THE INFLUENCE OF NATURAL AND ANTHROPOGENIC FACTORS ON HUMUS DYNAMICS AND WINTER WHEAT PRODUCTIVITY AT CONTINUOUS GROWING

Abstract

The reformation of the agrarian sector, the commercialization of agricultural production caused the nar-rowing of industrial specialization, concentration, maximum saturation of crop rotations with leading crops or their re-cultivation, even in single-crop system. However, the world and national agronomic science have considerable experimental material on reducing yields at continuous sowing − growing the same crop for a long time on a permanent plot. The aim of the study was to determine the effect of different fertilization sys-tems and long-term continuous cultivation on the soil organic matter dynamics and the level of winter wheat productivity. The following scientific methods were used in the research: analysis, synthesis, field, and statis-tical ones. The results of agrochemical analyzing soil samples of a long-term field experiment at continuous winter wheat cultivation show that on the control plot (without fertilizers), as well as at applying mineral fertilizers (N51P51K55) and 30 t/ha of manure annually or once every three years, humus reserves in the ara-ble soil layer decreased by 5.6; 0.4; 2.4 t/ha respectively during the period of 33 years (1983–2016), or the average humus loss during a year was minus 0.17; minus 0.01; minus 0.07 t/ha, respectively. It was estab-lished that the variants of winter wheat fertilization studied in the experiment ensured decreasing the intensi-ty of humus loss from the soil, in comparison with the control (without fertilizers) by 1.7 and 2.4 times, re-spectively,. The research results show that even at long-term continuous cultivation winter wheat productivi-ty on fertilized plots is naturally higher. Thus, in comparison with the control (without fertilizers), the appli-cation of organic and mineral fertilizers ensured the increasing of crop yields by 0.85–0.97 t/ha or 31–35.4 % on the average for the years 1983–2017. It should be noted that applying 30 t/ha of manure once every three years or annually, at practically the same rate of mineral fertilizers, had no significant effect on the level of wheat productivity. The maximal yield of winter wheat, both on the control plot and at applying organic and mineral fertilizers, was obtained in 2008 − 5.90; 7.05 t/ha and the minimal yields, according to fertilization systems were 0.71 t/ha (1991) and 1.00 t/ha (1999).