Evaluation of the effects of phosphorus and nitrogen source on aerial and subsoil parameters of maize (Zea mays L.) during early growth and development

Understanding the nutrient requirements of maize is especially important during early vegetative growth and development, particularly when produced on highly weathered soils with low organic matter contents. Therefore, the growth response of maize to different nitrogen (N) sources viz. limestone ammonium nitrate and urea, phosphorus (P) sources viz. monoammonium phosphate, nitrophosphate and ammonium polyphosphate, as well as P application levels viz. 0, 10, 20, 30 and 40 kg ha−1 during early growth were evaluated. In pot trials with a sandy loam topsoil, aerial and subsoil plant parameters were measured to evaluate the effect of treatment and treatment combinations of P and N fertilisers on the vegetative growth and development of maize during the first five weeks after emergence. Plants treated with limestone ammonium nitrate had significantly greater plant parameter measurements compared with urea, primarily ascribed to immediate availability after application in addition to ease of uptake. Monoammonium phosphate and nitrophosphate (orthophosphate sources) yielded significantly greater aerial measurements compared with ammonium polyphosphate (polyphosphate source). Differences in subsoil plant parameter results for P source were not that clear. Aerial and subsoil plant parameter measurements were overall significantly greater with P applied at 40 kg ha−1 than the majority of lesser application rates.Keywords: nitrogen source, orthophosphate, plant growth parameters, polyphosphat