Dynamics of the content of mineral elements and effective fertility of alluvial meadow soil in vegetable crop rotation

In vegetable crop rotation with different fertilization systems of vegetable crops, the dynamics of the content of mineral elements of plant nutrition was determined, effective soil fertility was evaluated in comparison with potential under experimental conditions, and the most effective fertilizer system was identified not only to obtain the highest yields, but also to preserve and reproduce the potential fertility of alluvial meadow soil. The study was conducted in 2015–2019 in the Ramensky district of the Moscow region on the alluvial meadow medium loamy soil of the central floodplain of the Moscow River. The seasonal dynamics of the content of 3 elements of plant mineral nutrition (nitrate nitrogen, mobile phosphorus and potassium) in the carrot – beet – cabbage crop rotation was studied, using 3 main fertilization systems for vegetable crops (mineral, organic, organo-mineral). It was found that the maximum content of nitrate nitrogen (on average in crop rotation 47.4 mg/kg) and mobile potassium (on average 156 mg/kg) occurred in the third decade of June. The content of mobile phosphorus in the soil was high (200 mg/kg) at all accounting periods. A close correlation was determined between the yield of root crops and cabbage with the average content of nitrate nitrogen in the soil during the growing season (r = 0.735–0.934), mobile phosphorus (r = 0.539–0.972) and potassium (r = 0.532–0.976). The effective soil fertility of the site under 3 crops per crop rotation had the following characteristics: when using a mineral fertilizer system, the content of nitrate nitrogen was 21.3, organic – 10.1, organo-mineral – 22.1 mg/kg, the content of mobile phosphorus when using a mineral system – 40.4, organic – 34.1, organo-mineral – 47.9 mg/kg, the content of mobile potassium is 44.4, 20.6, 50.8 mg/kg, respectively. It was found that under crops of carrots and beets, the potential fertility of the soil during crop rotation was reproduced with the use of mineral (recommended dose of NPK) and organo-mineral fertilization systems of these crops, and the yield of carrots (67–69 t/ha) and beets (67–68 t/ ha) under these systems was high, more than expected estimated 60 t/ha. Under cabbage, late soil depletion also did not occur when using the recommended mineral and organo-mineral fertilizer systems, yields of 78 and 81 t/ha were close to the expected estimated yield of 80 t/ha. At the same time, the organo-mineral system had an advantage: during crop rotation, it retained 13% more nitrate nitrogen in the soil, 8% more mobile phosphorus and 40% more mobile potassium than the mineral one. One and a half and double doses of mineral fertilizers for late cabbage led to a significant increase in its yield (85–90 t/ha), but at the same time a significant part of nitrogen (on average for the season 33–41 mg/kg) was irretrievably lost in the soil.