Fertilizer circulation and nitrogen balance in the agrophytocenosis of sugar beet when acidizing typical chernozem (study with 15n)

The studies were carried out under the conditions of a microfield experiment on typical chernozem (Belgorod region) with two soils (pH 5.0 and 6.5) with the addition of urea (enriched in 15N, 17.1 at. %) And effluents from a pig-breeding complex (PSC) at doses of 6 and 12 g N/m2 (against the background of phosphate and potash fertilizers, P6K6). The largest amount of nitrogen was consumed by sugar beets with the combined introduction of CCA and urea (25.8 g N/m2). When the soil was acidified to pHsalt 5.0, the consumption of nitrogen in mineral fertilizers decreased by 15-18%, soil ni-trogen – by 21-52%, and waste nitrogen – by 16%. At the same time, the immobilization of nitrogen in the fertilizer decreased by 13-18%, and the loss of gaseous nitrogen compounds increased by 47-108%. The effluent from the pig-breeding complex increased the immobilization of nitrogen in mineral fertilizers (by 38-46%) and reduced gaseous nitrogen losses (by 22-44%). The highest stability and productivity (root crop yield 1654 g/m2, tops yield 239 g/m2) was exhibited by agrophytocenosis on soil with pH 6.5 with the combined application of CCA and urea. When the soil solution was acid-ified to pH 5.0, the yield of beet root crops decreased by 30% and the yield of tops – by 24%. On soil with pH 5.0, fertilizers increased the sugar content in root crops by 0.2-1.3%, on soil with pH 6.5, they decreased by 1.3-2.0%