Study On The Change Of Phosphorus Morphology In Soil And Phosphorus Balance Of Integrated Rice-crayfish Co-culture

The rice-crayfish co-culture is an ecological farming model that combines rice cultivation and aquaculture by applying ecological principles to realize the cultivation of crayfish in rice fields and the cultivation of rice.The introduction of crayfish into the paddy not only changed the material cycle of the paddy ecosystem,but also had a profound impact on the physicochemical properties of the paddy soil.In this study,we investigated the response mechanisms of soil phosphorus morphology and effectiveness,nutrient dynamics of rice plants and phosphorus balance of paddy systems under three different treatments of rice monoculture（RM）,rice-crayfish co-culture with feeding（RC1）and rice-crayfish co-culture without feeding（RC0）through two years of field localization experiments.The main findings are as follows.（1）After two years of field trials,the rice-crayfish co-culture significantly increased soil pH compared with the rice monoculture model;the rice-crayfish co-culture（RC1 and RC0）treatments significantly increased the organic matter,total nitrogen,total phosphorus and fast-acting potassium contents in the 0～10 cm soil layer of paddy soils compared with the rice monoculture（RM）treatment.At the end of the experiment,compared with the rice monoculture model,the rice-crayfish co-culture significantly increased the content of Olsen-P and organic phosphorus,and significantly increased the activation coefficient of soil phosphorus;there was no significant difference in the content of soil inorganic phosphorus and acid phosphatase.（2）Compared with the rice monoculture model,the rice-crayfish co-culture increased the proportion of available phosphorus to total phosphorus,decreased the proportion of moderately available phosphorus to total phosphorus,and had no significant effect on the proportion of nonlabile phosphorus to total phosphorus.The rice-crayfish co-culture（RC1and RC0）patterns significantly increased Na HCO₃-Pi and Na HCO₃-Po in the available phosphorus fraction and decreased Na OH-Po in the moderately available phosphorus fraction compared with the rice monoculture pattern,and the rice-crayfish co-culture with feeding（RC1）treatment significantly increased the content of the nonlabile phosphorus fractions(HCl._Conc-Pi,HCl._Conc-Po and Residual-P)content.Redundancy analysis（RDA）showed that the key factors affecting phosphorus morphology in the rice monoculture（RM）treatment were total nitrogen,organic matter and total phosphorus;the key factor affecting phosphorus morphology in the rice-crayfish co-culture with feeding（RC1）treatment was total phosphorus;and the key factor affecting phosphorus morphology in the rice-crayfish co-culture without feeding（RC0）treatment was p H.Correlation analysis and stepwise linear regression showed that the rice monoculture（RM）treatment with moderate The correlation analysis and stepwise linear regression showed that in rice monoculture（RM）treatment,available phosphorus and total nitrogen were significantly positively correlated,and closed-storage phosphorus and total phosphorus were significantly positively correlated.（3）The rice-crayfish co-culture（RC1 and RC0）model could increase phosphorus content in rice stems and leaves and phosphorus accumulation at plant maturity compared with the rice-shrimp monoculture model.The phosphorus balance of farmland showed surpluses in all three modes,and the phosphorus surplus in the rice-shrimp feeding mode was higher than that in the rice monoculture and rice-shrimp non-feeding modes,while the phosphorus cycling was lower than that in the rice-shrimp non-feeding mode;the rice-shrimp non-feeding mode reduced phosphorus retention in the environment and improved phosphorus use efficiencies（pue）.（4）In terms of paddy productivity,there were no significant differences in the components of rice monoculture（RM）,rice-crayfish co-culture with feeding（RC1）and rice-crayfish co-culture without feeding（RC0）,and the rice-crayfish co-culture model（RC1 and RC0treatments）had a tendency to increase rice yield,but the differences were not significant;in terms of ecological benefits,compared with the rice-crayfish co-culture with feeding model,the rice-crayfish co-culture without feeding model reduced paddy field surface water In terms of ecological benefits,compared with the rice-shrimp feeding model,the rice-shrimp crop without feeding model reduced the concentration of total phosphorus and dissolved phosphorus in water,which reduced the risk of agricultural surface pollution;in terms of economic benefits,the net income of the integrated rice-crayfish culture（RC1 and RC0treatments）increased by 8146（?）·hm^-2 and 8641（?）·hm^-2,respectively,compared with the rice-shrimp monoculture treatment.