Sustainable manure management

The sustainability of modern manure management is far from certain, with many demonstrating significant limitations from the stand point of efficient use of manure resources and protection of environmental quality and human health. As demonstrated through this review, for manure management to be sustainable, a broad array of issues must be considered and addressed, all in the context of highly competitive modern livestock production systems that largely seek to minimize costs to the consumer. In the past decade there have been major innovations in the areas of land application, manure treatment and processing and in the science of understanding the impact of manure management. As a result, major opportunities exist to improve the components of manure management. To be sustainable, these optimized components must work within the constraints of the broader livestock production system

Diffusion of Pt dimers on Pt(111)

We report the results of a density-functional study of the diffusion of Pt dimers on the (111) surface of Pt. The calculated activation energy of 0.37 eV is in {\em exact} agreement with the recent experiment of Kyuno {\em et al.} \protect{[}Surf. Sci. {\bf 397}, 191 (1998)\protect{]}. Our calculations establish that the dimers are mobile at temperatures of interest for adatom diffusion, and thus contribute to mass transport. They also indicate that the diffusion path for dimers consists of a sequence of one-atom and (concerted) two-atom jumps.Comment: Pour pages postscript formatted, including one figure; submitted to Physical Review B; other papers of interest can be found at url http://www.centrcn.umontreal.ca/~lewi

A Global Perspective on Phosphorus Management Decision Support in Agriculture: Lessons Learned and Future Directions

201

Managing crop nutrients to achieve water quality goals

Landscapes and watersheds are inherently leaky and some nutrient loss can be expected with productive agricultural systems. Minimizing these losses, without undermining system sustainability is challenging and should involve an open and constructive discussion among all stakeholders as to what nutrient loss is desired, achievable, and how differences between these two endpoints can be reconciled. This is complicated by short- and long-term variations in weather/climate are a major factor influencing nutrient loss from agricultural lands. Nitrogen (N) loss tends to be spatially extensive, with management of the rate and timing of application, along with cropping systems as being important determining factors. Phosphorus (P) loss, on the other hand tends to be a function of critical sources areas, where coincident source (e.g., soil P and rate, timing, method and type of P applied) and transport factors (e.g., runoff and erosion) define losses. Despite this, legacy N and P from prior land management can mask the benefits of current and future conservation practices (CPs) to reduce losses from agricultural systems. Here, the appropriate use of calibrated and validated nonpoint source watershed models to estimate relative contributions of nutrient sources and outcomes of CP implementation can inform future strategies. However, they must be used in conjunction with and cannot replace water quality monitoring programs. Great strides have been made in nutrient use efficiency via nutrient management, crop selection, and CP adoption, which have reduced the risk of nutrient loss to surface and ground waters. Even so, additional research is needed on the areas of nutrient management on drained lands, fluvial legacies, and socio-economic factors influencing the success of conservation strategies

The Promise, Practice, and State of Planning Tools to Assess Site Vulnerability to Runoff Phosphorus Loss

Publication history: Accepted - 23 October 2017; Published online - 1 November 2017.Over the past 20 yr, there has been a proliferation of phosphorus (P) site assessment tools for nutrient management planning, particularly in the United States. The 19 papers that make up this special section on P site assessment include decision support tools ranging from the P Index to fate-and-transport models to weather-forecast-based risk calculators. All require objective evaluation to ensure that they are effective in achieving intended benefits to protecting water quality. In the United States, efforts have been underway to compare, evaluate, and advance an array of P site assessment tools. Efforts to corroborate their performance using water quality monitoring data confirms previously documented discrepancies between different P site assessment tools but also highlights a surprisingly strong performance of many versions of the P Index as a predictor of water quality. At the same time, fate-and-transport models, often considered to be superior in their prediction of hydrology and water quality due to their complexity, reveal limitations when applied to site assessment. Indeed, one consistent theme from recent experience is the need to calibrate highly parameterized models. As P site assessment evolves, so too do routines representing important aspects of P cycling and transport. New classes of P site assessment tools are an opportunity to move P site assessment from general, strategic goals to web-based tools supporting daily, operational decision

Identifying challenges and opportunities for improved nutrient management through U.S.D.A's Dairy Agroecosystem Working Group

Nutrient management is a priority of U.S. dairy farms, although specific concerns vary across regions and management systems. To elucidate challenges and opportunities to improving nutrient use efficiencies, the USDA’s Dairy Agroecosystems Working Group investigated 10 case studies of confinement (including open lots and free stall housing) and grazing operations in the seven major U.S. dairy producing states. Simulation modeling was carried out using the Integrated Farm Systems Model over 25 years of historic weather data. Dairies with a preference for importing feed and exporting manure, common for simulated dry lot dairies of the arid west, had lower nutrient use efficiencies at the farm gate than freestall and tie-stall dairies in humid climates. Phosphorus (P) use efficiencies ranged from 33 to 82% of imported P, while N use efficiencies were 25 to 50% of imported N. When viewed from a P budgeting perspective, environmental losses of P were generally negligible, especially from dry lot dairies. Opportunities for greater P use efficiency reside primarily in increasing on-farm feed production and reducing excess P in diets. In contrast with P, environmental losses of nitrogen (N) were 50 to 75% of annual farm N inputs. For dry lot dairies, the greatest potential for N conservation is associated with ammonia (NH3) control from housing, whereas for freestall and tie-stall operations, N conservation opportunities vary with soil and manure management system. Given that fertilizer expenses are equivalent to 2 to 6% of annual farm profits, cost incentives do exist to improve nutrient use efficiencies. However, augmenting on-farm feed production represents an even greater opportunity, especially on large operations with high animal unit densities

Trends and transitions in the institutional environment for public and private science

The last quarter-century bore witness to a sea change in academic involvement with commerce. Widespread university-based efforts to identify, manage, and market intellectual property (IP) have accompanied broad shifts in the relationship between academic and proprietary approaches to the dissemination and use of science and engineering research. Such transformations are indicators of institutional changes at work in the environment faced by universities. This paper draws upon a fifteen-year panel (1981–1995) of university-level data for 87 research-intensive US campuses in order to document trends and transitions in relationships among multiple indicators of academic and commercial engagement. The institutional environment for public and private science is volatile, shifting in fits and starts from a situation conducive to organizational learning through high volume patenting to a more challenging arrangement that links indiscriminate pursuit of IP with declines in both the volume and impact of academic science. The pattern and timing of these transitions may support an enduring system of stratification that offers increasing returns to first-movers while limiting the opportunities available to universities that are later entrants to the commercial realm. Unpacking the systematic effects of university research commercialization requires focused attention on the sources and trajectories of profound institutional change.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42839/1/10734_2004_Article_2916.pd

Managing crop nutrients to achieve water quality goals

Landscapes and watersheds are inherently leaky and some nutrient loss can be expected with productive agricultural systems. Minimizing these losses, without undermining system sustainability is challenging and should involve an open and constructive discussion among all stakeholders as to what nutrient loss is desired, achievable, and how differences between these two endpoints can be reconciled. This is complicated by short- and long-term variations in weather/climate are a major factor influencing nutrient loss from agricultural lands. Nitrogen (N) loss tends to be spatially extensive, with management of the rate and timing of application, along with cropping systems as being important determining factors. Phosphorus (P) loss, on the other hand tends to be a function of critical sources areas, where coincident source (e.g., soil P and rate, timing, method and type of P applied) and transport factors (e.g., runoff and erosion) define losses. Despite this, legacy N and P from prior land management can mask the benefits of current and future conservation practices (CPs) to reduce losses from agricultural systems. Here, the appropriate use of calibrated and validated nonpoint source watershed models to estimate relative contributions of nutrient sources and outcomes of CP implementation can inform future strategies. However, they must be used in conjunction with and cannot replace water quality monitoring programs. Great strides have been made in nutrient use efficiency via nutrient management, crop selection, and CP adoption, which have reduced the risk of nutrient loss to surface and ground waters. Even so, additional research is needed on the areas of nutrient management on drained lands, fluvial legacies, and socio-economic factors influencing the success of conservation strategies