Dr Daniel Rasse¹, Dr Alice Budai¹, Mr Simon Weldon¹

¹NIBIO, Ås, Norway

There is a need for win-win solutions for increasing soil carbon sequestration and improving the recycling of nutrients from organic wastes, thereby benefiting both climate mitigation and food production. In terms of carbon sequestration, biochar has been presented as a major solution for stabilizing vast amounts of carbon in soils. Analysis reveals that biochar technology outcompetes other methods for storing CO2 from bioenergy systems only if it also leads to increases in crop productivity. However, improved agronomic results have not always been forthcoming, especially in temperate fertile soils, and farmers need to see greater agronomic benefits in order to adopt the technology. This is why recent research recommends improving the fertilizer value of biochar by combining it with organic nutrient sources, especially N & P, fixed to or absorbed on its surface. In theory, the solution is ideal; biochar as a sorbent material has the capacity to capture nutrients in waste streams such as digestate and manure, reduce volatile N losses and GHG emissions, improve nutrient use efficiency and reduce N leaching. However, the mechanisms controlling this nutrient retention capacity are still poorly understood. Here, we report on a meta-analysis of biochar properties that control the retention and release of multiple forms of N and P sources. We further discuss implications for making compound fertilizers with biochar and nutrient-rich wastes.

Biography:
Daniel Rasse holds a PhD in soil science from Michigan State University and is currently heading the Soil Quality department at the Norwegian Institute of Bioeconomy Research. He has coordinated the European Networking Programme MOLTER (2008-2013) on molecular structures in the terrestrial C cycle, and is PI of several large-scale projects. His main research focus is on soil organic matter and the factors influencing its accumulation and its feedback on ecosystem functions. In the last decade, he has been working intensively on biochar technology as a mean to increase C sequestration in soil and improve fertility.