He long-term dynamics of chernozems agro-chemical properties under apple orchards

The long-term dynamics of agrochemical properties for leached chernozem under an orchard monoculture has been studied. The objects of monitoring are two testing areas in the south (“Krasnodar”) and in the center of the European part of Russia (“Michurinsk”) without applying of organo-mineral fertilizers and chemical melioration to the soil. A significant decrease of the main fertility indicators within the soils humus horizon has been revealed during the period of intensive growth and stabilization of apple trees yields for the testing area in the south of Russia: a reduction in the nitrogen mineral forms stores and nitrification ability, and in exchange potassium stores. As for the area in the center of the European part of Russia, a trend for the content of mobile forms of phosphorus and potassium decreasing during the growth and stabilization of apple yields has been revealed. The regression models obtained as a result of the analysis were linear and revealed probable significant trend of the decrease for the observed indicators over time. Quantitative changes in the parameters of the organic matter content in soils within the boundaries of the testing area made it possible to identify the processes of dehumification: in conditions of monoculture at the natural level of fertility. During the period from 1990 to 2014, the depletion of soil organic matter contained 7.5%. It is shown that the processes of soil organic matter depletion occur differently under different soil and climatic conditions. It is established that apple plantations, consuming the amount of available forms of mineral elements needed for the forming of sustainable yields, create prerequisites for the development of processes of chernozems chemical degradation. Absence of fertilizers and chemical reclamation on this background contribute to aggravation of this process.