Soil acid-base buffering in the step agriculture lands

Abstract

Modern studies of chernozem soils in the northwestern Black Sea region have shown intense dehumification due to disruption of biogeochemical cycles caused by anthropogenic removal of organic matter and associated biophile elements. At former time, the humus zoning was typical for southern chernozems and now we noted the smoothing of this zoning. Acid-base buffering has a significant role in counteracting degradation processes, the buffering parameters could be integral indicators of soil chemicals balance. We studied the automorphic soils (arable chernozems) of the northwestern Black Sea region, their humus state, particle size distribution, and acid-base buffering parameters. We studied ordinary modal and micellar-carbonate chernozems on arable land and 40-year-old fallows, southern chernozems removed from irrigation 15 years ago and southern carbonate chernozems of the second floodplain terrace of the Danube River. We determined the neutralization index, degree of buffering capacity in the acid and alkaline ranges, equilibrium coefficient, and sodium absorption ratio to characterize the acid-base buffering. The studied soils belong to stable buffer agriculture lands by their acid-base buffer ability. We determined that soils have the parameters of chernozem type: low humus content, humate and humate-fulvate type of humus, average content of insoluble residue, high degree of humification, heavy-medium loam particle size distribution, and neutral soil solution. The acid-base buffer capacity is characterized by average values, the buffer capacity in the acid interval increases with depth, while decreases in the alkaline interval. We revealed a significant correlation between the ability to counteract the acid load and the content of physical clay. We believe that the agricultural use of southern chernozems leads to a decrease in soil resistance to acidification.