Fate of the nitrogen from fertilizers in field-grown maize

Abstract

The nitrogen (N) from fertilizers has different fate, some of which affect the environment or the human health, e. g. nitrates in groundwater. We determined the fate (plant organs, soil organic matter, remaining nitrates and volatilization) of the N applied to field-grown direct drilling maize. An experiment was carried out in a Typic Argiudoll at Chivilcoy, Argentina (35 o02′S, 60 o06′W). Treatments were: control; 70; 140 and 250 kg N ha -1. Microplots were fertilized with urea tagged with 15N (1.5 % abundance). Plant biomass and N concentration were determined at flowering and at physiological maturity. Soil organic N (0-30 cm) and nitrates and ammoniacal N concentrations (0-300 cm) at harvest, and ammonia volatilization were determined. 15N was determined in all samples. The crop was the main sink, recovering an average of 56 % of the N from the fertilizer. Both the soil organic fraction and ammonia volatilization were the second N sink. The N remaining as residual nitrates averaged 8.6 % and the leached nitrates were only 0.8 % of the fertilizer applied. Most N leached after maize cropping could be accredited to mineralization of organic N. Organic matter could then be a temporary sink, which reduces N leaching from a single fertilization but releases nitrates the following years. © 2012 Springer Science+Business Media B.V.