Mineral nitrogen depending on the intensity of nitrogen fertilization of sugar beet monoculture

Mineral nitrogen dynamism in the top soil layer, depending on various N sources was investigated on the chernozem type of soil. The experiment had the following variants:1)control, 2)40 t/ha of manure each year, 3)100 N, 100 P2O5 and 100 K23 kg/ha in the form of mineral fertilizers:4) 160 N, 160 P2O5 and 160 K2O kg/ha in the form of mineral fertilizers, 5)40 t/ha of manure+100 N, 100 P2O5 and 100 K2O kg/ha in the form of mineral fertilizers. The results obtained in the 1 st year are:the poorest supply with mineral N was in the non-fertilized soil (65.1 kg N/ha), then in the variant with manure (88.1 kg N/ha), in the one with 100 kg N/ha (99.2 kg N/ha)respectively;the next 60 kg/ha of NPK fertilizer improved the crop supply with N by 14.1 kg/ha. The largest quantity of mineral N was with combined fertilizing with manure+100 kg NPK/ha (128.0 kg N/ha). The mineral N dynamism depended on the source of supply. Results in the 2nd year show as follows:as in the previous year, in fertilization with manure, larger quantity of accessible N was in the 2nd part of the vegetation. Mineral N quantities in the soil under the crop increased with fertilization intensity. The increase was not in proportion with the doses. The results in the 3rd year show the following:N supply during the vegetation was the poorest in the control. With increased fertilization dose the beginning of vegetation and in Aug. The following is concluded:in all investigated years, in 2nd part of vegetation mineral N quantity is higher with fertilization with manure and manure+mineral fertilizer combination. The maximum mineral N quantity was in May, both in the fertilized and unfertilized plots. At the time of intensive sugar beet growth mineral N quantity decreased rapidly.