Evaluation of timing and rates for nitrogen application for optimizing maize growth and development and maximizing yield

Accurately applying N fertilizer is challenging for maize (Zea mays L.) farmers in semiarid regions. The goal of this study was, therefore, to identify the best rates and timing of N applications for optimum maize development and maximum grain yield (GY). A 2-yr study (2009 to 2010) was conducted in the semiarid conditions of Faisalabad, Pakistan. Five N application rates were administered at three different times during each growing season. Photosynthesis, GY, N uptake, and N recovery efficiency (NRE) were significantly affected (P < 0.05) by the rate and timing of N applications. Photosynthesis, GY, and NRE increased linearly following application of 1/3 N at V2, 1/3 N at V16, and 1/3 N at R1 stages (treatment T₂) with 250 kg N ha^-1In contrast, the maximum N uptake was observed with an application of 300 kg N ha^-1 without a significant increase in GY. The results suggest that N fertilizer recommendations should not be solely based on plant N uptake but also take into account the physiological processes of maize and NRE. Since the optimal N application rate for maximum GY was 250 kg N ha^-1applied in three applications (1/3 N at V2, 1/3 N at V16, and 1/3 N at R1 stages), this rate and timing should be considered as the best fertilizer management practice for semiarid conditions.