Abstract:

The suitable nitrogen application rate of ratooning rice in crayfish field was studied to provide theoretical basis for reasonable nitrogen application in ratooning rice field under rice-crayfish coculture in southern Henan and promoting the popularization and application of ratooning rice in crayfish field. In this experiment, ‘Tianliangyou 616’, the main cultivated variety of ratooning rice in southern Henan paddy fields, was used as the research object. Under the same field management conditions, six different nitrogen fertilizer levels, including N0 (0 kg/hm²), N1 (249.27 kg/hm²), N2 (302.69 kg/hm²), N3 (356.10 kg/hm²), N4 (409.52 kg/hm²) and N5 (462.93 kg/hm²), were set up to study the effects of different nitrogen application rates on the two-season yield and economic benefits of ratooning rice in crayfish fields. The results showed that with the increase of nitrogen fertilizer application amount, the two-season yield of ratooning rice showed a trend of first increasing and then decreasing, with the highest yield in the N4 treatment. Moreover, as the nitrogen application amount increased, the annual economic benefit of ratooning rice became negative. The comprehensive economic benefit curve showed that the best benefit could be obtained when the nitrogen application rate was 386.68 kg/hm². The study results indicated that appropriate nitrogen fertilizer application could increase the yield and economic benefits of ratooning rice, and the optimal nitrogen application rate for the rice-crayfish culture in the southern Henan paddy fields was recommended to be 386.68 kg/hm². This study could provide a theoretical basis for reasonable nitrogen application in ratooning rice fields under rice-crayfish coculture in southern Henan.

Key words: southern Henan paddy fields, ratooning rice, rice-crayfish coculture, yield, economic benefits, suitable nitrogen application rate