RETROSPECTIVE AND MODERN CONDITIONS OF THE CHERNOZEMS OF THE NYZHNIODNIESTROVSKAYA IRRIGATION SYSTEM

Abstract

Problem Statement and Purpose The experience of the using large-scale regular irrigation in the south of Ukraine shows that along with the positive productive effect of irrigation, there is a worsening of the ameliorative state of irrigated soils. In the present conditions of a significant decrease in the actual irrigated lands andthe intensity of irrigation on the background of the extension of agriculture, there is an increasing need to monitor and evaluate the reclamation-resource state of the soil in order to develop timely environmental measures. Accordingly, the purpose of the article is to assess the ameliorative-resource state of the southern chernozems and modern trends of its change.Data & Methods. The studies were carried out on the territory of land use of “Agrofirm Petrodolinskoe” of the Ovidiopolsky district of the Odesa region, which is located within the Nyzhniodniestrovskaya irrigation system. Laboratory and analytical studies were performed according to standard certified methods followed by statistical processing, which included determining the salt composition of the aqueous extract, physical and chemical properties of the soil and the humus, mineral nitrogen, mobile phosphorus and potassium contents in the soil (according to the method of Machigin).Results. According to the results of the study, the southern chernozems of the Nyzhniodniestrovskaya irrigation system are classified as non-degraded because of the risk of irrigation salinity. With a decrease in the intensity of irrigation and its periodic use, the content of carbonates significantly increases and the boiling line increases from 10% HCl to 76 cm with systematic irrigation to 57 cm in recent years. Soil alkalinity occurs throughout the study territory. In the conditions of decreasing the intensity of irrigation and extensification of agriculture, disaggregation is noticeable like consolidation of the composition of the upper horizons of the soil. A decrease in the degree of aggregation and the potential ability for the structuring of southern chernozems is established in the southern chernozems. According to the results of the analysis of the retrospective and modern state of chernozem in the southern Nyzhniodniestrovskaya irrigation system, a general pattern of degradation of their agrochemical properties has been established. During the investigated period, the humus contents in the upper horizons decreases to 0,1 %. In the present economic conditions of land use there is a decrease in the mineral nitrogen and mobile phosphorus contents in soils, the spatial variability of phosphorus and potassium contents is reduced, while the distribution of mineral nitrogen contents remains significantly heterogeneous. Despite of some changes, the southern chernozems are suitable for irrigation, but with agromeliorative measures to maintain and increase their fertility.