Calcium balance in agrocenoses of Forest Steppe (on the example of agro-industrial complex of Cherkasy region)
Authors: Bulygin S. , Demidenko O. , Kryvda Yu. 
Published: December 2020

For 63 years in the agro-industrial complex ofCherkasy region there was a radical transformationof the structure of sown areas, when the whole period can be divided into a period of increasing intensity of livestock (1956–1995), a transition period (1996–2005) from intensive livestock to intensive grain production. and 2006–2019 — a period of business management of the structure of sown areas and weak development of the livestock industry. Such changes in management lead to the fact that in agriculture the main means of fertility management is by-products of crop production, the yield of which directly depends on the existing structure of sown areas. Circulation of Ca in agriculture of Cherkasy region directly correlates with changes in the structure of sown areas and the type of applied organic fertilizers. With the introduction of manure on an increasing trend are the conditions for increasing the capacity of the balanceof Ca, but with the saturation of the structure of sown areas with fodder crops and removal of by-products for economic purposes, calcium removal increases to 36–47%, and for by-products total removal decreases to 28–35% for reducing the capacity of the balance of Ca. If we do not take into account the content of Ca in the root system in the balance, the balance indicators deteriorate, both during the application of manure and when it is replaced by by-products. It was found that during the period of increasing the yield of manure for growing livestock, the ratio between the newly formed humus and calcium involved remained in the range of 8.1–9.9 to 1 with increasing components of the ratio, and the increase in areas and volumes of liming in this period should be associated with an excess of fresh organic matter from manure and unilateral withdrawal of calcium from livestock and insufficient return to the agrocenosis, which required an increase in liming areas to consolidate the excess of newly formed humus. When replacing manure with by-products, the ratio between the newly formed humus and calcium remained stable against the background of a decrease in the amount of newly formed humus and circulating calcium (up to 12 to 1 in 2016–2019) while reducing the average humus content and soil area with acid reaction, indicating insufficient amount of calcium per unit of humus formed during the critical transformation of the structure of sown areas and increased mineralization of its excess, which should be compensated by theintroduction of lime. Analysis of the dynamics of the economic balance of Ca shows that livestock and poultry is an aggressive factor against agrocenoses in terms of Ca removal. With developed animal husbandry, it is possible to reach a deficit of Ca balance with a population of about 9.56 million heads, and further increase of the population to 12.2 million heads makes the balance negative. With the transformation of livestock in the direction of poultry there is an increase in the deficit of the economic balance in terms of area of agricultural land, which indicates the need for soil liming.