Balance of nutrients and changes in agrochemical parameters of soddy-podzolic soil during a grain-grass crop rotation cycle
2008
Kononchuk, V. V. | Shtyrkhunov, V.D. | Timoshenko, S.M. | Liseenko, E.N., Research and Development Inst. of Agriculture of Central Regions of Non-Chernozem Zone of the RF, Moscow Region (Russian Federation)
The highest productivity of grain-grass crop rotation with 67% of leguminous crops (3.0-3.2 000 kg/ha) was obtained without fertilizers in the treatments with red clover, alfalfa, cats clover, and a red clover-ryegrass mixture. The gain in the crop yield due to the activity of symbiotic nitrogen-fixing bacteria (symbiotic nitrogen) was comparable to the gain due to the annual application of 60 kg N/ha for cereal crops planted after unfertilized ryegrass during three years; its value was 0.9-1.1 000 kg/ha (29-35%). The high content of legumes in crop rotation favored the creation of positive annual nitrogen balance in the soil (11-26 kg/ha) at 70-75% of symbiotic nitrogen and the enrichment of soil with it by 24-30 kg/ha annually. The average annual rate of humus increase was 0.03-0.07%, and its final content was 1.79-1.94%. The deficit of phosphorus and potassium was 31-34 P2O5 and 67-81 kg K2O/ha; the rates of decrease in the content of exchangeable forms of these elements were 12-15 and 15-20 mg/kg per year, respectively. The use of average annual NPK rates of 30 kg/ha each in the complete mineral fertilizer decreased the deficit of P205 and K2O to 1-3 and 38-51 kg/ha, respectively; this compensated their removal by 91-97 and 38-44%
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