Effects of Thirty‐Seven Years of Stocking and Fertility Regimens on Soil Chemical Properties in Bermudagrass Pastures

Management of bermudagrass [Cynodon dactylon(L) Pers.] pastures on Coastal Plain soils in the southeastern United States incorporates multiple strategies for N fertilization, liming, and stocking rate (SR). This study documented long‐term changes in soil pH and extractable NO3–N K, Ca, and Mg in Coastal and common bermudagrass pastures continuously stocked at different intensities for 37 yr (1969–2004). Soil fertility regimens were established in 1985 and consisted of (i) inorganic nitrogen fertilizer with overseeded annual ryegrass (Lolium multiflorumLam.) (NRYG) and (ii) no nitrogen with overseeded clover (Trifoliumspp.) (NoNCLV). Soil samples (0–120‐cm depth) were collected in 1985, 1989, 1994, 1996, and 2004 and analyzed for pH and extractable NO3–N, K, Ca, and Mg levels. Fertility regimen showed significant effects on soil NO3–N concentration (0–15 cm) with greater values generally observed in the pastures receiving N (average NO3–N concentration of ∼ 4 mg kg−1in NoNCLV vs. 14.15 mg kg−1in NRYG treatments). Differences in N fertilizer application levels throughout the study period also affected soil NO3–N concentration. Conversely, bermudagrass pastures receiving no inorganic N and overseeded with clover showed relatively constant soil NO3–N concentrations during the study period. Soil K levels increased (42 to 48%) over time and were generally greater in the NoNCLV pastures. It was concluded that overseeding clover without N fertilization onto bermudagrass pastures can be a viable, long‐term management strategy to sustain adequate soil nutrient levels while achieving satisfactory forage and animal production.