Economics of widespread manure application to irrigated crops: Raw and composted feedlot manure in eastern Colorado

We used linear programming to simulate adoption of manure disposal technologies in eastern Colorado. Manure, either raw or composted, is assumed to be applied to irrigated cropland within 20 miles of feedlots in five subregions of eastern Colorado. We constrained the application so that total N application is no more than the amount used by the crop. N, P and K contents are taken into account, but no benefits are assigned to organic matter or trace minerals and no costs are assigned to soil compaction, weed seed propagation, or inconvenience. Irrigated land within 10 miles of feedlots can easily absorb all manure generated under this scenario. Manure is found to be an economical substitute for chemical fertilizers, assuming N content to be at least 50% that of fresh manure. Composted manure is either more or less profitable than raw manure, depending on its N content. Hauling costs are lower for compost, but composting costs are between $1 and $2 per finished ton. The model does not allow for mixed application of compost and chemical fertilizers, which would increase the value of compost significantly. A feedlot waste sector that composted all feedlot manure in eastern Colorado is predicted to create between 80 and 200 additional jobs.