Ecological assessment of soil contamination with heavy metals due to the application of mineral fertilisers

The article presents the results of monitoring the aftereffect of the use of excessive zonal doses of mineral fertilisers on soil contamination with heavy metals (HM). With traditional soybean cultivation technology, the level of soil contamination when applying excessive doses (N 60P 180K 90) of fertilisers is quite high and indicates violations of the ecological balance of the agroecosystem. By the nature of the accumulation of heavy metals in meadow-chestnut soil, depending on the application of the studied doses (P 60K 30, N 30P 60K 30, N 60P 180K 90) of fertiliser, the content of HM (Pb, Zn, Cd) increases. The greatest contamination of the soil with Cu was revealed, the content of which increases to 3.2 mg∙kg –1 of soil, which is higher than the threshold of the maximum permissible concentration (MPC) – 3.0 mg∙kg–1. According to the level of contamination of the soil with copper, it belongs to the highly dangerous classes. In a comparative assessment of the level of soil contamination with HM, optimal norms of mineral fertilisers have been established, namely, against the background of effective resource-saving technology for growing soybeans. The application of fertilisers at a dose of P 60K 30 and N 30P 60K 30 does not significantly affect the level of soil contamination with HM, optimises the ecological state and nutrient regime of the soil, preserves and restores soil fertility indicators, and increases soybean productivity. This resource-saving technology provides a safe environment for soybean cultivation and a significant increase of 34.5–38.6% in crop productivity (0.53–0.76 Mg∙ha –1) and yield (2.57 Mg∙ha –1).