Abstract:

【Objective】 In a field plot experiment, three measures including conventional cultivation, root layer regulation agent and straw retention were used to reduce soil nitrate accumulation in catch crop of sweet corn (Zea mays L.). 【Method】 Four treatments of conventional cultivation, soil conditioner , straw returning to soil and fallow field were designed. 【Result】 At the condition of this experiment, the above ground biomass of the treatment of soil conditioner was the highest among the three treatments, and N uptake were not significantly different from that of the treatment of straw returning to soil, but N uptake of the treatments of soil conditioner and straw returning to soil was significantly higher than that of the treatment of conventional cultivation. NO3--N reduction of 0-100 cm soil layer was significantly higher than that of 100-200 cm. The residual NO3--N of 0-100 cm of the two kinds of root layer regulation measures was significantly lower than that of conventional cultivation, but the residual nitrate of 100-200 cm was similar among the three treatments. Fallow led to high residual NO3--N and serious leaching. Root density and root dry weight under the conditions of straw returning to soil and soil conditioner in 30-60 cm and 60-100 cm were higher than that of conventional cultivation, the root length density was very significantly correlated with NO3--N reduction. The NO3--N leakage under the conditions of soil conditioner and straw retention in 100 cm depth was 68.4% and 52.6% less than conventional cultivation respectively. 【Conclusion】 In high NO3--N accumulation soil, the soil conditioner and straw returning to soil are effective measures to reduce NO3--N accumulation with catch crops planting.

Key words: catch crops, root layer, NO3--N, control measures