Assessment of agrogenic impact on tea plantation soils by analysis of their enzymatic activity

Abstract

Brown forest acidic soils of the humid subtropical zone of Russia, on which tea is mainly cultivated, are largely exposed to agrogenic effects, which reduce their bio-productivity. An early diagnosis of these processes is possible by evaluating the biological activity of soils, in particular by the parameters of soil enzymes that regulate the main cycles of biogenic elements. Under the influence of various types and doses of mineral fertilizers relative to the background soils, they have been graduated and a scale for rating the agrogenic load has been developed on the basis of the established actual level of variation in the catalase activity (0.4-13.2 ml of O2/1 g of soil in 1 min), urease (0.1-21.8 mg of NH3/10 g in 24 hours), invertase (21-190 mg of glucose/1 g of soil in 24 hours) and phosphatase (0.01-1.7 mg of P2O5/ 100 g of soil in 1 hour).Four levels of exposure have been distinguished – permissible, maximum permissible, critical, unacceptable levels. 20 % relative to the soils of the background territory for all studied soil enzymes have been taken for a critically significant value for normalizing agrogenic load for brown forest acidic soils, which determines an unacceptable level. Decrease to 30-70 % of the enzymatic activity of soils in the background territory (depending on the type of enzyme) have been considered maximum permissible and permissible levels.

Keywords

• brown forest acidic soils
• tea
• agrogenic loads
• mineral fertilizers
• pesticides
• enzymatic activity
• urease
• catalase
• biomonitoring
• rating scale
• the black sea coast of russia