A whole-farm modeling approach applied to survey data was used to assess the economic impacts on Heartland hog farms of alternative manure management regulations on manure application. Results showed differential economic impacts on the hog operations. Many large farms (over 2,500 hogs) had to lease additional land to meet restrictions on manure phosphorous application, with reductions in net crop returns exceeding those of medium size operations (750-2,500 hogs). Feeding hogs a phytase diet to lessen phosphorous in manure reduced the additional land needed and moderated the increase in manure application costs, but net crop returns still dropped for most operations.