2013 Annual Report
1a.Objectives (from AD-416):
The title of the ARS in-house project (#5402-11000-010-00D), addressed by this research is "Management Practices to Mitigate Global Climate Change, Enhance Bioenergy Production, Increase Soil C stocks & Sustain Soil Productivity." This Dung Beetle project will investigate the potential beneficial role of dung-beetles to improve (1) nutrient-cycling and (2) soil carbon sequestration and to (3) decrease greenhouse gas emissions in semi-arid rangeland ecosystems. Determine the influence of grazing practices and stocking density on (1) the distribution of livestock manure pats,.
2)rate of nutrient cycling of livestock manure by dung beetles, and.
3)the longevity of livestock manure pats.
1b.Approach (from AD-416):
Grazing practices and stocking density will be compared at the USDA-ARS Central Plains Experimental Range (CPER). Traditional Grazing Management (TGM) practice consists of season-long (mid-May to early October) grazing in pastures at moderate stocking rates. With TGM, grazing animals (cattle) are in the same pasture all season at low stocking densities (20 yearling-steers per 320 acre pasture). A novel Adaptive Grazing Management (AGM) practice will be initiated in 2013 where grazing will still occur from mid-May to early October at moderate stocking rates, but grazing animals (cattle) will rotate among 10 different pastures. This will enable shorter grazing periods (weeks) rather than season-long, and much higher stocking densities (200 yearling steers per 320 acre pastures, or ten-fold increase over the TGM practice). Livestock manure distribution will be quantified following grazing periods in each pasture using belt transects extending from pasture corners to centers of pastures to determine if the AGM practice results in more even distribution of manure (associated with the higher stocking densities). Fifty individual manure pats will be permanently marked and GPS coordinates obtained on each of 10 pairs of pastures comparing TGM and AGM grazing practices to determine if the grazing practices influence the longevity of manure pats. Soil samples will be taken at selected manure pat locations three times over each of 2 years to determine rates of nutrient cycling, and greenhouse gas emissions will be determined on additional selected manure locations.
ARS and Colorado State University have incorporated database, programming, and computer systems and improved methodologies into GHG inventory and mitigation analyses. These improved methodologies resulted in more reliable emission estimates and are described in the 2013 EPA Inventory of U.S. Greenhouse Gas Emissions and Sinks and in the 4th edition of the U.S. Agriculture and Forestry Greenhouse Gas Inventory to be published by USDA in 2014. The DayCent and CENTURY models were used to help develop Technical Guidelines for Quantifying Greenhouse Gas Sources and Sinks in the Forest and Agriculture Sectors mandated in the 2008 Farm Bill and will be published in 2013. The DayCent model was used to project the impacts of converting pasture to energy can production in Florida. The model has also been used to assess the impacts of winter season biofuel crops on plant production, greenhouse gas emissions, and nitrate leaching in selected counties in the US and regionally for the Chesapeake Bay watershed. Major model improvements have recently been implemented including a methane production submodel and a more sophisticated forest model.
ADODR monitoring was conducted via phone calls, e-mails, and on-site meetings.