The level of soil nitrate content at different management of organic fertilizers application

Changes in N-NO(3)(-)content and N-NO3- increase after incubation were studied in 1992-1998 in soils of two farms situated in identical soil and climatic conditions (in spring and autumn seasons). The two farms produce sugar beet and grain crops, but since 1991 they have used different types of organic fertilizers. Farmyard manure has regularly been applied to root crops on Dobra Voda farm; since Chvalina farm does not have animal production, green manure and plowing-in of beet tops and straw are used for organic fertilization. Soils with regular applications of farmyard manure show a trend of lower N-NO3- content than the soils of the farm without animal production. At Dobra Voda N-NO3- content was about 12 ppm N in spring and 9 ppm N in the autumn season while the respective values for Chvalina were 14 and 10 ppm N. On the hand, N-NO3- increase after soil incubation (12-14 ppm N) was higher in Dobra Voda soils than in soils from Chvalina farm (5-8 ppm N).