Hajime Araki

By Hajime Araki

One of the ways to reduce chemical fertilizer application is the use of cover crops, which improve soil properties and supply nutrition to subsequent crops. Hairy vetch (Vicia villosa R.; HV) is one of the processing legume cover crops. A similar yield of fresh marketable tomato (Solanum lycopersicum L.) was obtained in the soil with HV mulch and incorporation even if the reduction of chemical N fertilizer input compared with the conventional production with 240 kg-N/ha fertilizer in the greenhouse from 2006 to 2012. Using 15N-labeling method, HV residue incorporated into soil was decomposed rapidly for about 1 month and N released from HV residue was absorbed into the tomato plant. Nitrogen was absorbed by tomato through out production period. The rate of N uptake derived from HV to total N uptake in tomato plants (%Ndfhv) in the small amount N fertilizer was higher than that with high amount of N fertilizer application. It ranged from 24.8% in 240 kg-N/ha to 37.1% in no N fertilizer. The nitrogen use efficiency (NUE) from HV-derived N by tomato plant reached about 50% during the tomato production with HV incorporation. Other 50% of HV-derived N remained in the soil and 4% of were absorbed by tomato in the next year’s production. HV has the possibility of alternative material for basal N fertilizer to ensure the tomato growth of early period after transplanting, and continuous supply of N is necessary to late stage of tomato. The combined system of incorporation of HV cultivated at the seeding density of 20–50 kg/ha before tomato planting and the slow released N fertilizer was established for the reduction N fertilizer application and obtaining conventional tomato yield in plastic house.

Part of the book: Alternative Crops and Cropping Systems

By Rafael A. Muchanga and Hajime Araki

Adequate residue management may enhance the benefits of cover crops on greenhouse tomato (Solanum lycopersicum L.) productivity, soil N pool, N cycling, and environmental quality. Regardless of management, cover crops may maintain or increase soil N storage at 10 cm depth compared with bare fallow. Cover crops may also enhance microbial biomass N, as a result, soil N availability may increase with cover crops, except rye (Secale cereale L.), more so with hairy vetch (Vicia villosa R.; HV) incorporation than HV mulch and the biculture of HV and rye. Residual inorganic N at surface soil may increase with cover crops, more so with HV and rye monocultures than the biculture. Tomato yield may increase more with the biculture than either HV incorporation or HV mulch because of an efficient residue-N use by tomatoes. The biculture may change the N release pattern from both cover crops: rye of the biculture may release more N than the monoculture, while HV may release a similar or more N in the late than in the early period of tomato growth. With adequate seeding HV/rye ratio (2/1), biculture may maintain or increase soil N storage, increase N cycling and tomato yield, and improve environmental quality.

Part of the book: Nitrogen in Agriculture