soil moisture

Stoichiometry Experiment - CO2

Abstract: 

Soil communities in the McMurdo Dry Valleys are subject to many limitations, including resource limitations. However, the nutrients that are predominantly limiting to growth and diversity of soil biota are not known. Additionally, landscape history (N deposition, P weathering) and native N and P content (glacial till provenance) may influence the ability of soil communities to respond to nutrient additions or changes in nutrient availability associated with environmental change. Long-term experiments in the Bonney and Fryxell basins have been established with yearly application of aqueous nutrient additions: C, N, P, CN, and CP. Multiple nutrients additions were made at the Redfield Ratio of 106:16:1 (C:N:P). Responses of soil chemistry, CO2 flux, and biota are reported.

Core Areas: 

Dataset ID: 

4014

Associated Personnel: 

326
327
328

Short name: 

SE_CO2

Methods: 

Three sites were chosen on generally flat areas of moderately patterned soil. Plots were laid out in an identical design at each site. There are 7 treatments replicated 8 times in blocks. Treatments were randomly assigned to the plots within each block. Each plot measures 1 m x 1 m (with a 0.83 m diameter area within used for experimental treatments and analyses). Plots are delineated by nails inserted in the soil, and the margins of each site are marked by PVC stakes approximately 60 cm high.

Water and aqueous nutrient treatments were applied annually at a rate of 5.6 L per plot, with 15 g C m-2 as mannitol, 2.5 g N m-2 as NH4NO3, and/or 0.75 g P m-2 as Na3PO4 (see Treatment Codes under Additional Information). Each plot was fitted with a 10-cm diameter PVC collar that created a seal with the soil. Soil CO2 flux from each PVC collar was measured using a LI-COR 8100 (Lincoln, NE), fitted with a soil respiration survey chamber. At each measurement, soil temperature in the surrounding soil was measured using soil temperature probe Type E. Soil moisture of the surrounding soil was measured using a Theta probe Model ML2. Measurements of CO2 flux, temperature, and moisture were taken within 2 weeks prior to annual treatment application, then again approx. 2 weeks after annual treatment application.

Data sources: 

SOILS_SE_CO2

Maintenance: 

Jan, 2010 - Sue Welch created this metadata and accompanying Oracle data table from metadata info and an Excel spreadsheet from Becky Ball .

Additional information: 

In the attribute table, the treatment is the manipulation for a given plot from which the soil was collected. The treatments are: (C) carbon additions as mannitol, (N) nitrogen additions as NH4NO3, (P) phosphorus additions as Na3PO4, (CN) carbon and nitrogen additions, (CP) carbon and phosphorus additions, (W) water-only additions, and (U) un-amended plots.

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