Nutrient imbalances persist at multiple scales in modern US agriculture.
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Manureshed management is a platform for coordination and weighing tradeoffs.
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We mapped sources and sinks to understand the challenges and opportunities.
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Sources vs. sinks split at 37˚N, pointing to options for national manureshed management.
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Land use change and movement of animal farms affect regional manureshed management.
Abstract
The uncoupling of animal and crop production has resulted in long-term accumulation of manure nutrients in many areas, contributing to nutrient pollution. Prudent recycling of manure's nutrient resources requires reconnecting operations that produce manure with agricultural lands in need of nutrients. Thus the need to frame manure management via “manuresheds": the land (i.e. cropland, rangeland) surrounding livestock production operations where nutrients can be recycled on agricultural lands while balancing goals for production, environmental quality, and quality of life. We explore manureshed management as an evolution of national, regional, and local trends in nutrient sources and sinks. Results of our temporal assessments highlight not only system inertia, but the dynamic nature of nutrient flows and the potential for manureshed management to reverse nutrient imbalances at various scales. As a tool for a circular economy, manureshed management requires coordination beyond the farmgate, engaging specialists, industries, and other stakeholders.
Graphical abstract
Uni-directional (a) and circular (b) models of nutrient flows in agriculture .
Keywords
Circular systems
Agricultural geography
Nutrients
Waste
Manureshed
Data availability
Data are publicly available for use. Databases are pointed to within the text.