Long-term Variation in Agricultural Edge-of-Field Phosphorus Transport during Snowmelt, Rain, and Mixed Runoff Events.

Runoff of nutrients and erosion of soil from agricultural lands affect soil fertility and are important nonpoint contributors of P and N to surface and ground waters, yet studies of edge-of-field nutrient transport from snowmelt or rainfall runoff on frozen ground are limited. The objective of this study was to quantify the temporal and spatial variation in edge-of-field snowmelt, rain, and mixed (rain on snow) runoff events for sediment and P loadings in five agricultural subwatersheds over a 12-yr period. Edge-of-field runoff events from five subwatersheds at Pioneer Farm near Platteville, WI, ranging in size from approximately 4 to 30 ha were sampled using automated samplers from 2002 through 2014 to determine sediment and P yields (mass loads). Mean dissolved reactive P (DRP) runoff concentrations for each event type (rain = 1.24 mg L, snow = 1.90 mg L, mix = 2.23 mg L) were above total P (TP) water quality guidelines for surface waters. The percentages of TP that was DRP for snow, mixed, and rain events were 74, 84, and 39%, respectively. Although variation in total annual P yield in edge-of-field runoff was noted between years and among sites within a given year, when aggregated over the study period, the subwatersheds showed similar transport characteristics with respect to DRP and TP yield. This study highlights the importance of examining long-term datasets in quantifying annual yields and understanding the timing of DRP and TP transport for developing best management practices and improving model accuracy in cold weather agricultural systems.

Cost-effective treatment of constipation in the elderly: a randomized double-blind comparison of sorbitol and lactulose.

PURPOSE: The purpose of this study was to evaluate the use of sorbitol as an inexpensive alternative to lactulose for treating constipation in the elderly. PATIENTS AND METHODS: Thirty men aged 65 to 86 with chronic constipation were studied in a randomized, double-blind, cross-over trial in which lactulose and 70% sorbitol (0 to 60 mL daily) were each given for 4 weeks preceded by a 2-week washout period. RESULTS: The average number of bowel movements per week was 6.71 with sorbitol and 7.02 with lactulose (95% confidence interval of the difference: -0.43 to 1.06), and the average number of days per week with bowel movements was 5.23 with sorbitol and 5.31 with lactulose (95% confidence interval of the difference: -0.32 to 0.48). Eleven patients stated a preference for sorbitol, 12 for lactulose, and seven had no preference. On a visual analogue scale measuring severity of constipation (0 to 100 mm), the average score for sorbitol was 35.6 mm versus 37.1 mm for lactulose (95% confidence interval of the difference: -6.4 to 9.3). The sorbitol and lactulose treatment periods were also similar in percent of bowel movements recorded as "normal," frequency and severity of symptoms such as bloating, cramping, and excessive flatulence, and overall health status as assessed by a previously validated five-category questionnaire. There were no significant differences between sorbitol and lactulose in any outcome measured except nausea, which was increased with lactulose (p less than 0.05). CONCLUSION: These results support the hypothesis that sorbitol and lactulose have no clinically significant differences in laxative effect. Sorbitol can be recommended as a cost-effective alternative to lactulose for the treatment of constipation in the elderly.