Submitted to: High Plains Beef Conference
Publication Type: Proceedings
Publication Acceptance Date: 8/19/1999
Publication Date: N/A
Technical Abstract: Large feedyards (FYs) are increasingly under the scrutiny of federal and state regulatory agencies for their possible contribution in lowering the quality of air, soil, and water. Therefore, it is in the best interest of FYs to determine what air, soil, and water quality is. This study is about the quality of dry soil in three FY shallow lakes (playas), and they are compared to two non-FY playas in the Southern High Plains of Texas. Feedyard playas serve as lagoons with no outlets and little or no percolation through a natural impervious clay that lines the playa bottoms. The major bacterial components of manure are Gram negative staining bacteria, and these have an outer membrane which is composed of lippolysaccharide molecules, also called endotoxin (ET), which are very stable. This marker (endotoxin) was determined on each side of three FY playas at 1 cm (22,010 ET ng/g of soil) and at 60 cm (4107 ET ng/g) depths in the dry portion of the playas, and the ET concentration was compared with two non-FY playas at 1 cm (9429 ET ng/g) and 60 cm (1197 ET ng/g). Feedyards on the average contribute more endotoxin to their playa soils than non-FY pastured playas. However, one of three FY playas was not significantly greater in ET than the average of two non-FY playas. Endotoxin concentrations are greatly diminished at 60 cm and as such, it does not appear to be a threat to the groundwater.