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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.