ESTCP Project #1011, Rhizosphere
Final Report
plants with nutrients, with controls for each. This resulted in four treatments: 1) a control, 2)
added nutrients, 3) plants without nutrients, and 4) plants plus nutrients.
At each site, a factorial experiment with the above four treatments were arranged as Randomized
Complete Block (RCB) with four replications. This allowed the data to be statistically analyzed
for effects due to plants, nutrients, their interactions, or block effects that may have been caused
by spatial trends at the sites.
3.5.7 Sampling Plan
Soil Sampling Methods. To obtain meaningful soil samples we used three sampling
methods:
1. Grab samples as typically used for Alaska Department of Environmental Conservation
(ADEC) regulatory purposes. These samples will only be taken at the beginning and end
of the treatment demonstration.
2. Composite samples. Six to eight grab samples are taken on each plot and thoroughly
mixed together.
3. Soil-sock samples. This procedure is a derivative of that used in litter decomposition
studies. Approximately 200 samples were randomly taken prior to seeding or fertilization
and mixed by rotary mixer. These large mixed samples, generally 10 to 20 ft3 of soil,
were then apportioned into fine mesh, cylindrical, open-topped bags (soil socks) that
were buried vertically in the plots from which we had taken the samples. Sufficient bags
were buried so that a soil sock could be removed from each plot at each sampling time
and sacrificed for analysis.
Where the field conditions suggested that there were areas that were different, based on initial
chemical measurements, visual clues, or landscape position, we attempted to use statistical
blocking, so that each "distinct" area included one replication of each of the four treatments. At
each site, the samples taken for the soil socks were obtained from and returned to the same
block.
19
Previous Page
