Soil compaction and erosion are problems in many Pacific Northwestern
potato fields. We wanted to determine if zone-subsoiling would reduce
these problems and improve potato yields and or grade without adversel
y impacting other production practices. Studies were conducted in Sout
hern Idaho at six locations over two years on different soils and with
different irrigation methods to assess the effects of zone-subsoiling
immediately after planting on tuber yield and grade. Reservoir-tillag
e comparisons were made at three locations where sprinkler water appli
cation rates were higher than soil infiltration rates. Russet Burbank
was represented by eight location-years and Russet Norkotah by two. Zo
ne-subsoiling consistently improved tuber grade or increased tuber siz
e. The biggest improvement was under furrow irrigation. Zone-subsoilin
g also tended to increase total yield in eight of ten location-years.
Reservoir-tillage improved yield and grade, but zone-subsoiling did no
t without reservoir-tillage when water application rates were high. At
no location did zone-subsoiling significantly decrease tuber grade or
yield. Zone-subsoiling had no appreciable effects on hill configurati
on or seed-piece dislocation. Surface cracking and ''water piping'' oc
curred under furrow irrigation but were not significant problems. Resu
lts were similar for both cultivars. Additional studies will be needed
to successfully incorporate zone-subsoiling into commercial productio
n practices.