Runoff and dissolved organic carbon loss from a paired-watershed study of three adjacent agricultural Watersheds

Organic matter plays several important roles in the biogeochemistry of terrestrial and aquatic ecosystems including the mobilization and transport of nutrients and pollutants. Cropping, tillage practices and vegetative buffer strip installation affect losses of dissolved organic carbon (DOC). While many studies show reductions in pollutant export from agroecosystems where vegetative buffers have been implemented, buffer strips may be a source of DOC and contribute to surface water pollution. Using a paired-watershed approach, the objectives of this study were to determine the effect of grass and agroforestry buffers on runoff and DOC loss, compare runoff and DOC losses between the growing and fallow seasons, and investigate crop effects on runoff and DOC losses. The study design consisted of three small agricultural Watersheds in a no-till, maize-soybean rotation located in the claypan region of northeast Missouri, USA; one watershed was planted with grass buffer strips, one with agroforestry buffer strips, and one unaltered watershed served as the control. Runoff and DOC loss were measured during a six-year calibration period (1991–1997) prior to buffer installation and for a nine-year treatment period (1997–2006). The grass buffer strips significantly decreased runoff by 8.4% (p = 0.015) during the treatment period while the agroforestry buffer system exhibited no significant change in runoff (p = 0.207). Loss of DOC was not significantly affected by grass or agroforestry buffer installation (p = 0.535 and p = 0.246, respectively). Additionally, no significant difference in runoff or DOC loss was found between crops (maize and soybean) or between seasons (growing and fallow). Overall, this study indicates that grass buffer systems are effective at reducing runoff and that DOC contamination of surface waters is not exacerbated by either type of vegetative buffer strip.     

Development and Evaluation of a Multiplexed Real-Time TaqMan RT-PCR Assay with a Sample Process Control for Detection of F-specific RNA Coliphage Genogroups I and IV

There are increasing concerns of zoonotic transmission of some animal enteric viruses, such as calicivirus, hepatitis E virus, and rotavirus, which are closely related to human pathogenic strains. Most enteric viruses are detected by molecular techniques because they cannot be cultured. Surrogates such as F-RNA coliphages are cultivable but few molecular methods exist. Individual real-time TaqMan RT-PCR assays for the replicase gene of F-RNA coliphage genogroups I and IV were developed and multiplexed with a real-time TaqMan RT-PCR assay for feline calicivirus as a sample process control for the simultaneous detection and enumeration of genogroup I and IV F-RNA coliphages. Genogroup IV were successfully detected with the multiplexed assay in 80% of fecal samples that contained F-RNA coliphage levels ≥3.2 log plaque forming units (pfu). F-RNA coliphage were at or below the limit of detection in most fecal samples when levels were ≤4 log pfu/g.     

Forest Management for Greenhouse Gas Benefits: Resolving Monitoring Issues Across Project and National Boundaries

Demand for new environmental services from forests requires improved monitoring of these services at three scales: project-, regional-, and national-level. Most forest management activities are organized at the project scale, while the Framework Convention on Climate Change (FCCC) recognizes the nation as the party to the agreement. Hence, measurement and monitoring issues are emerging at the intersections of the project and national scales, referred to here as monitoring-domain edge effects. The following actions are necessary to improve existing monitoring capabilities and to help resolve project/national edge effects: (1) consensus on standard methods and protocols for monitoring mitigation activities, their off-site greenhouse gas (GHG) impacts, the fate of forest products and their relation to national GHG inventories (baselines); (2) a global program for collecting land use, land cover, biomass burning, and other data essential for national baselines; (3) the development of new nested-monitoring-domain methods that allow projects to be identified in national GHG inventories (baselines), and permit tracking of leakage of GHGs and wood product flows outside project boundary and over time; and (4) presentation of a set of credible, carefully designed, and well-documented forest mitigation activities that resolve most of the current issues.     

NUTGRANJA 2.0: a simple mass balance model to explore the effects of different management strategies on nitrogen and greenhouse gases losses and soil phosphorus changes in dairy farms

Farm nutrient management has been identified as one of the most important factors determining the economic and environmental performance of dairy cattle (Bos taurus) farming systems. Given the environmental problems associated with dairy farms, such as emissions of greenhouse gases (GHG), and the complex interaction between farm management, environment and genetics, there is a need to develop robust tools which enable scientists and policy makers to study all these interactions. This paper describes the development of a simple model called NUTGRANJA 2.0 to evaluate GHG emissions and nitrogen (N) and phosphorus (P) losses from dairy farms. NUTGRANJA 2.0 is an empirical mass-balance model developed in order to simulate the main transfers and flows of N and P through the different stages of the dairy farm management. A model sensitivity test was carried out to explore some of the sensitivities of the model in relation to the simulation of GHG and N emissions. This test indicated that both management (e.g. milk yield per cow, annual fertiliser N rate) and site-specific factors (e.g. % clover (Trifolium) in the sward, soil type, and % land slope) had a large effect on most of the model state variables studied (e.g. GHG and N losses).     

Impact of bioenergy crops in a carbon dioxide constrained world: an application of the MiniCAM energy-agriculture and land use model

In the coming century, modern bioenergy crops have the potential to play a crucial role in the global energy mix, especially under policies to reduce carbon dioxide emissions as proposed by many in the international community. Previous studies have not fully addressed many of the dynamic interactions and effects of a policy-induced expansion of bioenergy crop production, particularly on crop yields and human food demand. This study combines an updated agriculture and land use (AgLU) model with a well-developed energy-economic model to provide an analysis of the effects of bioenergy crops on energy, agricultural and land use systems. The results indicate that carbon dioxide mitigation policies can stimulate a large production of bioenergy crops, dependent on the level of the policy. This production of bioenergy crops can lead to several impacts on the agriculture and land use system: decreases in forestland and unmanaged land, decreases in the average yield of food crops, increases in the prices of food crops, and decreases in the level of human demand of calories.