Responses of Rice to Green Manure and Nitrogen Fertilizer Application

The effect of green manure and nitrogen fertilizer applications on rice performance and post-harvest nutrient status of the soil was studied at the Regional Wheat Research Station of Bangladesh Agricultural Research Institute (BARI), Shyampur, Rajshahi, Bangladesh. The experiment comprised two sets of treatments: (i) green manure application (Crotalaria jusncea, Sesbania aculeata, Sesbania rostrata,Vigna radiata, and Phaseolus mungo) and (ii) application of different nitrogen levels (0, 40, 80, and 120 kg ha^-1). Both treatments had a significant effect on the growth and yield of transplanted aman (T. aman) rice. We show that soil fertility can be maintained and rice yield can be improved through incorporation of green manuring and nitrogen fertilizer management. Green manure and nitrogen management generated positive responses in important morpho-physiological traits such as leaf area index (LAI), specific leaf area (SLA), crop growth rate (CGR), leaf relative growth rate (LRGR), leaf weight ratio (LWR), and net assimilation rate (NAR), which may result in a greater contribution of yield-determining traits and eventually higher grain yield. The results indicate that all green manures in combination with higher N levels accelerate SLA, LWR, LAI and CGR. Better performance of potential yield-contributing characters and relatively higher nitrogen uptake and higher N and protein content in grain and straw were found in combination with all green manure and higher N level treatments. An increasing level of post-harvest soil nitrogen content was observed with the application of higher levels of nitrogen in combination with green manures. Therefore, green manuring in combination with judicial nitrogen fertilizer management is deemed necessary for sustainable T. aman rice cultivation.