Nitrogen uptake and grain yield of maize (Zea mays L.) as influenced by soil amendments of neem (Azadirachta indica L.) cake and oil extracts and NPK fertilizer in Guinea savannah zone of Ghana

Abstract

Maize (Zea mays L.) has high response to N and the efficient uptake of N is a major factor influencing grain yield. The effect of inorganic NPK fertilizer and Neem cake and neem oil as soil amendments were examined on maize N uptake and grain yield. A 3 × 3 × 2 factorial experiment was laid out in a Randomized Complete Block Design with three replications at the University for Development Studies farms at Nyankpala near Tamale, in northern Ghana. The treatments consisted of combinations of three levels of neem cake (0, 200 and 400 kg ha-1), three levels of neem oil (0, 10 and 20 L ha-1) and two levels of NPK (0 and 250 kg ha-1). The results showed that NPK at 250 kg ha-1 combined with neem cake at 400 kg ha-1 significantly (p < 0.05) increased N uptake in maize by 31% (from 111.3 kg ha-1 to 146.9 kg ha-1) compared to the recommended NPK rate. Maize grain yield was significantly maximized by that treatment at 7,471 kg ha-1. Grain yield was significantly associated with N uptake; therefore 250 kg ha-1 NPK with 400 kg ha-1 neem cake could be recommended for maize farmers in the project area. In contrast, neem oil extracts significantly reduced N uptake. The results of the study posited important implications for soil fertility management and climate change mitigation strategies for enhanced maize production.