Influence of legume inclusion on greenhouse gas emissions from pasture systems in
the southern high plains of Texas
Student/presenter: Raavi Arora, Graduate Research Assistant (Ph.D.), Soil Microbial Ecology
Format: Oral presentation
Title: Influence of legume inclusion on greenhouse gas emissions from pasture systems in
the southern high plains of Texas
Raavi Arora1, Lindsey C. Slaughter1, Charles P. West1, Sanjit K. Deb1, and Veronica Acosta-Martinez2
1Texas Tech University Department of Plant and Soil Science, Lubbock, TX, USA
2USDA-ARS Cropping Systems Research Laboratory, Wind Erosion and Water Conservation
Unit, Lubbock, TX, USA
Abstract
Semi-arid ecosystems, such as the Southern High Plains (SHP) of Texas, hold enormous
potential for providing a variety of ecosystem services such as agricultural production,
nutrient and water cycling, and extreme weather mitigation. Although these systems
cover over thirty percent of the arable land area in North America, agricultural productivity
is severely limited by water scarcity and degraded soils. The Ogallala Aquifer, which
is the main source of irrigation in the SHP, is at a risk of extinction due to over-extraction
and pollution, forcing the growers to switch from row crops to less soil disturbing
and more water efficient perennial forages and livestock. Some studies have shown
that incorporation of legume plants to these perennial grasses can potentially reduce
methane emissions from the soil and nurture healthier livestock in addition to minimizing
the need for external inputs. The information regarding the influence of these soil
improving practices on soil greenhouse gas (GHG) emissions is currently lacking. Our
objective is to quantify and comprehend the role of legume (alfalfa, Medicago sativa L.) presence and density on soil GHG flux in established long-term pastures (WW-B.Dahl
Old World bluestem) as compared to N-fertilized monoculture pastures. Soil GHG samples
(CO2, CH4, N2O) were collected using static chamber method on a monthly basis (fall to spring),
and on a bi-weekly basis (late spring to early fall) to see the greenhouse gas flux
throughout the year. Microbial community structure, nitrate and ammonia in the soil
will also be analysed. The results of our study will help producers make management
decisions to increase profitability and reduce climate impacts with more efficient
use of resources, as well as allow us to prepare a model that builds healthy and productive
soils in regions facing water and nutrient scarcity.
