Effects of Anaerobic Fermentation Residues on Nitrate Accumulation in Leaf Vegetables

A set of orthogonal experiments was conducted to study effects of Anaerobic Fermentation Residues (AFR) on nitrate accumulation in rape and spinach, respectively. In the sequence of significance, the factors which contribute to the nitrate accumulation significantly in spinach were ammonium sulfate, digested sewage and sprayed digested slurry, while in rape, the order was: ammonium sulfate, digested sewage and irrigated digested slurry. The measure for fertilization was optimized according to the principle of high yield and low nitrate. The results showed that applying AFR on vegetables was a procedure of being able to utilize the agricultural waste, to avoid the pollution of anaerobic fermentation, to reduce the production cost by saving the chemical fertilizer, facilitating the demands for high yield and quality.