Twenty 6 x 6 m plots were established with a 3 m buffer between plots.
Five plots were randomly assigned to one of four treatments: (1)
chlordane amendment 100ml AI (active ingredients) per 10,000 ml) to
exclude microarthropods, (2) sprinkler irrigation (6 mm per week), (3)
sprinkler irrigation (6 mm/week) plus chlordate amendment (as above),
(4) control (no treatment). Three randomly located subsamples were
taken from each plot.
Net minerizable N was estimated using a batch incubation procedure
Soil subsamples (25g) were incubated at 35 C in 50-ml plastic vials
covered with 0.0125 mm polyethylene film and sealed with rubber bands
to reduce soil moisture loss. Moisture content was adjusted to 10%
water content by weight at weekly intervals. Sub-samples were analyzed
for ammonium and nitrate content following 0, 2, 4 and 8 weeks of
incubation. Inorganic N was extracted by placing 10 g of soil into
polyethylene bottles containing 100 ml of 2.0 Molar KCL + PMA. Samples
were shaken 30 times, and let sit for 24 hours, and then filtered. NH4
was measured by an automated slicylate procedure, and NO3 + NO2 by an
automated cadmium reduction procedure
Net N mineralization was calculated as the net change in N occuring
from the beginning to the end of each incubation period.
