Integrated conservation management strategies for improving soil struture and carbon in grain production systems

Abstract

The use of conservationist systems, such as no-tillage (NT) and crop diversification, has proven to be a promising strategy for restoring degraded or low-productivity areas. Despite the well-documented benefits of NT compared to conventional tillage, intensive machinery use combined with low crop diversification in this system has contributed to soil compaction— capable of reducing crop yields by up to 75% and compromising soil environmental resilience. Occasional (or strategic) tillage, combined with diversified cropping systems, emerges as a vi- able alternative not only to mitigate this issue but also to enhance the productive capacity of agricultural systems and sequester carbon in the soil. Thus, this study explores two intercon- nected aspects aimed at improving the production environment: the impacts of diversified pro- duction systems and the effectiveness of combined methods in managing soil compaction. The first aspect is based on a long-term study of grain and forage cropping systems under NT in the Cerrado biome. The experiment, conducted over 10 years, investigated the dynamics of soil organic carbon and physical quality in cropping systems that included rotations with Piatã grass (Brachiaria brizantha) during the maize season, compared to monocultures. The results showed that diversified systems, especially those integrating Piatã grass in rotations, improved soil physical quality and increased organic carbon storage, performing similarly to native vegetation. On the other hand, monocultures such as soybean reduced carbon stocks by up to 25%, rein- forcing the need for more sustainable practices. The second aspect evaluates the efficiency of biological and mechanical management methods, applied either individually or in combination, to mitigate soil compaction in NT systems. The study was conducted under rainfed conditions, employing different levels of initial compaction caused by agricultural machinery traffic. Treat- ments included subsoiling, cover crops, and the combination of both methods during the winter season, aiming to assess the impacts of these management practices on soil physical quality, carbon storage, and grain yield over two years. The results showed that the adoption of cover crops - ruzigrass (Brachiaria ruziziensis) and sunn hemp (Crotalaria juncea) - in combination with subsoiling is a promising strategy for mitigating the impacts of soil compaction in NT systems. The integration of these interconnected aspects provides a comprehensive approach, highlighting both the benefits of well-established practices and the need to develop and validate innovative strategies for sustainable soil management. It is expected that the results will con- tribute to scientific and technological advancements in compacted soil management, promoting greater sustainability in agricultural production.