Agricultural practices that increase SOC also supports higher and sustained food production, improved soil health, multiple ecosystem services, and reduced environmental footprints. This can be a win-win solution for farmers and society as a whole .A global meta-analysis was conducted to estimate the potential SOC sequestration in the soils of South Asia, and the potential for the mitigation of GHG emissions under major management options. Inventories of SOC stocks at various depths of soil and GHG emissions under different management practices were carried out. The practices were broadly categorized into synthetic fertilizer inputs, INM, where fertilizer inputs were partially substituted with organic sources, organic amendment as the source of nutrients, CA, and AWD . Where varying amounts of residues or different sources and doses of fertilizers were used, the conventional practice with a similar combination of treatments was taken as the control . Four depths of soil were considered in the analysis of soil C stock over the period. For the GHG inventory, direct emissions of CH4 and N2O ; emission matrices, viz. GWP ; and yield-scaled GWP were evaluated. To eliminate large variations reported in the studies, air racking the CO2-e of CH4 and N2O for the 100-yr period of IPCC), Myhre et al., 2013 were used to compute the total GWP in each study. Only studies where a practice was continuously followed for at least four years were selected. Data were grouped into cereal-cereal and cereal-legume rotations for soil C stock analysis, and into major cereal crops for GHG emission analysis.
Data were also organized into broad soil textural groups of fine, moderately fine, medium, moderately coarse, and coarse. The meta-analysis was performed by using ‘meta for’ in R programming platform .Overall, improved management practices reduced methane emissions by 12% in rice , resulting in an 8% reduction in GWP, and almost the same magnitude of reduction when expressed as yield-scaled changes . However, N2O emissions in upland soils remained unaffected by improved management practices. Conservation agriculture and fertilization reduced the GWP by 11 and 14%, respectively, while non-submerged conditions led to a large reduction in GWP in rice . A meta-analysis from China indicated a reduction in GWP by 25% in rice paddies and 2% in upland soils . Alternate-wetting-drying reduced CH4 emissions in rice cultivation by 39–83% in the USA . Estimates from a global study indicated a 66% reduction in GWP from no-till compared to the conventional tillage system . GWP increased with the organic amendment, either with or without inorganic fertilizer. A 12% increase in N2O emissions was reported with manure treatment compared to fertilizer treatment globally . Studies reported increases in N2O emissions associated with greater amounts of N applications through manure . Our yield-scaled GWP estimation followed similar trends except for INM, where higher yields compensated the increase in GWP . Reduction in N2O emission was related to reduction in yield under CA through a global meta-analysis . Another global analysis suggested increase in yield-scaled N2O emissions in zero tillage with <10 yrs of duration, which decreased after 10 yrs, compared to conventional tillage .
Soil texture appeared to have no influence on CH4 emissions in rice, while N2O emissions increased by 36% in fine-textured soil . The yield-scaled GWP was similar in wheat and maize, but lower in rice by adopting CA . This agreed with the findings of Linquist et al. , who reported greater mitigation opportunities in rice systems, compared to maize and wheat systems. There was no change in either GWP or yield-scaled GWP in wheat with improved management practices. In a global study, yield-scaled reduction in GWP in rice was 21% with optimal N applications .South Asian agriculture is a global ‘hot spot’ for climate change vulnerability and rapid population growth. Meeting a projected food demand of at least 40 percent will be constrained by climate unpredictability including rising temperature. Currently, South Asia accounted for 7.5% of total world’s fossils CO2 emissions which is bound to increase with continuing agriculture expansion along with rapid economic growth. There is no argument that sequestration of C in soils, plants, and plant products holds huge potential both to improve soil health and create C sinks that reduce atmospheric CO2 and combat climate change. There are several promising agronomic practices to enhance soil C stocks and mitigate GHG emissions. Notably, CA which is getting increasing attention in South Asia has proven potential. Our estimates suggest that existing soil management practices has potential to mitigate around ~18 Mg C ha 1 C year 1 which can compensate up to 8% reduction in GHG emissions. There is urgent need for supporting campaigns and efforts to increase soil C sequestration, both on a policy level and through programs which incentivizes farmers to adopt more C positive agricultural practices.
Expanding support and working together with global initiatives such as the 4p1000 Initiative, regional public-private partnership initiatives on C credits for Regenerative Agriculture as well as research and policy changes, will be important to the success of soil C sequestration. The current strategies to deliver knowledge, technologies, and incentives to promote the adoption of sound technical practices to the farmers are not adequate which need much support. Our future research efforts should also be devoted to develop monitoring and verification protocols for C sequestration in South Asia which will assist economists and policy makers to assess economic value of soil C and formulate right policies. Future studies should focus more on agroforestry and crop diversification, as there is limited information available on their potential for C sequestration. Effect of climate variables on SOC have been least studied. More work is needed to better quantify benefits of C sequestration on soil quality, productivity, and water and air quality. Further, the potential impact of climate variability on the stability of sequestered C in soils and plants should be evaluated. New generation of long-term studies to assess the potential of new management practices in C sequestration and its stabilization on a long-term basis is needed to advance our knowledge.Successful productivity growth in agriculture has been the source of early development and subsequent structural transformation and industrialization in most of today’s high income countries. This has been amply documented by the work of historians such as Bairoch who analyzed at the Western industrialization experience, cascading from England in the mid- 1700s, to France and Germany around 1820, the United States and Russia in the mid-1800s, and finally Japan with restauration of the Meiji emperors in 1880. Following WWII, agriculture has similarly been the engine of growth and transformation for the Asian industrialization miracles in Taiwan, South Korea, China , and Vietnam . In all these countries, an agricultural revolution preceded a subsequent industrial take-off, typically by something like a half century. Agriculture has also fulfilled an important role in facilitating industrialization in countries like India, Brazil, and Chile . Agriculture remains today the expected engine of growth for the “agriculture-based countries”, those countries with a high contribution of agriculture to GDP growth and a high share of their poor in the rural sector . These are also countries where the farm population is importantly composed of smallholder farmers , in some cases exclusively and in others coexisting with larger commercial farms . In both cases, weed dryer agricultural growth importantly requires modernization of the operation of SHFs. With labor-intensive industrialization increasingly compromised by robotization and the reshoring of industries toward the industrialized countries , agriculture with agroindustry and the associated linkages to services and non-tradable consumption has been heralded as a potentially effective strategy for GDP growth in these countries .
This includes most of the Sub-Saharan Africa countries. This approach is a major departure from the classical structural transformation approach based on labor-intensive industrialization advocated in the dual economy models . The World Development Report Agriculture for Development’s main message was that agriculture-based countries should invest more in agriculture in order to fully capture its potential for growth and poverty reduction. Following the world food crisis of 2008, there was a short-term positive response by governments, international organizations, and the donor community with a sharp increase in investment in agriculture. The number of countries meeting the CAADEP goal of allocating at least 10% of government expenditures to agriculture increased from 3 in 2007 to 10 in 2009. Overseas development assistance to agriculture increased by 60% between 2007 and 2009. But this response has not been sustained. In 2014 only 2 SSA countries out of 43 met the CAADEP goal. The modal SSA country spends only 5% of its public expenditures on agriculture. No SSA country spends a percentage of its public budget on agriculture that reaches the percentage contribution of agriculture to GDP, and 75% of the countries spend less than half that percentage . CAADEP also set a goal for public spending on agricultural Research-and-Development to reach 1% of agricultural GDP. Returns to investing in agricultural research are typically significantly in excess of cost relative to other public programs, indicating under-investment . This takes extreme forms in SSA where investment is by far the lowest among regions and has been declining over the last decade. In 2011, only six countries met the CAADEP research goal . With failure to invest in agriculture, the yield gap on cereals has continued to increase between SSA and other regions of the world. This gap is correlated with a growing chemical fertilizer gap and a large deficit in irrigation. Today, the World Development Report’s main message continues to be advocated by international development organizations such as the World Bank, the Food and Agriculture Organization, and the International Fund for Agricultural Development . This is motivated by the observation that 51% of the world extreme poor live in SSA, a share that continues to rise, and 78% of the world extreme poor work in agriculture in spite of rapid urbanization. Success in using Agriculture for Development is thus essential to meet the Sustainable Development Goals on poverty and hunger. In the current global economic context for the SSA countries, investing in agriculture where the poor work has proven more effective for poverty reduction than taking the poor out of agriculture and to an urban-industrial environment through a Lewis -type structural transformation. Research shows that the poor are not found in agriculture due to adverse selection. Poverty reduction, where it has happened, has been more effective through productivity growth where the poor work than through structural transformation . A Solow-type decomposition of sources of growth shows that agricultural output growth in SSA in the 1985- 2012 period originated for 63% from area expansion compared to 8% from factor deepening and 29% from productivity growth . This is not sustainable due to an effective land constraint and declining farm size in most countries as a consequence of rapid population growth. Take Malawi as an example where agricultural land for households engaged in agricultural production fell from 2.3 acres in 2004, to 1.8 in 2010, and 1.4 in 2016 . Productivity growth and factor deepening consequently have to be the main sources of growth in SSA agriculture as in the rest of the developing world where they account for 83% of agricultural output growth. This opinion on the role of agriculture for development is far from universally shared in the development community. Gollin et al. and Collier and Dercon have argued that rural poverty reduction has to come from employment creation in the urban-industrial environment and a structural transformation of the economy. As seen above, governments have correspondingly not invested public resources in agriculture to the recommended levels. Hence the puzzle in using agriculture for development is: why has the World Development Report/CAADEP recommendation not been followed? We argue here that it is because the mainly supply-side approach used for implementation has proved insufficiently effective, and needs to be complemented for this by a more explicit demand-side approach. There are African countries to look at for successful progress toward productivity growth in staple foods and a rural transformation . Chemical fertilizer use is overall low , but uneven across countries. The LSMS-ISA data show that the share of cultivating households using chemical fertilizer reaches 77% in Malawi, 56% in Ethiopia, and 41% in Nigeria, while remaining at 17% in Niger and Tanzania, and 3% in Uganda .