An Assessment of Nitrogen‐Based Manure Application Rates on 39 U.S. Swine Operations

Abstract

Water quality concerns and revised regulations are changing how confined animal feeding operations manage manure. Devising acceptable and feasible changes in manure practices requires a full understanding of the forces shaping current manure management decisions. Previous theoretical models have shown that a wide range of factors influence the lowest cost solution for manure management. We used a mechanistic model to characterize the manure management practices on 39 swine operations (20 unagitated lagoon and 19 slurry operations) in five states (Iowa, Missouri, North Carolina, Oklahoma, and Pennsylvania). Information was collected from each operation about animal numbers, feed and water use, manure handling and storage characteristics, field locations, crop rotation, fertilizer need, and equipment inventory and usage. Collected data were used as input and to validate results from a mechanistic model that determined acres required for manure application, manure application rate, time required for manure application, value of manure, and costs of manure management. The 39 farms had a mean of 984 animal units (AU) per operation, 18.2 AU ha(-1) (7.4 AU acre(-1)), and manure application costs of dollar 10.49 AU(-1) yr(-1). Significant factors affecting manure management included operation size, manure handling system, state, and ownership structure. Larger operations had lower manure management costs (r2 = 0.32). Manure value potentially exceeded manure application costs on 58% of slurry and 15% of lagoon operations. But 38% of slurry operations needed to apply manure off the farm whereas all lagoon operations had sufficient land for N-based manure management. Manure management was a higher percentage of gross income on contract operations compared with independents (P < 0.01). This research emphasized the importance of site-specific factors affecting manure management decisions and the economics of U.S. swine operations.

Assessment of the Iowa River's South Fork watershed: Part 2. Conservation practices

“…The results of geographic modeling identify areas most likely to receive manure applications (figure 2), considering corn as the only crop to receive manure. The estimated volumetric rate of slurry application, based on assumed manure excretion rates and nutrient loads, was 39 m 3 ha -1 , (4,180 gal ac -1 ), which is in the range reported for confined deep-pit swine operations in this region (Lory et al 2004).…”

Feasibility and Costs of Phosphorus Application Limits on 39 U.S. Swine Operations

“…All information was not available on all farms. Key attributes of the farms are listed in a companion paper (Lory et al, 2004).…”

“…The mechanistic simulation model used contains the following three modules: (i) a manure storage design module and nutrient generation module, (ii) a manure land‐application module, and (iii) an economic simulation of swine production module (Massey et al, 2000). A more detailed description of the mechanistic simulation model is in a companion paper (Lory et al, 2004).…”

“…Attributes of manure management systems differ among swine farms based on operation size, type of manure management system, region of the U.S., and ownership structure (Boland et al, 1999; Gollehon et al, 2001; Fleming et al, 1998; Lory et al, 2004). Transition from N‐ to P‐based manure management has the potential to affect many aspects of how the farmer manages land application of manure including land needs, equipment needs, cost and value of manure, and time requirement for manure application.…”

“…The potential differential effect on contract versus independent operations also has not been considered. Manure management costs are a much greater percentage of gross income on contract operations (Lory et al, 2004), potentially making them more susceptible to economic hardship associated with adopting P limits.…”