These methods, instrumentation and/or protocols apply to all data in this dataset:Methods and protocols used in the collection of this data package |
---|
Description: |
Study site characteristics
Study sites were chosen via a stratified random approach – stratified by geomorphology and located randomly within areas of known gypsum (n = 10) or non-gypsum (n=10) soils. Non-gypsum soils were primarily limestone (n = 7 out of 10 sites), with others containing mixed alluvium or residuum derived from dolomite, sandstone, siltstone, shale, quartzite, and traces of other igneous, metamorphic, and sedimentary rocks. Sites were grouped into 10 pairs so every gypsum site was paired with a non-gypsum partner site in the same region. 5 site pairs occurred in the northern Chihuahuan Desert, New Mexico, and 5 site pairs occurred in the eastern Mojave Desert, Nevada. Paired site characteristics (topography, climate, elevation, slope, aspect, and presence of biocrusts), except soil type, were held relatively constant. Coordinates (decimal degree), bearing, elevation, slope, and aspect were measured at the origin of the central transect for each site. Sites were located at least 50 m from roads, trails, or human-use areas (except for JER-G (~17 m away), as establishing full-length transects at this site, further from the road was not possible due to a change in environment. Site info and characteristics data can be accessed at knb-lter-jrn.210616001.
| Instrument(s): | Soil type: SoilWeb & reconnaissance visits to study sites before field sampling; elevation & coordinate data: GPS (GARMIN, Oregon® 600 GPS Unit, Datum WGS 84); slope data: clinometer & Google Earth Pro 7.3.6.9345 | Data Source | | Data Source | |
| | | Description: |
Field sampling design
To account for variations in soil outcrop size and topography of the sampling area of interest (AOI), study sites followed one of the following designs:
(1) When the AOI was > 50 m long/wide, three parallel transects (50 m long, 25 m apart) were established.
(2) When the AOI was > 50 m long, < 50 m wide, one transect (50 m long) was established.
(3) When the AOI was < 50 m long/wide, one transect (25 m long) was established.
| Instrument(s): | 50m-long measuring tapes |
| Description: |
Soil sample collection
AOI Condition 1 and 2: samples (n = 10 samples, 1 composite per site) were collected every 5 m along the central transect (50 m long) of each study site. AOI Condition 3: samples (n = 5 samples, 1 composite per site) were collected every 5 m along the central transect (25 m long) of each study site. Samples were collected from the soil surface to 3 cm depth, using a 6 cm diameter metal soil corer. Total soil mass was determined in the field using Pesola ® Medio-Line Spring Scales. Soils were sieved (< 2 mm) and the mass of the < 2 mm fraction of the soil was determined. Gravel (soil fraction that did not pass through < 2 mm sieve) was discarded in the field at each study site. Soil gravel mass was calculated as the difference between soil total mass and < 2 mm fraction mass. Soil percent < 2 mm fraction and percent gravel were determined. Soils were air-dried prior to storage in Whirl-Pak® Sterile Sample Bags.
| Instrument(s): | Pesola® Medio-Line Spring Scales, Pesola® Präzisionswaagen AG, Switzerland; Whirl-Pak® Sterile Sample Bags, Nasco Sampling LLC, Chicago, IL, USA |
| Description: |
Methods for assessing soil aggregate stability
AOI Condition 1 and 2: soil stability tests (n = 10 aggregate soil stability assessment procedure; Herrick et al., 2001; Kemper and Rosenau, 1986) were performed every 5 m along the central transect (50 m long) of each study site. AOI Condition 3: soil stability tests (n = 5 aggregate soil stability assessment procedure) were performed every 5 m along the central transect (25 m long) of each study site.
| Instrument(s): | soil stability test kit |
| Description: |
Methods for assessing soil compaction
AOI Condition 1 and 2: soil compaction (n = 10; pocket penetrometer) was measured every 5 m along the central transect (50 m long) of each study site. AOI Condition 3: soil compaction (n = 5; pocket penetrometer) was measured every 5 m along the central transect (25 m long) of each study site.
| Instrument(s): | pocket penetrometer, Forestry Suppliers, Inc., Jackson, Mississippi, USA |
| Description: |
Methods for assessing soil pH and electric conductivity (EC)
Soil pH and EC were measured from saturated paste extracts (U.S. Salinity Laboratory Staff, 1954) via HACH® sensionTM156.
| Instrument(s): | HACH® sensionTM156, HACH®, Loveland, Colorado, USA |
| Description: |
Methods for assessing soil soluble salts, sulfur, and phosphorus
Saturated paste extracts (U.S. Salinity Laboratory Staff, 1954) were analyzed via ICP-OES for concentrations (ppm) of soil soluble salts (Ca^2+, K^+, Mg^2+), S (representing mostly SO4^2-), and P, (representing mostly H2PO4^-, or HPO4^2-).
| Instrument(s): | ICP-OES, Plasma 400; PerkinElmer, Waltham, Massachusetts, USA |
| Description: |
Methods for assessing soil percent gypsum composition
Soil percent gypsum content was determined following Artieda et al. (2006).
|
| Description: |
References
Artieda, O., Herrero, J., Drohan, P.J., 2006. Refinement of the differential water loss method for gypsum determination in soils. Soil Science Society of America Journal 70(6), 1932–1935. https://doi.org/10.2136/sssaj2006.0043N.
Herrick, J.E., Whitford, W.G., de Soyza, A.G., Van Zee, J.W., Havstad, K.M., Seybold, C.A., Walton, M., 2001. Field soil aggregate stability kit for soil quality and rangeland health evaluations. Catena 44(1), 27–35. https://doi.org/10.1016/S0341-8162(00)00173-9.
Kemper, W.D., Rosenau, R.C., Aggregate stability and size distribution. In: Klute, A. (Ed.), Methods of Soil Analysis: Part 1 Physical and Mineralogical Methods, 5.1, Second Edition. American Society of Agronomy, Inc., Madison, WI, pp. 425–433. https://doi.org/10.2136/sssabookser5.1.2ed.c17.
U.S. Salinity Laboratory Staff, Allison, L.E., Bernstein, L., Bower, C.A., Brown, J.W., Fireman, M., Hatcher, J.T., Hayward, H.E., Pearson, G.A., Reeve, R.C., Richards, L.A., Wilcox, L.V., 1954. Diagnosis and Improvement of Saline and Alkali Soils. United States Department of Agriculture, Washington, D.C., pp. 1–159.
|
|
|
|