Climate change and aridization of the Southern Steppe of Ukraine

Abstract

Purpose. To study climate changes in the southof Ukraine and their impact on the accumulation of moisturein the soil, the dynamics of its reserves, the efficiencyof the use of precipitation, the water supply of agrocenoses and propose measures to prevent aridizationof the territory. Methods: field, laboratory, statistical,analytical, computational and comparative. Results. Inthe south of Ukraine, the climate has changed significantlyover 138 years. For the period from 1882 to 1971,precipitation fell on average 347.3 mm, and over the next38 years (1972–2010) there was already 458.1 mm, whichis 110.8 mm more, therefore, during this period, the supplyof plants with moisture is significantly has improved. Butin practice in agriculture, this is almost imperceptible. Itwas revealed that very little precipitation is absorbed bythe soil. So, out of 196 mm that fell during the autumnwinterperiod, on average over the years of observation, onwheat crops after corn for silage, only 42% was absorbedby the soil, 20% for fallow, and 16% of the precipitation onirrigation. The rest of the precipitation – 58–84% probablyfled to the lowlands, part of it evaporated or froze outand was lost, not bringing any benefit. For the arid zone,such large moisture losses are unacceptable, becausethis is essentially a lost grain harvest. It is becauseof the large losses of precipitation, with a greater amountof precipitation, that the water regime of the soil on wheatcrops has not improved. Fuller absorption of autumnwinterprecipitation is one of the great reserves forimproving the provision of wheat with water. In the period2011–2020, in comparison with the previous period(1972–2010), there was a decrease in the annual amountof precipitation from 458 to 387 mm, and the annual airtemperature increased to 2.0°С. In the last five years, inthis zone, the water and thermal regimes for agriculturalcrops have deteriorated, and there is a significantacceleration in the aridization of the Southern Steppe.Conclusions. In the Kherson region, over the past10 years, the amount of precipitation has decreased by71 mm, and the temperature has increased by 2.0°С, whichthreatens desertification of the territory and a decrease inthe productivity of agrocenoses. During autumn and winter,the soil absorbs a very small amount of precipitation –20–60%, and the rest of the precipitation water – 40–80%is lost. The loss of moisture from precipitation is so greatthat it becomes threatening for farming, especially giventhe warming climate. For better provision of agrocenoseswith moisture and containment of aridization of the territory,it is necessary to improve the agrophysical propertiesof soils by introducing manure, chopped straw, corn stalksand other organic residues, introducing appropriate croprotations, improving soil cultivation methods, and increasingthe area of irrigated land.