Soil carbon and nitrogen and tomato yield response to cover crop management

Abstract

AbstractDepending on management, cover crops may improve soil and environmental quality and tomato (Solanum lycopersicum L.) yield. We evaluated the effects of hairy vetch (HV; Vicia villosa R.) residue management and the biculture of HV and rye (Secale cereale L.) on soil organic carbon (SOC) and total nitrogen (STN), microbial biomass nitrogen (MBN), soil inorganic nitrogen, and tomato yield for 2 yr in a plastic high tunnel. The SOC in the surface 10‐cm depth was 2.87–17.5% significantly greater in HV incorporation (HVI), HV mulch (HVM), and the biculture of HV and rye treatments (HV+RYE), than in a no cover crop treatment (bare fallow). However, cover crop management effects on STN varied with soil depths (0‐ to 10‐ and 10‐ to 30‐cm depths) and years, and HVI tended to be more effective than other treatments in increasing STN. Residual soil nitrate−N was increased by cover crops, more so by HV monoculture than HV+RYE. The MBN and inorganic N (NO3−−N + NH4+−N) were greater in HVI than either HVM or HV+RYE. Tomato total yield was 11.1–43.8% significantly greater in HVI and HVM than in bare fallow. However, the effects of HV+RYE on MBN, inorganic N, and tomato yield varied with C/N ratio of residues and best results were obtained with a C/N ratio of 17.6 than with 23.7. Therefore, if an adequate seeding HV/rye ratio (2:1) is used, HV+RYE is a better management practice to increase SOC and STN at topsoil and tomato yield with least residual N.