Applied Engineering in Agriculture Vol. 32(1): 63-68 © 2016 American Society of Agricultural and Biological Engineers ISSN 0883-8542 DOI 10.13031/aea.32.10883 63 TECHNICAL NOTE: INEXPENSIVE IN-FIELD MANURE SOLIDS TESTER R. A. Larson, J. Panuska, J. Sanford, C. Burnson ABSTRACT. Manure losses from crop fields via surface and subsurface pathways following land application can lead to eutrophication and habitat destruction in surface waters. High solids manure has less susceptibility to runoff and leaching, which is particularly important in high risk fields with increased loss potential. Unfortunately, the determination of manure solids content is typically conducted by laboratory analysis where results are provided after field application has occurred. An inexpensive solids tester (less than $40 to construct) was developed out of readily available materials for manure applicators to determine the solids content of liquid dairy manure in-field and in real time prior to application. As manure samples are passed through the screen, solids are captured on the screen while more dilute manure passes through. In order to evaluate the solids tester, 33 manure samples were collected from 6 separate dairies with a variety of bedding types (3 farms used sand and 3 farms used recycled digested solids for bedding) and manure handling and processing systems. Results indicated that the manure volume that is retained on the screen can be related to the solids content of dairy manure from 3% to 9%. An equation was produced to relate manure solids to the volume retained on the screen, TS=1.7953e 0.0046Vr , with an r-squared value of 0.82. Manure samples with less than 3% solids were shown to pass through the screen completely, therefore results were inaccurate for low TS content. The results did not vary significantly for dairies which used sand bedding and those that used recycled manure solids. This quick in-field measurement of total solids content allows for application to appropriate fields, thus reducing the risk of manure losses to nearby waterways. Keywords. Dairy manure, Manure application, Manure characteristics, Total solids. pproximately 1.3 million dairy cattle in the United States (USDA-NASS, 2012) produce over 8 billion gallons of dairy manure annually. Nearly all dairy manure currently produced is land applied to supply cropland with organic matter and the necessary nutrients for plant growth. Prior to application, manure is transported in and around the farmstead, processed, and in many operations stored. The variability in manure solids content can be considerable leading to operational complications and difficult management decisions throughout the entire manure management system. Fresh dairy manure has been reported to contain around 13% total solids (TS) when excreted (MWPS, 2004). However, changes in dairy herd management, manure processing, and constituents in manure storages have significantly impacted the solids content of dairy manure, commonly reducing TS at many facilities. A reduction in TS content is in part due to solid liquid separation systems which allow producers to separate and manage low and high solids content manures as well as the addition of low TS wastewater (e.g., farmstead runoff and milkhouse waste) to manure storages. In 2012, the TS content of 19,085 liquid/slurry dairy manure samples analyzed in Wisconsin laboratories ranged from <1% to 11.5% TS, with an average of 4.8% (samples over 11.5% solids were considered solid manure samples) (Peters, 2013). These data indicate that many facilities are applying manure with TS content lower than excreted values. Manure TS content from one facility can vary significantly making the design of manure handling systems and land application more difficult (Safley et al., 1986). This also makes handling and agitation of manure during application variable from day to day or even between tanker loads. More importantly, changes in manure content affect application rates and management decisions concerning application area/location. When manure is applied to cropland correctly, it is a sustainable practice that returns nutrients and organic matter to soils maintaining fertility and health (Haynes and Naidu, 1998). However, when low solids content manure is applied to fields with a high runoff likelihood, it can increase the movement of manure and/or associated nutrients to surface waters resulting in eutrophication, algal blooms, fish kills, and habitat destruction. This movement and resulting environmental impact can be accentuated in sensitive areas or locations which have increased drainage/runoff such as croplands with significant slopes, soils with low infiltration capacity, or soils with increased Submitted for review in July 2014 as manuscript number NRES 10883; approved as a Technical Note for publication by the Natural Resources & Environmental Systems Community of ASABE in September 2015. The authors are Rebecca A. Larson, Assistant Professor, John Panuska, ASABE Member, Extension Specialist, Joseph Sanford, ASABE Member, Graduate Student, and Christian Burnson, ASABE Member, Water Resources Engineer, Montgomery Associates, Cottage Grove, Wisconsin. Corresponding author: Rebecca A. Larson, 460 Henry Mall, Madison, WI, 53706; phone: 608-444-7662; e-mail: ralarson2@wisc.edu. A