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No‐till, crop diversity and integrated crop–livestock systems are proposed managements to increase agriculture sustainability in the rice paddies of the Southern Brazilian lowlands and avoid degradation in the region. Because soil is considered a key medium in which management modifications can be measured, our study aimed to evaluate soil‐quality impacts by measuring carbon and nitrogen stocks and microbial activity 18 months after the adoption of different paddy‐farming systems in an Albaqualf soil of Southern Brazil. The treatments consisted of five paddy‐farming systems with a range of vegetation diversity (both in time and in space) and grazing seasons. In addition, a reference area (i.e. native forest) was sampled for comparison. We verified that soil quality was affected over the short term through the adoption of no‐till, crop diversity and integrated grazing practices. However, during the study period, only the system with low anthropic and/or mechanical intervention and high plant diversity differed from the traditional paddy land‐use approach in Brazil in terms of soil‐quality effects. This system achieved a carbon management index of 49 (approximately half that of the native forest) and had the highest enzymatic activity (similar to native forest). These outcomes were primarily due to an increase in the particulate organic matter fraction of the soil carbon stock (4·6 Mg ha−1 more than in rice monocropping). To evaluate changes in soil quality over the long term, additional studies are required. Copyright © 2016 John Wiley & Sons, Ltd.

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Integrated crop-livestock systems (ICLS) associated with crop rotation and soil conservation management cause numerous changes in nutrient fluxes and soil biochemical dynamics. In this sense, there is a gap in the impact of integrated production systems on nutrient dynamics and soil microbial activity in lowlands. In this context, this work had the objective of evaluating the nutrient availability and the activity of extracellular enzymes in a Gleyic Luvic Planosol under ICLS. The experiment has five paddy-farming systems with a range of crop diversity (both in time and space) and

Soil management systems cause many changes in the microenvironment that directly affect activity and diversity of microorganisms. In lowlands, there is a gap in relation to the adoption of no-tillage (zero-tillage) and the impact it has on soil under cultivation of irrigated rice. This study, an in-field experiment, evaluated the microbial enzymatic activity and diversity in an Entisol cultivated with rice under different managements for 22 years. The experiment started in the 1994/95 growing season, and the treatments were no-tillage, conventional, and pregerminated management systems. After 22 years, the data obtained on most of the evaluation dates indicated that no-tillage increased microbial biomass carbon (+45%), microbial biomass nitrogen (+54%), and basal respiration (+54%). No-tillage compared to management under soil tillage (pregerminated and conventional tillage) increased the activity of β-glucosidase (+43%), acid phosphatase (+68%), diacetate fluorescein (+34%), and urease (+96%).The enzyme activity was correlated with the soil organic carbon content and particulate fraction. Despite the relatively high enzyme activity with no-tillage, bacterial richness was maintained in this soil management system. The Proteobacteria phylum has a greater abundance in the NT (43.2%) in relation to the CT (32.3%). Bacteroidetes phylum has a lower abundance in the NT (10.0%) in relation to the CT (15.2%). The Verrucomicrobia phylum has a greater abundance in NT (8.9%) in relation to CT (4.9%). The results suggest that no-tillage is an important management tool in the recovery of irrigated rice areas whose soil has undergone microbiological degradation.

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