| Popis: |
The potassium status of different types of soils with various textures, and the content and distribution of forms of soil potassium, were studied in long-term experiments in various agrolandscapes. It was shown that the content of forms of soil potassium naturally increased from soils of the non-chernozem zone to soils of the forest-steppe and the steppe, and within a zone when the texture was fine. The profile distribution of forms of potassium in the explored soils was unequal. It was found that under agro-depleting conditions (long-term agricultural use of soils without fertilization) as a result of uncompensated removal of soil potassium by plants, a minimum level of exchangeable potassium (K2Omin) was reached. The part played by exchangeable and non-exchangeable soil potassium in crop formation under agro-depleting conditions was determined in various agricultural landscapes. It was shown that without the application of fertilizers, potassium removal with a harvest significantly exceeded the decrease in the amount of exchangeable potassium from soils, and a harvest formed due to the mobilization of the natural non-exchangeable potassium under the influence of plants. The annual mobilization of potassium from stocks of sod-podsolic soils and gray forest soils was 40–62 kg/ha of K2O, while that from chernozem and light chestnut soils was 57–130 kg/ha. To ensure that plants receive the optimal level of potassium and to prevent the soil from being depleted of potassium, the regular use of potash fertilizers is necessary. |
