THE RELATIONSHIP BEYWEEN $0M. ANALYSIS AND CULTURAL PMCT ICES OF A PEACH ORCHARD Thai: for The beam d Pix. D. MICHIGAN STATE COQEGE Shun Shah Kwong 1954 This is to certify that the thesis entitled The Relationship Between Soil Analysis and Cultural Practices of a Peach Orchard presented by Shue Shah .Kwong has been accepted towards fulfillment of the requirements for Ph. D. degree in Horticulture if Major professor Dateflzy/Z /?~§j THE RELATIONSHIP BETWEEN SOIL ANALYSIS AND CULTURAL PRACTICES OF A PEACH ORCHARD BY Shue Shan Kwong A THESIS Submitted to the School of Graduate Studies of Michigan State College of Agricultura and Applied Science in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Horticulture Year lQSu *- Information on the soil-mulch interrelationship will aid in the successful use of the sod-mulch system.of soil management in Michigan peach orchards. The purpose of this experiment was to determine the nutritional status of the soil as influenced by mulching and fertilizer applications in the peach orchard. Emperimental Procedure A peach orchard near Grand Rapids, Michigan contained mulched and unmulched blocks in which there were rows receiving nitrogen (N), nitrogen and phosphorus (NP), and nitrogen, phosphorus, and potassium (NPK). Trees which did not receive any fertilizer were used as a check. A Halehaven tree in each row was selected for soil sampling. Soil samples were taken in August 1952, at five soil depths: 0-1;, h-12, 12-20 , 20-28, and 28-36 inches beneath each tree at three locations midway from.the trunk to the outer branches. The soil samples were air-dried, crushed with a wooden pin, screened through a 2 mm. sieve, thoroughly mixed and stored in containers for analysis. Soil pH was determined on a 1:1 soil water suspension with a Beckman model H-2 pH meter. Exchangeable calcium, magnesium, and potassium were determined by leaching a 20-gram soil sample with 200 milliliters of neutral normal ammonium.acetate and measured with a Beckman model DU and model B spectrOphotometers. The after leached original soil sample was then saturated with 40 milliliters of 10 per cent acidified sodium.chloride solution and again leached with 100 milliliters of neutral normal ammonium acetate. -2- The leachate was collected for determining exchangeable sodium photometrically as a measure of the cation exchange capacity. Acetate soluble phosphorus was determined colorimetrically using the standard A. 0. A. C. micro-method. Results and Conclusions The exchangeable calcium under mulch with fertilizer was lower than unmulched at all corresponding depths. The per cent calcium saturation under mulch and receiving fertilizer was steadily increased as the soil depths increased. Exchangeable magnesium was definitely lower under mulch with nitrogen fertilizer alone. When no fertilizer was applied, the mulched samples showed higher exp changeable magnesium.than samples with no mulch. The per cent magnesium saturation under mulch with fertilizer was also lower than samples without mulch. The exchangeable potassium was higher under mulch at 0-12 inch depths than in other soil depths when nitrOgen, nitrogen and phosphorus, or nitrogen, phosphorus, and potassium fertilizer was applied, respectively. However, the amount at 0-12 inches under mulch without fertilizer was lower than the unmulched samples. A higher cation exchange capacity was found at all soil depths under mulch than the unmulched samples when no fertilizer was applied. A higher exchange capacity and per cent base saturation was also found at the upper depths under mulch with fertilizer. An increase of acetate soluble phosphonus occurred at the 0-h inch depth under mulch with fertilizer. However, a great total .‘__...——.- -3- amount of acetate soluble phosphorus was found from.unmulched than from the mulched samples when no fertilizer was added. The pH value at the surface soil was decreased under mulch when fertilizer was applied. There was a significant correlation of pH with per cent magnesium.saturation, and a highly significant correlation of pH with per cent calcium saturation and with the total per cent saturation with calcium, magnesium, and potassium. A negative correlation of pH to acetate soluble phosphorus was also found highly significant. The results of this investigation indicated that mulching influenced the nutritional status in the soil. In order to obtain the full advantage of complete fertilizers in such peach orchards, an adequate mulching program.should be maintained and the use of dolomitic lime seems desirable. THESIS TABLE OF CONTENTS Page Introduction 1 Review of Literature 2 Experimental Procedure 12 Collection of soil samples 13 Soil analyses 13 Results 16 Exchangeable calcium 16 Per cent calcium saturation of exchange capacity 19 Exchangeable magnesium 22 Per cent magnesium saturation of exchange capacity 2h Exchangeable potassium 27 Per cent potassium saturation of exchange capacity 30 Cation exchange capacity 35 Per cent saturation with exchangeable calcium, magnesium and potassium 38 Acetate soluble phosphorus hl Soil pH uh Correlation studies h? Discussion 52 Effect of mulch upon exchangeable calcium in soil samples 52 Effect of mulch upon exchangeable magnesium in soil samples Sh ii Ca C.“ F413 «5 .3 L3 Page Effect of mulch upon exchangeable potassium in soil samples 57 Effect of mulch upon exchange capacity of soil samples 58 Effect of mulch upon acetate soluble phOSphorus in soil samples 59 Soil pH 59 Summary and Conclusions 61 References Cited 6h iii 10. 11. LIST OF TABLES Page Exchangeable calcium at different soil depths as influenced by fertilizer application and cultural practices 1? Per cent calcium saturation at different depths as influenced by fertilizer application and cultural practices 20 Exchangeable magnesium at different soil depths as influenced by fertilizer application and cultural practices 23 Per cent magnesium at different soil depths as influenced by fertilizer application and cultural practices 26 Exchangeable potassium at different depths as influenced by fertilizer application and cultural practices 29 Per cent potassium at different soil depths as influenced by fertilizer application and cultural practices 32 Cation exchange capacity at different soil depths as influenced by fertilizer application and cultural practices 36 Per cent calcium, magnesium and potassium saturation at different soil depths as influenc- ed by fertilizer application and cultural practices 39 Acetate soluble phosphorus at different soil depth as influenced by fertilizer application and cultural practices A2 pH value at different soil depths as influenced by fertilizer application and cultural practices H5 The relation of yield and circumference of peach trees to the amount of exchangeable calcium, magnesium and potassium in soil as influenced by fertilizer application and cultural practices 55 iv LIST OF FIGURES CONTINUED Page 12. The relationship between soil pH value and per cent magnesium saturation at different soil depths as influenced by fertilizer appli- cation and cultural practices h9 13. The relationship between soil pH value and per cent saturation with exchangeable cations (Ca, Mg, K) at different soil depths as in- fluenced by fertilizer application and cultural practices 50 in. The relationship between soil pH value and acetate soluble phOSphorus at different soil depths as influenced by fertilizer application and cultural practices 51 15. Relation of yield and circumference of peach trees to the amount of exchangeable calcium, magnesium, potassium and acetate soluble phosphorus (on 2,000,000 pounds of soil basis) in soil as influenced by fertilizer applica- tion and cultural practices 56 v1 ACKNOW LED GME NT The author wishes to eXpress his sincere apprecia- tion to Dr. A. L. Kenworthy for his guidance, advice and encouragement throughout this study; to Mr. Walter Toenjes who made available the facilities of the Graham Horticulture Experimental Station and gave valuable assistance in this study. The author also wishes to thank Dre. C. R. Megee of the School of Agriculture, K. Lawton of the Soils Depart- ment, G. P. Steinbauer of the Department of Botany and Plant Pathology, and R. L. Carolus of the Department of Horticulture for serving on his guidance committee. Further acknowledgment is made to Mrs. Jane Hinsvark, and to Dr. and Mrs. J. C. Lee for their assistance during the course of the investigation. INTRODUCTION Mulching is a cultural practice which has long been known to fruit growers. The influence of mulch on various soil properties as a direct result of adding inorganic and organic components to the soil, when decomposed, or as a sequence of rendering the soil constituents more avail- able to plants is largely dependent upon the nature of the mulched material, the conditions and the inherent charac- teristics of the soil. Recently the sod-mulch system has been introduced in the Michigan peach orchards. In order to assure the success of such a cultural practice, the need of study on the soil-mulch inter-relationship is apparent. An adequate supply of available nutrient-elements in soils is a fundamental requirement leading to the success of an orchard. A soil with high exchange capacity would be able to hold a greater quantity of essential nutrient-ele- ments for use by the plant. Chemical analysis is usually employed as a tool for appraising soil fertility. With this thought in mind, the purpose of this experiment was to de- termine the nutritional status of the soil as influenced by mulching in a peach orchard. REVIEW OF LITERATURE Because of the possibility that nitrates may be reduced, some investigators have postulated that fruit trees received no benefits from the use of mulch on orchard soils. Albrecht (1922) studied nitrate accumulation under straw mulch and Concluded that mulching with straw reduces the concentration of nitrates in the soil, and the only crops that did well were those that were able to obtain their nitrogen from this low concentration. Havis (1938) reported on a soil manage- ment study that the principal factor limiting the growth of the young peach trees in the blue grass sod and straw mulch has evidently been lack of nitrates. From a comparison of a permanent straw mulch with clean cultivation in a rasp- berry planting on a Sassafras sandy loam, Darrow and Magness (1938) stated that growth and fruiting under mulch were satisfactory but not superior to what was usually obtained with cultivation in good raspberry areas. However, the op- posite effect of mulching on tree growth and nutrient rela- tions in the soil has been noted by Beaumont, Sissions and Kelly (1927), Beaumont and Crooks (1933). Shaw and Southwick (1936), Clark (l9h0), Chandler and Mason (l9u9), and Shaw (l9h3). They verified that the increase of production and vigor of tree growth was directly influenced by either the accumulation of nitrates or increased conservation of soil moisture as a result of mulching. Soil constituents are the main source of mineral elements to plants. The quantity of these exchangeable mineral ele- ments in soils is ordinarily altered to a certain degree by the addition of fertilizers alone or associated with the ap- plication of mulching. Merkle (1928) reported that a fertil- izer experiment in Hagerstown silt loam soil showed that the amount of exchangeable calcium in the manured plot was about the same as that found on the unfertilized plot. How- ever, those plots receiving either ammonium sulfate or dried blood with phOSphorus and potash showed a reduction in ex- changeable calcium, and the plots treated with nitrate of soda showed nearly five times as much exchangeable calcium as compared to the one receiving.ammonium sulfate. Van Alstine (1918) stated that ammonium salts caused a marked loss of calcium as carbonate and this loss was proportionally related to an increase in acidity. A few years later, Wilson (1930) continued this study on three types of silt loam soils and concluded that the exchangeable calcium of the untreated soils was related to their hydrogen-ion concentration. When fertilizers were added to the soils in forms of nitrate of soda, acid phosphate and muriate of potash, with or without limestone, there was little or no effect on the quantity of exchangeable calcium found in the soils. Mulching has been recognized by Shaw (l9h3), Harley, Moon and Regeimbal (1951) and Kenworthy and Gilligan (l9h8) as effectively liberating nutrient-elements directly to the soil. The nutrient-elements thus released were available to plants. In studies of the effect of mulch upon the ex- changeable calcium in soils, Wander and Gourley (19h3) us- ing wheat straw on a Wooster silt loam in Ohio, and Weeks, Smith and Mack (1950), using low grade hay on Weathersfield loam in Massachusetts, concluded that the mulch increased the amount of exchangeable calcium as compared with culti- vation in apple orchards. However, Wander and Gourley (19h3) emphasized that the increase in exchangeable calcium was greater in the surface beneath the mulch and less in medium depths of 6-12 and 12-18 inches. Recently, Goodman (1953) put bluegrass hay, oat and wheat straw in separate rows as mulches and maintained a heavy permanent bluegrass sod as a control. He suggested that the "forced" migration of exchange calcium from the immediate soil surface under the hay mulch was due to the action of one or more acids formed during its decomposition. A great number of investigators visualized that the adsorbed bases in the soil are replaced by other cations from their neutral salts in accordance with the lyotropic series. Wiegner and Jenny (1927) stated that the order of difficulty in diaplacement of the divalent cations from the soil complex was magnesium. 11 Exchange capacity is an indication of the soil's capa- city to retain essential elements in a form readily avail- able to plants, and is related to the amount of clay and organic matter in the soil. Albrecht (l9kl) stated that ion adsorption and ion exchange are physical and chemical pro- cesses taking place in organic matter, and that the humus frac- tion has from 2 to 6 times more exchange capacity per unit weight than the clay fraction. Reuther (l9hl) found mulch treatment appeared to have increased the exchange capacity of the soil slightly when compared to sod or cultivation treatments in a McIntosh apple orchard. The total replaceable hydrogen in the soils with a high colloid fraction increases with the degree of unsaturation. Joffe and McLean (1927) indicated that the degree of satura- tion or unsaturation of the top and subsurface soil gives a picture of the process of podsolization and the fate of the cations replaced. The subsoils, therefore, showed a higher degree of saturation than the surface soils of similar pH values. In general, it was found that the highly weathered soils have a lower degree of saturation at a given pH value than less weathered soils. Furthermore, there was no rela- tionship between the organic matter content of soils and the per cent base saturation of the soils at similar pH values (Pierre and Scarseth 1931). The base saturation of a light sandy soil is increased from 25 to 75% by increasing the pH of a soil from 5 to 6 (Peech l9hl). 12 EXPERIMENTAL PROCEDURE An orchard of one—year-old peach trees was planted in Miami silt loam on April, 19h8 at the Graham Horticulture Experiment Station, Grand Rapids, Michigan. The orchard con- tained Redhaven, Halehaven and Elberta varieties. Each row contained three trees of each variety with additional border trees of Redhaven and Halehaven. The orchard was divided into three portions. A Chewing fescue sod was established on the area, including rows 1 to 6 and 10 to 15. Rows 7 to 9 were clean cultivated with a rye cover crop. The trees in rows 10 to 15 were mulched. The initial mulching was with 30 to to pounds of straw per tree in l9h8. Fifty pounds of weedy hay was added in July of 1950 to each of the mulched trees. The mulch was applied over an area extending from the trunk to the perifery of the tree. The trees in rows 1 and 15 did not receive any fertil- iger and were used as a check. All of the remaining trees were given commercial fertilizers of various analyses in varying amount, depending on the age of the trees. The trees growing in sod or sod-mulch and receiving the higher rates of application of nitrogen (u and 12), nitrogen and phosphorus (2 and 10), and nitrogen, phosphorus and potassium (3 and 11) were selected for soil sampling. 13 Nitrogen (20-0-0) was applied to individual trees at rates of 0.67 pounds in 19h9, 1.33 pounds in 1950, 2.0 pounds in 1951 and 2.67 pounds in 1952. Phosphorus (0-20-0) was applied at rates of 6.0 pounds in 19h8, 2.0 pounds in 1950, 2 pounds in 1951, and 4.0 pounds in 1952. Potassium (0-0-20) was applied at rates of 6.0 pounds in l9h8, 2.0 pounds in 1950 and h.0 pounds in 1952. Collection of Soil Samples A Halehaven tree in each of the rows was selected for soil sampling. The soil samples were taken in August, 1952, with a Veihmeyer soil tube. The samples were taken at five soil depths: O-h, h-12, 12-20, 20-28 and 28-36 inches. Three samples were taken beneath each tree at a position midway from the trunk to the outer branches. One sample was taken from each of the row middles. Each sample from each depth was stored in a round pint food container (Sealright). After the samples were air-dried, they were crushed with a wooden pin, screened through a 2 mm. sieve, thoroughly mixed and stored in the original container for analysis. Soil Analysis The samples were analyzed in duplicates for pH, exchangeable calcium, exchangeable magnesium, exchangeable potassium, acetate soluble phOSphorus and exchange capacity. Soil pH was determined on a 1:1 soil-water suspension by use of a Beckman model H-2 pH meter with a glass electrode. 1A For the determination of exchangeable calcium, magnesium and potassium a soil extract was prepared by agitating a 20 gram sample with 100 ml. of neutral normal ammonium acetate for 30 minutes. After agitation, the sample was filtered and washed with an additional 100 ml. of ammonium acetate and brought to 200 ml. volume. A 10 ml. aliquot was used for the determination of ex- changeable calcium and magnesium. The remaining leachate was evaporated to dryness with infrared lamps, ignited at 5-6 hours. 'Phe ash was then dis- ’ h00° C in a furnace for solved with a few drops of concentrated hydrochloric acid and dried with infrared lamps. When dry, the residue was dis- solved with 25 ml. of 1.0 per cent hydrochloric acid and filtered. The filtrate was used to determine exchangeable potassium and acetate soluble phosphorus. Exchange capacity was determined by using the original 20 gram soil sample. After extracting with neutral normal ammonium.acetate, the sample was washed with 50 m1. of 95 per cent ethyl alcohol. The exchange complex was saturated with sodium by washing with no ml. of 10 per cent sodium chloride. To remove the excess sodium chloride, the sample was then washed with 100 ml. of 95 per cent ethyl alcohol. The soil was then leached with 100 m1. of neutral normal ammonium acetate and the leachate used to determine exchange- able sodium as a measure of the cation exchange capacity. 15 Acetate soluble phosphorus was determined colorimetrical- 1y, using the standardized A. O. A. C. method. A Beckman model B spectrophotometer with a flame attachment was used for determining calcium, potassium and sodium, using an acetylene-oxygen flame. A Beckman model DU spectrophotometer with a flame attachment was used for determining magnesium, using a hydrogen-oxygen flame. Calcium was measured by using a wave length of 55A millimicrons and a slit width of 0.28 mm.; magnesium, a wave length of 371 millimicrons with a slit width of 0.538 mm.; potassium, wave length of 762 milli- microns with a slit width of 0.1 mm.; sodium, wave length of 585 millimicrons with a slit width of 0.05 mm. Exchangeable calcium, magnesium, potassium and cation exchange capacity were expressed as m.e. per 100 gm. of dry soil. Exchangeable calcium, magnesium and potassium were also calculated as per cent saturation of the cation exchange capacity. 16 RESULTS Exchangeable Calcium In an exchangeable form, calcium is the most abundant base in mineral soils. The amount of this element, in general, increased with soil depth. The content of ex- changeable calcium found at each soil depth from the various treatments is given in Table l. The data showed that the lowest amount of this element (l.h8 m.e./100 gram) occurred at the first soil depth (O-h inches) in ammonium nitrate fertilized plots that had been mulched for a h-year period. The highest amount (7.685 m.e./100 gram) of this element was found at the fifth soil depth (28-36 inches) of the un- fertilized mulched plots. In Figure l, the graphs show that the upper soil layers (0-12 inches) had a lower content of exchangeable calcium regardless of mulching. All samples under mulch with ad- dition of fertilizer had a lower amount of calcium in all soil depths as compared with the unmulched samples. 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O 4'- [2 2'0 23 3': Soil Def/'58 - (inc/19$) H—H Unmu/c/tea’ °‘ '°‘ '°‘ ‘° Mu/cbea’ LL? mulch showed a higher pH at the first depth (O-h inches) and a lower pH at the lower depths than the unmulched samples. Analyses of variance indicated a highly significant difference between fertilizer treatments and between soil depths. The check sample was higher than N-fertilizer sam- ples. For soil depths, samples taken from 28-36 inches had a higher pH than samples from 0-12 inches. Correlation Studies The relationship of soil pH to per cent calcium satura- tion; magnesium saturation; total per cent saturation with calcium, magnesium and potassium; and available phosphorus is plotted in scatter diagrams as shown in Figures 11, 12, 13 and la, reSpectively. The correlation coefficient of pH value to calcium saturation was highly significant ( r = +0.92). The correlation coefficient of pH to magnesium saturation was +O.u7 and was significant. A highly signi- ficant positive correlation (r = +0.89) was also obtained between pH and the total saturation with calcium, magnesium and potassium. However, the highly significant correlation coefficient between pH to the available phOSphorus was nega- tive (r = -O.86). Figure 11. The relationship between soil pH value and per cent calcium saturation at different soil depths as influenced by fertilizer application and cultural practices. 1" = 0092 Y = 3029 + 0.0% 148 >s0>hfit3k96 3‘\~\U.~Vb RZWUQWQ fi\ Figure 12. The relationship between soil pH value and per cent magnesium saturation at dif- ferent soil depths as influenced by fertilizer application and cultural practices. r = 0.1;? Y = 10.38 + 0.0% ’49 Oh: P >s02. «€95 Va. 23‘» W>>w v.3 k 2NUQWQ o a. hm. om. hm. om fix 3 0 p b _ r p » TN 3.5. Figure 13. The relationship between soil pH value and per cent saturation with exchange- able cations (Ca, Mg, K) at different soil depths as influenced by fertilizer application and cultural practices. r = 0.89 Y = 3.33 + 0.03X >6? ESL R0 3580. .R 0Q 03.. X‘QmmszS .2333 .5 2.333 50 rm 00 TV 00 rw Figure lb. The relationship between soil pH value and acetate soluble phOSphorus at dif- ferent soil depths as influenced by fertilizer application and cultural practices. r = -O.86 Y = 5.65 - 0.67X 51 . .K.n\!.. E ”\E‘Ox‘nxmnxuq WVQ§NO$ WKXNNUV 0‘ 0. m m .o m 0. m m A 52 DISCUSSION Mineral soil is rather complex in nature. There are a great many variations of characteristics existing in dif- ferent soil horizons. According to Byers, Kellogg, Anderson and Thorp (1938), Miami silt loam soils are derived from gla- cial till and the B-horizon is distinctly heavier in tex- ture than the A-horizon. Kellogg and Orvedal (1951) pointed out that these soils are leached, acid, and have relative- ly low availability of most plant nutrients. They are also rather low in organic matter. However, they are highly re- sponsive to management. Since the conditions of these soils are known, addition of adequate fertilizer and lime should correct the inherent Shortages of the soil and result in higher productivity. Effect of Mulch upon Exchangeable Calcium in Soil Samples Soil reaction is one of the principal factors influenc- ing leaching and fixation of many nutrient elements in soils (Peech l9ul). The exchangeable calcium and magnesium are expected to be more abundant in the lower depths than in the surface soil as was found in this investigation. Goodman (1953) postulated that the migration of exchangeable calcium from the immediate soil surface under the hay mulch was due to the action of one or more acids formed in the decomposi- 53 tion of the hay mulch. Thus, the resulting effect would be dependent on the nature of the mulch material used. A com- parison of the pH values of the check samples, mulched and unmulched, shows that the first soil depth (O-h inches) immediately under mulch had a slightly higher pH value (u.u6) than the unmulched samples with pH n.39 (Table 10). Thus, the mineralization of grass hay would not appear to be effective in promoting the movement of calcium from the sur- face to the deeper soil layers. This is in agreement with Wander and Gourley (l9h3), Weeks, Smith and Mack (1950) who found that mulching increased the amount of exchangeable calcium as compared with cultivation in an apple orchard. The results of this investigation showed that the check sam- ples under mulch had a higher per cent calcium saturation at the first soil depth (Figure 2) and the total amount of ex- changeable calcium in five soil depths was one-third more than that from the unmulched soil. There was a reduction of exchangeable calcium in the up- per soil depths under mulch with an addition of fertilizer, particularly in the form of ammonium nitrate with phosphorus and potash (Figure 2). Merkle (1928) reporting on his ex- periment in Hagerstown silt loam stated that those plots re- ceiving ammonium sulfate with phOSphorus and potash or re- ceiving dried blood with phosphorus and potash showed a re- duction of exchangeable calcium. This reduction may have Sh been due to two factors: (1) the leaching action as a result of adding acid forming ammonium salts in the soil; or (2) the depletion of a greater quantity of exchangeable calcium by the fruit tree as a result of better growth under mulch. The leaching effect was more severe under mulch condition (Figure 2 and Figure In) and may have been an indirect ef- fect of an accelerated mineralization because of better moisture under mulch. The possibility of additional tree growth depleting greater quantities of exchangeable calcium is illustrated by the results shown in Table 11 and Figure 15. Effect of Mulch upon Exchangeable Magnesium in Soil Samples The behavior of exchangeable magnesium was very similar to that of calcium. Magnesium, however, may be more sub- jected to the phenomenon of "forced" migration because of its position in the lyotropic series. A comparison of magnesium content of the soil with the yield or circumference of the trees under mulch and unmulched (Figure 15), indicates that, besides leaching, the severe reduction of magnesium may have been a result of absorption by the trees in a greater amount to support their higher yield and better growth under mulch. Weeks, Tyson and Drake (1950) stated that the exchange- able magnesium was increased at the lower soil depths (6-12 and 12-18 inches) under the low grade hay mulch in a bear- ing apple orchard. The results of the check samples in this investigation showed an agreement with their findings. It is SS 0200 20m HHom Mo mccsom ooo.ooo.m mo mfimwn no 0000350000 0000 Log mcadom .monoaa 0010 you omwnobwuumomhawcw 3200* 5.3 3.003 5.303 0.2023 00.02 00.533 002 0.0 5.5m 0.003 0.0530 m5.03 00.003 02 0.0 0.33 0.20 5.0002 05.03 00.532 2 0.2 3.35 0.033 2.0002 00.32 00.002 00020 00000 concasz 2.0 0.30 0.203 0.0052 05.0 00.55 002 0.0 0.50 0.000 0.0032 00.0 00.55 02 3.0 2.00 3.503 0.0002 00.0 00.03 2 3.0 0.00 0.000 0.0003 --- --- 00000 00029 wmgoazgcp onow\.mba oaow\.mna mpow\.mna 0000\Wmna oomp\.mna Monadfipnmh mdnoflmmoflm 550000000 summonwwz Edaofiwo .mCauuoonogmh .Hom mumpmo< mammomcwnoxm nESomfio 02500 *mMOHBodmm A¢mbmamb Qz< ZOH9' 6 ~°Aaco ABCD °Aaco ABCD Ferfi/I'zer ff 3°” (Unmulched) (Mu/cited) ’gaowUnmu/ched) (Mulched) < . U £2000 3400 i s S 2 2 loco :3 200 3 z < u: U § °ABCD ABCD °Aaco ABCD Fer‘fi/fzer rim (Unmu/c/red) ( Mule/190’) 3 G (Unmulched) (Mu/c/reJ) <1 a" 3 :3, I20 3; 4 s a 2 g 2 ‘0 ‘5 :1: n. a. . °Aaco 'ABCD °ABCD aaco 'Fer fly/Z er A2001. 3: .v- mix/xx..— c: NP— {.29 0: NPK- fart 1;F.,.I».I:MUW - v. mi. {it 57 interesting to note that the exchangeable magnesium was higher under mulch.than unmulched at the surface depth (O-h inches) when NP or NPK-fertilizer was added. However, this was not true with the addition of nitrogen fertilizer alone. Such findings indicate that phosphorus might have a certain effect on the soil colloid and increase the adsorp— tive surface for magnesium or the phOSphorus may have com- bined directly with.magnesium. Either or both factors would tend to increase exchangeable magnesium. Effect of Mulch upon Exchangeable Potassium in Soil Samples According to Bregger and Musser (1939), Wander and Gourley (1937, 1938), Boiler and Stephenson (19u6) and Drake (1950), exchangeable potassium was increased in deeper soil layers under mulch than with cultivation. The result obtained from the check samples under mulch in this investigation indi- cated that exchangeable potassium was increased and penetra- ted deeper into the soil than in.the unmulched samples. This probably was associated with a more uniform supply of soil moisture that, in turn, would reduce the fixation of potas- sium and promote its migration into the soil. The data in Table 5 showed that the potassium was higher at the first two depths (0-12 inches) under mulch than un- mulched when nitrogen (N) or nitrogen with phosphorus (NP) was used as fertilizer. Samples from under mulch with 58 addition of a complete fertilizer (NPK) showed a much higher level of potassium than the unmulched samples at all depths. It would seem that the upper two soil depths (0-12 inches) had a much higher adsorptive power for potassium under mulch. According to Albrecht (l9u3), potassium is adsorbed on the colloidal surface in a mobile form. Therefore, the increase of exchangeable potassium under mulch with N and NP-fertil- izers may have been the result of mineralization of the mulch material. As soon as the mulch material decomposed, and in- crease of potassium in the soil would be expected. The in- crease of adsorbed potassium on the colloid surface would continue and any "excess" of this element should migrate into the deeper soil layers as was evident when NPK-fertilizers were applied. Merkle (1928), Wilson (1930), Murphy (l93u) and Hoover (lth) stated that potassium may accumulate in the A horizon in replaceable form when applied in excess of plant needs. Mulching would appear to reduce such an accumulation. Effect of Mulch upon Exchange Capacity of Soil Samples Figure 7 indicated that the exchange capacity of soil was much higher for the mulch than for the unmulched samples on unfertilized plots. These data are in agreement with Reuther (lghl) who found that mulch appeared to have increased the exchange capacity of the soil slightly when compared to sod or cultivation in McIntosh apple orchards. However, in this S9 investigation, samples under mulch with the addition of fertilizer showed higher exchange capacity than the unmulched samples only in the surface soil. Such a result may be ex- plained, as Albrecht (19ul) stated, by the high ion adsorp- tion and ion exchange, as physical and chemical processes, of organic matter. The decomposition of the mulch material may have induced the migration of certain organic colloids into the soil and thus increase the exchange capacity. Effect of Mulch upon Acetate Soluble Phosphorus in Soil Samples Figure 9 indicated that acetate soluble phosphorus was higher in the surface soil than at lower depths for every comparison. There was no significant effect of mulch upon the vertical movement of acetate soluble phosphorus. These results showed agreement with Boller and Stephenson (lQhé). However, they did not agree with the study of Weeks, Tyson and Drake (1950). The reduction in acetate soluble phos- phorus under a mulch with no fertilizer or nitrogen (N) may be associated with greater tree growth (Figure 15). Soil pH Turk and Partridge (19h?) stated that there was a definite decrease in the pH in Miami soil with alfalfa and straw mulches which had received ammonium sulfate. The re- sults of this study showed that the mulched samples with nitrogen fertilizer always had a lower pH at the first depth 60 as compared with the unmulched samples. This is apparently in agreement with the results obtained by Turk and Partridge. The decrease in pH may have resulted from the release of certain organic acids in the process of decomposition of the mulch. 61 SUMMARY AND CONCLUSIONS The relation of cultural practices and fertilizer (N, NP, or NPK) application to the exchangeable calcium, magnesium, potassium, exchange capacity, acetate soluble phOSphorus and soil pH at five depths of a Miami silt loam was studied. The amount of exchangeable calcium under mulch with fertilizer was lower than unmulched at all corresponding depths. The lowest quantity of calcium occurred at the O-h inch soil depth under mulch when nitrogen fertilizer was ap- plied. The per cent calcium saturation under mulch receiving fertilizer was steadily increased as the soil depth increased. Exchangeable magnesium was definitely lower in quantity under mulch which had received only nitrogen. When no fertil- izer was applied, the mulched samples showed a higher quan- tity of exchangeable magnesium than samples from unmulched plots. The per cent magnesium saturation under mulch with addition of fertilizer was also lower than samples under no mulch. The amount of exchangeable potassium was higher at 0-12 inches depth when N-or NP-fertilizer was applied, and very much higher at all depths when NPK-fertilizer was applied with mulch than without mulch. However, it was lower in 62 quantity at 0-12 inches when under mulch without fertilizer application as compared with the unmulched samples. The total amount of exchangeable potassium was higher for the mulched samples than for the unmulched samples, except for those with addition of nitrogen. A higher cation exchange capacity was found under mulch than with the unmulched samples when no fertilizer was ap- plied. The first soil depth (O-h inches) was also higher in exchange capacity under mulch with addition of fertilizer. The per cent calcium, magnesium and potassium saturation was higher for the samples under no mulch than for the mulched samples. With applications of fertilizer, the base satura- tion at 0-12 inches was higher under mulch. There was a greater amount of acetate soluble phosphorus from unmulched than from mulched soils when no fertilizer was applied. An increase, however, was obtained at the first soil depth (O-u inches) under mulch with fertilizer when compared to the unmulched samples. The pH value of the surface soil (O-h inches) under mulch with no fertilizer application was slightly increased. When fertilizer had been added the pH value at the surface soil was decreased under mulch. There was a significant correlation of pH with per cent magnesium saturation, and a highly significant correlation of pH with per cent calcium saturation and with the total per 63 cent saturation with calcium, magnesium and potassium. A negative correlation of pH to acetate soluble phOSphorus was also highly significant. The result of soil analysis in this investigation indi- cated that mulching influenced the nutritional status in the soil. In order to obtain the full advantage of a com- plete fertilizer in an orchard on Miami silt loam an ade- quate mulching program should be used. The analysis of the soil also indicates the need for additions of dolomitic lime. 6h REFERENCES CITED Albrecht, W. A. 1922 Nitrate accumulation under straw mulch. Soil Sci. 1h: 299-305. Albrecht, w. A. l9u1 Soil organic matter and ion avail- ability for plants. Soil Sci. 51: u87-h9u. Albrecht, W. A. l9h3 Potassium in the soil colloid com- plex and plant nutrition. Soil Sci. 55: 13-20. Alway, F. J. and C. 0. Host 1916 Vertical distribution of phosphorus in the surface soil of prairies. Soil Sci. 2: h93-h97- Association of Official Agricultural Chemists 19h0 Official and tentative methods for analysis. 5th ed. Beaumont, A. B., A. C. Sissions, and O. W. Kelly 1927 Nitrate accumulation under a mulch. Soil Sci. 2h: 177-185. Beaumont, A. B., and G. C. Crooks 1933 The influence of a mulch on soil nitrates. Soil Sci. 36: 121-123. Boiler, C. A. and H. E. Stephenson 19h6 Some effects of mulches on soil properties. Amer. Soc. Hort. Sci. Proc. h8: 37-39- Bregger, J. T. and Musser, A. M. 1939 Observations on ef- fects of soil covers as conservation practices in peach orchards. Amer. Soc. Hort. Sci. Proc. 37: 1-6. Bryan, O. C. 1933 The accumulation and availability of phosphorus in old citrus grove soils. Soil Sci. 36: ZMS-ZSu- Byers, H. G., C. E. Kellogg, M. S. Anderson and J. Thorp 1938 Soils and men-—Yearbook of Agriculture. United States Department of Agriculture. pp. 973, 1033. Chandler, F. B. and I. C. Mason l9h2 The effect of mulch on soil moisture, soil temperature, and growth of blueberry plants. Amer. Soc. Hort. Sci. Proc. hO: 335-337- 65 Clark, J. H. l9u0 The effects of mulching red raspberries on growth and production. Amer. Soc. Hort. Sci. Cole, C. V. and M. L. Jackson 1950 Colloidal dihydroxy phOSphates of aluminum and iron with crystalline character established by esectron and x-ray dif- fraction. J. of Phys. and Colloid Chem. 5h: 128-1u2. Darrow, G. M. and J. R. Magness 1938 Investigations on mulching red raspberries. Amer. Soc. Hort. Sci. Proc. 36: h8l-h8h. DeTurk, E. E., L. K. Wood and R. H. Bray l9h3 Potash fixa- tion in corn belt soils. Soil Sci. 55: 1-12. Dunkle, E. C., F. G. Merkle and R. D. Anthony 1939 Potash availability studies in Pennsylvania orchard soils. J. Amer. Soc. Agron. 31: h38-u58. Goodman, R. N. 1953 Influence of organic mulches on reaction and exchangeable calcium content of soil. Soil Sci. 75: h59-h66. Harding, R. B. 1953 Soil phosphorus in California orange orchards in relation to yield, fruit size and phosphorus in leaves. Amer. Soc. Hort. Sci. Proc. 61: 31-37. Harley, C. P., H. H., Moon and L. O. Regeimbal 1951 The release of certain nutrient elements from simulated orchard grass mulch. Amer. Soc. Hort. Sci. 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Murphy, N. J. l93h The replaceable potassium content com- pared with field response to potash fertilization of some Oklahoma soils. J. Amer. Soc. Agron. 26: 3h-37. 67 Nearpass, D. C., M. Drosdoff and R. T. Brown l9h8 Effect of fertilizing tung trees with potash and other materials on the exchangeable cation content of Red Bay fine sandy loam. J. Amer. Soc. Agron. to: 771-776. Peech, M. 19u1 Availability of ions in light sandy soils as affected by soil reaction. Soil Sci. u73-u85. Pierre, W. H. and G0 D. Scarseth 1931 Determination of the percentage base saturation of soils and its value in different soils at definite pH values. Soil Sci. 31: 99-11u. Prince, A. L. and S. J. Toth 1937 Electrodialysis and cation exchange studies on soils of varying organic matter content. Soil Sci. M3: 205-217. Reuther, W. 19h1 Effect of certain practices on the potas- sium status of a New York fruit soil. Soil Sci. 52: 155-165. Robinson, W. O. 191M The inorganic compounds of some important American soils. U. S. D. A. Bull. 122: 2?. Shaw, J. K. and L. Southwick 1936 Heavy mulching in bear- ing apple orchards. Mass. Agr. Exp. Sta. Bull. 328. Shaw, J. K. 19u3 Hay mulches in apple orchards. Amer. Soc. Hort. Sci. Proc. u2: 30-32. Smith, P. F., W. Reuther and F. E. Gardner 19h9 Phosphate fertilizer trials with oranges in Florida. I. Effects on yield, growth and leaf and soil composition. Amer. Soc. Hort. Sci. Proc. 53: 71-8h. Spencer, V. E. and R. Stewart 193M Soil penetration of some organic and inorganic phosphates. Soil Sci. 38: 65‘790 Stephenson, R. E. and H. D. Chapman 1931 Phosphate penetra- tion in field soils. J. Amer. Soc. Agron. 23: 759-770- Swenson, R. M., C. V. Cole and D. H. Sieling l9h9 Fixation of phosphate by iron and aluminum and replacement by organic and inorganic ions. Soil Sci. 67: 3-22. 68 Titus, J. S. and D. Boynton 1953 The relationship between soil analysis and leaf analysis in eighty New York McIntosh apple orchards. Amer. Soc. Hort. Sci. Proc. 61: 6-25. Turk, L. M., and N. L. Partridge 1947. Effect of various mulching materials on orchard soils. Soil Sci. 6h: 111-l2h. Volk, N. J. 1934 The fixation of potash in difficultly available form in soils. Soil Sci. 37: 267-287. Wander, I. W. and J. H. Gourley 1937 The potassium content of soil beneath a straw mulch. Science 86: 5h6-5u7. Wander, I. W. and J. H. Gourley 1938 Available potassium in orchard soils as affected by a heavy straw mulch. J. Amer. Soc. Agron. 30: h38-uu6. Wander, I. W. and J. H. Gourley 1939 A study of lateral movement of potassium and phosphorus in an orchard soil. Amer. Soc. Hort. Sci. Proc. 37: 27-31. Wander, I. W. and J. H. Gourley 19h3 Effect of heavy mulch in an apple orchard on several soil constituents and the mineral content of foliage and fruit. Amer. Soc. Hort. Sci. Proc. AZ: 1-6. Wander, I. W. and J. H. Gourley l9h5 Increasing available potassium to greater depths in an orchard soil by adding potash fertilizers on a mulch. Amer. Soc. Hort. Sci. Proc. A6: 21-2h. Wander, I. W. 19h7 Calcium and phosphorus penetration in an orchard soil. Amer. Soc. Hort. Sci. Proc. #9: 1-6. Wander, I. W. 1950 The effect of calcium phosphate accumula- tion in sandy soil on the retention of magnesium and manganese and the resultant effect on the growth and production of grapefruit. Amer. Soc. Hort. Sci. Proc. 55: 81-92. Weeks, W. D., S. C. Tyson and M. Drake 1950 Residual effects of heavy mulching in a bearing apple orchard on soil nutrients. Amer. Soc. Hort. Sci. Proc. 56: 1-u. 69 Wiegner, G. and Jenny 1927 On basic exchange Abs. Proc. First International Congress, Soil Sci. 2: h6-51. Wilson, B. D. 1930 Exchangeable calcium and potassium in soils as affected by cropping and fertilization. 8011 SCI. 29: 91-1000 'i E 1‘:th AE ‘ . '1'. u... a if" : .