Agroecological assessment of long-term use of mineral fertilizers in maize (<i>Zea mays</i> L.) agrocenoses in the Central Black Earth region
A comprehensive assessment of the effect of long-term use of mineral fertilizers on maize grown in monoculture and crop rotation for 5 rotations of 10-field rotation was carried out on leached Chernozem in stationary experiments. Five aspects of the stability of maize agrocenoses were analyzed depending on the place of its cultivation and the fertilizers used: yield, agrochemical and water-physical properties of the black soil, microbial community, and the content of heavy metals. High efficiency of fertilizers was achieved when applying N60P60K60, where the average annual productivity of green mass and grain exceeded the control by 33.6 % and 37.7 % in the crop rotation, by 45.7 and 47.0 % in the monoculture, with yields on the non-fertilized background in the crop rotation of 26.2 and 3.42 t / ha, in the monoculture of 22.1 and 2.81 t/ha. Crop rotation and fertilizers enhaced humification process K hum = 1,36-1.78, in the non-occupied fallow Khum < 1. Indicators of soil density, regardless of agricultural techniques, did not differ significantly, only in the forest belt they had minimum values of 0.9-1.5 g / cm3. The structural coefficient was the lowest in the permanent non-occupied fallow and the highest in the forest belt. In the rhizosphere of Zea mays L. the stable specific aerobic-anaerobic Association Mycobacterium/Rhodococusspp.wasidentifiedas dominatinginallthestudiedvariants.Propionibacterium spp. and the diverse coenosis of microorganisms, due to the trophic relationships of the entire soil coenosis with plants, acts as a regulatory factor in the agrophytocenosis of maize. Application of complete mineral fertilizer at the dose of 60 kg active ingredient/ha for 50 years did not significantly affect the content of Mn, Zn, Cu, Pb, Ni, and Cd in the soil, which corresponded to the background for the zone and was significantly lower than the MPC levels.