engleski

Impact of nitrogen fertilization and irrigation on nitrate leaching

The long-term stationary field experiment with irrigation and nitrogen fertilization has been started in spring of 2006 on the experimental field of Agricultural Institute Osijek (Osijek- Barannya County, Croatia). The experiment was duplicated for maize – soybean rotation. Soil moisture maintained by two steps of irrigation (from 60-100% and 80-100% of field water capacity, while not irrigated plot was the control. N fertilization treatments were as follows: the control (non-fertilized for 2006- 2009 period), 100 kg N ha-1 and 200 kg N ha-1. Nitrogen was added in two equal portions (ploughed in autumn and incorporated in soil by seedbed preparation treatment in spring) in form of urea (46% N).P and K fertilization was equal for all treatments including N- unfertilized plots. Aim of this study was testing of nitrate leaching in 2006 – 2009 period. Percolate was collected in Ebermayer, s lysdimeter reservoir and pumped by mechanical pumps 5 to 7 days after the rain or irrigation treatment. Nitrate was determined spectrophotometricaly in laboratory of Osijek Water-System by 2, 6- dimethylphenol method. Average NO3-N leaching in tested 4-year period was 5.82 kg N/ha. The ranges of N leaching were from 2.65 to 10.10 kg N/ha (year effect), from 4.05 to 7.42 N/ha (irrigation effect: 4-year average) and from 2.43 to 8.81 mg N/ha (fertilization effect: 4-year average). The lowest NO3-N leaching was under non-irrigated and N-unfertilized conditions (4-year average: 2.05 kg N/ha), while N leaching under conditions of the treatment the higher rate of irrigation and fertilization 200 kg N/ha was 11.97 kg N/ha.

Nitrate leaching ; nitrogen fertilization effect ; irrigation effect ; year effect

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