Haby, Vincent A.

Kerby, Joel L.

Nimr, Gary H.

Rouquette, F. M., Jr.

Silveira, M. L.

English

Texas A&M University

Soil Depth Changes in pH in Coastal and Common Bermudagrass Pastures Under Long-term Stocking and Fertility Management

Texas A&amp;M Repository

    PUBLICATIONS 2006 SOIL DEPTH CHANGES IN pH IN COASTAL AND COMMON BERMUDAGRASSPASTURES UNDER LONG-TERM STOCKING AND FERTILITY MANAGEMENTM.L. Silveira, F.M. Rouquette, Jr., J.L. Kerby, G.H. Nimr, V.A. Haby, and G.R. SmithBackground. A detailed description of stocking rates and fertility regimens from 1969through 2005 are presented in a companion 2006 Field Day Report by Rouquette et al. Theobjective of this experiment was to evaluate changes in soil pH in bermudagrass pastures underdifferent fertility management strategies.Research Findings. From 1969 to 1987, bermudagrass pastures received limestoneapplication rates varying from 1 to 2 tons/ac. On average, about 9 tons of limestone were appliedto bermudagrass pastures during this period. From 1988 to 2001, only bermudagrass pasturesfertilized with Nand overseeded with ryegrass were limed. In 2002, all pastures were treated withlimestone. Soil pH markedly increased from 1985 (average pH = 5.3) to 2004 (average pH = 6.0)(Figure 1). Larger increases in soil pH were observed from 1985 to 1994. Bermudagrass pasturesreceiving no N, K, and clover exhibited a slight decline in soil pH from 1994 to 2004, especiallyin the top 0-6-in depth due to the low rate of lime application during this period (total of 1 ton/acapplied in 2002). Even with much less limestone applied, soil pH in the bermudagrass -no N-clover pasture remained well above that for pastures fertilized with N.Bermudagrass pastures overseeded with clover and without N fertilizer showed greatersoil pH than pastures overseeded with ryegrass and fertilized with N. Although bermudagrass +N+ryegrass pastures received greater (total of 3 tons) lime applications than bermudagrass withoutN +clover pastures, soil pH in the upper horizons was almost one unit smaller (more acidic) in theN fertilized pastures. That occurred because bermudagrass +N pastures received considerableamounts of N fertilizer. Conversion of the ammonium form to nitrate (nitrification), contributedto soil acidification, and larger lime application rates were required to maintain adequate soil pHfor forage growth. In contrast, bermudagrass without N +clover pastures, receiving no lime formore than 14 years (1988-200 I), maintained higher pH values. That suggests that symbiotic N1fixation by clover had much less effect on lowering soil pH, and less limestone was needed tomaintain favorable soil conditions for bermudagrass-clover pastures.There were no significant differences in soil pH between common and Coastalbermudagrass pastures. Similarly, stocking rates showed no effect on soil pH. As expected,fertility regimens played a much more important role than bermudagrass species and stockingrates on soil pH.51Applications. Bermudagrass pastures should be soil sampled on a routine basis andduring the same season to determine lime requirements. Nitrogen fertilization can considerablyincrease soil acidity, and additional lime application may be required to maintain an adequate soilpH for forage production. Clover is an economic and agronomically viable alternative to supplyN to bermudagrass pastures and to reduce lime applications on acidic soils.Common Bermudagrassa. N +Ryegrass b. no N +CloverpH pH6.0 7.0 5.0 6.0 7.0612~~ 18.s 24Q,CD30'0'036en42485.06 +--o--....,...~-----'"12;g: 18=24Q,~ 30'0 36rJ)4248Coastal Bermudagrassa. N +Ryegrass b. NoN +CloverpH pH5.0 6.0 7.0 5.0 6.0 7.06 612 12:§. 18 ;[ 18=24 .s 24Q, Q,Ql CD 30"C 30 '0'0 36'0 36rJ) en42 4248 48 ~o 1985 .1994 &2004Figure I. Soil pH in common and Coastal bermudagrass pastures under different fertilityregimens.52

https://oaktrust.library.tamu.edu/bitstream/1969.1/189693/1/article31.pdf

Soil Depth Changes in pH in Coastal and Common Bermudagrass Pastures Under Long-term Stocking and Fertility Management

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Texas A&M University

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Soil Depth Changes in pH in Coastal and Common Bermudagrass Pastures Under Long-term Stocking and Fertility Management

Abstract

Similar works

Full text

Available Versions

Texas A&M University

Texas A&amp;M Repository

Texas A&M Repository