Reserves of nutrients and soil organic components of Haplic Chernozems

The focus of this investigation is to present the reserves, soil nutrients and organic matter components along the profile depth of Haplic Chernozems near village Krupen, Kavarna municipality, South Dobrudzha region. The data confirm our previous investigations that they are one of the most fertility soils in Bulgaria. The profile is also marked by a variation of nutrients reserves according to the genetic horizon. All investigated reserves gradually decreased which is typical for the group of izohumic soils. The N_total reserves varied from 66.37% in А_horizon to 8.86% in С_horizon of the total stocks counting to 3.247 kg/ha. The reserves of total phosphorus in А_0-84 cm add up to 1.723 kg/m², which is 45.94% from the total reserves of through profile, while in soil formation material horizon (С_horizon) they reached to 0.782 kg/m² (20.85%). The C_org reserves in the study profile (0-195 cm) are 326.131 kg/m² and 67.50% of the stocks are concentrated in the humus accumulative horizon. In transition horizon (В_84-152) all nutrient reserves gradually decreased and reached lowest values in soil formation material horizon (С_152-195). These two genetic horizons have a higher degree of enrichment of humus with nitrogen compared to the humus-accumulative horizon. Throughout the depth of the profile, the degree of enrichment of humus with nitrogen is defined as "average". We established essential correlations between the investigated indices as follows: Reserves of C-total are in a strong correlation with reserves of N-total (0.993**); Cres. (0.982**); C-THS (0.949**); Mineralization ability after 56 days incubation (0.665**) and exchable potassium.