EFFECT OF SAPROPELS ON POTATO YIELD AND FERTILITY OF LEACHED CHERNOZEM
Deficit of manure makes farmers to look for alternative sources of enrichment of soil organic matter. Significant reserve for the production of organic fertilizers in the South Urals is sapropel - freshwater sediments, containing in the dry residue of more than 15 % of organic matter. Field experiments in the forest-steppe zone of the Southern Urals have shown that the use of sapropel deposits as a fertilizer for potatoes has a positive effect on soil fertility and yield of tubers. Balanced mineral nutrition improves potato tuber quality indicators. Exerting a positive influence on the photosynthetic activity, fertilizer lays the groundwork for improving the yield and quality of potato tubers. Application of organo- calcareous sapropel noticeable effect on soil acidity leached chernozem. Analysis of the chemical composition and environmental safety assessment of the investigated sapropels in their use as fertilizer showed that the content of environmentally sensitive elements such as cadmium, arsenic and mercury, does not exceed the maximum permissible concentration (MPC). Meteorological conditions during the studies were different. Field experiments in the forest-steppe zone of the Southern Urals have shown that the application of sapropel deposits as fertilizer for potatoes has a positive effect on soil fertility and yield of tubers. Organic-calcareous sapropel at a dose of 80 t/ha reduced the soil bulk density of 0.05 g/cm <sup>3</sup>, and the organic sapropel at a dose of 100 t/ha - 0.06 g/cm <sup>3</sup>. The acidity of the soil while decreasing by 0.18 and 0.10 pH units, and the humus content in the plow layer increased by 0.08 and 0.34%, respectively. Adding 80 t/ha of organic-lime sapropel increased potato yield by 30.4%, and 100 t/ha organic sapropel - 31.9% compared with control.