Trials were located near Pahala and Volcano, Hawaii on land managed by Kamehameha Schools. The Pahala site
was used for cultivation of sugar cane through the early 1990s,
while the Volcano site was used as pasture through 2002; both
sites were in fallow grass cover for a least a decade prior to planting
koa. The locations were selected to minimize differences in
slope, with both sites at less than 5% slope overall. The Pahala
and Volcano sites receive similar amounts of annual rainfall. For
the first year of the study during which Pahala was measured,
Pahala received 728 mm according to NOAA weather station,
Pahala Mauka