Effects of urea-N fertilizer dosage supplemented with Ipil-Ipil tree litter on yield of rice and insect prevalence

摘要

The present study was undertaken to determine the effects of different levels of urea-N fertilizer in addition to ipil-ipil tree litter on yield of rice and insect prevalence. The field study was conducted at the Agroforestry Field Laboratory, Bangladesh Agricultural University, Mymensingh during July-December 2004. The treatments included 0, 90, 180, and 270 kg urea per hectare. All four treatments received five tons ipil-ipil tree litter per hectare. The experiment was laid out in a randomized complete block design (RCBD) with four replications. The results showed that the different treatments significantly influenced the yield and yield component viz. total tillers/hill, effective tillers/hill, filled grains and unfilled grains/panicle. The highest yield of 4.62 t·hm-2 with an increase of 21.57% over the control was recorded in treatment 180 kg urea·hm-2, which was statistically similar to treatment 90 kg urea·hm-2. The prevalence of insects viz. green leafhopper, brown plant hopper, rice bugs, leaf folder and stem borers were mostly correlated with N-levels. The prevalence of insects in general gradually increased with the increase of N. Therefore, this study suggests that the combined application of organic materials (tree litter of ipil-ipil) and N-fertilizer of 90 kg·hm-2 may produce good yield while minimizing insect prevalence in the rice field.