Microbial populations and the activity of the soil under agricultural and agricultural–pastoral systems

Abstract

The effects of agricultural-pastoral and tillage practices on soil microbial populations and activities have not been systematically investigated. The effect of no-tillage (NT), no-tillage agricultural-pastoral integrated systems (NT-I) and conventional tillage (CT) at soil depths of 0-10, 10-20 and 20-30 cm on the microbial populations (bacteria and fungi), biomass-C, potential nitrification, urease and protease activities, total organic matter and total N contents were investigated. The crops used were soybean (in NT, NT-I and CT systems), corn (in NT and NT-I systems) and Tanner grass (Brachiaria sp.) (in NT-I system); a forest system was used as a control. Urease and protease activities, biomass-C and the content of organic matter and total N were higher (p 5 0.05) in the forest soil than the other soils. Potential nitrification was significantly higher in the NT-I system in comparison with the other systems. Bacteria numbers were similar in all systems. Fungi counts were similar in the CT and forest, but both were higher than in NT. All of these variables were dependent on the organic matter content and decreased (p 5 0.05) from the upper soil layer to the deeper soil layers. These results indicate that the no-tillage agricultural-pasture-integrated systems may be useful for soil conservation.

Humic fractions of forest, pasture and maize crop soils resulting from microbial activity

“…It can be concluded that, as well as the amount of N, the organic matter resulting from different vegetation cover can influence the nitrification potential, as in our study. It is possible that animal excretions, being richer in nitrogen compounds, have influenced the results found in the pasture soil ( Garcia and Nahas, 2012 ) when compared to maize.…”

Control of Acid Phosphatases Expression from Aspergillus niger by Soil Characteristics

“…However, these results disagreed with those reported by Gargova and Sariyska (2003), who found the optimum pH to be 2.1 for acid phosphatase from A. niger 307. At 0-10 cm soil depth, the pH ranged from 5.4 to 6.5 in four crop sequences (Marcelo et al 2009) and from 4.4 to 6.2 in agricultural and agricultural-pastoral systems (Garcia and Nahas 2012). It was concluded that secreted acid phosphatase activity from A. niger could be severely inhibited in these soils.…”

Soil enzyme activities in dependence on tree litter and season of a social forest, Burdwan, India

“…The enzymes play a key role in biochemical functions, in the overall process of organic matter decomposition (Sinsabaugh et al 1993) and for the maintenance of concentration of soil ions and climate (Jimenez et al 2002) in the soil system. They are important for catalysing several vital reactions necessary for the life processes of microorganisms in soils and are also important for the stabilization of soil structure, formation of organic matter, nutrient cycling and decomposition of organic wastes, hence playing an important role in agriculture and agroforestry (Dick et al 1994;Dick 1997;Dilly et al 2007;Trasar-Cepeda et al 2008;Sinsabaugh et al 2009;Ulrich et al 2010;Garcia & Nahas 2012). Soil quality is always determined by several factors and soil enzymes are key factors for maintaining soil fertility.…”