Leveraging agroecology for solutions in food, energy, and water

Global agriculture is facing growing challenges at the nexus of interconnected food, energy and water systems, including but not limited to persistent food insecurity and diet-related diseases; growing demands for energy and consequences for climate change; and declining water resources, water pollution, floods and droughts. Further, soil degradation and biodiversity loss are both triggers for and consequences of these problems. In this commentary, we argue that expanding agroecological principles, tools, and technologies and enhancing biological diversity can address these challenges and achieve better socioeconomic outcomes. Agroecology is often described as multi- or transdiscplinary, and applies ecological principles to the design and management of agricultural systems through scientific research, practice and collective action. While agroecology has roots in the study of food systems, agricultural land use has many direct and indirect linkages to water and energy systems that could benefit from agroecological insights, including use of water resources and the development of bio-based energy products. Although opportunities from the science and the practice of agroecology transcend national boundaries, obstacles to widespread adoption vary. In this article, we therefore focus on the United States, where key barriers include a shortage of research funds, limited supporting infrastructure, and cultural obstacles. Nevertheless, simply scaling up current models of agricultural production and land use practices will not solve many of the issues specific to food related challenges nor would such an approach address related energy and water concerns. We conclude that a first critical step to discovering solutions at the food, energy, water nexus will be to move past yield as a sole measure of success in agricultural systems, and call for more holistic considerations of the co-benefits and tradeoffs of different agricultural management options, particularly as they relate to environmental and equity outcomes

Managing grazing lands to improve soils and promote climate change adaptation and mitigation: A global synthesis

The potential to improve soils to help farmers and ranchers adapt to and mitigate climate change has generated significant enthusiasm. Within this discussion, grasslands have surfaced as being particularly important, due to their geographic range, their capacity to store substantial quantities of carbon relative to cultivated croplands and their potential role in mitigating droughts and floods. However, leveraging grasslands for climate change mitigation and adaptation will require a better understanding of how farmers and ranchers who rely on them for their livelihoods can improve management and related outcomes. To investigate opportunities for such improvements, we conducted a meta-analysis of field experiments that investigated how soil water infiltration rates are affected by a range of management options: adding complexity to grazing patterns, reducing stocking rates or extended rest from grazing. Further, to explore the relationships between observed changes in soil water infiltration and soil carbon, we identified papers that reported data on both metrics. We found that in 81.9% of all cases, responses of infiltration rates to identified management treatments (response ratios) were above zero, with infiltration rates increasing by 59.3 ± 7.3%. Mean response ratios from unique management categories were not significantly different, although the effect of extended rest (67.9 ± 8.5%, n = 140 from 31 experiments) was slightly higher than from reducing stocking rates (42.0 ± 10.8%; n = 63 from 17 experiments) or adding complexity (34.0 ± 14.1%, n = 17 from 11 experiments).We did not find a significant effect of several other variables, including treatment duration, mean annual precipitation or soil texture; however, analysis of aridity indices suggested that grazing management may have a slightly larger effect in more humid environments. Within our database, we found that 42% of complexity studies, 41% of stocking rate studies and 29% of extended rest studies also reported at least some measure of soil carbon. Within the subset of cases where both infiltration rates and carbon were reported, response ratios were largely positive for both variables (at least 64% of cases had positive mean response ratios in all management categories). Overall, our findings reveal that a variety of management strategies have the potential to improve soil water infiltration rates, with possible benefits for soil carbon as well. However, we identified a shortage of well-replicated and detailed experiments in all grazing management categories, and call for additional research of both soil water and soil carbon properties for these critical agroecosystems. Includes supplemental materials

The state of sustainable agriculture and agroecology research and impacts: A survey of U.S. scientists

A growing body of research suggests that although sustainable agriculture, particularly agroecology, can address challenges such as those related to climate change, ecosystem services, food insecurity, and farmer livelihoods, the transition to such systems remains limited. To gain insight into the state of U.S. sustainable agriculture and agroecology, we developed a 28-question mixed-method survey that was administered to scientists in these fields. Respondents (N=168) represented diverse locations, institutions, and career stages. They offered varied definitions of sustainable agriculture, with 40% considering economic and social well-being to be core components. Respondents identified the amount and duration of public research funding as important obstacles to conducting research on sus- tainable agriculture (85% and 61%, respectively). Further, most expressed challenges in communi- cating findings beyond academia, including to the media and policymakers, potentially limiting the impacts of such research. However, respondents expressed satisfaction in several areas, including relationships with community members (81%) and local producers (81%), and interest from students (80%) and research communities (73%), suggesting positive momentum in this field. Earlier versus later career scientists rated research on “human dimensions” as more important, expressed greater concerns over career stability, and were less satisfied with opportunities for policy engagement. Results imply that greater public investments, particularly fostering human dimensions, could support a transition to agroecology and its associated benefits

Improving water resilience with more perennially based agriculture

Land conversion from natural to managed ecosystems, while necessary for food production, continues to occur at high rates with significant water impacts. Further, increased rainfall variability exposes agricultural systems to impacts from flood and drought events. In many regions, water limitations are overcome through technological approaches such as irrigation and tile drainage, which may not be sustainable in the long term. A more sustainable approach to combat episodes of floods and droughts is to increase soil water storage and the overall green water efficiency of agroecosystems. Agricultural practices that promote “continuous living cover,” such as perennial grasses, agroforestry and cover crops, can improve water management relative to annual crop systems. Such practices ensure living roots in agricultural systems throughout the year and offer an approach to agroecosystem design that mimics ecological dynamics of native perennial vegetation. We review how these practices have been shown to improve elements of the water balance in a range of environments, with an emphasis on increased soil hydrologic function. A specific focus on the agriculturally intensive state of Iowa provides insight into how land use centered on agroecological principles affords greater water resilience, for individual farms as well as for broader community and ecosystem health

Comparing infiltration rates in soils managed with conventional and alternative farming methods: A meta-analysis

Identifying agricultural practices that enhance water cycling is critical, particularly with increased rainfall variability and greater risks of droughts and floods. Soil infiltration rates offer useful insights to water cycling in farming systems because they affect both yields (through soil water availability) and other ecosystem outcomes (such as pollution and flooding from runoff). For example, conventional agricultural practices that leave soils bare and vulnerable to degradation are believed to limit the capacity of soils to quickly absorb and retain water needed for crop growth. Further, it is widely assumed that farming methods such as no-till and cover crops can improve infiltration rates. Despite interest in the impacts of agricultural practices on infiltration rates, this effect has not been systematically quantified across a range of practices. To evaluate how conventional practices affect infiltration rates relative to select alternative practices (no-till, cover crops, crop rotation, introducing perennials, crop and livestock systems), we performed a meta-analysis that included 89 studies with field trials comparing at least one such alternative practice to conventional management. We found that introducing perennials (grasses, agroforestry, managed forestry) or cover crops led to the largest increases in infiltration rates (mean responses of 59.2 ± 20.9% and 34.8 ± 7.7%, respectively). Also, although the overall effect of no-till was non-significant (5.7 ± 9.7%), the practice led to increases in wetter climates and when combined with residue retention. The effect of crop rotation on infiltration rate was non-significant (18.5 ± 13.2%), and studies evaluating impacts of grazing on croplands indicated that this practice reduced infiltration rates (-21.3 ± 14.9%). Findings suggest that practices promoting ground cover and continuous roots, both of which improve soil structure, were most effective at increasing infiltration rates

Improving water resilience with more perennially based agriculture

Land conversion from natural to managed ecosystems, while necessary for food production, continues to occur at high rates with significant water impacts. Further, increased rainfall variability exposes agricultural systems to impacts from flood and drought events. In many regions, water limitations are overcome through technological approaches such as irrigation and tile drainage, which may not be sustainable in the long term. A more sustainable approach to combat episodes of floods and droughts is to increase soil water storage and the overall green water efficiency of agroecosystems. Agricultural practices that promote “continuous living cover,” such as perennial grasses, agroforestry and cover crops, can improve water management relative to annual crop systems. Such practices ensure living roots in agricultural systems throughout the year and offer an approach to agroecosystem design that mimics ecological dynamics of native perennial vegetation. We review how these practices have been shown to improve elements of the water balance in a range of environments, with an emphasis on increased soil hydrologic function. A specific focus on the agriculturally intensive state of Iowa provides insight into how land use centered on agroecological principles affords greater water resilience, for individual farms as well as for broader community and ecosystem health

Research topics to scale up cover crop use: Reflections from innovative Iowa farmers

Cover crops as a conservation practice continue to receive attention from farmers, researchers, media, and policy makers, given their ability to effectively reduce water pollution and improve soil quality. Recent estimates of cover crop use across the midwestern Corn Belt, as well as the United States, demonstrate large acreage increases over the last number of years. The annual Sustainable Agriculture Research and Education–Conservation Technology Information Center (SARE– CTIC) survey found that nationally cover crop acreage doubled from 2011 to 2016, based on farmers self-reporting cover crop planting (CTIC 2016). However, the total cover crop acreage based on 2012 Census of Agriculture data only represents 3.2% of harvested cropland nationally and just 2.3% of the total cropland in the US Corn Belt (USDA NASS 2014a, 2014b)

Predicting long-term cover crop impacts on soil quality using a cropping systems model

Increased attention is being paid to cover crops as an option to reduce water pollution and decrease soil degradation in Iowa. More producers are experimenting with cover crops to increase soil productivity. However, when this project began there was little research to demonstrate the long-term impacts that cover crops have on crop yields. There were no estimates to quantify how much environmental benefit a cover crop could provide in terms of erosion and soil carbon changes. Such estimates are beneficial to demonstrate the long-term improvements that a cover crop affords in Iowa, particularly for corn-soybean rotations where the winter planting window is narrow, presenting a significant short-term challenge for producers. Using a cropping systems model such as APSIM (Agricultural Production Systems sIMulator) can offer estimates of potential benefits for farmers and policy makers which might take many years to observe in a traditional field trial. The objectives of this research were to: • Measure crop growth and soil properties at a representative corn-soybean field site with a winter rye cover crop to provide specific parameters necessary to establish and test APSIM and to analyze field data for treatment effects of the cover crop. • Use APSIM simulations to estimate the impact of long-term cover crops on soil carbon, soil erosion, soil water dynamics, and average main crop yields as well as cover crop impacts following more variable rainfall seasons, a projected climate change impact for the Midwest United States

Climate change challenges require collaborative research to drive agrifood system transformation

The recent Climate Science Special Report released as part of the Fourth National Climate Assessment confirms that we are living through the warmest period in modern civilization and that human activities are the primary driver of this warming (Wuebbles et al., 2017). These climatic changes have and will continue to impact global agricultural production, with food security and production consequences that will be felt unequally across the planet. Agricultural activities contribute to global warming emissions, while also offering opportunities for greenhouse gas mitigation. It is clear that the agrifood system will have to adapt to a changing climate. To better assess climate influences on agricultural systems in this themed issue of Renewable Agriculture and Food Systems, we challenged authors to submit interdisciplinary research that examines climate change adaptation and mitigation in agriculture and subsequent interconnected impacts to the food system. Indeed, agrifood systems provide a fertile context for examining climate change from multiple disciplines

The state of sustainable agriculture and agroecology research and impacts: A survey of U.S. scientists

A growing body of research suggests that although sustainable agriculture, particularly agroecology, can address challenges such as those related to climate change, ecosystem services, food insecurity, and farmer livelihoods, the transition to such systems remains limited. To gain insight into the state of U.S. sustainable agriculture and agroecology, we developed a 28-question mixed-method survey that was administered to scientists in these fields. Respondents (N=168) represented diverse locations, institutions, and career stages. They offered varied definitions of sustainable agriculture, with 40% considering economic and social well-being to be core components. Respondents identified the amount and duration of public research funding as important obstacles to conducting research on sus- tainable agriculture (85% and 61%, respectively). Further, most expressed challenges in communi- cating findings beyond academia, including to the media and policymakers, potentially limiting the impacts of such research. However, respondents expressed satisfaction in several areas, including relationships with community members (81%) and local producers (81%), and interest from students (80%) and research communities (73%), suggesting positive momentum in this field. Earlier versus later career scientists rated research on “human dimensions” as more important, expressed greater concerns over career stability, and were less satisfied with opportunities for policy engagement. Results imply that greater public investments, particularly fostering human dimensions, could support a transition to agroecology and its associated benefits