Date of this Version
Implementation of nitrogen management plans by Natural Resource Districts may require feedlots to evaluate the environmental soundness of their waste management plans. Composting may be a manure management system that can provide a method of using the nutrients in feedlot manure as a resource in an environmentally sound manner. Composting is an aerobic (oxygen requiring) decomposition of organic matters. such as manure, by microorganisms. Composting has been shown to provide many benefits. Moisture content and volume of composted feedlot manure are reduced 50% compared with raw feedlot manure. This improves handling and requires fewer trips to the field when applied to cropland. It may also be economically feasible for compost to be transported longer distances and be used as a valuable resource for crop production. Composting stabilizes nitrogen and makes it less susceptible to leaching and runoff when surface applied. This also provides flexibility in application to cropland. Unlike raw manure, compost does not have to be incorporated into the soil immediately following application to prevent nitrogen losses. Odor is generally reduced compared with stockpiled manure: and land applied composted feedlot manure is nearly odorless.
Drawbacks to composting include: time. money. land, and potential loss of nitrogen. Composting takes considerable labor, time and careful management if done properly. It may require the purchase of additional equipment to turn the windrows. Adequate land is needed for properly locating the composting site so it can function correctly. Runoff needs to be controlled. but adequate drainage is required to reduce muddy conditions during wet periods. In composting feedlot manure. loss of nitrogen from volatilization of ammonia is a major concern. Compost may contain only 50% of the nitrogen that was in raw manure. This may be due to a low (C:N) ratio, approximately 15: 1. While adding carbon sources to the feedlot manure would reduce this problem. it usually is not economically feasible unless a source is delivered to the site free or a fee is received for the carbon source.
The objectives of this study were: 1) Determine the cost of composting beef feedlot manure. 2) Determine the nitrogen and phosphorus content and economic value of composted feedlot manure. 3) Calculate the recovery of organic matter and nitrogen during the composting process. and 4) Evaluate crop response to application of compost.