No-till technology as a factor of activity of soil invertebrate in agricultural chernozems of Stavropol region

Soil macro- and mesofauna is highly sensitive to various methods of agricultural cultivation, therefore soil invertebrates are used as bioindicators of agrocenoses ecological condition. Since the macro- and mesofauna to a largely extent control the water balance of the soil and participate in the formation of humus, special attention should be paid to soil fauna in arid regions, primarily in the Cernozem Region. In this work, for the first time, an integrated estimation of the population density and ecological and functional diversity of macro- and mesofauna of Vorony-Calcic Chernozem in the Stavropol region is given. The possibility of using these groups of invertebrates as bioindicators of the ecological status of agrocenoses has been shown. It is proved that the use of no-till technology stimulates the activity and number of all groups of macro- and mesofauna. The purpose of the work is to estimate the numbers and taxonomic diversity of ecological and functional groups of macro- and mesofauna with various technologies of soil cultivation (traditional plowing and no-till) with and without mineral fertilizers on the agrochernozems of the Stavropol region. Experiments on research no-till technology were carried out in 2012-2019 in an experimental farm of the North Caucasus Federal Scientific Agrarian Center (Shpakovsky district of the Stavropol region). In 2019 we studied plots of fields with three types of factors: tillage (plowing and no-till technology); presence/absence of fertilizers; agricultural crops. The soil is Vorony-Calcic Chernozem. Crop rotation: maize ( Zea mays L.) variety Mashuk, soybean ( Glycine max L.) variety Duniza (until 2018), which was replaced later by peas ( Pisum sativum L.) variety Phaeton, winter wheat ( Triticum aestivum L.) variety Deya, sunflower ( Helianthus annuus L.) variety Bagrat. Deposit soil near the experimental fields served as a control. Fertilizers were applied at the time of sowing (N160P90K60 for winter wheat, N72P58K32 for sunflower, N80P48K48 for corn, and N60P60K60 for soybeans and peas). The soil macrofauna was registered by the method of excavation of areas 25×25×30 cm and manual analysis of soil samples. Soil mesofauna was isolated from the soil monolith by the method of eklectors, identified and counted using a microscope Biomed-5 PR LUM (Russia) at a magnification of ×40. Most abundant among the macrofauna were centipedes ( Myriapoda ), adults and larvae of coleopterans ( Coleoptera ), spiders ( Araneae ) and earthworms ( Lumbricidae ). Aporrectodea caliginosa dominated among earthworms, while single of A. rosea were found only in deposit lands. The minimum number of A. caliginosa (32 ind/m2) was recorded under peas and sunflower with traditional plowing, the maximum - under corn on no-till plots and on plowed plots (556 and 512 ind/m2, respectively). In general, the number of earthworms was higher in no-till fields under all crops (excluding sunflower) in comparison with plowed plots. Among other groups of soil macrofauna, the most numerous were centipedes (up to 1500 ind/m2), as well as spiders (up to 500 ind/m2) and beetles (up to 500 ind/m2). Woodlice ( Oniscidea ) and molluscs ( Gastropoda ) were also encountered. The density of centipedes, spiders, coleoptera and earthworms was always higher for no-till options than for plowed fields, regardless of crop. The application of mineral fertilizers, as a rule, reduced the number and diversity of the macrofauna representatives. Among the mesofauna, ticks ( Acari ) and collembolans ( Collembola ) prevailed in terms of abundance and diversity. Mesofauna of no-till fields was taxonomically more diverse than plowed plots. The minimum number of mesofauna representative was found under peas and corn, the maximum - under winter wheat and sunflower. In general, the distribution of soil invertebrates (macro- and mesofauna) was significantly influenced by the method of soil cultivation, however, the agricultural culture often influenced the abundance indicators. The use of fertilizers reduced the biodiversity of macrofauna and decreased its number in all plots, regardless of the method of soil cultivation.