Influence of manure application on surface energy and snow cover: model development and sensitivities

Winter landspreading is an important part of manure management in the U.S. Upper Midwest. Although the practice is thought to lead to excessive P runoff losses, surprisingly little has been learned from field experiments or current water quality models. We captured knowledge gained from winter manure landspreading experiments by modifying a mechanistic snow ablation model to include manure. The physically based, modified model simulated the observed delay in snow cover disappearance and surface energy balance changes caused by application of the manure. Additional model simulations of surface energy balance estimates of radiation and turbulent fluxes showed that during intense melting events the manure on top of snow significantly reduced the energy available for melt of the snow underneath, slowing melt. The effect was most pronounced when snowmelt was driven by both relatively high solar radiation and turbulent heat fluxes. High absorbed shortwave radiation caused significant warming of the manure, which led to substantial losses in turbulent fluxes and longwave radiation. Simulations of snowmelt also showed that manure applications between 45 and 100 Mg ha(-1) significantly reduced peak snowmelt rates, in proportion to the manure applied. Lower snowmelt rates beneath manure may allow more infiltration of meltwater compared with bare snow. This infiltration and attenuated snowmelt runoff may partially mitigate the enhanced likelihood of P runoff from unincorporated winter-spread manure.     

Greenhouse gas emissions from conventional, agri-environmental scheme, and organic Irish suckler-beef units

The problems of overproduction within the European Union countries and the environmental impact of agriculture have lead to the introduction of schemes that aim to reduce both. Beef (Bos taurus) production forms a large component of the Irish agricultural industry and accounts for more than one quarter of agricultural economic output. Recently, the European CAP (Common Agricultural Policy) has been re-evaluated to include supplementary measures that encompass the environmental role of agriculture rather than just the production role. A life cycle assessment (LCA) method was adopted to estimate emissions per kilogram of CO2 equivalent per kilogram of live weight (LW) leaving the farm gate per annum (kg CO2 kg(-1) LW yr(-1)) and per hectare (kg CO2 ha(-1) yr(-1)). Fifteen units engaged in suckler-beef production (five conventional, five in an Irish agri-environmental scheme, and five organic units) were evaluated for emissions per unit product and area. The average emissions from the conventional units were 13.0 kg CO2 kg(-1) LW yr(-1), from the agri-environmental scheme units 12.2 kg CO2 kg(-1) LW yr(-1), and from the organic units 11.1 kg CO2 kg LW yr(-1). The average emissions per unit area from the conventional units was 5346 kg CO2 ha(-1) yr(-1), from the agri-environmental scheme units 4372 kg CO2 ha(-1) yr(-1), and from the organic units 2302 kg CO2 ha(-1) yr(-1). Results indicated that moving toward extensive production could reduce emissions per unit product and area but live weight production per hectare would be reduced.     

NITROGEN TRANSFORMATIONS IN SEDIMENTS AS AFFECTED BY CHEMICAL AMENDMENTS1

ABSTRACT: A study was conducted to elucidate some of the chemical factors affecting the rate and pathways of N transformations in lake sediments. The main emphasis was placed on modifying a noncalcareous sediment with CaCO₃ to approximate the composition of a calcareous sediment. Additionally, the effects of Ca²⁺, CO₃^2-, Mg2⁺ and OH^- were evaluated by using appropriate chemicals. Further, the effect of aluminum sulfate was evaluated with both sediment types. Sediment pH at 7 days was not affected by CaCO₃, but was decreased by aluminum sulfate. The CaCO₃ treatment increased the rate of ammonification, nitrification, reduction of acetylene to ethylene and methane formation, while with few exceptions the other treatments decreased the rate of the transformations studied. Aluminum sulfate, which has been proposed as a lake restoration treatment, increased ammonification but decreased most of the other transformations.     

Interpreting dynamics of aquatic resources: A perspective for resource managers

Since the presentation of the Leopold Report (Leopold et al. 1963) to the United States Secretary of the Interior, recommendations in the document for managing natural park resources on the ecosystem level have been included in the management policies of the National Park Service. In many instances, however, management programs have continued to focus on individual resource problems, without apparent concern for the ecological consequences on ecosystems. Without knowledge of the interrelationships of ecosystem components, solving one problem may result in other resource problems. Graphic approaches are presented as potential tools to view these complex interrelationships relative to the needs of the resource manager. Interpreting the dynamics of aquatic systems is emphasized.     

REGIONAL PLANNING FOR LAND DISPOSAL OF WASTEWATER1

ABSTRACT This paper describes the development and use of a mixed integer programming model for the planning of land disposal wastewater treatment facilities. Consideration is given to relevant construction and operating costs for land sites, transmission arteries, land acquisition costs, tangible benefits from land use, controls on aquifers, and various other engineering and technical constraints The model is used to determine which land disposal sites should serve which treatment plants, when initial construction should be initiated and completed, and when capacity expansion should occur. The model's application to the St. Louis Standard Metropolitan Statistical Area is illustrated and discussed.     

NITROGEN AND PHOSPHORUS IN SURFACE WATERS OF THE UPPER COLORADO RWER BASIN1

ABSTRACT: As part of a basinwide water-quality study, nitrogen and phosphorus data for the Upper Colorado River Basin from the Colorado-Utah State line to the Continental Divide were analyzed for spatial distributions, concentrations associated with various land uses, and temporal trends. Nitrogen and phosphorus concentrations generally increased in a downstream direction. Some nutrient concentrations were elevated at some sites in the upper parts of the basin in areas influenced by increasing urbanization. Sites were grouped according to land use and site type, and median nutrient concentrations were compared among groups. Sites within the agricultural areas of the basin generally had the highest concentrations of nitrogen and phosphorus; concentrations for main-stem, tributary, and urbanization sites were slightly lower than for the agricultural sites. Background sites, or sites with minimal land-use impacts, had very low median nutrient concentrations. Several sites with long-term data were analyzed for temporal trends in concentrations. Several statistically significant downward trends of low and moderate magnitude were observed for nitrogen and phosphorus species. No upward trends were observed in the data at any site.     

GEOMORPHIC PARAMETERS PREDICT HYDROGRAPH CHARACTERISTICS IN THE SOUTHWEST1

ABSTRACT: Critical design characteristics of ephermal runoff such as hydrograph rise time, duration, mean peak discharge, volume, peak-volume ratio, and maximum flood were related to physical basin parameters such as area, shape, slope, drainage density, basin relief, stream length, and combinations of these in intermontane watersheds representative of the Mexican Highland section of the Basin and Range Province. Parameters used were restricted to those easily obtainable from maps or aerial photographs. A parameter expressing basin shape and size was developed which proved to be as accurate a predictor as others used in existing prediction equations tested and was simpler and faster to derive. Simple prediction equations derived for hydrograph characteristics were all significant except for volume at the 5% level; three were significant at the 1% level. Relationships determined are applicable in semi-arid basins of the Southwest up to 60 square miles (155 km²) in area.