| Agricultural non-point source pollution has seriously affected the quality of rural water bodies and the ecological environment.The excessive use of chemical fertilizers is one of the main sources of agricultural non-point source pollution.In this study,under the two rotation planting modes of rice-rape and rice-cabbage,four different treatments including no fertilization,purified fertilizer,50%organic fertilizer replacement,and carbon-based fertilizer were used to explore the effects of rotation mode and fertilizer types on rice field runoff loss and nutrient utilization Impact.The main findings are as follows:1.The two rotation modes produced 10 runoffs,including 7 in the rice season and 3 in the vegetable season.The concentration of nitrogen and phosphorus in the runoff produced in the short term after fertilization was significantly higher than that of no fertilization.The nitrogen in the runoff of the rice season is mainly ammonia nitrogen,and the nitrate nitrogen in the vegetable season.The total nitrogen concentration in the runoff water of the three treatments of rice-rape model,including purified fertilizer,50%organic fertilizer substitution,and carbon-based fertilizer,were 0.86～28.11,0.94～26.63,0.91～17.25 mg·L-1,and the total phosphorus concentration was 0.23～4.57,0.17～5.15,0.23～3.64mg·L-1.The three treatments of rice-vegetable model of purified fertilizer,50%organic fertilizer substitution,and carbon-based fertilizer included total nitrogen concentration of 0.86～25.10,0.94～27.44,0.90～27.30mg·L-1,and total phosphorus concentration of 0.23～4.10,0.24～3.70,0.21～3.78mg·L-1.2.There was no significant difference between rice-rae rotation and rice-vegetable crop rotation on soil properties.The runoff nitrogen loss of rice-rape(20.01-22.14 kg·hm-2)was significantly lower than that of rice-vegetable cropping(33.87-38.31kg·hm-2),a year-on-year decrease of 39.3-42.21%;The runoff loss of rice-rape,rice-vegetable phosphorus was 2.54～2.97,2.82～3.21kg·hm-2,respectively.There was no significant difference between the two rotation modes.3.There were no significant differences in soil fertility,runoff nitrogen and phosphorus loss between the three fertilizers.Fertilization significantly increases crop nitrogen and phosphorus absorption,thereby significantly improving crop growth characteristics and yield;compared with no fertilization,the yield of rice,rape,and cabbage increased by 41.9%～51.9%,128.4%～148.9%,26.0%～31.8%;there is no significant difference in nitrogen and phosphorus absorption and fertilizer utilization of rice and rape crops among different treatments;the nitrogen absorption of cabbage under50%organic fertilizer replacement treatment is significantly higher than that of purified fertilizer and carbon-based fertilizer treatment（P<0.05）,the phosphorus uptake of cabbage showed as purified fertilizer>50%organic fertilizer substitution>carbon-based fertilizer,the difference between different treatments reached a significant level（P<0.05）;after fertilization,rice,rape,and cabbage nitrogen absorption the amount increased by 40.08%～67.10%,116.71%～147.02%,33.75%～53.56%.The phosphorus absorption increased by 22.79%～66.5%,rape 69.09%～105.53%,and cabbage increased by165.53%～267.83%.The nitrogen and phosphorus uptake of rice-vegetable crops throughout the year was significantly higher than that of rice-rape（P<0.05）. |
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