Influence of predecessors on soil nutrient regime and yield of winter wheat in the Left Bank Forest Steppe zone of Ukraine

Abstract

In Ukraine, winter wheat (Triticum aestivum L.) is the main food crop, the yield of which is formed under the influence of natural and climatic factors of the area of cultivation, material and, technical support of the cultivation technology. The study was conducted during 2016‒2020 on the experimental field of the Poltava State Agricultural Research Station named M. Vavylov in a long-term stationary field experiment for the investigation of crop rotations with short rotation. According to the results of the research, it was found that the content of basic nutrients in the soil, when growing winter wheat, changes not only under the influence of predecessors, but also before the crop predecessors. The lowest content of easily hydrolyzable nitrogen in the soil layer 0‒40 cm was observed in crop rotations where the winter wheat predecessor was sunflower (14.34‒14.62 mg/100 g of soil). When the crop was sown after sugar beet, the predecessor of which was spring barley, the content of easily hydrolyzed nitrogen was higher on 8.1-10.2 % in comparison with prepredecessor which was sunflower. With the above-mentioned location of winter wheat in the crop rotation, the content of mobile phosphorus in the soil also was the highest (19.78 mg/100 g of soil). The lowest content of the exchangeable potassium was noted in the crop rotation, where the predecessor and precursor of winter wheat were sunflower and sugar beet accordingly. Based on the experimental results, it was found that the most productive winter wheat crops are those placed in the crop rotation after chikling vetch and common vetch with oats for green fodder. In crop rotations where soybeans were the predecessor of winter wheat, a reduction in crop yield by 9.2‒10.5 % was observed compared to the best predecessors. However, on average for 2016‒2020, the yield of winter wheat after soybeans was quite high and reached 5.35‒5.43 t/ha. Therefore, considering the small sown areas of the best predecessors for winter wheat, it is reasonable to sow the crop after harvesting early maturing soybean varieties. The worst predecessors of the crop in the experiment were sunflower and sugar beet. When sowing the winter wheat after these predecessors, the grain yield was the lowest and amounted to 5.17 and 5.23 t/ha, respectively.