Studies in southeastern Idaho evaluated the potential of tillage under
the potato row (zoned tillage) to influence tuber yield and grade. Su
ch tillage is estimated to provide significant improvement in control
of water erosion. The 'Russet Burbank' variety was grown on silt loam
soil under sprinkler irrigation. Major variables included 1) depth of
tillage; 2) timing of tillage; 3) amount of irrigation; 4) amount and
timing of nitrogen applications; and 5) depletion of soil moisture. Zo
ned tillage with the Tye Paratill was also compared to that of a conve
ntional chisel. Zoned tillage did not generally affect total yield, bu
t sometimes reduced the amount of malformed tubers. Zoned tillage tend
ed to perform better as plant stress conditions became more severe. La
te application of zoned tillage can reduce yield due to plant root dis
turbance. Lower soil bulk density persisted longer after zoned tillage
than after conventional chiseling. The most suitable depth of zoned t
illage appears to be 38 to 46 cm. Field traction conditions for zoned
tillage are not favorable for large drawbar pull which will limit mach
ine width.