Microbiological parameters of soil set aside before and after desiccation

Abstract

Herbaceous cover of luvic chernozem (seven years set aside) with legumes, perennial grasses and their mixture was desiccated by the glyphosate herbicide Roundup Biaktiv (5 1/ha at July 2003 and 4 1/ha at June 2004). 165 soil samples were collected before (November 2002-July 2003) and after desiccation (September 2003-August 2004). Desiccation had a strong positive effect on immobilization of organic carbon from herbaceous cover and underground biomass to microbial biomass carbon (MBC) and to soil organic carbon (Corg), respectively. A significant increase after desiccation (P < 0.01) was confirmed in the parameters: Corg, MBC and in the ratio MBC/Corg. At the same time the desiccation had a retardation effect on mineralization of C org, Norg and Sorg. A significant decrease after desiccation (P < 0.01) was confirmed in the basal and potential respiration (with nitrogen, with nitrogen and glucose), actual content of N-NH4+ without and with pre-incubation, control ammonification, and (P < 0.05) in arylsulphatase activity. The actual content of NO3- and the control nitrification increased significantly (P < 0.01) after desiccation. Plots management before desiccation included black and spontaneous fallow, mulching (one or two per year) and cutting (three times per year), plots with 4 legumes, 4 grasses and their mixtures. Mulching variants showed the best results both before and after desiccation. The soils with cutting treatment ranked 8th-1O th out of 11 studied combinations.