Regional differences in phosphorus budgets in intensive soybean agriculture

Author Posting. © American Institute of Biological Sciences, 2013. This article is posted here by permission of University of California Press for personal use, not for redistribution. The definitive version was published in BioScience 63 (2013): 49-54, doi:10.1525/bio.2013.63.1.10.Fertilizer-intensive agriculture has been integral to increasing food production over the past half century but has been accompanied by environmental costs. We use case studies of phosphorus fertilizer use in the world’s most productive soybean-growing regions, Iowa (United States), Mato Grosso (Brazil), and Buenos Aires (Argentina), to examine influences of management and soil type on agriculture’s most prevalent phosphorusrelated environmental consequences: eutrophication and consumption of Earth’s finite phosphorus reserves. With increasing phosphorus inputs, achieving high yields on tropical soils with high phosphorus-binding capacity is becoming more common. This system has low eutrophication risks but increases demands on phosphorus supplies. In contrast, production in traditional breadbaskets, on soils with lower phosphorus-binding capacities, is being sustained with decreasing phosphorus inputs. However, in these regions, historical overuse of phosphorus may mean continued eutrophication risk even as pressures on phosphorus reserves diminish. We focus here on soybean production but illustrate how achieving sustainable agriculture involves an intricate optimization of local, regional, and global considerations.SP is supported by the Andrew Mellon Foundation, and CN and SHR’s work in Mato Grosso was funded by National Science Foundation grant no. NSF-DEB-0640661 and through collaboration with the Instituto de Pesquisa Ambiental da Amazonia

Connecting urban food plans to the countryside: leveraging Denver's food vision to explore meaningful rural-urban linkages

Includes bibliographical references (pages 14-18).Cities are increasingly turning to food policy plans to support goals related to food access, food security, the environment, and economic development. This paper investigates ways that rural farmers, communities, and economies can both support and be supported by metropolitan food-focused initiatives. Specifically, our research question asked what opportunities and barriers exist to developing food policies that support urban food goals, particularly related to local procurement, as well as rural economic development. To address this question, we described and analyzed a meeting of urban stakeholders and larger-scale rural producers related to Colorado’s Denver Food Vision and Plan. We documented and explored “findings” gleaned from a supply chain diagraming and data compilation process that were then used to inform an event that brought together diverse supply chain partners. Three findings stand out. First, facilitating dialog between urban food policymakers and rural producers to understand potential tensions, mitigate such tensions, and capitalize on opportunities is essential. Second, perceptions and expectations surrounding “good food” are nuanced—a timely finding given the number of preferred procurement programs emerging across the county. Third, critical evaluation is needed across a diverse set of value chain strategies (e.g., conventional and alternative distribution) if food policy intends to support heterogeneous producers, their communities, and urban food policy goals

Linking soil microbial community structure to potential carbon mineralization: A continental scale assessment of reduced tillage

Potential carbon mineralization (Cmin) is a commonly used indicator of soil health, with greater Cmin values interpreted as healthier soil. While Cmin values are typically greater in agricultural soils managed with minimal physical disturbance, the mechanisms driving the increases remain poorly understood. This study assessed bacterial and archaeal community structure and potential microbial drivers of Cmin in soils maintained under various degrees of physical disturbance. Potential carbon mineralization, 16S rRNA sequences, and soil characterization data were collected as part of the North American Project to Evaluate Soil Health Measurements (NAPESHM). Results showed that type of cropping system, intensity of physical disturbance, and soil pH influenced microbial sensitivity to physical disturbance. Furthermore, 28% of amplicon sequence variants (ASVs), which were important in modeling Cmin, were enriched under soils managed with minimal physical disturbance. Sequences identified as enriched under minimal disturbance and important for modeling Cmin, were linked to organisms which could produce extracellular polymeric substances and contained metabolic strategies suited for tolerating environmental stressors. Understanding how physical disturbance shapes microbial communities across climates and inherent soil properties and drives changes in Cmin provides the context necessary to evaluate management impacts on standardized measures of soil microbial activity

Overcoming agricultural sustainability challenges in water-limited environments through soil health and water conservation: insights from the Ogallala Aquifer Region, USA

A rapid decline in water availability for crop production has driven substantial changes in cropping systems in the arid and semi-arid regions, including transitions from irrigated to dryland cropping. Management decisions play a critical role in the sustainability of agricultural systems facing transitions. Specifically, adopting practices that increase crop water use efficiency, improve soil health, and conserve water in the soil profile could improve agricultural sustainability. This review discusses published literature on the challenges associated with crop production and highlights management strategies to sustain soil health, enhance agricultural production, and farm profitability in the Ogallala Aquifer region to elucidate pathways to agricultural sustainability in water-limited environments around the world. We searched for published papers discussing soil health and water conservation practices, including conservation tillage, crop residue management, crop diversification, cover cropping, and livestock integration in cropping systems. These studies demonstrate adopting conservation systems can increase soil organic carbon (SOC) storage, water infiltration, soil microbial activities, water use efficiency, and decrease N fertilizer inputs compared to conventional systems. Integrating more than one soil and water conservation practice can complement to enhance soil health and sustainability of dryland or limited-irrigation agriculture in the Ogallala Aquifer region and similar agroecosystems across the world

Cover Crop Mixture Effects on Maize, Soybean, and Wheat Yield in Rotation

Despite the popularity of multispecies cover crop mixtures, there is little published evidence of their effects on subsequent crop yields, especially for multiple crops grown in rotation. We examined the effects of fall-planted cover crops—both mixtures and their component monocultures—on subsequent crop yields in an organically managed maize ( L.)–soybean [ (L.) Merr.]–winter wheat ( L.) rotation in central Pennsylvania. We hypothesized that cover crop biomass C/N ratio would be negatively correlated with crop yields. This held true for maize ( = 0.134, < 0.0001), but there was no cover crop effect on soybean or wheat yields. All multispecies mixtures produced high biomass, and none affected maize yield relative to fallow. Our findings suggest that both multispecies cover crops and diverse crop rotations may increase opportunities to gain the benefits of cover crops with high biomass and C/N ratio—such as erosion control, weed suppression, N retention, and soil C accumulation—without compromising yield

Ecosystem Services and Disservices Are Bundled in Simple and Diverse Cover Cropping Systems

Agroecosystems are increasingly expected to provide multiple ecosystem services. We tested whether and how cover crop selection (identity and number of species) affects provisioning of multiple services (multifunctionality). In a 3-yr study of 10 cover crop treatments and eight ecosystem services, certain services consistently co-occurred. One such service “bundle” included cover crop biomass production, weed suppression, and nitrogen retention. Another set of bundled services included cash crop production, nitrogen supply, and profitability. We also identified trade-offs: as some services increased, other disservices arose, limiting multifunctionality. However, functionally diverse mixtures ameliorated disservices associated with certain monocultures, thereby increasing cover crop multifunctionality

Connecting Urban Food Plans to the Countryside: Leveraging Denver’s Food Vision to Explore Meaningful Rural–Urban Linkages

Cities are increasingly turning to food policy plans to support goals related to food access, food security, the environment, and economic development. This paper investigates ways that rural farmers, communities, and economies can both support and be supported by metropolitan food-focused initiatives. Specifically, our research question asked what opportunities and barriers exist to developing food policies that support urban food goals, particularly related to local procurement, as well as rural economic development. To address this question, we described and analyzed a meeting of urban stakeholders and larger-scale rural producers related to Colorado&#8217;s Denver Food Vision and Plan. We documented and explored &#8220;findings&#8222; gleaned from a supply chain diagraming and data compilation process that were then used to inform an event that brought together diverse supply chain partners. Three findings stand out. First, facilitating dialog between urban food policymakers and rural producers to understand potential tensions, mitigate such tensions, and capitalize on opportunities is essential. Second, perceptions and expectations surrounding &#8220;good food&#8222; are nuanced&#8212;a timely finding given the number of preferred procurement programs emerging across the county. Third, critical evaluation is needed across a diverse set of value chain strategies (e.g., conventional and alternative distribution) if food policy intends to support heterogeneous producers, their communities, and urban food policy goals