Runoff and drainage water quality from geotextile and gravel pads used in livestock feeding and loafing areas

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 livestock facilities to minimize mud, runoff and erosion of heavy traffic areas. The objective of this study was to compare different combinations of geotextile and gravel used in heavy livestock traffic areas that minimize the potential for water pollution. Three different pad combinations were constructed in 2.4 · 6-m plots as follows: (i) woven geotextile + 100 mm of gravel + 50 mm Dense Grade Aggregate (DGA); (ii) woven geotextile + geoweb + 100 mm DGA; and (iii) non-woven geotextile + 152 mm of gravel + 50 mm DGA; (iv) mud lots as control. The third combination was equivalent to one of the base treatments specified by the Kentucky Natural Resource and Conservation Service (NRCS). All treatment combinations were duplicated. Lysimeter pans were installed in four out of eight plots for the collection of leachate or drainage water. Runoff was collected at the lower end of the plots. About 14 kg of beef cattle manure were added evenly to the plots. Rainfall at 50 mm/h was applied using rainfall simulators. In the first five of ten experiments, manure was removed from the surface of the pads after each experiment. In the remaining five experiments manure accumulated on the surface of the pads. The effect of pad treatment was significant on the electrical conductivity (EC), total solids (TS), chemical oxygen demand (COD), nitrite (NO2–N), total nitrogen (TN) and total phosphorus (TP) values in surface runoff at the 5% level. Manure removal did not have any significant effect on the nutrient content of runoff or leachate samples except for ammonia (NH4–N) values. Although a mass balance indicated relatively small amounts of organic matter and nutrients were lost by runoff and leaching, the actual contamination level of both runoff and leachate samples were high; TP levels as high as 12 mg/l (5.4 mg/m2) in runoff and nitrate (NO3– N) values as high as 10.8 mg/l (1.6 mg/m2) in leachate were observed.