VERTICAL WATER MOVEMENT THROUGH GEOTEXTILE AND GRAVEL PADS USED IN HEAVY LIVESTOCK TRAFFIC AREAS

摘要

Geotextile and gravel pads offer a low-cost alternative to concrete for providing all-weather surfaces for cattle and vehicle traffic, and are used in many beef and dairy facilities to minimize mud problems in heavy traffic areas. A pilot-scale studywas conducted to determine the effect of different geotextile and gravel layer combinations on the vertical movement of water and contaminants (total solids and chemical oxygen demand) from beef cattle manure. Thirty-four tanks (0.6 m diameter) were constructed to accommodate 16 different geotextile and gravel pad combinations. Treatments were replicated and compared to a control using the base treatment specified in the Kentucky Natural Resources and Conservation Service guidelines. Different amounts of beef lot manure (1,2.5 and 5 kg) were added to the top of each tank. Rainfall was simulated at 25,50, and 100-mm depths using nozzles that delivered water in a uniform pattern to the surface of the pads. The amount of leachate collected was measured and analyzed for pH, electrical conductivity, total solids, and chemical oxygen demand. Two possible pad combinations gave the best reductions in total solids and chemical oxygen demand masses: (i) woven geotextile + 10-cm gravel + 5-cm dense grade aggregate; and (ii) woven geotextile + geoweb~(R)+ 10-cm dense grade aggregate. The type of geotextile as well as the amount of manure and rainfall depth combination significantly affected (p-value < 0.05) both total solids and chemical oxygen demand masses.