Control of nitrate pollution by application of controlled release fertilizer (CRF), compost and an optimized irrigation system

Abstract

A nitrogenous controlled reléase fertilizer (Floranid 32) and a treatment of municipal organic waste compost were tested under two irrigation managements (conventional and ET-adjusted irrigation rales) with the aim of assessing risk of nitrate leaching to the aquifer. A check without N fertilizer was introduced. The experiment was carried out at La Poveda Field Station (30 km SE Madrid, Spain) in alluvial soils with water table depth at 4 m and under maize cropping. The experiment was laid out in a randomized complete block design with three replications, allocating 12 plots to each irrigation management. Although N fertilizer rate (150 kg ha-1) was reduced at half as related to a previous experiment, no difference in grain yields was observed. This result relates to a high content of soil-N. Floranid showed promising results in controlling N-leaching in comparison with urea that exhibited an accelerated rate of N reléase which finally determines low use of N by the plant and marked NO3- leaching. Treatment of municipal waste compost showed NO3- concentrations in the soil water solution of similar valúes as those of urea at 140 cm. ET-adjusted irrigation showed no drainage during the corn growing season and lower NO3- concentrations in the soil water solution which could indicate a general lower rate of N solubilization.