Zone tillage effects on soil properties and yield and quality of potatoes ( Solanum tuberosum L.)

Soil compaction and erosion are key factors limiting potato yield and quality. This study evaluated the effects of zone tillage, a system of in-the-row subsoiling, with cover crops and no tillage in the interrow, on soil properties and on yield and quality of Russet Burbank potatoes in west central Michigan on a McBride sandy loam (coarse-loamy, mixed, frigid Alfic Fragiorthod) from 1985 to 1988. Zone tillage, subsoiling in the row with a Bush Hog Ro-till or Tye Paratill, decreased bulk density and soil strength, and increased the volume of large pores in the zone of compaction. In a preliminary study in 1985, zone tillage in the spring generally increased marketable yields (4.2–5.2 Mg ha −1), but not total yields, compared with conventional plowing. In a subsequent 3 year study from 1986 to 1988, zone tillage generally increased total yields (2.9–8.7 Mg ha −1) but only at seed spacings of 25 and 28 cm, not at 36 cm. Marketable yields were increased by zone tillage in 1986 (4.6–6.0 Mg ha −1). In 1987, the Tye Paratill reduced marketable yields at the 36 cm seed spacing (4.8–8.1 Mg ha −1), but showed an increase ( P < 0.10) at the 25 cm seed spacing. In 1988, a year of drought and high temperature stresses, potato yields were lower than in other years, and zone tillage increased total yield, but had no effect on marketable yields. Zone tillage had little effect on specific gravity. A small increase in the incidence of hollow heart was apparent under zone tillage, but was reduced by closer seed spacing. Overall, zone tillage improved soil physical conditions in the zone of compaction (20–30 cm) and generally increased total and marketable yields of Russet Burbank potatoes in most years.