Cover crops and nitrogen fertilization effects on soil carbon and nitrogenand tomato yield

Cover crops can influence soil properties and crop yield. We examined the i nfluence of legume [hairy vetch (Vicia villosa Roth) and crimson clover (Tr ifolium incarnatum L.)] and nonlegume [rye (Secale cereale L.)] cover crops and N fertilization (0, 90, nd 180 kg N ha(-1)) on the short- and long-ter m effects on soil C and N and tomato yield and N uptake. We measured organi c C and N (long-term effects), potential C and N mineralization (PCM and PN M) and inorganic N (short-term effects) periodically on a Greenville fine s andy loam (fine-loamy, kaolinitic, thermic, Rhodic Kandiudults) planted wit h tomato (Lycopersicum esculentum Mill) from April to August in 1996 and 19 97 in Georgia USA. Soil C and N concentrations increased early in the growi ng season with cover crop residue incorporation, but decreased as the resid ue decomposed. Rye increased organic N and maintained greater levels of org anic C and PCM after 3 yr than other treatments. In contrast, hairy vetch a nd crimson clover increased PNM and inorganic N soon after residue incorpor ation into the soil and produced tomato yield and N uptake similar to that produced by 90 and 180 kg N ha(-1). Nitrogen fertilization increased PNM an d inorganic N after split application and tomato yield and N uptake but dec reased organic C and N and PCM compared with rye. Compared with 0 kg N ha(- 1), nonlegume cover crops, such as rye can increase organic C and N and PCM but legume cover crops, such as hairy vetch and crimson clover, can enrich soil N and produce tomato yield and N uptake similar to that produced by 9 0 and 180 kg N ha(-1).