European Journal of Sustainable Agroecosystems

Background: Soil organic carbon (SOC) sequestration and aggregate stability are important indicators of the health and sustainability of agroecosystem soils. Conservation agriculture (CA) practices have been widely promoted as sustainable alternatives to conventional tillage; however, long-term field evidence on SOC dynamics and structural stability is limited in diverse agroeclimatic regions.
Objectives: This long-term field study evaluated the impact of conservation agriculture practices on dynamics of soil organic carbon, aggregate stability, physical and biological properties, and potential for carbon sequestration over 18 years of continuous management in a temperate agroecosystem.
Methods: The experimental station, located in the transition zone between the temperate and subtropical climates, was established according to a randomized complete block design. Three management systems were compared: (1) conventional tillage with removal of residue, (2) reduced tillage with partial residue retention, and (3) zero tillage with complete residue retention. Soil sampling was conducted biannually to determine SOC concentration, aggregate stability indices, bulk density, microbial biomass, soil respiration, enzyme activities and related soil physical and biological properties.
Results: Zero tillage with full residue retention increased SOC concentration and carbon stock by 34.2% and 31.8% respectively compared with conventional tillage over 18 years. Aggregate stability (mean weight diameter, MWD) increased by 28.6% under conservation agriculture compared to conventional practices. Zero tillage caused significant increases in microbial biomass carbon (43%), soil respiration rates (51%) and enzyme activities. In zero tillage, the water-stable aggregates > 2 mm increased from 22% to 51% indicating substantial improvement in soil structure. Zero tillage showed an average long-term rate of carbon sequestration of 0.62 Mg C ha−1 year−1 with a great potential for climate change mitigation.
Scientific Significance: This study shows that conservation agriculture practices, especially zero tillage combined with residue retention, greatly enhance soil carbon sequestration, structural stability, and soil biological activity. The results quantitatively support the adoption of conservation agriculture for sustainable soil management and climate change mitigation in temperate agroecosystems.
Conclusion: Long-term conservation agriculture practices are effective strategies to improve soil health, carbon sequestration, aggregate stability and maintaining productive capacity and contribute to climate change mitigation objectives.