Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9456637 | Environmental Pollution | 2005 | 8 Pages |
Abstract
Nutrients in animal manure are valuable inputs in agronomic crop production. Rapid and timely information about manure nutrient content are needed to minimize the risks of phosphorus (P) over-application and losses of dissolved P (DP) in runoff from fields treated with manure. We evaluated the suitability of a commercial hand-held reflectometer, a hydrometer, and an electrical conductivity (EC) meter for determining DP and total P (TP) in dairy manures. Bulk samples (n = 107) collected from farms across CT, MD, NY, PA, and VA were highly variable in total solids (TS) concentration, ranging from 11 to 213 g Lâ1, in suspensions' pH (6.3-9.2), and EC (6.2-53.3 dS mâ1). Manure DP concentrations measured using the RQFlex reflectometer (RQFlex-DPs) were related to molybdate-reactive P (MRPs) concentrations as follows: RQFlex-DPs = 0.471 Ã MRPs + 1102 (r2 = 0.29). Inclusion of pH and squared-pH terms improved the prediction of manure DP from RQFlex results (r2 = 0.66). Excluding five outlier samples that had pH â¤Â 6.9 the coefficient of determination (r2) for the MRPs and RQFlex-DPs relationship was 0.83 for 95% of the samples. Manure TS were related to hydrometer specific gravity readings (r2 = 0.53) that were in turn related to TP (r2 = 0.34), but not to either RQFlex-DP or MRP. Relationships between suspensions' EC and DP or TP were non-significant. Therefore, the RQFlex method is the only viable option for on-site quick estimates of DP that can be made more robust when complemented with TS and pH measurements. The DP quick test can provide near real-time information on soluble manure nutrient content across a wide range of handling and storage conditions on dairy farms and quick estimates of potential soluble P losses in runoff following land applications of manure.
Related Topics
Life Sciences
Environmental Science
Environmental Chemistry
Authors
A. Lugo-Ospina, Thanh H. Dao, J.A. Van Kessel, J.B. III,