Fertilizer nitrogen use by cereal crops in arid conditions of Buryatia

Abstract

The results of research in a long-term (1982–2021) stationary experiment to determine the coefficients of nitrogen use of mineral fertilizers by the crops of grain and fallow crop rotation in the conditions of the dry-steppe zone of Buryatia are presented. Chestnut loamy sand soil on the studied variants was characterized by very low content of humus, total nitrogen and nitrates before sowing of the crops. During the research period, the prevalence of dry years was noted. Nitrogen use coefficients of mineral fertilizers in the conditions of the dry-steppe zone of Buryatia on average for 39 years of research were 69% for wheat, 54% for oats and 90% for oats for grain haylage. The variation of the coefficients was significantly influenced by summer moistening conditions. They were 32% under extreme and severe drought, 57% under moderate and weak drought, and increased significantly (up to 124%) under favorable moisture conditions. The utilization of nitrogen of solid mineral fertilizers was maximum in the third crop (oats for grain haylage) and more responsive to the atmospheric moistening. The smallest consumption coefficients and the range of its changes were observed in oats for grain. The first crop of the rotation (fallow wheat) occupied an intermediate position in this assessment. The data on the influence of soil moisture and hydrothermal conditions of separate critical periods of vegetation on the variation of the coefficient of mineral fertilizer nitrogen utilization (N40) by wheat, oats, and oats for grain haylage were obtained. The correlation analysis showed that the most critical period for nitrogen consumption in wheat is June (r = 0.61), in oats – July (r = 0.51) and July–August for oats for grain haylage (r = 0.50–0.52). Multiple linear models of dependence of N fertilizer use coefficients on productive moisture content and hydrothermal conditions were made.