Methods and time of application of labelled nitrogen and phosphorus fertilizers in maize (Zea mays L.) cultivation

Abstract

SummaryIn this study two field experiments were conducted on a heavy to medium heavy, calcareous, recent alluvial soil of Central Greece. The main aim of these experiments was to study the effect of the most common nitrogen sources, applied in one or two doses, on maize growth and fertilizer utilization. Foliar application of urea was also a treatment included in these experiments.Phosphorus alone had no significant effect on maize yield. Nitrogen (various forms), alone or in combination with phosphorus, increased the yield and nitrogen content of maize. Maize yield was not significantly affected by the form of nitrogen or by dividing the application of nitrogen. Foliar applications of urea were as effective as soil applications in increasing maize grain yields.The percentage of fertilizer nitrogen taken up (utilization coefficient) ranged between ca. 58% for sodium nitrate and ammonium nitrate, and ca. 39% for ammonium sulphate and urea, when the fertilizers were applied about 10 weeks after sowing. Foliar urea was nearly as efficiently utilized as urea applied as a sidedressing. Application of the tested fertilizers before sowing was nearly as efficient as or more efficient than application of the fertilizers as a sidedressing at 70 cm plant height (38 days after sowing). Finally, addition of 120 kg N/ha enhanced the amount of soil nitrogen taken up in the maize crop by 33%.