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Although use of micro‐irrigation has risen steadily in Georgia, few studies have been reported describing its effect on yield or rooting distribution of tomato (Licopersicon esculentum). The objective of this experiment was to determine the effects of mulch type (plastic mesh and straw) and micro‐irrigation on soil physical properties and growth of ‘Celebrity’ tomato. In 1986, an experiment was initiated on a Cecil sandy loam (clayey, kaolinitic, thermic, Typic Kanhapludult) at Griffin, GA. Tomato yield and root growth, soil temperature, and water potential in 1987 and 1988 were compared using black plastic mesh and straw mulches and three micro‐irrigation frequencies: control (no irrigation), daily, and twice weekly. Soil properties beneath the two types of mulches were compared in terms of surface evaporation, measured during 24‐h periods several times each year and bulk density, organic C, pH, infiltration rate, and cone index measured at the end of the 1988 growing season. Straw mulch resulted in a significantly greater infiltration rate, and lower pH, bulk density, surface evaporation, cone index, soil temperature and matric potential than the plastic mulch. Yields were higher under the straw mulch compared to the plastic mulch and irrigation increased yield with a straw mulch in 1987 but not 1988. Yields were not increased by irrigation of the plastic mulch treatment. Straw mulches have the potential to improve tomato yields in high‐temperature environments, provided soil pH is controlled.

Coal-bed methane (CBM) co-produced discharge waters in the Powder River Basin of Wyoming, resulting from extraction of methane from coal seams, have become a priority for chemical, hydrological and biological research during the last few years. Soil and vegetation samples were taken from affected and reference sites (upland elevations and wetted gully) in Juniper Draw to investigate the effects of CBM discharge waters on soil physical and chemical properties and on native and introduced vegetation density and diversity. Results indicate an increase of salinity and sodicity within local soil ecosystems at sites directly exposed to CBM discharge waters. Elevated concentrations of sodium in the soil are correlated with consistent exposure to CBM waters. Clay-loam soils in the study area have a much larger specific surface area than the sandy soils and facilitate a greater sodium adsorption. However, there was no significant relation between increasing water sodium adsorption ratio (SAR) values and increasing sediment SAR values downstream; however, soils exposed to the CBM water ranged from the moderate to severe SAR hazard index. Native vegetation species density was highest at the reference (upland and gully) and CBM affected upland sites. The affected gully had the greatest percent composition of introduced vegetation species. Salt-tolerant species had the greatest richness at the affected gully, implying a potential threat of invasion and competition to established native vegetation. These findings suggest that CBM waters could affect agricultural production operations and long-term water quality.

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