Long-term effect of different manure and fertilizer treatments on grain yield of upland rice

In order to optimize manure and fertilizer application in rice under rainfed upland condition for high and sustainable yield over years and climatic changes, different manure and fertilizer combinations were tested in the research farm of AICRPDA, OUAT, Phulbani, Odisha, India during 1997 to 2008. Highest mean rice yield of 1.50 t ha-1 with lowest coefficient of variation was obtained with FYM to supply 30 kg N along with 30kg N+ 40 kg P2O5 + 40kg K2O ha-1 in form of chemical fertilizer showing the importance of combined application of organic manure and chemical fertilizers for sustainable yield under rainfed upland situation. This was closely followed by the treatment with FYM to supply 30 kg N along with 20 kg P2O5 + 20 kg K2O ha-1 giving 1.47 t ha-1. These two treatments gave almost three times yield over control (4.84 q/ha) and also exhibited higher net income and B:C ratio. Among the monsoon months (June to September), highest monthly rainfall was recorded in August (365.11 mm) followed by July (339.02 mm) but the coefficient of variation was lowest in July (52.15) and highest in August (65.51) indicating more rainfall variation over years during August. Negative correlation between crop yields in different treatments and crop seasonal rainfall predicted either excess rainfall over requirement or improper rainfall distribution in the years of high precipitation affecting yield.