N-catch crops affect soil profile nitrate-N accumulation during vegetable cultivation

Abstract

To reduce nitrate leaching, the effects of three N-catch crops of sweet corn (Zea mays L.), amaranth (Amaranthus spp.), and sweet sorghum (Sorghum Linn.) on nitrate-N accumulation in the soil profile were examined using an incubation experiment. Results showed that the biomass and N absorbed by sweet corn were the largest compared with the other two N-catch crop treatments. Root length density for sweet corn, amaranth, and sweet sorghum in the 0–150 cm soil layer was 0.66, 0.34 and 0.46 cm/cm3, respectively, and root dry weight was 0.065, 0.021 and 0.038 mg/cm3, respectively. In the 0–200 cm soil layer, nitrate-N accumulation for fallow, mature sweet sorghum, amaranth, and sweet corn was 1124.7, 899.4, 867.4 and 794.2 kg/hm2, respectively, where the treatment of sweet corn had the smallest N-accumulation. The nitrate-N leachability of fallow, sweet corn, amaranth, and sweet sorghum treatment was 3.6, 1.9, 2.4 and 2.6 kg/hm2, respectively, indicating that cropping of sweet corn, amaranth, and sweet sorghum could reduce the leachability by 47%, 35% and 28% in comparison with fallow treatment. Therefore, the cultivation of N-catch crops can reduce nitrate leaching in seasonal soil, and the sweet corn might be the most suitable catch crop.