|Title||Manuresheds: Advancing nutrient recycling in US agriculture|
|Publication Type||Journal Article|
|Year of Publication||2020|
|Authors||Spiegal SA, Kleinman P, Endale D, Bryant RB, Dell C, Goslee S.C., Meinen RJ, Flynn KC, Baker JM, Browning DM, McCarty GW, Bittman S, Carter JD, Cavigelli MA, Duncan E, Gowda PH, Li X, Ponce G.E., Raj C, Silveira M, Smith DR, Arthur DK, Yang Q|
|ARIS Log Number||368308|
|Keywords||Livestock manure, Long-Term Agroecosystem Research (LTAR) network, nitrogen, nutrients, phosphorus|
Nutrient recycling is fundamental to sustainable agricultural systems, but few mechanisms exist to ensure that surplus manure nutrients from confined animal feeding operations are transported for use in nutrient-deficient croplands. As a result, surplus manure nutrients concentrate in locations where they can threaten environmental health and devalue manure as a fertilizer resource. This study advances the concept of the “manureshed” – the lands surrounding animal production operations where manure nutrients can be redistributed to meet environmental, production and economic goals. Manuresheds can be managed at multiple scales, for example, on farms with both animals and crops where manure is applied to the farm’'s croplands, among animal farms and crop farms within a county, or even among animal and crop farms in neighboring or distant counties. With a focus on redistribution among counties, we classified the 3109 counties of the contiguous United States by their capacity to either supply manure phosphorus (P) and nitrogen (N) from confined livestock production (“sources”) or to assimilate and remove excess P and N via crops (“sinks”). Manure nutrient source counties were identified in 40 of the 48 states, with a substantial concentration in southern states. Source counties of manure P greatly outnumbered source counties of manure N (390 vs. 100), and all but one manure N source counties were also manure P source counties. Conversely, sink counties for manure N (2766 counties) outnumbered sink counties for manure P (2317 counties). We used the P balances of the source and sink counties to delineate four manuresheds with source areas dominated by various combinations of confined hog, poultry, dairy, and beef industries. The four manuresheds differed in the transport distances needed to assimilate excess manure P from their respective source areas (from 147 ± 51 km for a beef dominated manureshed to 368 ± 140 km for a poultry dominated manureshed), highlighting the need for systems-level strategies to promote manure nutrient recycling that operate across local, county, regional and national scales.