Winter cover crops have been shown to reduce nitrate-N (NO3-N) losses in runoff water and are recommended by the Illinois Nutrient Loss Reduction Strategy (NLRS) for reducing nutrient losses from agricultural fields. ...Winter cover crops have been shown to reduce nitrate-N (NO3-N) losses in runoff water and are recommended by the Illinois Nutrient Loss Reduction Strategy (NLRS) for reducing nutrient losses from agricultural fields. With an estimated 80 percent of the NO3-N load in Illinois coming from agriculture, the NLRS stresses the importance of farmers’ voluntary implementation of best management strategies in order to reach these goals. This study compares the difference in NO3-N losses from tile drainage water from an annual ryegrass (AR, Lolium multiflorum) winter cover-cropped treatment to a conventional tillage (CT) control (fall chisel and spring field cultivation). Throughout the maize (Zea mays L.) growing season, tile drainage water was collected and analyzed for NO3-N concentrations. Despite the AR treatment having a 29% lower mean daily NO3-N concentration, there was no significant difference in total daily NO3-N flux between AR and CT for this study period of April-July 2015. The cumulative losses of NO3-N were calculated at 11.65 and 10.56 kg ha?1 NO3-N for the CT and AR treatment, respectively, or a 9.4% reduction in the AR treatment during the period of study. When the season was divided based on growing season periods, the NO3-N flux values were less for the cover crop while the AR was actively growing, greater for the cover crop for the period following annual ryegrass termination through maximum crop canopy, and lower for the cover crop in the late stages of vegetative growth through relative maturity.展开更多
Rotavirus is a leading cause of gastrointestinal illness worldwide. Rotavirus transmission occurs fecalorally, and becomes a critical water quality issue when soil and water resources are contaminated with feces. Tran...Rotavirus is a leading cause of gastrointestinal illness worldwide. Rotavirus transmission occurs fecalorally, and becomes a critical water quality issue when soil and water resources are contaminated with feces. Transport of pathogens to surface water sources depends on their survival in the soil, especially considering the fact that large amounts of fecal material are often applied to agricultural lands as fertilizer. In this study, rotavirus survival was investigated in three different soil fractions and at three different temperatures (4℃, 25℃ and 37℃). A rotavirus suspension was mixed with whole soil, sand, and clay and allowed to incubate for up to 18 days. Samples were collected daily to investigate virus survival over time, which was quantified using a tissue-culture infectivity assay. Results indicated, in the absence of any soil particles, rotavirus survival was highest at 4℃, with survival decreasing as temperature increased. These data also indicated whole soil had some protective effect, allowing rotavirus to survive better in soil for the entire range of temperatures and for more than a week at 37℃. The results also showed that sand fractions were the most effective media for reducing rotavirus recovery at all temperature conditions tested. Although the mechanism responsible for the low recovery from sand is unknown, there is little or no infective rotavirus extracted from sand fractions. This finding strongly supports the use of sand as a filtering material to remove rotavirus from both point and nonpoint sources of water pollution.展开更多
文摘Winter cover crops have been shown to reduce nitrate-N (NO3-N) losses in runoff water and are recommended by the Illinois Nutrient Loss Reduction Strategy (NLRS) for reducing nutrient losses from agricultural fields. With an estimated 80 percent of the NO3-N load in Illinois coming from agriculture, the NLRS stresses the importance of farmers’ voluntary implementation of best management strategies in order to reach these goals. This study compares the difference in NO3-N losses from tile drainage water from an annual ryegrass (AR, Lolium multiflorum) winter cover-cropped treatment to a conventional tillage (CT) control (fall chisel and spring field cultivation). Throughout the maize (Zea mays L.) growing season, tile drainage water was collected and analyzed for NO3-N concentrations. Despite the AR treatment having a 29% lower mean daily NO3-N concentration, there was no significant difference in total daily NO3-N flux between AR and CT for this study period of April-July 2015. The cumulative losses of NO3-N were calculated at 11.65 and 10.56 kg ha?1 NO3-N for the CT and AR treatment, respectively, or a 9.4% reduction in the AR treatment during the period of study. When the season was divided based on growing season periods, the NO3-N flux values were less for the cover crop while the AR was actively growing, greater for the cover crop for the period following annual ryegrass termination through maximum crop canopy, and lower for the cover crop in the late stages of vegetative growth through relative maturity.
文摘Rotavirus is a leading cause of gastrointestinal illness worldwide. Rotavirus transmission occurs fecalorally, and becomes a critical water quality issue when soil and water resources are contaminated with feces. Transport of pathogens to surface water sources depends on their survival in the soil, especially considering the fact that large amounts of fecal material are often applied to agricultural lands as fertilizer. In this study, rotavirus survival was investigated in three different soil fractions and at three different temperatures (4℃, 25℃ and 37℃). A rotavirus suspension was mixed with whole soil, sand, and clay and allowed to incubate for up to 18 days. Samples were collected daily to investigate virus survival over time, which was quantified using a tissue-culture infectivity assay. Results indicated, in the absence of any soil particles, rotavirus survival was highest at 4℃, with survival decreasing as temperature increased. These data also indicated whole soil had some protective effect, allowing rotavirus to survive better in soil for the entire range of temperatures and for more than a week at 37℃. The results also showed that sand fractions were the most effective media for reducing rotavirus recovery at all temperature conditions tested. Although the mechanism responsible for the low recovery from sand is unknown, there is little or no infective rotavirus extracted from sand fractions. This finding strongly supports the use of sand as a filtering material to remove rotavirus from both point and nonpoint sources of water pollution.
