Recipient Organization
NEW MEXICO STATE UNIVERSITY
1620 STANDLEY DR ACADEMIC RESH A RM 110
LAS CRUCES,NM 88003-1239
Performing Department
Plant and Environmental Sciences
Non Technical Summary
Climate change is an important issue at local, state, national, and international levels. Results from this study will increase our understanding about climate change and potential ways to confront it. First, by investing the "soil memory" of climate changes in the past we will provide insight about natural cycles of climate change and thus provide baseline data against which to compare the rate of current climate change. Similarly, investing how calcium carbonate in desert soils responds to climate change will increase our understanding of how an expandingdesert around the worldmight set into place feedbacks that ameliorate atmospheric carbon dioxide levels that are increasing as the result of burning fossil fuel. Third, microbial biomineralization of calcium carbonate will provide a new technology for carbon sequestration. Currently, much work is being conducted on carbon sequestration using organic carbon (e.g., biochar and restoring soil organic matter using no-till). In desert soils, however, calcium carbonate-C is generally 10-times greater than organic carbon. In addition, biomineralization by microorganisms has implications for finding evidence of early life on Earth and extraterrestrial life because mineral fossils of microbes have a much greater likelihood of surviving the geologic record than soft-body organisms themselves.
Animal Health Component
(N/A)
Research Effort Categories
Basic
50%
Applied
(N/A)
Developmental
50%
Goals / Objectives
Thegoal of this Hatch project is to develop a greater understanding of how expanding deserts will impact carbon sequestration, especially CaCO3-carbon. To guide this investigation three questions will be addressed. (1) Do desert soils in New Mexico have a "memory" of the expansion and contraction of the Chihuahuan Desert based on carbon amounts and isotopes? (2) How will CaCO3-carbon currently stored in desert soils respond to current climate change? (3) Can desert soils be amended to stimulate carbon sequestration via microbial biomineralizaton of CaCO3-carbon?
Project Methods
(1) To test the first hypothesis that soils have a "memory" of the expansion and contraction of the Chihuahuan Desert a carbon isotope study will be conducted at the Jornada Experimental Range in collaboration with the Asombro Institute and the Chihuahuan Desert Nature Park. The boundary of the Chihuahuan Desert crosses the Nature Park with greater amounts of creosotebush downslope on the middle and distal bajada and greater amounts of grass upslope on the proximal bajada and mountain slopes. A transect that collects soil samples from the grass area to the creosotebush area will be conducted. From previous studies in this region, we know that organic matter and coeval pedogenic carbonate in the grass are isotopically distinct and differ by 10‰ from the organic matter and pedogenic carbonate in the creosotebush (Monger et al., 2009). This transect will provide information about far downslope the grass migrated in the past and how far upslope the creosotebush migrated. The Nature Park also has vertical stratigraphy important for chronologic control. Arroyos in this area have exposed buried soils with charcoal determined to be 5700 years old (Beta Analytic, Boca Raton FL, Beta-230192). In addition, stage IV petrocalcic horizons contain laminae that can be dissected and radiocarbon dated (Monger et al., 1998). Both the buried soils and laminae radiocarbon dates will allow us to use carbon isotopes to make inferences about the grass-shrub boundary in the late Quaternary. Our plan is to include elementary school students throughout the study to gather, sieve, and label samples. The goal is to help students to understand climate change, including the uncertainties involved with measuring it.This study will be combined with current isotope studies in the Cañada Alamosa at the northern boundary of the Chihuahuan Desert (Monger et al., 2014) and former studies in the Sacramento Mountains at the northeast boundary (Cruz, 2008), Pyramid Mountains at the northwest boundary (Kipp and Monger 1999), Sierra Madre Mountains in Mexico at the western boundary, and the Mapimi Biosphere Reserve in Mexico at the southern boundary (Martinez and Monger, 2002). This Hatch project will also involve the completion of a map of the boundary, landforms, and pluvial lakes of the Chihuahuan Desert, which is being constructed in collaboration with Dr. Alfredo Granados of the Universidad de Juarez and Dr. Juan Martinez of the Universidad de Durango.(2) To test the second hypothesis that carbonate-carbon in desert soils will increase in response to global warming a study will be conducted that involves re-sampling the Desert Project sites. Based on land survey notes, the Desert Project area and Jornada Experimental Range were covered with grasslands and much fewer shrubs in the mid-1800s (Buffington and Herbel, 1965; Gile 1966). Since that time, shrub encroachment has replaced the grassland and continues to do so. This shrub advancement can be thought of as an expanding Chihuahuan Desert which has passed over this region. Thus, a re-sampling of the Desert Project sites, which were first sampled in 1959, will give us an idea about carbon change during the last 55 years as the landscape has progressively become occupied by greater numbers of shrubs. All the Desert Project sites have been recorded with GPS and many of them have been marked with brass-cap survey markers (Gile et al., 2007). When they were sampled, much detail was given to describing and analyzing the horizons, included not only organic carbon and calcium carbonate, but also particle size, bulk density, color, pH, cation exchange capacity, extractable cations and anions, electrical conductivity, and clay mineralogy (Gile and Grossman, 1979).(3) To test the third hypothesis that desert soils can be amended to stimulate carbon sequestration via microbial biomineralizaton of calcium carbonate two studies have been started and will continue into the time frame of this Hatch project. The first is funded by the National Park Service and involves burying ceramic tiles in soil and harvesting them at monthly time intervals. These porous, non-glazed tiles are analyzed to determine if carbonate forms on such a short time frame and, if so, in what seasons does it form. At the same time, tiles treated with potassium hydroxide and calcium chloride are also buried and harvested monthly. The potassium hydroxide is added in a well drilled into the tile to provide hydroxyls to combine with carbon dioxide to form bicarbonate. The calcium chloride is added in a neighboring well to provide calcium to combine with the bicarbonate to form calcium carbonate. This provides information about how much carbonate-C can be formed using inorganic amendments.The second experiment adds liquid growth medium directly to soil samples in porous plastic containers. After the soil samples are inoculated with the growth medium, the plastic containers are wrapped in nylon mesh with pores large enough for fungal hyphae to penetrate, and replaced in the auger holes from which the soil samples were obtained. These studies are being conducted in native shrublands and grasslands, and in irrigated turf plots. Both organic and inorganic carbon is measured, as well as 13C/12C ratios, and the samples are examined with scanning electron microscopy to document the biomineralization by microbes.