Agroecological assessment of short crop rotation on sod-podzolic soil

In the conditions of drained lands with unsatisfactory work of reclamation systems, in the Polissia zone it became possible to grow commercially attractive crops, in particular, such as winter rapeseed and corn for grain. A short-rotation crop rotation was analyzed: lupine — winter rapeseed — winter rye — corn, on the basis of which various variants of the fertilization system were studied, including by replacing litter manure with siderate and by-products of all crops in combination with the recommended for the zone and increased (intensive) mineral norms fertilizers. The goal of the task was to determine the optimal agrochemical support for grain crop rotation to obtain stable crop productivity and preserve soil fertility. It was noted that during the 2016–2020 research, during the growing season of agricultural crops, the reserves of productive moisture in the meter-long layer of drained sod-podzolic sandy soil decreased to 60–80 mm, that is, to a critical level. It was established that the overall productivity of the crop rotation depended on its saturation with corn, the grain yield of which was 6.01–7.13 t/ha on average over 5 years at different levels of organic and mineral nutrition. The highest yield of grain and fodder units from 1 ha of crop rotation area (4.23 and 4.52 tons, respectively) was obtained when by-products were applied together with an increased rate of mineral fertilizers (N67P84K91). It was established that the replacement of litter manure with the by-products of grain, leguminous and oilseed crops as an organic fertilizer, together with the use of the recommended (N45P56K61) and increased (N67P84K91) mineral fertilizer rates, does not reduce the productivity of crop rotation, ensures a deficit-free nitrogen balance and the annual accumulation of humus in the amount of 320 and 440 kg, respectively, which guarantees extended reproduction and increased soil fertility.