The objective of this trial was to compare the effect of silage covering systems on fermentation, nutritional quality, and estimated OM loss in the outer layer of whole-plant corn silage stored in a large drive-over pile on a dairy farm in the People’s Republic of China. On 22 and 23 September 2015 whole-plant corn was packed into about 50 linear meters in the center of a 22,000-ton capacity pile. The apex of the forage was about 4 meters, and the whole-plant had an average DM content of 32 percent. The silage covering systems were: 1) conventional white-on-black polyethylene (PE) plastic (PE plastic) and 2) oxygen barrier (OB) underlay film (www.silostop.com) plus conventional white-on-black PE (OB film). The conventional PE plastic protected the OB underlay film from UV light and physical damage. The surface of packed forage in the center of the pile was divided into eight, 5-meter by 5-meter areas; four areas were covered with PE plastic; four areas, with OB film. Covering systems were arranged alternately, and there was a 1-meter border around each area. The covering materials were removed before feed-out after 156 days of storage, and samples collected at 0 to 45 cm from the surface at three locations within each area. Samples of the crop at harvest and silage were analyzed for fermentation components and chemical composition. Loss of OM was estimated from the ash content in the crop at harvest and in the silage. Silage pH and lactic acid content were the only fermentation traits affected (P<0.05) by covering system. Silage protected with OB film had higher nutritional quality than silage protected with PE plastic, as evidenced by a lower (P<0.05) ADF and NDF content and higher (P<0.05) NDF digestibility. Ash content was lower (P<0.05) in silage covered with OB film than in silage covered with PE plastic. Estimated loss of OM in the upper 45 cm layer of silage was 14.2% under OB film versus 20.2% under PE plastic. Whole-pile estimated net economic benefit to the OB underlay film compared to PE plastic was 0.30 to 0.50 US dollars per ton of crop ensiled.