Monday, November 13, 2006

Response of a Bermudagrass and White Clover Mixture to Fertilizer on Reclaimed Mine Soil.

David Lang, Mississippi State Univ, Box 9555, Box 9555, Mississippi State, MS 39762-9555

Binary mixtures of grasses and legumes favor the grass when fertilized with nitrogen. Heavily fertilized bermudagrass (Cynodon dactylon) generally is not considered a favorable environment for white clover (Trifolium repens). Topsoil substitute from a Smithdale subsoil (Fine-loamy, siliceous, thermic Typic Paleudults) was spread in 2001. Browntop millet (Urochloa ramose) and ‘Common’ bermudagrass were planted in 2001 on a reconstructed mine soil. Three rates of 15-5-10 (none, moderate and high) corresponding to 0, 280, and 560 kg/ha were applied after each harvest beginning in 2003 for three years. Following harvest in October 2003, ‘Durana’ white clover was surface broadcast over all plots. Species composition as a percentage of ground cover was determined visually. There was a linear yield response (P< 0.05) to fertilizer rate. Bermudagrass growing in reconstructed mine soil exceeded the native soil’s yield potential of 7.8 Mg/ha by 112% in 2003, 209% in 2004 and 208% in 2005. Initial white clover establishment was negatively affected by fertilizer application in 2003. During 2005, plots receiving no fertilizer maintained clover ground cover greater than 50% except in September when it dropped to 18%. Ground cover of clover in plots receiving moderate levels of fertilizer ranged from a high of 17% in May to a low of 1% in September while plots receiving high levels of fertilizer had no clover remaining after June of 2005. Ground cover of clover over the winter of 2005-2006 increased and was restored to all plots, including those that had received high rates of fertilizer. By the end of April 2006 clover ground cover increased to 94%, 47% and 23% in plots that previously received no fertilizer, or moderate and high levels, respectively. These data indicate that Durana white clover can compete and persist in bermudagrass even if the bermudagrass is heavily fertilized.

Handout (.pdf format, 407.0 kb)