Changes of soil nitrogen-phosphorus regime under the influence of mineral fertilizers when growing cucumbers under cover in the Lower Don region

Abstract

In the territory of the Bagaevskiy District of the Rostov Region, agrochemical experiments were conducted from 2021 through 2023 to increase the effectiveness of mineral fertilizer application on cucumbers. The Kiborg F1 cucumber hybrid (Gavrish) was grown in plastic-covered houses without artificial heating in a short rotation (April-July) using drip irrigation. Mineral fertilizers were applied: ammonium nitrate, phosphorus-ammonia fertilizer, potassium sulfate and monopotassium phosphate. The following fertilizer application techniques were studied: pre-planting broadcast application with rotavation, and post-planting fertigation. On the years of the experiments on all variants, there was decrease of nitrate nitrogen content in the soil under cucumber from planting to the moment of the last harvest in all layers up to one meter depth. Under the influence of fertilizers, the content of mineral nitrogen in the soil increased by 3.4-17.0 g m² compared to the control by the time of the second soil sampling. The content of mobile phosphorus in one meter deep soil layer averaged 20.2 mg kg of soil in 2021-2023. Under the influence of mineral fertilizers, the content of mobile phosphorus increased by 3.2-9.6 mg kg of soil compared to the control. In all variants, the content of mobile phosphorus decreased in all soil layers during cucumber growing period. According to the results of 20 harvests on control (without fertilizers), the average yield for 2021-2023 reached 12.17 kg m². Cucumber yield increased by 1.87 kg m²_, or by 15.4%, after single application of N₁₅₀P₁₅₀K₁₅₀ with pre-planting rotavation. In all experimental variants, the cucumber fruits did not exceed the maximum permissible levels of nitrate nitrogen.