Healthy soils for sustainable agriculture: the role of SOM
3–7 September 2017 • Rothamsted Research • Harpenden (United Kingdom)
Chairs: Mirjam Pulleman (Wageningen University, NL/ International Center for Tropical Agriculture (CIAT), CO)
Ranjan Bhattacharya (Indian Agricultural Research Institute (IARI), IN)
Adequate soil organic matter (SOM) levels are of key importance for sustained nutrient provision, soil biological activity, soil water retention and maintenance of soil structure. In recent years attention for SOM management has grown rapidly, due to its potential to contribute to climate change mitigation in addition to the before-mentioned benefits. However, there are still many challenges and uncertainties associated with SOM management and carbon (C) sequestration that need to be overcome to better inform decision making. Understanding how soil use and management affects SOM decomposition and to what extent it is stabilized versus mineralized under different management practices, climates and soil types continues to be a topic of great interest. To date, many questions remain, such as (i) the effects of crop type or management practices on SOM dynamics across soil depths in different soil types or climates; or (ii) the role of agroecosystem diversification, including associations with legumes, for soil C stabilization versus mineralization (iii) the contribution of deep soil biology and root-derived SOM formation in different soil orders (iv) the effect of initial soil degradation levels on SOM restoration rates and best practices. Moreover, changes in total SOM contents are typically slow and it takes several years before significant changes can be detected, even though the quantitative relevance for GHG mitigation or soil functioning can be substantial. We welcome contributions from (long-term) experiments or chrono-sequences that advance our mechanistic and quantitative understanding of land use and management effects on SOM mineralization and stabilization over time. Studies evaluating temperature, ozone or CO2 sensitivity of C decomposition under different agroecosystems are of interest, as well as studies related to early indicators of SOM accumulation and associated co-benefits for soil health that generate positive feedback loops. In this session we aim to provide an overview of novel science on SOM management to guide decision making on the sustainable use of our soils, soil restoration, and climate change mitigation thereby addressing several key global challenges.