University of Arkansas Division of Agriculture Database of Dairy, Poultry, and Swine Manure/Litter Chemical and Physical Properties [2026 release]

<b>Nathan A. Slaton, Rajveer Singh, Uzair Ahmad, Cheri Villines, Russell Delong, and Otis Robinson</b>[Note: Updated for 2026 release]. The database contains select properties of 17,378 dairy, poultry, and swine manure samples submitted to the University of Arkansas Division of Agriculture Fayetteville Agricultural Diagnostic Laboratory (FADL) between 1 January 2005 and 31 December 2025. Most samples were submitted by clients with active animal production farms for use in nutrient management planning. When state information was provided, the majority of samples originated from Arkansas (5,412), followed by Tennessee (392) and Oklahoma (297); however, many samples collected between 2005 and 2022 do not include county or state identifiers. Based on submission patterns, Arkansas is considered the primary state of origin for these records.Metadata describing the production system, manure collection and storage methods, sample age, and bedding were provided by clients and assumed to be reasonably accurate. When not provided, categorical metadata fields such as animal type, bedding type, and manure type were designated as “Unknown,” while missing values for sample age (days), state, county, and some analytes were left blank. Beginning in 2025, the database was expanded to include a fourth animal category (“Other”) to capture samples from additional animal types (e.g., beef, horse, sheep, bat) and biochar.<b>Poultry litter (Dry) Samples</b>The database includes information for &gt;14,500 poultry samples submitted from 1 January 2005 through 31 December 2025. Samples in the database represented Broiler, Hen, Pullet, Turkey, Cornish, Rooster, and Unknown (no animal-specific production system noted). An example manure submission form is shown in Figure 1. Manure types include Cake, Cleanout, Compost, Dead bird compost, Deep stack, Dry stack, Fresh litter, In-house, Lagoon liquid, Lagoon sludge, Loose, Pellets, Sludge, and Unknown. Bedding materials include Rice (<i>Oryza sativa</i> L.) hulls, Sawdust, Wood shavings, mixtures of Rice hulls and Sawdust, Rice hulls and Wood shavings, Wood shavings and Sawdust, Straw and Wood shavings, and Unknown.Arkansas clients usually deliver samples directly to the FADL or a local county Extension office, where a sample submission form (Figure 1) is completed, and the sample is shipped to the laboratory. Samples from Oklahoma are often delivered directly to the FADL. When a sample arrives at the lab, the date received and the lab identification number are added to the sample’s submission form, which is filed for record-keeping. The lab identification numbers contain 5-6 digits, are numbered sequentially in the order received at the lab, and represent information including (from left to right): Letter M (Manure; note some samples include M and others do not because “M” was omitted when entered into the database); first or second number (1-10 or 20) stands for the year; and the last 4 numbers in the lab number are the order the sample was logged in at the FADL. The dataset also includes columns for the year and date received.Using a scoop or spatula, the bulk manure sample (as received) is split into two representative subsamples (~100 mL or cm³ each) and placed into plastic bags. The subsamples are refrigerated at 4°C until further analysis. One of the subsamples is homogenized and ground using a coffee bean grinder for pH, electrical conductivity, and total nutrient analysis. The second subsample remains unaltered (as-received) and is used for moisture determination and water-extractable phosphorus (WEP) analysis. A homogenized, ground subsample was initially used for WEP, but starting in 2009, the unaltered, “as-received” sample has been used for WEP analysis. The change was made because of speculation that homogenizing the subsample increased the WEP, and the research performed to develop the Arkansas P index used unaltered, “as-received” litter. Any remaining bulk sample is stored at room temperature until analysis is complete and the results are reported to the client. The FADL has participated in the Minnesota Manure Proficiency Program (https://www.mda.state.mn.us/pesticide-fertilizer/certified-testing-laboratories-manure-soil) as part of the quality assurance and control program since 2005.The database includes two columns for WEP data (i.e., Arkansas WEP and Universal WEP). Water-extractable P was originally performed using the 10:1 water/litter (v:w) ratio, identified as the Arkansas method (Wolf et al., 2009). The Universal WEP method (Spargo, 2022; Wolf et al., 2009) is now used to determine water-extractable nutrients in manure samples. The Arkansas WEP method was used on poultry litter samples through 2009 since this was required for samples submitted from the Eucha-Spavinaw watershed (Sharpley et al., 2009; 2010). Beginning in 2010, the laboratory switched WEP analyses to the Universal WEP method. The Universal water-extraction method (100:1) is the only method used for the determination of water-extractable potassium (WEK).The counties and states of sample origin were not recorded in the original poultry litter dataset but were added for samples submitted beginning 1 January 2023. The county and state details before 2023 were added to random samples that were checked for accuracy of analytical information. Please note that even when the county of litter origin is provided, it may not be accurate since the county Extension office that received the sample may not be consistent with the county of production. Information included in the column identified as “Clients” has two levels: “ESWMT” (Eucha-Spavinaw Watershed Management Team) and “Other”. Samples with the client identified as ESWMT were submitted from poultry farms located within the Eucha-Spavinaw watershed, spanning Delaware and Mayes Counties in Oklahoma and Benton County in Arkansas (DeLaune et al., 2006; Sharpley et al., 2009). The ESWMT label identified these samples for the analysis requirements set by the watershed regulations, requiring all poultry litter samples be analyzed for WEP (OCCWQD, 2007).<b>Dairy and Swine Liquid Manure Samples</b>The database includes dairy and swine manure properties and metadata for 680 dairy and 1996 swine samples submitted from 1 January 2007 through 31 December 2025. The dairy and swine data include samples of dry and liquid manure forms. Most samples include geographic origin metadata at the state and county levels. Metadata for dairy and swine sample manure types include Cleanout, Compost, Dry stack, Fresh from floor, Lagoon sludge, Lagoon liquid, Milk wash water, Pit, Holding Pond, Settling basin liquid, Settling basin sludge, Sludge, Tank, Wash water, and Unknown. Sample age metadata should be used with caution since some values are very low (e.g., 1–7 days) and may misrepresent the requested information.Clients are provided with 500 ml (16.9 oz; 73×164 mm D×H: 53 mm cap) leakproof plastic bottles and shipping boxes (Figure 2). Upon delivery, samples are refrigerated until the requested analyses are completed. The analyses include the percent solids for liquid samples or percent moisture for dry samples.<b>References: </b>See Related Materials or Documentation files.