Optical Imaging continued Using AKST to improve Health and Nutrition

420 | IAASTD Global Report emissions Ball et al., 1999; Duxbury, 2005. This outcome, however, may be location speciic e.g., humid climatic con- ditions as revealed by a comprehensive review of Canadian agroecosystem studies Helgason et al., 2005. Globally, farmers continue to adopt no-till as their con- ventional production system. As of 2001, no-till agriculture had been adopted across more than 70 million ha worldwide with major expansion in South America e.g., Argentina, Brazil, and Paraguay Izaurralde and Rice, 2006. With an area under cropland estimated globally at 1.5 billion ha, there exists a signiicant potential to increase the adoption of no-till as well as other improved agricultural practices, which would have other environmental beneits such as im- proved soil quality and fertility, reduced soil erosion, and improved habitat for wildlife. Much work remains to be done, however, in order to adapt no-till agriculture to the great variety of topographic, climatic, edaphic, land tenure, land size, economic, and cultural conditions that exist in agricultural regions of the world. In developing strategies all potential GHG emissions need to be considered for example, efforts to reduce CH 4 emissions in rice can lead to greater N 2 O emissions through changes in soil nitrogen dynamics Wassmann et al., 2004; DeAngelo et al., 2005; Yue et al., 2005; Li et al., 2006. Similarly, conservation tillage for soil C sequestration can result in elevated N 2 O emissions through increased fertilizer use and accelerated denitriication in soils Ball et al., 1999; Duxbury, 2005. However, one of the most comprehensive long-term studies of GHG emissions across several land use practices in Michigan Robertson et al., 2000 revealed that no-till agricultural methods had the lowest Global Warm- ing Potential when compared to conventional and organic agricultural methods. From a GHG mitigation standpoint, strategies that em- phasize the avoidance of N 2 O and CH 4 emissions have a permanent effect as long as avoided emissions are tied to higher productivity, such as through increased energy efi- ciency and better factor productivity Smith et al., 2007. In- deed, many of the practices that avoid GHG emissions and increase C sequestration also improve agricultural eficiency and the economics of production. For example, improving water and fertilizer use eficiency to reduce CH 4 and N 2 O emissions also leads to gains in factor productivity Gupta and Seth, 2006; Hobbs et al., 2003 while practices that promote soil C sequestration can greatly enhance soil qual- ity Lal, 2005. Improved water management in rice produc- tion can have multiple beneits including saving water while maintaining yields, reducing CH 4 emissions, and reducing disease such as malaria and Japanese encephalitis van der Hoek et al., 2007. There is signiicant scale for achieving this “win-win” approach, with the approach largely determined by the size and input intensity of the production system, e.g., N-ixing legumes in smallholder systems and precision agriculture in large systems Gregory et al., 2000. There is potential for achieving signiicant future reduc- tions in CH 4 emissions from rice through improved water management. For example, CH 4 emissions from China’s rice paddies have declined by an average of 40 over the last two decades, with an additional 20 to 60 reduction possible by 2020 through combining the current practice of mid-season drainage with the adoption of shallow looding, conditions that spur local action towards natural resource improvements, and an understanding of this dynamic is needed to effectively support local initiatives. Stabilizing and improving the natural resource base of agriculture are essential preconditions for investing in technologies for long-term adaptation to climate change Stocking, 2003; Sanchez, 2005. Reduction of greenhouse gas emission for agriculture. Re- duction of N 2 O emissions from agriculture could be achieved by better matching fertilizer application with plant demand through the use of site-speciic nutrient management that only uses fertilizer N to meet the increment not supplied by indigenous nutrient sources; split fertilizer applications; use of slow-release fertilizer N; and nitriication inhibitors DeAngelo et al, 2005; Pampolino et al., 2007. Another op- tion to address N 2 O emissions would be the use of biological means to inhibit or control nitriication in soils. Gene trans- fer from species exhibiting biological nitriication inhibition to cultivated species could offer another way to reduce N 2 O emissions to the atmosphere and nitrate pollution of water bodies Fillery, 2007; Subbarao et al., 2007. Improved management of agriculture and rangelands targeted at soil conservation, agroforestry, conservation tillage especially no-till, agricultural intensiication, and rehabilitation of degraded land can yield C sequestration beneits IPCC, 2000; Izaurralde et al., 2001; Lal, 2004. Carbon sequestration potential in soils is greatest on de- graded soils Lal, 2004, especially those with relatively high clay content Duxbury, 2005; Lal, 2004. Another promising approach would be to use plant material to produce biochar and store it in soil Lehman, 2007a. Heating plant biomass without oxygen a process known as low-temperature pyrolysis converts plant mate- rial trees, grasses or crop residues into bioenergy, and in the process creates biochar as a coproduct. Biochar is a very stable compound with a high carbon content, surface area, and charge density; it has high stability against decay, and superior nutrient retention capacity relative to other forms of soil organic matter Lehmann et al., 2006. The potential environmental beneits of pyrolysis combined with biochar application to soil include a net withdrawal of atmospheric CO 2 , enhancement of soil fertility, and reduced pollution of waterways through retention of fertilizer N and P to bio- char surfaces Lehmann, 2007b. Future research is needed to more fully understand the effect of pyrolysis conditions, feedstock type, and soil properties on the longevity and nu- trient retention capacity of biochar. The robustness of soil carbon sequestration as a perma- nent climate change mitigation strategy has been questioned because soil carbon, like any other biological reservoir, may be reverted back to the atmosphere as CO 2 if the carbon sequestering practice e.g., no till practice were to be aban- doned or practiced less intensively. Increasing soil organic matter through carbon sequestering practices contributes directly to the long-term productivity of soil, water, and food resources IPCC, 2000; Lal, 2004. Thus it would seem unlikely that farmers would suddenly abandon systems of production that bring so many economic and environmen- tal beneits. Other reports suggest that certain soil carbon sequestering practices, such as no till, may increase N 2 O