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91.
Managing the nitrogen cycle to reduce greenhouse gas emissions from crop production and biofuel expansion 总被引:1,自引:0,他引:1
Stephen M. Ogle Bruce A. McCarl Justin Baker Stephen J. Del Grosso Paul R. Adler Keith Paustian William J. Parton 《Mitigation and Adaptation Strategies for Global Change》2016,21(8):1197-1212
Public policies are promoting biofuels as an alternative to fossil fuel consumption in order to mitigate greenhouse gas (GHG) emissions. However, the mitigation benefit can be at least partially compromised by emissions occurring during feedstock production. One of the key sources of GHG emissions from biofuel feedstock production, as well as conventional crops, is soil nitrous oxide (N2O), which is largely driven by nitrogen (N) management. Our objective was to determine how much GHG emissions could be reduced by encouraging alternative N management practices through application of nitrification inhibitors and a cap on N fertilization. We used the US Renewable Fuel Standards (RFS2) as the basis for a case study to evaluate technical and economic drivers influencing the N management mitigation strategies. We estimated soil N2O emissions using the DayCent ecosystem model and applied the US Forest and Agricultural Sector Optimization Model with Greenhouse Gases (FASOMGHG) to project GHG emissions for the agricultural sector, as influenced by biofuel scenarios and N management options. Relative to the current RSF2 policy with no N management interventions, results show decreases in N2O emissions ranging from 3 to 4 % for the agricultural sector (5.5–6.5 million metric tonnes CO2?eq.?year?1; 1 million metric tonnes is equivalent to a Teragram) in response to a cap that reduces N fertilizer application and even larger reductions with application of nitrification inhibitors, ranging from 9 to 10 % (15.5–16.6 million tonnes CO2?eq.?year?1). The results demonstrate that climate and energy policies promoting biofuel production could consider options to manage the N cycle with alternative fertilization practices for the agricultural sector and likely enhance the mitigation of GHG emissions associated with biofuels. 相似文献
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The existence of sex is one of the major unsolved problems in biology. We use computer simulations to model conditions in
which sex may first become established. We develop an individual-based population model and show that a hypothetical facultative
sex gene can fix, provided that the initial cost is low. It is demonstrated that the equilibrium fitness in the population
increases with increasing population size and decreasing mutation rate. The probability of the establishment of the sex gene
is found not to be directly related to the fitness difference between the asexual and sexual populations. This change in fitness
on changing the parameters of the model is investigated. 相似文献
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