Distribution of Nutrients Among Soil–Plant Pools in ‘Tifton 85’ Bermudagrass Pastures Grazed at Different Intensities
2011
Liu, Kesi | Sollenberger, Lynn E. | Silveira, Maria L. | Vendramini, João M.B. | Newman, Yoana C.
Choice of grazing intensity (i.e., stocking rate or grazed sward height) has an important role in the functioning of grassland ecosystems; however, the effect of grazing intensity on size and relative importance of various grassland nutrient pools is not well understood. The objective of this 2-yr study, conducted on soils from the Plummer and Sparr series, was to determine the effect of stubble height after grazing (SH) on nutrient distribution among plant and soil (0- to 20-cm depth) nutrient pools in ‘Tifton 85’ bermudagrass (Cynodon spp.) pastures. Swards were stocked rotationally and grazed every 28 d to SH of 8, 16, and 24 cm. Green herbage, plant litter, and root–rhizome pool masses increased as SH increased. Plant nutrient concentrations (g kg⁻¹) were relatively unresponsive to SH, but soil C and N concentrations increased by 23 and 34%, respectively, as SH increased. Nutrient content (kg ha⁻¹) of all plant pools increased as SH increased, mainly a function of increasing pool mass. Soil pool P and K content (Mehlich-1) were not affected by SH, but total C (17%) and N (27%) content increased with taller SH. The soil pool to 20 cm contained approximately 40, 85, 90, and 80% of K, P, N, and C, respectively. Reducing grazing intensity of Tifton 85 bermudagrass pastures appears to be a viable strategy for increasing nutrient content of most plant pools and for increasing the N and C content of the soil pool.
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