Effects of co-operating straw incorporation with Azolla on rice yield,grain quality and nitrogen use efficiency
Straw incorporation has demonstrated great potential in improving rice yield and soil fertility.However,straw incorporation may lead to microbial-mediated nitrogen immobilization and inhibit the growth and nitrogen uptake of rice in early stage of rice growth.Nitrogen-fixing Azolla can be used as high-quality green manure in the rice field,which can provide nitrogen to meet the requirement of rice's growth and alleviate the nitrogen deficiency caused by straw incorporation.Field experiment was conducted to study the combined effects of straw incorporation and Azolla on grain yield,nitrogen use efficiency and grain quality of rice.There were five treatments,namely no fertilization application(CK),conventional chemical fertilization application(F),conventional chemical fertilization application+straw incorporation(FS),conventional chemical fertilization application+Azolla(FA),conventional chemical fertilization application+straw incorporation+Azolla(FSA).There was no significant difference in the rice yield,nitrogen accumulation,nitrogen use efficiency,brown rice rate,milled rice rate,chalky grain rate,chalkiness,amylose content,protein content,and magnesium,zinc and iron contents between FS and F treatment.Calcium content of FS treatment was significant lower than that of F treatment(P<0.05).There were no remarkable differences in brown rice rate,milled rice rate,protein content,magnesium and iron contents between FA and F treatment.The rice yield,nitrogen accumulation,apparent nitrogen recovery,chalky grain rate and chalkiness of FA treatment were remarkable higher than that of F treatment(P<0.05),and amylose content,calcium and zinc contents were significantly lower than that of F treatment(P<0.05).There were no significant differences in protein content,calcium,magnesium,zinc and iron contents between FSA and F treatment.The rice yield,nitrogen accumulation,agronomic nitrogen efficiency,apparent nitrogen recovery,chalky grain rate and chalkiness of FSA treatment were significantly higher than that of F treatment(P<0.05),amylose content,brown rice rate and milled rice rate of FSA treatment were significantly lower than that of F treatment.In conclusion,the co-operation of straw incorporation and Azolla significantly improved the rice yield and nitrogen use efficiency without reducing the nutritional quality of rice,making it a promising farming measure for southern paddy fields.
straw incorporationrice-Azolla cropping systemnitrogen use efficiency
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