Use of soil enzyme activity in assessing the effect of No-Till in the South of Russia

The activity of 11 enzymes (catalase, dehydrogenases, peroxydases,polyphenoloxidases, ascorbateoxidase, ferrireductase, β-fructofuranosidase, amylase, urease,phosphatase and protease) was assessed under conditions of steppe zone in the south of Russiawhen using different tillages. Winter wheat and sunflower are main crops in these soils.Moreover, chickpea, coriander, lint, barley, corn and some other crop are cultivated here in thecrop rotation duration 6 years. Enzyme activity was compared in soils of 15 fields with long-termno-till (NT) versus to 15 fields with conventional tillage (CT). The researches were held alongthe whole Haplic Chernozem Loamic at a depth of 0–65 cm. Special attention was paid to topsoil (0–10 cm), which is directly subject to the mechanical effect. The carbon cycle enzyme(β-fructofuranosidase) activity was the most sensitive indication for NT use. In top soil theenzyme activity was greater by 16–35% at NT versus to СТ. Activity of this enzyme reduces by28–293% when soil depth increasing in both the tillages. Enzymes of different classes haddifferent behaviours in soils depending on season, crops and tillage thanks to biochemical nature.Hydrolases and oxidoreductases were assessed by the indices characterizing soil condition andhealth. For this purpose geometric mean by hydrolase activity (GMEhd) and geometric mean byoxidoreductase (GMEox), as well as integral index of biological soil condition (IIBC) were used.Index GMEox in soil under sunflower reduced by 16% in summer versus to spring. Thereby,hydrolase index GMEhd reduced by 60%. At NT activity of oxidoreductase was lower by 10 and13%, and activity of hydrolase was increased by 12 and 14% versus to СТ. Soil IIBS values atNT increased by 18–35% at average within three years (2016–2018). The use of NT technologycontributes to an increase in the activity of hydrolases and soil quality due to the conservation ofmoisture in the soil.