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The study was conducted with the aim of investigating the effect of split application of nitrogen on growth and yield of NERICA 1 and NERICA 4 rice varieties at Tsukuba International Center, Japan from April to September 2013 cropping season. The varieties were investigated for establishment, plant height, tiller number, SPAD value, shoot dry matter, panicle dry matter, nitrogen uptake, panicle number, spikelet number, panicle length, ripening ratio, thousand grain weight, harvest index and paddy yield. The result showed that NERICA 1 had significantly greater establishment percentage, shoot dry matter, panicle length and thousand grain weight than NERICA 4, but its leaves were significantly (p<0.05) less green than the latter after 55 days of sowing. Dividing 80kg N ha -1 into two and applying half rate at sowing as basal and top dressing at panicle initiation gave significantly more green leaves than either at once application of full rate or half rate as basal and half rate top dressing at heading applications from 90-115 days after sowing. However, application of half rate of 80kg N ha -1 at sowing and heading time produced significantly (p<0.05) more green leaves than at once and half as basal and at panicle initiation after 115 days of sowing. It also produced significantly longer panicles than the other two modes of N applications. In all of the evaluated parameters, varieties and split nitrogen applications failed to show significant (p>0.05) interaction. Splitting 80kg N ha -1 in to two and applying half of it at sowing and the remaining half at panicle initiation as well as applying half of it at sowing and the remaining half at heading time increase panicle length compared to applying full rate at once during sowing.

The study was conducted to investigate growth and nodulation response of Clark 63-K soybean variety to Bradyrhizobium japonicum inoculation and phosphorus levels under lath house condition at Jima Agricultural Research Center in 2010. The crop was evaluated in terms of nodule number, nodule volume, nodule dry weight, shoot nitrogen content, plant height, number of pod bearing branches, shoot dry matter and root dry matter. The result revealed that an interaction effect of the main factors did not significantly (P < 0.05) influence number of pod bearing branches, shoot dry matter and root dry matter yield of the crop. In terms of shoot nitrogen content and plant height, Clark 63-K soybean had no response to inoculation when it was grown without phosphorus. However, inoculation significantly (p < 0.05) increased these parameters over the uninoculated control when 60, 120 and 180 mg kg-1 phosphorus were applied. For uninoculated and inoculated treatments, phosphorus significantly (p < 0.05) influenced all nodulation and growth traits. The three phosphorus treatments (60, 120 and 180 mg kg-1) significantly (p < 0.05) improved pod bearing branches, shoot and root dry matter yield over the untreated control. Inoculation coupled with 120 mg kg-1 phosphorus level being considered an optimal combination for Clark 63-K soybean production in the area.

Optimal nutrient application is required for sustainable crop production and farm profitability in Ethiopian smallholder farmer. In this study, N, P and K requirement of maize was estimated for the current and future maize production levels in East Shewa and Jimma zones of Ethiopia. Current yield was assessed from Spatial Production Allocation Model (SPAM) database and yield responses and agronomic N, P and K use efficiencies were assessed from literatures. Future yields were interpolated from the current yield. Yield responses and agronomic efficiencies of N, P and K were combined to estimate N, P and K requirement of maize for achieving the current and future yields. The result demonstrated that yield and N, P and K requirement of maize is to increase by about 4%. The minimum of nutrient requirement for maize production in East Shewa is 5.8, 4.1, and 5.1 tons of N, P and K, respectively whereas in Jimma zone the estimated nutrients are 11.5, 4.3 and 10.7 tons of N, P and K, respectively. The nutrient requirement of maize can further be increased if farmers apply good crop husbandry and achieve higher yields than predicted. It is concluded that yield responses and agronomic efficiency of nutrients should be considered for estimating nutrient requirement of a crop.