Genesis and comprehensive diagnosis of black earth soils of the Forest-Steppe of Ukraine

Abstract

Purpose. The purpose of the study was to summarizescientific research on the genesis, composition, andmorphological properties of chernozem soils of the ForestSteppe of Ukraine and to determine the influence of themain factors of soil formation.Methods. Historical (analysis of the genesis of soilproperties), comparative (identification of similaritiesand differences in processes, properties and conditionof chernozems); mathematical (information processing,analysis and synthesis).Results. The Lisostep of Ukraine is used for intensiveagriculture, and covers a total area of 20,2 million hectares,which is 33,6% of all land in Ukraine. Land under plowing is 13,7 million hectares, or 67,4% of the total soil areaof the zone. The soil and climatic conditions of the zoneare favorable for the cultivation of important and mostproductive agricultural crops – grain, fruit and vegetablecrops, sugar beet, oil crops – corn and sunflower.Black soils are the most common soils of the LisoStepof Ukraine, formed under meadow-steppe vegetation oncarbonate loess rocks. In the granulometric composition oftypical chernozems, the number of silty particles (physicalclay) increases from 24,98 to 28,40, and physical sanddecreases from 81,99 to 78,59, which makes it suitablefor growing more crops. The soil absorption complex ofchernozems is saturated with cations Ca2+: Mg2+ – 6:1, whichcontributes to the formation of an agronomically valuablestructure. The reaction of the soil solution of chernozempH = 6,9–7,2. Soils are well ventilated, warmed by the sunand therefore remain in a favorable condition for cultivationfor a relatively long time.In the upper horizon A, the humus content rangesfrom 4,2 to 4,6%, and decreases to 1 to 2% with depth.Typical chernozems have high biological activity due to thecontent of humus: total nitrogen (0,2–0,5%), phosphorus(0,33–0,16) and total potassium (1–2,4%). The high activityand diversity of soil microbiota is associated with theactivation of soil processes as a result of calcification andthe presence of significant biomass of forest plant remains,as well as favorable water, air and temperature regimes.Podzolized chernozems are characterized by relativelygood physical properties. Thus, in the upper humus horizon,the density of composition is 1,02–1,22 g/cm3, and thedensity of the solid phase is 2,64–2,70 g/cm3. In the upperarable layer, the content of humus reaches 3–4%, whichdecreases with depth to 1,2–1,5%. The reaction of the soilsolution is pH = 5,7–6,3. Podzolized chernozems: grossnitrogen (0,18–0,3%), phosphorus (0,11%), potassium(1,91–2,07%). The deep penetration and distributionof humus along the soil profile is primarily related to theinfluence of forest and steppe herbaceous vegetation in thegenesis of soil formation.Findings. A complex of soil formation factors duringgenesis can lead to soil changes, therefore, for diagnosisand further development of actions to restore soil fertility, itis necessary to take into account all pedogenic processes:use of organic and mineral substances and soil treatmenttechnologies; loss of part of the soil due to wind and watererosion, movement within the profile from one horizonto another; climatic changes, and changes in biologicaldiversity of soils.