Effect of mineral fertilization on NO3-N leaching on clay soil
2005
Izsaki, Z. | Ivanyi, I.
To evaluate the environmentally friendly N fertilization practice is important to study the N balance of the soil as well as the NO3-N accumulation and leaching in a given land site. This work aimed at providing data about the effect of N fertilization on the N balance of the soil and NO3-N leaching on the basis of an 11-year experiment. At four N application rates-0, 80, 160, 240 kg ha(-1)-of a long-term NPK mineral fertilization experiment was set up in 1989, on chernozem meadow soil, at Szarvas, the NO3-N content of the 0-300 cm soil layer, the depth distribution of the NO3-N and the N balance of the selected plots were measured, in the 4th, 8th and 11th year of the experiment. On chernozem meadow soil with 3.0-3.2% humus the removal of N by the crops was 1126 kg ha(-1) during the 11-year experimental period. At an application rate of 80 kg N ha(-1) the N balance was negative. At 160 kg ha(-1) N fertilization the N balance went into equilibrium approximately in the 8th and 11th year. The 240 kg ha(-1) N dose resulted in an increasingly positive N balance. The N pool in the soil increased at each N application rate compared to the unfertilized treatment. The leaching of NO3-N began after the 4th year at on application rate of 160 kg N ha(-1). After the 8th year the NO3-N leaching was significant on each N treated plots and the zone at which the accumulation of NO3-N was maximised was between 140 and 180 cm. Nitrogen leaching was observed without N fertilization if the growing season was dry and low N-demanding crops were grown. The shifting of the water table after an extremely wet and dry period resulted in a huge NO3-N losses. The harmful environmental side-effects of N over-fertilization can be avoided by determining the mineral N pool of the soil and the N requirements of the cultivated crop.
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