| Rationally combining application of organic fertilizer and chemical fertilizer is an inevitable choice for Chinese current agriculture that approaches to sustainable development.This experiment selected the field-position experiment on intercropping and mixed cropping of rape with Chinese milk vetch in rice-rape rotation system,exploring the effects of which on next rice season yield,nutrient uptake and soil fertility.At the same time,exploring the effects of returning green manure and rape straw to field on fertilizer saving,to provide basis for rational utilization of green manure and straw to improve the sustainable utilization of cultivated land in rice-rape rotation system.The main results are as follows:(1)The reasonable intercropping and mixed cropping of rape with Chinese milk vetch have significant adverse impact on the rape yield.Conversely,it can achieve a certain amount of production of the Chinese milk vetch.The yield of intercropping and mixed cropping of rape with Chinese milk vetch system was lower than that of unicast rape treatment by 4.12%-8.82%,and the difference was not significant.In rice-rape rotation system,the soil fertility of paddy field has a rising trend,which shows that the total nitrogen,available phosphorus,available potassium and organic matter content of soil increase.The direct income of the intercropping of rape with Chinese milk vetch in rice-rape rotation system,decreased by 244 Yuan/ ha,and that of the mixed cropping pattern increased by 701 Yuan/ ha.(2)The intercropping and mixed cropping of rape with Chinese milk vetch pattern has no obvious effect on nutrient absorption of rape,and has a promoting effect on nutrient absorption and utilization in later season.The contents of nitrogen and potassium in rice has increasing trend compared with rape unicast treatment,the increase was 8.03%,16.96%,8.35% and 7.9% respectively.After intercropping and mixed cropping of rape with Chinese milk vetch,the utilization efficiency of nutrients(N,P and K)of late season rice was higher than that of unicast rape.Rape straw and green manure returned to the field increased the yield of the latter season rice,increasing by 4.62%~7.73%.Two years of continuous experiment showed that the soil fertility in rice field had an increasing trend under intercropping of rape with Chinese milk vetch in rice-rape rotation system.Soil total nitrogen,available phosphorus,available potassium and organic matter content have an increasing trend.(3)When rape mixed cropping with Chinese milk vetch,the straw and Chinese milk vetch can replace 15%-30% rice fertilizer after rape harvest.At the same time,the utilization efficiency of fertilizers has an increasing trend compared with the treatment of conventional fertilization,and rice fertilizer recycling efficiency,partial productivity has significantly improved in 70% CF treatment compared with conventional fertilization treatment.On the other hand,the rice yield still has an increasing trend of 1.54%-8.50% compared with the treatment of rape monoculture,with an increase of cost-saving 841~1111 Yuan/ha.Meanwhile,soil fertility,soil total nitrogen,available phosphorus,available potassium and organic matter all have a tendency to increase in different degrees.Above all,mixed cropping of rape with Chinese milk vetch,the rape yield will not be reduced and some of Chinese milk vetch can be harvested as green manure at the same time.Returning rape straw to the field which can partly replace the chemical fertilizer in rice season,maintain the increasing trend of rice yield and the annual economic income of ricerape rotation system. |
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