Effect of anaerobic fermentation residues on nitrate accumulation in leaf vegetables

The experiments in pot culture and field are conducted to study the factors of anaerobic fermentation residues (AFR)on nitrate accumulation in leaf vegetables．The exploration of strategy in nitrate accumulation aims at supporting the improvement of energy-environment engineering and the production of safe food．The results show that compared to chemical fertilizer，AFR can decrease the nitrate accumulation in rape and spinach；nitrate content in plant tissue is increased with the increase of percentage of chemical nitrogen in the mixture of chemical fertilizer and AFR．Comparing spraying dressing digested slurry with irrigation，spraying method can reduce the nitrate content of rape，however，a reverse result is found in spinach．The nitrate accumulation in rape affected by AFR has more apparent effect in high fertility soil than that in low one，and the regulation effect is more effectively in high fertility soil．To regulate the nitrate accumulation in plant has more apparent effect on rape under greenhouse cultivation and more apparent effect on spinach under open—air cultivation．