报 告 人：Lars Bakken 教授 Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Norway
Cultivated soils are profoundly manipulated ecosystems, and their nitrogen transformations are controlled by the soil management to enhance the nitrogen delivery to growing crops, and to minimize the losses of reactive nitrogen via nitrate leaching and ammonia volatilization. This is called “good agronomic practice” (GAP). However, to make “climate smart agriculture”, GAP is not enough: we need to develop techniques that effectively reduce the N2O emissions. This is because N2O is the Achilles heel of climate smart agriculture, illustrated by the fact that the effect of C-sequestration on the climate forcing of food production is negated by the enhanced N2O emissions. Mitigating N2O emission is far from trivial, but I am convinced that deep understanding of the physiology and ecology of the organisms that produce and reduce N2O can provide some clue. In my talk, I will describe one possible approach, which is taken by our new Sino-Norwegian research project: “New generation biofertilizers for improved nitrogen management, sustainable food production and low greenhouse gas emissions” (NENIM). The central idea is that anaerobic digestion (AD) provides an excellent platform for low cost large scale production of N2O reducing bacteria in the digestates, which can then be used as biofertilizers that effectively reduce the N2O emissions from soils. In addition, we can use partial inhibition of nitrification to reduce the risk for nitrifier-induced denitrification in soils fertilized with the digestates. Core technologies for NENIM are metagenomics and metaproteomics, as well as the incubation robotics for determining denitrification kinetics in single bacteria and soils, thus drawing heavily on the expertise and infrastructure of the Chinese partners, which includes Jiaotong University Shanghai. Preliminary results are quite promising, suggesting that this project may indeed provide a tool for effective reduction of the N2O emission from food production. In addition, NENIM will unravel a number of interesting aspects of the physiology and ecology of the microbes responsible for the N2O turnover in soil.
Lars Bakken used to be a “jack of all trades” in soil biology, and even spent 10 years on collaboration with environmental economists. In 2005 he decided to concentrate on prokaryotes’ nitrogen transformations in general, and anoxic respiration in particular, and formed the NMBU Nitrogen group (http://www.nmbu.no/en/research/groups/nitrogen) together with Åsa Frostegård and Peter Dörsch. NMBUNG has become a robust and productive group, breaking barriers in the research on physiology of microbial nitrogen transformations and the formation of NO and N2O. The group is well integrated into the international network of leading biochemistry and microbiology nitrogen research groups, hosting many guest researchers from US, Europe, China and Oceania (2-4 per year, 2-6 months each). Microbial ecology with main focus on prokaryotes in soils and their roles in biogeochemistry of nitrogen. Experimental approaches include molecular biology, stable isotope techniques, traditional microbiology and process studies in situ. Recent focus has been on the ecology and regulatory biology of denitrifying bacteria. Mathematical modelling include biogeochemical models for soil-plan systems and modelling of process kinetics and regulation.