Sowing Date and Timing of Nitrogen Fertilizer Application Effects on Soil Water Content and Maize Yield in the Central Highlands of Kenya.

Small scale farmers especially in Sub Saharan Africa (SSA) are increasingly being faced with challenges of erratic rainfall, high cost of input especially nitrogenous fertilizers and limited knowledge on improved water and fertilizer management in agricultural production. This has contributed to the decline in per capita food availability in Sub-Saharan Africa (SSA) and hence the widespread and chronic food insecurity. The objective of this study was to evaluate the effects of rainfall distribution, planting date and timing of nitrogen application on soil water content and maize (Zea mays) yields. The study was carried out in a site located at Kiamaogo Primary school, Tharaka Nithi County in the Central Highlands of Kenya. The field experiment was run for four seasons beginning short rains season of 2009 (SR09) up to long rains season of 2011 (LR11). The experimental design was factorial with three way interaction – 2 planting dates; 2 Nitrogen application methods; and 2 Nitrogen fertilizer rates – in a randomized complete block arrangement with three replications. Late planting and split application of 35 Kg/ha of N showed significantly (p=0.05) dismal grain yield performance. Wet planting generally led to low soil water content compared to late planting. This was probably as a result of the maize crop growth difference and their utilization of soil water. In general, wet planting significantly (p =0.05) increased grain yields by 12% while late planting significantly (p =0.05) favoured stover performance by 27%. On average, the better option combination of the effects of planting dates, N application method and N rates on maize productivity was; wet planting, split application of N and 35 kg ha^-1 of N. The combination yielded the highest quantity of grain during the study period. From the study, key observations on when to plant, when and how to apply N fertilizer were explored and key insights highlighted. Planting time plays a key role in grain yields and early/wet planting had a positive effect while late planting showed to boost stover yields. The findings are crucial in farmer’s decision making on the best time to plant, method of application and amount of N fertilizers to use in maize production, hence impact on the overall agricultural productivity.