摘要：Using data from the Census of Agriculture on animal inventory and sales, weestimate manure nutrient production on farms with confined livestock. Using reported on-farmproduction of crops on these same farms, we estimate the nutrient uptake for major field cropsand pastureland. This enables us to examine the balance between manure nutrient productionand nutrient need measured by crop uptake at a farm level.Examination at alternative spatial scales, shows that 75 percent of counties in the U.S. havefarms that produce more manure nutrients than can be assimilated on the farm of production(excess nitrogen). The vast majority of the counties that produce excess nitrogen have adequateland in the county to spread the manure at agronomic rates. Thus, proposed policies that focuson land application have the potential to limit manure nutrient movement to waterways in mostareas, if properly managed. However, moving manure to crop farms that formerly had not usedmanure will increase costs. There were about 5 percent of counties where the manure nitrogenproduction levels from confined animal production exceeded half the nitrogen assimilativecapacity of all the cropland and pastureland in the county. These areas have the greatest need formechanisms to encourage off-farm solutions to utilize manure as a feedstock for commercialenterprises or central processing.
