Removal and balance of nutrients in the agrocenosis of sugar beet under biologization and modernization of the fertilization system

Abstract

Purpose. To study the effect of nitrogen fertilizers and micronutrients on the balance of nutrients in the agrocenosis of sugar beet under an alternative straw-based organic-mineral fertilization system.
 Меthods. Short-term field and analytical.
 Results. Research data on the content, removal and balance of nutrients in the agrocenosis of sugar beet under the use of alternative organic-mineral fertilization systems are presented. It was established that in conditions of sufficient soil water content of leached chernozem, alternative organic-mineral fertilization of sugar beet ensured a positive balance of nutrients in the soil only when the leaves were left on the field. With the removal of leaves from the field, a sharp deficit of nitrogen and potassium in the soil occurred; meanwhile, a positive balance of phosphorus was maintained.
 Conclusions. At harvest, the content of nitrogen in roots was 0.82–0.87%, phosphorus 0.20–0.22%, and potassium 0.90–0.95%; in leaves 2.13–2.19%, 0.49–0.51% and 2.62–2.66%, respectively. The accumulation of nutrients in leaf biomass exceeded their content in roots by 2.1–2.8 times and did not depend on the fertilization system. Application of 5 t/ha of straw + P90K130 at ploughing, N120 at seedbed preparation and foliar application of micronutrients along with the main nitrogen fertilization in spring resulted in the maximum removal of nutrients from the soil: nitrogen 213–214 kg/ha, phosphorus 51 kg/ha, and potassium 244–246 kg/ha, which exceeded the control (zero fertilization) by 79–84 kg/ha, 18–19 kg/ha and 93–98 kg/ha, respectively. Nutrient removal with roots was 1.7–2.2 times higher than with leaf biomass. In the studied organic-mineral fertilization systems, a positive soil nutrient balance was provided only when leaf biomass was left on the field. Application of 5 t/ha of straw + P90K130 at ploughing + N90 at seedbed preparation ensured a positive balance of nitrogen in the soil and a high positive balance of phosphorus and potassium, with the intensity of nitrogen balance of 95%, phosphorus 319%, and potassium 132%. Additional foliar application of micronutrients maintained the intensity of nitrogen balance at 91–92%, phosphorus 319–330%, and potassium 126–129%. Restoration of the nutrient regime of leached chernozem was achieved by applying 120 kg/ha of nitrogen at seedbed preparation on the background of 5 t/ha of straw + P90K130 at ploughing and only in the case of leaving leaf biomass on the ground. Under such conditions, the accumulation of nitrogen in the soil was 18 kg/ha, phosphorus 68 kg/ha, and potassium 38 kg/ha at the balance intensity of 114%, 319% and 128%, respectively.