Production and application of manure nitrogen and phosphorus in the continental U.S. during 1860-2017

Livestock manure, as organic sources for nitrogen (N) and phosphorus (P), plays an important role in nutrient cycling. Except for a small proportion of manure that is applied to agricultural soils to facilitate crop growth, the majority excesses to the ecosystem either through volatilization or leaching and runoff processes, resulting in environmental pollution. Thus, it is of great importance to estimate the spatial variations and temporal trajectories of manure production and its application in countries with high livestock production. Here, we develop annual manure N and P productions and applications dataset in the continental U.S. at 30 arc seconds resolution over the period of 1860-2017. The dataset combines multiple data sources including long-term information on numbers of multiple animal species and their excretion at the county level, the spatial distribution of livestock, as well as land-use types. The total productions of manure N and P were 4.59 ± 1.75 Tg N and 1.26 ±0.60 Tg P during 1860-2017. Prior to the 1960s, manure N and P productions increased significantly, at the speed of 0.045 Tg N/yr and 0.014 Tg P/yr, respectively, and during 1960-2017, the productions became stable with fluctuations in small magnitude. The high-nutrient region mainly concentrated in the north-central of the U.S. (e.g. Iowa, South Dakota, and Nebraska) before the 1930s, then the scope enlarged toward the south (e.g. Texas, North Carolina). Manure application gradually expanded from inland to seashore, which may cause massive nutrient export to the estuary. This long-term manure N and P dataset can provide detailed information for further research on nutrient allocations and cycling in land and aquatic ecosystems.