The goal of this project is to determine the nature and magnitude of changes in the hydrologic properties of arid soils with increasing amounts of pedogenic calcium carbonate. The amount and morphology of the calcium carbonate in arid soils varies laterally and vertically with changes in the age of the soils, thus the hydrologic properties also vary systematically The calcium carbonate cements soil particles changing the apparent texture of the soil horizon and thus other soil properties such as structure, porosity, moisture retention, and unsaturated and saturated hydraulic conductivity also change significantly. There has been no systematic study of the impact of increasing amounts of calcium carbonate on the hydrologic properties of semi-arid soils. The ultimate goal of this study is to provide a basis for developing more accurate pedotransfer functions, which are the main methods for obtaining soil hydrologic properties of rangeland soils.
Selection of Surfaces: Three terraces of different ages were chosen at the outlet of a small watershed basin at the base of Sierra Ladrones in North West Sevilleta National Wildlife Refuge. These surfaces have shown varying stages of calcic horizons.
Digging Pits: 3 Pits up to a meter deep were dug on each surface.
Describing the Soils: the soil profile in each pit was described using USDA soil survey guidelines.
Soil Sampling: From every pit, soil samples were collected every 10 cm. Also soil peds were collected from every horizon for bulk density analysis.
Infiltration Experiment: In order to check the soil hydraulic conductivity, a tension disk infiltrometer was used on every soil horizon in each pit.
Laboratory Analysis: The soil samples were split and sieved for laboratory analysis
CaCO3 Content: The total inorganic carbonate content was calculated using Chittick’s apparatus
Bulk Density: The bulk density of the soil peds was calculated using the Clod’s apparatus.
PSDA: Particle size distribution analysis was carried out with the presence of carbonate on the 2mm sample.
Carbonate Digestion: The carbonate was digested to remove the amount of carbonate from the sample. PSDA was performed again on the soil samples without the carbonate.
Information on Collection Sites:
Study Area 1:
Study Area Name: Surface 1(Pit 1)(Young Surface)
Study Area Location: Outlet of the small watershed basin at the base of Sierra Ladrones
Study Area Description:
Elevation: 1623 m
Geology: Quaternary Sierra Ladrones Formation
Soils: Laborcita-Pilabo-Lemitar complex
Climate: Semi arid, Rainfall ~ 250 mm
North Coordinate: 34° 24.5’
West Coordinate: 106° 58.1'
Study Area 2:
Study Area Name: Surface 2 (Pit 2)(Intermediate Surface)
Elevation: 1615 m
Geology: Quaternary Sierra Ladrones Formation
Climate: Semi-arid, Rainfall ~250 mm
North Coordinate: 34° 24.491'
West Coordinate: 106° 58.046'
Study Area 3:
Study Area Name: Surface 3 (Pit 3) (Oldest Surface)
Elevation: 1633 m
Climate: Semi-arid, Rainfall~250 mm
North Coordinate: 34° 24.405'
West Coordinate: 106° 58.020'
Other Field Crew Members: Ritchie Andre and Ramirez Carlos
The primary objective of this study is to examine the control that substrate quality and climate have on patterns of long-term decomposition and nitrogen accumulation in above- and below-ground fine litter. Of particular interest will be to examine the degree these two factors control the formation of stable organic matter and nitrogen after extensive decay.
Sevilleta data from a study testing the degree to which substrate quality and macroclimate control the carbon and nitrogen dynamics of decomposing leaf, wood, and fine-root litter in a 10-year, 28 site (17 LTER) team experiment.
A sun photometer was installed at the Sevilleta Field Station in 1994.It is part of a network of such instruments deployed around the world within a program called AERONET (AErosol RObotic NETwork http://aeronet.gsfc.nasa.gov/new_web/system_descriptions.html) established by NASA to obtain a measure of atmospheric aerosols around the globe. Individual photometer units are designed to view the sun and sky at preprogrammed intervals throughout the day for the measurement of aerosol optical thickness, water vapor amounts, ozone levels, particle size distribution, aerosol scattering, phase function, and single scattering albedo. These measurements can also be used to radiometrically correct satellite imagery. The unit consists of A) the photometer, B) a robot for directing the photometer at the sun, C) a CIMEL datalogger which directs the data collection and storage, D) a DCP (Data Collection Platform) which controls hourly data transmission to the GOES satellite and E) an antenna for facilitating this DCP to satellite link. Solar measurements are made at 1021, 871, 669, 498, 437, 379, and 339 nm. The Sevilleta LTER is responsible for maintenance of the unit on site while NASA takes care of data processing and and storage and annual re-calibration of the unit. Data can be obtained from NASA via:http://aeronet.gsfc.nasa.gov/cgi-bin/type_piece_of_map_opera_v2_new.