Nutrient Hot-spot variability plots
Location: Providence, top of P303 and mid-elevation P301.
Contact info: Dale Johnson ( dwj@cabnr.unr.edu
) and Matt Meadows
(mmeadows@ucmerced.edu)
We have established small plots in two locations: one near the tower (Site 1) and one near lysimeter site P 303 (Site 2) within the Providence watersheds.
Sampling has been similar at both sites. We installed a total of twelve water run-off and snow melt collectors at the two sites, ~six at each site (Figure 2 and 3). At each site we established a
6x6 meter grid and installed resin lysimeters of the design described by Susfalk and Johnson
(2002), PRS nutrient probes and resin capsules. These resin lysimeters will be removed and soil core samples were taken within the plot after one-year, to determine what the annual nutrient yield at each point.
Resin lysimeters consist of a 5.5 cm long, 4 cm inside diameter PVC pipe within which
10 g of Rexyn® I-300 (H-OH) resin was sandwiched between sheets of Nitex® nylon sheets which were in turn sandwiched between 20 g layer of moist, washed silica sand at the bottom of the tube and covered with another 20 g layer of silica sand at the top. The resin lysimeters were installed by excavating a small hole and tunneling beneath the O horizons (Figure 1). PRS probes and nutrient capsules are inserted below the litter layer.
Within the same 6x6 meter grids we installed 16 WECSA soil access systems each at depths of 20, 40, and 60 cm at each node near the existing resin lysimeters. The WECSA system consists of a 5 cm diameter outer pvc tube which is installed at an angle in the soil to the desired depth. An inner pvc tube is then fitted with a resin capsule at the far end and inserted into the outer tube in order to monitor soil nutrient status at a point of known depth (Figure 4, note that pictures are not from the research site but of a similar setup). The system is described at this website: http://www.wecsa.com/
Reference
Susfalk, R.B., and D.W. Johnson. 2002. Ion exchange resin based soil solution lysimeters and snowmelt collectors. Comm. Soil Sci. Plant Anal.
33: 1261-1275.