Cover crops and conservation management in soil biological activity

Conservation systems, such as no-till farming and crop rotation, promote soil health by favoring the microorganisms that are essential for the sustainability and fertility of agricultural production. The aim of this study was to evaluate the health of the soil in an agricultural area after soybean harvesting, under a conservation system for 12 years. The study was carried out on a typical dystrophic LATOSSOLO VERMELHO, which has been under a no-till system for 12 years under field conditions in the municipality of Selvíria/MS/BR, at the Teaching, Research and Extension Farm of UNESP/Campus of Ilha Solteira.
The soil management systems evaluated were: 1) reduced tillage (RT); 2) minimum tillage (MT); 3) no-till system (SPD) alternated with MT (SPD/MT); 4) MT alternated with SPD (MT/SPD); 5) SPD with Rod; and 6) SPD with Disk. In winter, the area was cultivated with sorghum (cultivar Pionner 50A40) and a mixture of cover crops (Urochloa brizantha cv. Marandu, Urochloa brizantha cv. Ipyporã and buckwheat (Fagopyrum esculentum). The experimental design was randomized blocks, with composite soil samples (5 single samples; 0 - 0.10 and 0.10 - 0.20 m). At both depths, organic matter and its subsequent transformation into soil organic carbon were determined, in addition to assessing basal soil respiration. The activity of the β-glucosidase enzyme was only determined in the 0 - 0.10 m diagnostic layer. 
The results were subjected to analysis of variance (ANOVA) and the Scott-Knott test (p < 0.10) to compare the means between treatments. The results indicated that soil organic carbon was influenced by depth (p = 0.000), with the 0 - 0.10 m layer showing the highest levels. Basal soil respiration showed significant differences between the cover crops used (p = 0.000), with U. brizantha cv. Ipyporã promoting greater basal soil respiration.
The activity of β-glucosidase, a key enzyme in the carbon cycle, showed no significant differences between the treatments evaluated. These results suggest a possible stability in the carbon cycle in the management systems adopted, such as the no-till system implemented more than 12 years ago. The results show that the adoption of conservation practices, such as no-till farming, combined with the appropriate choice of vegetation cover and soil management, directly influences soil health. This strategy makes it possible to identify limiting factors and guide practices that maintain soil fertility and promote long-term agricultural sustainability.