Effect of swine liquid manure application in paddy field on water quality, soil fertility and crop yields

Land application of animal manure has been accepted as an effective method and disposal option, which has economic, environmental and social benefits, while also sometimes exists questions about its impact on soil and water quality and crop yields. This paper presents a field-scale study in Chongming Island, Shanghai, China, where land application of digested swine liquid manure with chemical fertilizer supplement in paddy field (SMC field) was conducted to study the short-term effect on soil quality in different depth, pollutant losses by surface runoff, pollutant concentrations in groundwater and crop yields, compared to conventional paddy field with land application of pure chemical fertilizer (CKC field). The results indicated that: (1) in groundwater, the concentrations of chemical oxygen demand (COD), nitrate nitrogen (Nitrate-N), total phosphorus (TP) and dissolved phosphorus (DP) were significantly increased by 24.69, 17.04, 11.76 and 21.05%, respectively, in the SMC field; (2) in surface runoff, the loss loading of COD, TP and DP was significantly increased by 32.18, 15.46 and 28.13%, respectively, while the ammonia nitrogen (Ammonia-N) was significantly decreased by 31.81%, in the SMC field; (3) in the different depth of soil, the contents of total nitrogen presented a greater decrease in the SMC field, while the contents of TP presented a greater decrease in the CKC field, compared to the properties of original soil; (4) for the crop yields, there was no significant difference between the SMC and CKC field. These practices had proved the feasibility for land application of swine liquid manure in the paddy field, and this approach could be extended after being rate modified to concern the nutrient utilization and pollution risk to water environment.