Soil Science 73: 305-313 (1935) ““011, EC, T088!) HO, mm, B. The effect of rate and placement of superphosphate on the yield and phosphorus uptake by established alfalfa standSe Soil Sci. Soc. Amer. Proc. 18: 56-62 (1951.) W”, KO, vm0c11’ J. The dissolution and migration of phosphorus from granular superphosphate in some Michigan Soils. Soil Sci. Soc. Amer. Proc. 18: 26—32 (19514) McAuliffe, 0., Stanford, G., Bradfield, R. Residual effects of phosphorus in soil at different pH levels as measured by yield and phosphorus uptake by oats. 3011 Science 73: 171-171 (1992) issue ”no...“ Hafivm 331.55,...15... a. .9» ma (10) (11) (12) (13) (1h) (15) (16) 59 Metzger, I. Phosphate fixation in relation to the iron and aluminium of the soil. Journal Amer. Soc. Agron. 33: 1093-1099 (191:1) Piper, Ce Soil and Plant Analysis. Interscience Publishers, Inc. , New York (19104) S‘tChell’ De The penetration of phosphates into soil aggregates, and into crystals of . PhD Thesis, North Caro ina State College Library, Raleigh, North Carolina (1951) Spumy, CO, 1.811.011, KO Soil Testing—A system of soil fertility diagnosis. Hichigan Agri. Exp. Sta. TBChe 31111615111 132, 14th revision. (19149) Stanford, G., McAuliffe, G., Bradfield, R. Movement of phosphorus in the soil. Agronomy Joumal 142: 1123-1126 (1950) Stanford, G. , Nelson, 1.. Utilization of phosphorus from various fertilizer materials, oats, and alfalfa in Iowa. Soil Science 68: 157-161 (1950) Upchurch, R., Lovvorn, R. Gross Morphological root habits of alfalfa in North Carolina. Agronomy Journal h3: h93-h98 (1952) ‘4; ”Hunt. u Ems. cm. .2 .1...ch (Ruin _\ APPENDIX 61 TABLE 12. DATA USED FOR CALCULATIONS. (Experiment I) PPM of phosphorus Counts per minute* Replicate Depth May 29 June 7 June 15 May 29 June 7 June 15 No Irrigation I Bdcst 9.1 6.8 6.7 4529 6079 2251 II Bdcet 9.4 6.7 7.5 4545 5954 2694 I 1 8.2 6.2 6.2 2789 5014 2241 II 1 9.1 6.5 4.8 2908 2917 1716 I 5 8.4 5.8 6.0 5558 6147 5587 II 5 9.4 6.8 5.9 1818 2844 1879 I 6 9.4 6.6 5.8 1895 2154 1867 II 6 9.0 6.6 5.8 1694 2559 1644 I 12 8.1 6.0 5.5 820 979 814 II 12 8.6 6.2 5.8 507 847 568 1 24 9.4- 6.5 5.2 166 529 515 II 24 8.1 5.5 5.0 179 445 220 1 Check 6.2 6.0 6.5 -- ... -- Irrigated I Bdcat 9.0 6.8 6.5 7558 5525 5955 II Bdcst 9.4 7.5 6.7 5086 6260 2595 I 1 8.4 6.0 5.2 5102 5542 5526 II 1 9.7 6.7 6.2 4052 5517 5245 I 5 9.5 6.1 6.0 2260 6114 2784 11 5 9.0 8.5 5.8 2055 2059 2109 I 6 8.1 6.1 6.5 1569 4846 2066 II 6 7.0 6.4 5.4 1518 2172 5194 I 12 8.0 5.6 5.6 287 872 1015 II 12 8.9 6.4 5.9 741 1406 1451 I 24 8.6 5.2 4.8 141 680 980 II 24 7.9 6.5 5.8 187 522 590 I Check -- 6.5 5.0 -- -- -—- T For the first cutting the counts per minute were 67824 for standard number 1 and 65876 for standard number 2. For the second cutting standard number 1 was 58850. For the third cutting standard number 1 was 27851 and standard number 2 was 27888. fig“ i: 1.3. s . a. 2...... 1 PREV 1 {v.01 ‘ 4 ha... —H_— .—74.. 62 .00sz 0.85 w campuses you use 60% 0.3: H passage you 09:54.3 .Hea spaces one. @8393 new." hash. on» .Hoh .833 one: u passage .Hom speeds you 3560 can mfippno snow 05:. 23 .Hom .085 open N p.398...» no.“ use 9803 one.» H pudendum no museums you 3560 one. wfippso at. 05:. one. .Hom .035 ones .0. nuances» you one «egg each H openness :0 08.958 you 3580 on» geese 29mm he: on» non a. us: as: 1:: us: 1:: H.4 m.m 1:: 48.40 HH all all. Isl-I. .IIII IIII- 00m mom I." 30030 H ma8 m8s ««m ««m o.m 6.4 «.m «.4 mH HH an» H«m amm om H.m «.4 «.4 m.m 8H H HmH4 mmOH 844 HmH ~.m 4.m 8.m 8.« «H HH a«4H m4HH 644 cmH «.m H.4 m.m m.4 «H H amo« H64« 68m ««H m.m m.m w.m «.4 8 HH msmH 4m~« ommH 8a4 8.4 «.8 5.4 «.m 8 H ««mm H4wm when 488 8.» 5.4 8.m 8.4 m HH «84m mmm« H4m« 8«HH 8.8 4.4 4.4 o.m m H «8mm m««4 mmmm «m8H ~.m o.m m.m «.m a HH 48mm mm8m m«8« «a4H m.m o.m o.m 8.4 H H Hmo« 4mom 8mmm «mmH 6.8 8.4 «.8 «.4 8.88m HH mo«4 omH« mHHm . mHmH «.8 «.4 m.8 «.m pecan H 8H ads 8« .as a. .86 S 5. 8H 82. 8« .82. a. .as a as. 4868 38:82 #385”: com _....qu 384988 «6 Em aHH enonauoaumv .szHHaHpuqao mom new: «Han .ma unmap . . w 1 r .» / _ . . . . C . . . e . e o H . C | C O . . . ’ . . . C . . O . ' C O . I Q ‘ . I U . . O . ‘ . H . ' ‘ . -3 II. ‘t I [I . . I A e I'I I O . . ll .1 O 1 . 5 x . O Q C {£2,221.53 a ran 4.. 1 04% _. ... . .. a" «1. _ 1 r. . m | .. ,. 65 TABLE 14. DATA USED FOR.CALOULATIONS. (Experiment III) . o g. e , _— Ifitiof phosphorus Gounts per minute:— -Replicate Depth July 9 July 20 Aug. 1 July 9 July 20 Aug.l No Irrigation 1 Bdcst 7.2 5.4 4.4 6108 4705 5704 II Bdcst 6.9 5.2 5.8 9405 8591 8026 l 1 5.7 4.9 4.0 2124 5719 2577 11 1 6.9 5.0 5.6 5282 4251 4587 1 5 6.7 5.8 5.5 I 2440 5664 2701 II 5 6.6 5.5 5.9 5229 4515 5072 I 6 6.5 5.0 5.7 1755 2907 5055 II 6 6.5 5.1 5.7 1465 2846 1924 I 12 6.5 4.5 5.2 924 1907 1768 11 12 6.2 5.0 5.1 555 827 1055 1 24 5.6 5.4 5.6 257 607 250 11 24 7.5 5.5 5.6 287 269 249 1 Check 5.6 5.9 5.5 -- ——- _.. Low Irrigation I Bdcst 7.0 5.8 4.2 4205 6787 5565 11 Bdcst 7.5 5.9 4.9 5275 8215 4721 I 1 7.5 6.4 4.2 1454 2071 1516 11 1 7.2 5.5 4.5 2250 5008 2414 I 5 4.4 5.5 4.8 411 2785 4250 II 5 7.2 6.2 4.2 1644 6055 5098 I 6 6.7 6.0 4.2 460 1277 1479 11 6 6.9 6.5 6.9 1517 1296 2221 I 12 7.1 5.6 4.0 205 705 471 11 12 6.9 5.9 4.9 511 _ 1451 1251 l 24 6.8 9.1 5.1 272 667 579 II 24 6.7 5.7 4.8 115 206 548 I Check 8.0 5.9 5.2 -- -- ——- * For the July 9 cutting the counts per minute were 11981 for standard 5 and 11651 for standard 4. The counts per minute for the July 20 cutting were 11891 for standard 5 and 11501 for standard 4. The counts per minute for the August 1 cutting for standard 5 were 11572 and 11572 for standard 4. . C . 1 _ I O I . . e e e _ s e e 0 Q . p n . . c a 7552....mfliu $3.“. “NJIJW Lewes“... 4.4% _... .ecw. .4H...A w’A-n TABLE 15. DATA USED FOR CALCULATIONS. (Experiment 111) PPM of phosphorus Counts per minute"I Replicate Depth July 9 July 20 Aug. 1 July 9 July 20 Aug. 1 High Irrigation I Bdcst 7.0 6.2 4.6 5191 5899 6005 11 Bdcst 7.1 5.9 4.4 9794 5610 5996 1 1 7.8 6.2 4.7 2561 4517 4545 11 1 6.6 6.2 4.5 2978 4675 4592 1 5 7.2 5.9 4.4 5261 4772 4612 II 5 7.2 5.8 4.5 2497 4451 4557 1 6 6.7 5.7 4.5 1948 5742 4061 II 6 5.9 5.9 4.2 2061 850 4029 l 12 6.4 5.9 5.9 667 705 --- 11 12 7.0 5.5 5.9 745 875 1580 I Check 5.2 5.5 4.8 -- -—- .—. * For the July 9 cutting the counts per minute were 11981 for standard 5 and 11651 for standard 4. The counts per minute for the July 20 cutting were 11891 for standard 5 and 11501 for standard 4. The counts per'minute for the August 1 cutting for standard 5 were 11572 and 11572 for standard 4. . O . < O D I e C C O Q e e I e e U . _ . 1 . . ' . 1‘ . lei. . _..“; _»I.- 12.3.21: _ .1 Interk -_~—_ _..-~— 65 TABLE 16. CALCULATION OF STANDARDS FROM LABELED FERTILIZER RECEIVED IN THE SPRING Standard Number 1 Used l2.m1. of solution from a flash containing 100 ml. of .151: H01 and 2.4746 gm. of 48.5}: P205. wet 5 grams of plant material. 2.4746 x 48.57. a 1.2002 grams of P205 in solution 1.2002 1: 12/100 - .14402 (amount fertilizer in 5 grams of hay) .14402 e 2/5 I .05761 (grams in 2 grams) .05761 e 2.29 = .02518 (grams fertilizer phosphorus in 2 grams) Standard Number 2 Used 11.1 ml. of solution from a flask containing 100 ml. of .15N H01 and 2.5918 grams of 48.5% P205. Net 5 grams of plant material. 2.5918 x 48.5%‘- 1.2570 grams of P205 in solution 1.2570 x 11.1/loo = .15955 (amount of fertilizer in 5 grams of hay) .15955 . 2/5 = .05575 (grams in 2 grams) .05575 e 2.29 B .02454 grams fertilizer phosphorus in 2 grams ._.. .__, __... I. v 4.0.3 *7. .o ., 1...... r51... ... 33:14.3. 1. . 1 . 1.18.9318 .I. - 66 TABLE 17. CALCULATION OF STANDARDS F'ROII LABELED FE“ "RTILIZER RIADEIVED - IN THE SID-TIER Standard Number 5 Dissolved 2 .5659 grams of 48% £205 in 500 m1. of .15N H01. Used 6 .9 ml. of solution to wet 55 grams of plant material. 2.5659 x 48% = 1.2507 grams P205 in solution 1.2507 x 6.9/500 = .01698 gm. of fertilizer phosphorus in 5 grams of hay .01698 + 2/5 = .00679 (gm. fertilizer phosphorus in 2 gms. of her) .00679 e 2.29 - .00296 (gm. of phosphorus in 2 gms. of hay) Standard Number 4 Dissolved 2 .5640 grams of 48% P 20 in 500 m1. of .15N H01. Used 6. 9 ml. of solution to wet 25 gms. of plant material. 2.5640 x 48% - 1.2507 grams of P205 in solution 1.2507 x 6.9/500 = .01698 gm. of fertilizer phosphorus in 5 grams of hay .01698 + 2/5 8 .00679 (gm. of fertilizer phosphorus in 2 gms. of bar) .00679 e 2.29 = .00296 (gm. of phosphorus in 2 gms. of hay) Feb 17 '58 ‘‘‘‘‘‘ 1 ".1 5'1 DAL 7971;??? UNI‘v‘FRSlT)’ MEN-"Af— ES ‘ ‘ ‘ ’ lf’i II III I ' ll lllwl II 31293 03177 4239 l I h