三种稻渔生态种养对稻田土壤化学性质和酶活性的影响OA

The rice-fish co-culture system is a type of sustainable ecological agriculture promoted under China's 14th Five-Year National Fishery Development Plan.To investigate the temporal changes in soil physicochemical properties and enzyme activities across different growth stages in various ecological farm-ing systems and to enrich the fundamental theory of rice-fish co-culture system,this study evaluated the impacts of three rice-fish co-culture systems in Chongqing on paddy soil fertility.The evaluation was based on the measurement of 12 indicators related to soil fertility and health during different rice growth stages.The results showed that the soil pH under three rice-fish co-culture systems was significantly higher(P＜0.05)than that of the control group during all stages of rice growth.However,the soil organic matter,to-tal nitrogen,alkaline hydrolysable nitrogen,available potassium,and soil alkaline phosphatase activity were significantly lower(P＜0.05)than that of the control group in most periods.Further analysis re-vealed a decline in soil fertility and nutrient levels across all three systems.The most severe delince was observed in the rice-turtle-duck group,followed by the rice-turtle group,while the rice-shrimp group ex-hibited a relatively milder decline.These results suggest that rice-fish co-culture systems with low stocking densities and limited feed input may lead to varying degrees of soil fertility depletion.It is recommended to appropriately increase animal stocking densities and feed input,and to supplement organic fertilizers ac-cording to the nutritional demands of rice at different growth stages,thereby promoting water and nutrient balance in paddy fields.