Abstract:

In order to determine the application effect of different proportions of organic fertilizer replacing chemical fertilizer in paddy fields, field experiments were conducted based on the conventional nitrogen application amount (210 kg·hm^-2). There were five treatments: no nitrogen fertilizer (CK), conventional fertilizer (T0), 75% nitrogen from organic fertilizer +25% nitrogen from inorganic fertilizer (T75), 50% nitrogen from organic fertilizer +50% nitrogen from inorganic fertilizer (T50) and 25% nitrogen from organic fertilizer +75% nitrogen from inorganic fertilizer (T25). The effects of different proportions of organic fertilizer on rice yield, nitrogen uptake, nitrogen efficiency and apparent balance were analyzed. The results showed that the grain yield of rice with 25% nitrogen from organic fertilizer and 75% nitrogen from inorganic fertilizer (T25) was the highest in both Yueshanxia village and Maozhuxia village. Although there was no significant change in grain yield in Yueshanxia village, the yield under T25 treatment was 8.63% higher than that under T0 treatment. Compared with CK, the effective panicle number of N-treated rice in Yueshaxia village and Maozhuxia village increased by 42.9%-53.8% and 32.2%-71.3%, respectively. In Maozhuxia village, the effective panicle number of T25 treatment was 29.6% higher than that of T0. In Yueshanxia village, though the grain nitrogen content of T50 was similar to that of T0 and T75, it was significantly higher than that of T25 treatment by 11.9%. The nitrogen content of rice straw in T50 was also significantly higher than that in T0 by 32.6%. Although the nitrogen content of T25 rice straw was similar to that of T0, it was 10.7% and 14.1% higher than that of T75 and T50. In Yueshanxia village, the nitrogen absorption of T75 straw was 41.8% higher than that of T0. Although the nitrogen efficiency of organic substitution treatment was similar, 26.3%-35.9% higher than that of T0 treatment, the apparent nitrogen efficiency of T25 in Maozhuxia village was the highest, 26.3%, and 20.7% higher than that of T75. In conclusion, under the conditions of conventional nitrogen application, organic substitution has a slight increase in rice yield compared with total fertilizer application. The combination scheme of 25% organic fertilizer and 75% inorganic fertilizer had the best effect on increasing rice yield and nitrogen apparent utilization.

Key words: rice, yield components, organic substitution, balance, internal utilization efficient, partial productivity