Optimizing nitrogen use efficiency and maize yield under varying fertilizer rates in kenya

Nitrogen (N) is a paramount macronutrient for plant growth, development and production. This study was carried out to determine the effect of N fertilizer at different rates on maize crop yield, N content and N use efficiency (NUE) in Rongo sub-county (Kambija and Koderobara sites), Western Kenya. The treatments were N (CAN) at four levels (0, 25, 50 and 75 kg N ha⁻¹). In Kambija, maize yield at 50 kg N ha⁻¹ (4.34 t ha⁻¹) was 62% higher than the control while in Koderobara, the highest yield (3.41 t ha⁻¹) was recorded at 50 kg N ha⁻¹ and it was 74% higher than in the control. The highest N content of 21 and 20 g kg⁻¹ were noted at heading growth stage in Kambija and Koderobara, respectively. Generally, partial factor productivity (PFP), partial nitrogen balance (PNB), agronomic N efficiency (N-AE), and nitrogen fertilizer recover (NFR) decreased with increasing N application across the sites. The yields exhibited strong relationship with N uptake in the plant tissues especially at harvest, with coefficient of determination ranging between 0.72 and 0.92. The study therefore has showed that application of N at 50 kg N ha⁻¹ was the most viable hence such information needs to be disseminated to farmers.