mineral nitrogen rate, manure, straw, nitrate, leaching, model
Abstract
The effects of organic and mineral nitrogen fertilization on nitrogen leaching and nitrate concentration in percolated water were simulated using the CANDY model. In a long-term IOSDV field experiment carried out from 1983 to the present in Lukavec, Czech Republic, increasing nitrogen rates from 0 kg to 200 kg N*ha-1 in mineral fertilizers were combined with the application of farmyard manure or straw, the control treatment was without organic fertilization. The simulation results of four rotations in the years 1996 – 2007 are presented. In the treatments, the average simulated nitrogen leaching ranged from 2 kg to 71 kg N*ha-1 y-1, the average nitrate concentrations were between 5 mg and 191 mg*l-1. The average year concentration of nitrate about 40 mg*l-1 indicated increasing occurrence of concentrations above 50 mg*l-1 at daily basis. Nitrogen leaching and nitrate concentrations were non-linearly related to the total nitrogen inputs (R2= 0.98), the organic fertilizer
treatments only negligibly altered the form of the relationship. The average nitrate concentration exceeded 50 mg*l-1 at a total nitrogen input level about 150 kg N*ha-1; this corresponding to an average leaching of 20 kg N*ha-1 y-1.
