Response of Ladino White Clover to Sulfur at Cool Temperatures

Abstract

AbstractEffective production of quality legumes during the cool portions of the growing season is of importance to animal production systems. However, it is unclear to what extent fertility requirements change under sub‐optimal environmental conditions. Ladino white clover (Trifolium repens L.) was grown in pots with a Lily silt loam (fine‐loamy, siliceous, mesic Typic Hapludult) soil under three temperature regimes. Environmentally controlled growth chambers were employed to approximate conditions common to the hilly terrain of Appalachia (mean air temperatures of 10.7°C, 14.7°C, and 18.2°C) Yield, tissue mineral composition, soil nutrient levels, and P‐, S‐, and N‐uptake were evaluated to determine the effects of S (0, 25, and 50 kg S ha−1 as MgSO4) on Ladino white clover at minimal and adequate P levels [75 and 450 kg P ha−1 as Ca(H2PO4)2·H20]. Shoot dry matter production for the initial 144‐d growth period and two subsequent 22‐d regrowths was significantly higher for the 450 kg P ha−1 rate at all temperatures; however, yield increase resulting from an increase in S was minimal (<10%) and inconsistent. Sulfur application increased uptake of S and N. Estimated N2‐fixation by acetylene reduction at three growth stages following the first harvest was significantly greater for the high rate of S under all temperature regimes. These studies suggest that Ladino white clover may recover faster during cool temperatures and assimilate more S and N with high applications of S.