THE ESTIMATION OF NITROGEN RATE (KG/HA) FOR WINTER WHEAT AND SUNFLOWER CROPS, IN AN AGRICULTURAL FARM LOCATED IN BOTO˘ ANI COUNTY

The aim of this paper is to present the estimation of nitrogen rate - N (kg/ha) for two agricultural crops - winter wheat and sunflower, as part of a rotation that includes soybean - winter wheat - sunflower, in a farm located in Botoani county, on a phaeozem soil type, whose characteristics have previously determined. The estimation is based on the method introduced by Davidescu D., which establishes the fertilizers rates in accordance to agrochemical indicators, by calculation, taking into account the following indicators: the quantity of N extracted from soil in relation to the predicted yield - Nex (kg); the soil total reserve in N - Nt (kg) and the coefficient of N using from fertilizers (%). By calculation, it was estimated that the N rate for winter wheat after soybean in rotation is 36 kg N/ha and the nitrogen rate for sunflower after wheat is 136.16 kg N/ha, for the considered region, its specific soil type and the predicted yield. The results in case of winter wheat indicated the influence of the leguminous crop in rotation, that provides a significant nitrogen intake in soil reserve. Thus, the residual nitrogen from previous crop (one of the components of soil nitrogen reserve) is 61.25 kg/ha at wheat after soybean, compared to only 19.16 kg/ha in case of sunflower after wheat.