Davis, J. V.

Gilbert, C. L.

Haby, Vincent A.

Leonard, Allen T.

Smith, Gerald R.

English

Texas A&M University

Subterranean Clover Response to Phosphorus and Boron Fertilization

Texas A&amp;M Repository

    PUBLICATIONS 1990 SUBTERRANEAN CLOVER RESPONSE TO PHOSPHORUSAND BORON FERTILIZATIONV.A.~y,G.R.Snriili,A.T.Leo~d,C.L.Gilbert,andJ.V.Da~SUMMARYClover production was increased by boron (B) treatment of the soil inprevious glasshouse and preliminary field studies. This study was designed toevaluate the response of subterranean clover to B fertilization in a replicated fieldtrial. Four rates of B and 5 rates of phosphorus (P) were applied in allcombinations to plots on a Keithville-Sawtown soil complex. Subterranean cloverwas planted in a prepared seedbed. Yield response was evaluated over a three-year period. Results indicated iliat subterranean clover responded to 1.5 Ib B/acilie first year of ilie study but yields were not increased for any B rates thereafter.Subterranean clover continued to respond to increasing P application ratesthroughout the study period. The plant P content and amount of uptake were alsoincreased by increasing rates of fertilizer P. The optimum P rate for subterraneanclover production was 22 Iblac (50 Ib P20r/ac) in this study.INTRODUCTIONClover stands are often difficult to obtain in the East Texas Timberlandsoils. A clover response x nutrient screening study indicated iliat P and B greatlyimproved clover yield in a glasshouse study. Preliminary field tests indicated thatB greatly increased vegetative growth and reseeding of rose clover. This test wasestablished to evaluate the response of subterranean clover to P and B in areplicated and randomized field study. Objectives of this study were: 1) Todetermine the optimum rates of P and B fertilization for annual clover production,2) To evaluate the B fertilizer requirement of subclovers under varying productionintensities, and 3) to calibrate the soil test for subclover response to B and P.PROCEDURESThe field research site was located on a Keithville-Sawtown soil complex(fine-loamy, siliceous, iliermic Aquic Paleudult) which was limed to approximatelypH 6.5. Boron rates of 0, 1.5, 3.0, and 4.5 Ib/ac and Prates 0, 22, 44, '88, and 176Ib/ac (0 to 400 Ib P20 6) were applied in all combinations in a randomized completeblock design study with 4 replications. Plots were 9 ft wide by 10 ft long. A 3 ft51alley-way was located between the ends of the plots. Potassium (K), magnesium(Mg), and sulfur (S) were uniformly applied and incorporated at rates of 156 lb ~O,68 lb S, and 34 lb Mg/ac prior to seeding 'Mt. Barker' subterranean clover.Treatments were incorporated into a prepared seed bed on the same site in 1986-1987 and 1987-1988. The experiment was moved to an alternate site on the samesoil complex for 1988-1989.RESULTSMain reactions to B were averaged over all P rates and reactions to P wereaveraged over all B rates except where interactions are presented. Subterraneanclover yield was significantly increased (15%) by B at the 1.5 lb/ac rate only in thefirst cutting in 1986-1987 (Table 1). This response remained visible in the totalyield that first year. The same rate tended to increase clover yield the followingtwo years but the increases in production were not statistically significant. Onlyone cutting was produced on the second site in year three. Boron treatment did notincrease subclover yield. Limestone treatment to eliminate strongly acid conditionsfollowed by tillage of the research site prior to establishing clover interact to favormineralization of organic matter. It is likely that sufficient B was made availablethrough mineralization to negate a clover response after the first cutting on site oneand no response on site two where only one harvest was produced.Phosphorus fertilization increased clover growth each year. The optimum Prate appeared to be 22 lb P (50 lb P20r/ac). There was no significant interactiveeffect of B and P on clover yield.Increased rates of B application increased plant uptake of B each of thethree years (Table 2). Clover produced by the zero B treatment in 1986·1987contained 19.3 ppm B, the lowest clover B level in the study. The statisticallysignificant yield increase occurred when the B content of the clover was increasedabove this level by the 1.5 lb B/ac rate. Boron uptake was not as great at thesecond site as it was the first two years at the first site. The recovery of appliedB (B uptake) was 5.3 % or less at the 1.5 lb B/ac rate and decreased as the B ratewas increased.When the B treatment was increased to 1.5 lb/ac or above, plant B contentwas increased by increased P rates up to the 88 lb/ac rate (Table 2a). Plant Bcontent remained relatively stable at the 22 and 44 lb P/ac rates as the B rate wasincreased from 1.5 to 4.5 lblac. At the 88 lb P/ac treatment, increasing rates of Bincreased plant B content. With no added B, applied P did not increase plant B52content.Each increase in P rate increased the P content of the clover all three years(Table 3). Phosphorus uptake by the clover increased but the percent uptake ofapplied P decreased as the P rate was increased. Percent uptake of applied P waslow and ranged from 11 to 1.9%.Soil test P levels were increased by increasing application of fertilizer P(Table 4). The amount of P20 6 required to raise the soil test 1 ppm decreased asthe rate of applied P was increased. The amount of fertilizer phosphorus requiredto raise the soil test 1 ppm agrees with results obtained on a Lilbert soil limed topH 6.2 in a previous study.TABLE 1. SUBTERRANEAN CLOVER YIELD RESPONSE TO B AND PFERTILIZATION OVER A THREE-YEAR PERIOD1988-1986-1987t 1987-1988 llBfL 3-yearBrate Cut 1 Cut 2 Total Cut 1 Cut 2 Total Total Totallb/ac --------------------------------------------------lb/ac-------------------------------------------------0 726 a 1587 a 2314 a 906 a 1688 a 2594 a 2736 a 7643 a1.5 1059 b 1594 a 2653 b 956 a 1732 a 2688 a 2916 a 8257 a3.0 739 a 1410 a 2148 a 817 a 1664 a 2481 a 2908 a 7537 a4.5 800 a 1478 a 2278 a 846 a 1643 a 2489 a 2852 a 7618 aPrate0 194 a 1122 a 1317 a 564 a 1487 a 2051 a 2377 a 5744 a22 747 b 1534 b 2282 b 992 b 1815 b 2807 b 2746 ab 7834 b44 932 bc 1589 b 2521 be 948 b 1756 b 2705 b 2961 b 8187 b88 1066 cd 1647 b 2713 c 917 b 1675 ab 2592 b 3010 b 8315 b176 1216 d 1693 b 2909 c 985 b 1675 ab 2660 b 3170 b 8740 btFor a given column and data set, values followed by the same letter are notdifferent at P S 0.05 based on Student-Newman-Keuls mean separation test.53TABLE 2. EFFECT OF B FERTILIZATION ON SUBTERRANEAN CLOVER BCONTENT AND UPTAKEAyera~ Plant B Content and UptaketB ratelb/ac1986 - 1987Content Uptakeppm lblac1987 - 1988Content Uptakeppm lblac1988 - 1989Content Uptakeppm lblaco1.53.04.519.3 a39.5 b48.2 c58.8 d0.043 a0.110 b0.112 b0.146 c45.8 a68.1 b79.6 b74.8 b0.128 a0.208 b0.244 b0.215 b21.3 a24.7 b24.8 b27.9 c0.058 a0.072 b0.072 b0.079 btFor a given column and data set, values followed by the same letter are notdifferent at P ~ 0.05 based on Student-Newman-Keuls mean separation test.TABLE 2a. EFFECT OF B AND P FERTILIZATION ON SUBTERRANEANCLOVER PLANT B CONTENTBoron rate Ob!ac)tPrateIblaco 1.5 3.0 4.5-----------------------------------------ppm------------------------------------------o22448817625.7119.8417.3016.7319.9025.2539.4939.9644.2238.3828.0936.9042.4052.6147.1440.9140.7442.4859.5649.25L.S.D. (0.05) = 11.92tData from harvest 1 in the 1986-1987 crop year.54TABLE 3. EFFECT OF P FERTILIZATION ON SUBTERRANEANCLOVER P CONTENT AND UPTAKEAyera~ Plant P Content and Uptaket1986 - 1987 1987 - 1988 1988 - 1989P raoot Content Uptake Content Uptake Content Uptakelb/ac % lblac % lblac % lblac0 0.19 a 2.49 a 0.24 a 4.71 a 0.21 a 5.02 a22 0.22 b 4.88 b 0.32 b 8.35 b 0.23 b 6.45 b44 0.26 c 6.18 c 0.34 c 8.78 b 0.29 c 8.47 c88 0.30 d 7.87 d 0.39 d 9.58 b 0.34 d 10.15 d176 0.35 e 10.11 e 0.44 e 11.28 c 0.38 e 12.03 etFor a given column and data set, values followed by the same letter are notdifferent at P s 0.05 based on Student-Newman-Keuls mean separation test.:j:Corresponds to 0, 50.4, 100.8, 201.6, and 403.3 lb P20r/ac.TABLE 4. EFFECT OF APPLIED P ON SOIL TEST LEVELS OF Pt1987-87 1987-88 1988-89Soil Soil SoilApplied Test P20 6 Test P20 6 Test P20 6Pt p Bea,§ p Bea.§ P Rea,§Ib/ac ppm Ib/ac ppm lb/ac ppm lb/ac0 9.1 a 5.9 a 1.3 a22 11.3 ab 23 9.1 a 32 2.5 a 4444 15.9 be 15 13.6 b 26 4.5 a 3288 20.9 c 17 18.6 c 32 11.9 b 19176 35.9 d 15 36.4 d 26 18.5 c 23tFor a given column and data set, values followed by the same letter are notdifferent at P s 0.05 based on Student-Newman-Keuls mean separation test.:j:Corresponds to 0, 50.4, 100.8, 201.6, and 403.3 lb P2Or/ac.§Pounds of fertilizer P206 required to increase soil test P one ppm.55

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Subterranean Clover Response to Phosphorus and Boron Fertilization

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Texas A&M University

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Subterranean Clover Response to Phosphorus and Boron Fertilization

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Texas A&M University

Texas A&amp;M Repository

Texas A&M Repository