Patrick M. Ewing

Soil Functional Zone Management: A Vehicle for Enhancing Production and Soil Ecosystem Services in Row-Crop Agroecosystems.

There is increasing global demand for food, bioenergy feedstocks and a wide variety of bio-based products. In response, agriculture has advanced production, but is increasingly depleting soil regulating and supporting ecosystem services. New production systems have emerged, such as no-tillage, that can enhance soil services but may limit yields. Moving forward, agricultural systems must reduce trade-offs between production and soil services. Soil functional zone management (SFZM) is a novel strategy for developing sustainable production systems that attempts to integrate the benefits of conventional, intensive agriculture, and no-tillage. SFZM creates distinct functional zones within crop row and inter-row spaces. By incorporating decimeter-scale spatial and temporal heterogeneity, SFZM attempts to foster greater soil biodiversity and integrate complementary soil processes at the sub-field level. Such integration maximizes soil services by creating zones of ‘active turnover’, optimized for crop growth and yield (provisioning services); and adjacent zones of ‘soil building’, that promote soil structure development, carbon storage, and moisture regulation (regulating and supporting services). These zones allow SFZM to secure existing agricultural productivity while avoiding or minimizing trade-offs with soil ecosystem services. Moreover, the specific properties of SFZM may enable sustainable increases in provisioning services via temporal intensification (expanding the portion of the year during which harvestable crops are grown). We present a conceptual model of ‘virtuous cycles’, illustrating how increases in crop yields within SFZM systems could create self-reinforcing feedback processes with desirable effects, including mitigation of trade-offs between yield maximization and soil ecosystem services. Through the creation of functionally distinct but interacting zones, SFZM may provide a vehicle for optimizing the delivery of multiple goods and services in agricultural systems, allowing sustainable temporal intensification while protecting and enhancing soil functioning.

Optimizing nitrogen rates in the midwestern United States for maximum ecosystem value

The importance of corn production to the midwestern United States cannot be overestimated. However, high production requires high nitrogen fertilization, which carries costs to environmental services such as water quality. Therefore, a trade-off exists between the production of corn yield and water quality. We used the Groundwater Vulnerability Assessment for Shallow depths and Crop Environment Resource Synthesis-Maize models to investigate the nature of this trade-off while testing the Simple Analytic Framework trade-offs featured in this Special Feature. First, we estimated the current levels of yield and water quality production in northeastern Iowa and southern Minnesota at the 1-square-kilometer, county, and regional scales. We then constructed an efficiency frontier from optimized nitrogen application patterns to maximize the production of both yield and water quality. Results highlight the context dependency of this trade-off, but show room for increasing the production of both services to the benefit of all stakeholders. We discuss these results in the context of spatial scale, biophysical limitations to the production of services, and stakeholder outcomes given disparate power balances and biophysical contexts.

Elevated, but highly variable, acetylene reduction in soils associated with the invasive shrub Rhamnus cathartica in a Midwestern oak forest

Common buckthorn (Rhamnus cathartica) is an important invasive shrub in North American forests, where it is thought that the plant’s retention of green leaves during autumn canopy senescence helps it succeed in deciduous understory habitat. This trait results in loss of nitrogen (N) in N-rich leaf litter, which has led some workers to suggest buckthorn may foster associative N-fixation in soil. We examined this possibility in an oak woodland understory in eastern Minnesota using the acetylene reduction assay to compare apparent nitrogenase activity in soils collected from beneath buckthorn individuals with soils collected from a canopy species (Quercus spp.), an important understory shrub (Prunus serotina), and non-vegetated areas. Buckthorn and non-buckthorn soils differed in variability of acetylene reduction (AR) rates, with buckthorn values covering a range 10× the range of non-buckthorn soils. Mean AR also differed between buckthorn and non-buckthorn soils, but the direction and magnitude of the difference varied with sampling location. Estimates of N inputs calculated from our data suggest that AR values at the high end of the buckthorn-associated range are biologically significant. Our results represent the first measurement of AR activity associated with common buckthorn, and are consistent with the hypothesis that this plant supports associative N fixation under some conditions. Suggestions for follow-up studies are provided.

A cooperative governance network for crop genome editing: The success of governance networks in other areas could help to find common ground for applying genome editing in agriculture

Emerging biotechnologies, such as genome editing, may revolutionize agricultural development through rapid and precise genetic manipulation of a wide range of crop traits without having to transfer foreign DNA [1]. If so, these new genetic‐engineering (GE) technologies can help to generate crop varieties to address critical challenges in agricultural development, such as climate resilience or nutrient uptake, or diet‐related problems in nutrition and health in poorer countries. However, society must also be protected from potential harmful effects of genetically manipulated crops on the environment, human health, or social welfare. Governance of these crops must therefore balance agricultural developments with risk assessment and prevention of potential harm. > …genome editing is being used to improve the characteristics of major crop plants, but the governance of crop genome editing is poorly defined and developed Presently, genome editing is being used to improve the characteristics of major crop plants, but the governance of crop genome editing is poorly defined and developed. Influential groups concerned with the potential hazards of such crops view this situation with growing alarm, which has created tensions with the academic community and regulatory agencies [2]. Both the USA and the European Commission are currently reviewing the governance of crops produced by genome editing and other new technologies. On the US side, at least, the review process appears unlikely to result in governance approaches that will satisfy parties that are concerned with either over‐ or under‐regulation of such crops, and tension and conflicts about them are likely to heighten. We propose an alternative approach for governance of these crops that may help to defuse tensions and enable exploration of genome editing technologies’ potential while protecting society from harm: a cooperative governance network. Such networks have performed well in …