Page - 19 - in options, Volume summer 2016

19summer 2016 + optionswww.iiasa.ac.at SOIL AND THE CLIMATE Models like Kaiser’s provide vital information for researchers looking at the bigger picture of how soil dynamics influence climate change. IIASA researcher Stefan Frank, for example, has been exploring the links between farming practices and climate mitigation. In  a  recent study, he found that the EU could reduce agricultural greenhouse gas emissions by up to 7% through enhanced carbon sequestration of cropland. These reductions would come through economic incentives (i.e., a carbon price of US$100 per ton of CO2) for farming practices that keep carbon in soil. As national policies also have impacts beyond country borders, Frank also assessed how reduction targets within Europe would affect emissions on a global scale. “If strict agricultural emissions targets are only adopted inside Europe this could lead to increased emissions in other parts of the world, which could significantly compromise global emission reduction targets,” he said. THE GOOD EARTH Soil is obviously also central to food production. And with an estimated 795 million people today who are undernourished, and a projected population size of 9 to 11 billion by the year 2050, future agricultural production poses a major question. Yet  Lal argues that more land for agriculture is not the solution— instead, he says, we need to increase yields on existing land, producing more from less. IIASA research backs him up. For example, a 2015 study showed that 24–80% more food calories could be produced worldwide by optimizing fertilizer and irrigation methods. Another IIASA  study from 2014 showed that imbalances between nitrogen and phosphorus are already limiting production in Africa and could  drive yields even lower in the future. While soil holds great potential for addressing the planet’s food security and climate challenges, researchers also point out the simplest way to reduce pressure on food security and soils could be in our own kitchens—each year an estimated one third of all food is spoiled or thrown away. Lal said, “Each one of us is  responsible. There are 7.2 billion of us. If everyone makes a very small incremental improvement, it can have a major impact.” KL Further info § Kaiser  C, Franklin  O, Richter  A, Dieckmann  U (2015). Social dynamics within decomposer communities lead to nitrogen retention and organic matter build-up in  soils. Nature Communications 6:8960 [doi:10.1038/ncomms9960]. § Frank  S, Schmid  E, Havlík  P, Schneider  UA, Böttcher  H, Balkovicˇ  J, Obersteiner  M (2015). The dynamic soil organic carbon mitigation potential of European cropland. Global Environmental Change 35:269–278 [doi:10.1016/j.gloenvcha.2015.08.004]. § van  der  Velde  M, Folberth  C, Balkovicˇ  J, Ciais  P, Fritz  S, Janssens  IA, Obersteiner  M, See  L, Skalský  R, Xiong  W, Peñuelas  J (2014). African crop yield reductions due to increasingly unbalanced Nitrogen and Phosphorus consumption. Global Change Biology 20(4):1278–1288 [doi:10.1111/gcb.12481]. § Pradhan  P, Fischer  G, van  Velthuizen  H, Reusser  DE, Kropp  JP (2015). Closing  yield gaps: How sustainable can we be? PLoS ONE 10(6):e0129487 [doi:10.1371/journal.pone.0129487]. Stefan Frank frank@iiasa.ac.at § Christina Kaiser kaiser@iiasa.ac.at “Just like birds  and animals can be endangered, some soils are endangered.” —Rattan Lal ONE MICROSITE Decay of enzymes Enzyme production Enzymatic breakdown Diffusion of labile substrates Labile substrates Enzymes Microbial biomass recycling DOM DIN N Mineralization and immobilization Respiration CO2 Dead microbial biomass Plant material MR-C MR-N Complex substrates Enz PM Enz MR-C Enz MR-N Microorganism MODELING SOIL DYNAMICS A theoretical model of microbial community dynamics provides insight into carbon and nitrogen cycles. spotlight