Effects of Detrital Inputs and Roots on Carbon Saturation Deficit of a Temperate Forest Soil

Soil C sequestration has been proposed as a tool for addressing climate change. However, models used to predict soil C sequestration do not account for C saturation and functional differences among soil C pools. In this study, we examined differences in soil C pool content of a forest soil in Pennsylvania following 20 yr of detrital manipulation (i.e., control, no roots, no leaf litter, no inputs, double leaf litter). Detrital input treatments had a highly significant (ANOVA, F = 10.6, p < 0.0001) effect on soil C in the 0- to 5-cm soil depth. However, soil C pools responded differently to the different treatments: the intra-microaggregate silt + clay, intra-microaggregate particulate organic matter (POM), and silt + clay within large macroaggregates in plots receiving no detrital inputs had significantly lower C concentrations (1.1, 2.5, and 0.4 g C kg−1 soil, respectively) than the control, double-leaf-litter, and no-roots plots. Carbon in coarse POM within small macroaggregates was significantly lower in double-leaf-litter (4.5 g C kg−1 soil) and no-leaf-litter plots (6.6 g C kg−1 soil) than all other treatments (15.3–28 g C kg−1 soil). The intra-microaggregate fractions in double-leaf-litter plots had greater C concentrations than in the control plots; along with moderate C concentrations in all bulk soil samples, this suggests that the soil is not yet approaching C saturation. This study reinforces the use of microaggregates within large macroaggregates as a diagnostic fraction for changes in soil C content and demonstrates that altering the organic matter source and quantity significantly affects soil C sequestration dynamics. Consideration of these factors will enable improved assessment of soil C sequestration capacity and management.This version of the article is available for viewing after January 31, 2016.Postprin

Climate-smart agriculture is good for business: A framework for establishing the business case for climate-smart agriculture investments

Climate-smart agriculture (CSA) makes financial sense for businesses. Governments are increasingly holding the private sector responsible for their role in climate change impacts. Extreme weather events are incredibly costly for businesses. This is particularly true in agriculture, which relies heavily on favorable weather conditions. CSA practices and technologies are central to the transformative changes necessary to maintain the stability—and profitability—of the food system in the face of climate change. Where robust information on the benefits, costs, and risks of interventions is missing or incomplete, would-be investors, including donors, governments, businesses, and farmers, remain uninformed of the potentially massive dividends climate-smart investments could offer. This dearth of viable business models ultimately hinders the mainstreaming of productive, climate-resilient, low-emissions agriculture. Robust business-case analyses of CSA could accelerate the scaling of promising, profitable technologies by transparently and rigorously laying out the monetary and nonmonetary values of performance. We use existing data from Evidence for Resilient Agriculture (ERA, previously known as The Compendium) to develop a general framework for establishing the business case for specific farm-level agricultural technologies. The framework focuses on the costs, benefits, and risks of adoption of CSA by smallholder farmers. We illustrate the application of the framework with two case studies in Kenya and Malawi to highlight opportunities, challenges, and lessons learned from building business cases for CSA. These give potential investors the tools to screen and select appropriate technologies and help de-risk investments where data are few and far between

Prioritizing Tanzania’s agricultural development policy to build smallholder climate resilience. Final report for the Bill & Melinda Gates Foundation Grand Challenges Explorations 22: Risk-explicit and Evidence-based Policy Prioritization (REAP)

Faced with myriad options, Sub-Saharan Africa policy makers struggle to prioritize actions. Commonly used modeling approaches perform poorly in data scare conditions or focus intently on tools at hand. Policies, by consequence, report ‘wish lists’, making them a challenge to implement given resource constraints. Here, we evaluate the potential of using an alternative approach, Bayesian Networks (BNs), to prioritize agricultural policy actions, specifically modeling seven ‘Investment Areas’ listed in Tanzania’s Agriculture Sector Development Programme II

Enhancing Soil Carbon in East Africa: The biophysical evidence, socio-economic incentives, and policy implications

This report provides a summary/sythesis of key research outputs and messages gathered from the four year BMZ-funded project on "Scaling up soil carbon enhancement interventions for food security and climate across complex landscapes in Kenya and Ethiopia.

Economic Feasibility of Irrigated Agricultural Land Use Buffers to Reduce Groundwater Nitrate in Rural Drinking Water Sources

Agricultural irrigation leachate is often the largest source for aquifer recharge in semi-arid groundwater basins, but contamination from fertilizers and other agro-chemicals may degrade the quality of groundwater. Affected communities are frequently economically disadvantaged, and water supply alternatives may be too costly. This study aimed to demonstrate that, when addressing these issues, environmental sustainability and market profitability are not incompatible. We investigated the viability of two low impact crops, alfalfa and vineyards, and new recharge basins as an alternative land use in recharge buffer zones around affected communities using an integrated hydrologic, socio-geographic, and economic analysis. In the southern Central Valley, California, study area, alfalfa and vineyards currently constitute 30% of all buffer zone cropland. Economic analyses of alternative land use scenarios indicate a wide range of revenue outcomes. Sector output gains and potential cost saving through land use conversion and resulting flood control result in gains of at least $2.3 billion, as compared to costs of$0.3 to $0.7 billion for treatment options over a 20 year period. Buffer zones would maintain the economic integrity of the region and concur with prevailing policy options. Thus, managed agricultural recharge buffer zones are a potentially attractive option for communities facing financial constraint and needing to diversify their portfolio of policy and infrastructure approaches to meet drinking water quality objectives

The potential of digital tools to promote sustainable production in the shrimp aquaculture sector: A case study of the Mekong Delta, Viet Nam

Viet Nam’s fishery sector plays a vital role in the economy. Together, aquaculture and capture fishing account for almost 5% of the national gross domestic product (GDP), and directly or indirectly provide income to 8.5 million people, or nearly 10% of the total population (FAO, 2019; Lebailly et al., 2017). Viet Nam’s vibrant aquaculture sector contributes approximately 65% of total fisheries exports and plays an important role in filling the gap between global seafood demand and the sustainable limits of capture fishing (Lebailly et al., 2017; Phung & Pham, 2018). The shrimp aquaculture sub-sector is a particularly critical pillar of the seafood industry; it represents the second largest share of national aquatic exports, making Viet Nam the third largest shrimp exporter globally (International Trade Centre (ITC), 1999; Phung & Pham, 2018). The brackish waters of Viet Nam’s Mekong Delta host the vast majority of the nation’s shrimp aquaculture, accounting for 84% of total production (GSO, 2020)