Influence of hog manure application on surface runoff water quality

Non-Peer ReviewedThis paper describes some preliminary results from a field-scale study of the effect of field application of hog manure by injection on surface runoff water quality. In the study, manure injection at rates of 7,000 and 10,000 gal ac-1 are compared to an inorganically fertilized control at sites near the Bear Hills Pork Producers barn at Perdue and the new Prairie Swine Centre at Elstow. Surface runoff water quality is assessed during snowmelt and by rainfall simulation. Analysis of the preliminary data from Perdue indicates that concentrations of total and ortho P and NH3 in snowmelt runoff from the basin receiving 10,000 gal ac-1 of hog manure increased relative to background measurements and the control basin. Concentrations of NH3 also appeared to increase in snowmelt runoff from the basin receiving 7,000 gal ac-1 of hog manure. Although the rainfall simulation data were less conclusive, nutrient concentrations in runoff from the plots receiving hog manure appeared to increase relative to the control. There was no indication that hog manure application led to increased coliform counts in runoff water

Water balance of a prairie cattle feedlot pen

Non-Peer ReviewedThe overall purpose of this study is to define the water balance of feedlot pens in a Saskatchewan cattle feeding operation. Although the initial intention of the study was focused upon an active feedlot circumstances resulted in our year of analysis being on an recently abandoned feedlot. During the study year (Sept 2003 to Aug 2004) there was very little precipitation until May 2004. Weirs in operation for only part of the summer recorded no runoff. Winter precipitation was very low (34 mm) and there was no observed runoff from it. Runoff models, using lab and field parameters found that at the most there might have been runoff from only one event, that of 26 mm 24 hr rainfall, and this would have only occurred on a pen scraped of manure. Drainage beneath 60 cm soil depth was zero mm. Of the 339 mm of precipitation that fell during the study year, some of it was stored within the manure pack and the rest lost as evaporation

A Model for the Soil Freezing Characteristic Curve That Represents the Dominant Role of Salt Exclusion

The phenomenon of freezing point depression in frozen soils results in the co-existence of ice and liquid water in soil pores at temperatures below 273.15 K (0°C), and is thought to have two causes: (a) capillary and adsorption effects, where the phase transition relationship is modified due to soil-air-water-ice interactions, and (b) solute effects, where the presence of salts lowers the freezing temperature. The soil freezing characteristic curve (SFC) characterizes the relationship between liquid water content and temperature in frozen soils. Most hydrological models represent the SFC using only capillary and adsorption effects with a relationship known as the Generalized Clapeyron Equation (GCE). In this study, we develop and test a salt exclusion model for characterizing the SFC, comparing this with the GCE-based model and a combined salt-GCE effect model. We test these models against measured SFCs in laboratory and field experiments with diverse soil textures and salinities. We consistently found that the GCE-based models under-predicted freezing-point depression. We were able to match the observations with the salt exclusion model and the combined model, suggesting that salinity is a dominant control on the SFC in real soils that always contain solutes. In modeling applications where the salinity is unknown, the soil bulk solute concentration can be treated as a single fitting parameter. Improved characterization of the SFC may result in improvements in coupled mass-heat transport models for simulating hydrological processes in cold regions, particularly the hydraulic properties of frozen soils and the hydraulic head in frozen soils that drives cryosuction