Research on changes of nitrogen regime of leached chernozem as affected by a long-term mineral fertilization
1997
Ikonomova, E. | Raikova, L. | Georgieva-Balabanova, R. | Koutev, V. (N. Poushkarov Institute of Soil Science and Agroecology, Sofia (Bulgaria)) | Dimitrov, D. ("Obraztzov Tchiflik" Institute of Seed Science and Seed Production, Rousse (Bulgaria))
The effect of N, P and K fertilizers' long-term application on the main characteristics of the nitrogen regime in a leached chernozem has been investigated. Studies were conducted with fertilization during 36 years, under field experimental conditions. Maize, wheat, beans and barley were grown under four fields crop rotation. The effect of the soil tilling, fertilization and crop rotation on the main leached chernozem agrochemical characteristics has been estimated for an uncultivated soil belonging to the same soil variety. The effect of mineral fertilizers (N=80, P2O5=75 and K2O=110 kg/ha), when they are applied separately or in combination, was investigated by comparing to unfertilized control. The data obtained show that the long-term N, P, K-fertilizers application at continuous crop growing on strongly leached chernozem causes degradation processes - soil acidification with 2 pH-units in average for the N-treatments compared to the unarable soils; negative changes of nitrogen regime - decrease of the total N content; unstabilized nonhydrolizable N-compounds; accumulation of residual mineral N in the soil after crop harvesting which increases from 9 mgN/kg soil in unfertilized control up to 20-40 mgN/kg soil for N-treatments at different crops, which creates danger for environmental pollution with nitrate.
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