Haby, Vincent A.

Leonard, Allen T.

English

Texas A&M University

Alfalfa response to potassium (K20) treatments affected by previous limestone quality and application methods

Texas A&amp;M Repository

    PUBLICATIONS 2004 ALFALFA RESPONSE TO POTASSIUM (1(10) TREATMENTS AFFECTED BYPREVIOUS LIMESTONE QUALITY AND APPLICATION MEmODSVincent Haby and Allen LeonardBackground. Beef cattle producers rarely are concerned about limestone methods ofapplication on their forage fields. In a perennial forage production system, limestone normally isspread on the soil surface and not tilled into the soil. We initiated a study of alfalfa response tofertilizer potassium (K) on a relimed site where limestone had previously been evaluatedaccording to the method of application. Unanticipated results from the study are reported.In late spring 1997, we applied ECCE 72% limestone (1440 lb effective limestone/ton) ata rate equivalent to 5.6 tons/acre in a randomized complete-block design. Treatments included(1) lime applied and the whole site was roto-tilled 6-inches deep; (2) limestone roto-tilled 2-indeep; (3) limestone left on the soil surface; and (4) a no-lime check. Immediately before planting,limestone from the same lot was applied at the same rate to one set of replicated plots and ECCE100% limestone was applied to other plots and left on the soil surface. All limestone treatmentsin the four replications were duplicated with 80 g of molybdenum added to determine its effect onyield. Alfalfa was grown on these plots for four years, and was eliminated. Limestone (ECCE100%) was uniformly applied at about 3.5 tons/acre to the whole site followed by diskincorporation and packing with a weighted roller. A blended fertilizer was prepared and spreadon Nov. 19,2002 to apply 35 lb N, 120 lb P20S, 40 lb sulfur, and 4lb boron/acre and the site wasseeded to 'Tahoe' alfalfa, a multi-leaf variety, Dec. 2, 2002 to evaluate response to rates ofpotassium split applied beginning in April 2003. Rainfall was insufficient to allow earlierplanting. The nitrogen was added to help the alfalfa seedlings become established because theseeding date was so late that we feared the rhizobia inoculated onto the seed might not besufficiently active to fix needed amounts of nitrogen for the new plants during the coming wintermonths. We maintained the integrity of the plots used in the previous limestone incorporationstudy. One-half of each potassium rate was applied Apr. 10, the other Sept. 4. The total rateswere 0, 80, 160, 240, 320, and 400 lb K20/acre.Research Findings. In order to cut the alfalfa as it reached about 10% bloom, five low-yielding alfalfa harvests were made in 2003 (Table 1). The first four cuttings had been fertilizedwith only the first half of the total potassium rate. Alfalfa dry matter yield was statisticallysimilar in any cutting and in the total for all cuttings due to increasing potassium rates. Theresidual potassium applied for the previous alfalfa study remained adequate and the alfalfagrowth was insufficient to stress the ability of the soil to supply potassium.13Table 1. Alfalfa response to muriate of potash rates applied to a Darco loamy fine sand in 2003.Potashrate(KzO)Ib/aco80160240320400harvest date---------------------- Total8/26 10/1 0 Yield------------------------------------------------lb/ac----------------------------------------------166nst 1713ns 405ns 202ns 319ns 2805ns204 1803 640 313 315 3301212 1967 766 205 317 3467322 1961 824 222 348 367760 1758 423 153 291 2685177 1763 504 309 268 3021R2 0.48C.V. 98.5ns indicates no statisticall si0.51 0.50 0.2010.0 46.6 72.2ificant differences in res onse data.0.4717.50.5319.9Yield data were evaluated based on the limestone surface or incorporated applicationsmade in 1997 (Table 2). Alfalfa yield patterns were similar to responses that occurred in alfalfagrown in the four years after those lime treatments. Yield was the same for limestoneincorporated either to the 6- or 2-in depths. Response to surface applied limestone, whetherapplied early or immediately before seeding, was similar. Limestone apparently had insufficienttime to react after the 3.5 ton/acre re-application was disked into the soil in early August, 2002.Table 2. Alfalfa response to method of limestone incorporation from treatments applied in 1997.LimestonetreatmentHow incOl;porated6-inches2-inchesSurfaceNo lime62% ECCE Surface100% ECCE Surface----------------D matter ield b harvest date--------------- Total5/16 6/25 7/24 8/26 10/10 Yield---------------------------------------Ibs/acre---------------------------------------232 ns 1926 at 754 a 226 ns 333 ns 3472 a259 1808 ab 705 a 297 315 3385 a78 1762 ab 321 b 179 280 2620 b51 1293 c 55 b 68 139 1605 c166 1532 bc 287 b 207 243 2435 b167 1755 ab 325 b 91 196 2534 bR2 0.67 0.83 0.89 0.65 0.76 0.85C.V. 101.7 12.3 42.0 77.5 29.5 20.6Yields followed b a different letter within a column are statisticall different at =0.05.Application. Data indicated that incorporation of lime is critical for crops that aresensitive to soil acidity. Even in a low-production year, alfalfa grown in plots where limestonewas incorporated yielded one-half ton/acre more dry matter compared to yield in plots withlimestone left on the soil surface. This effect was still evident five or more years after the initiallimestone treatment occurred.14

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Alfalfa response to potassium (K20) treatments affected by previous limestone quality and application methods

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Alfalfa response to potassium (K20) treatments affected by previous limestone quality and application methods

Abstract

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Full text

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Texas A&M University

Texas A&amp;M Repository

Texas A&M Repository