Improving Land Use Efficiency and Grower Revenue by Reducing Potato Row Width

The standard row width for potato production in the Columbia Basin of Washington and Oregon is 86 cm (34 in.), but the reasons for this are unclear. The goal of this research was to identify a row width that maximizes potato grower revenue by optimizing land use efficiency. A 2012 pilot study conducted in central WA with four potato varieties (Alturas, Ranger Russet (R.), R. Burbank, and Umatilla R.) and four row width treatments (76, 81, 86, and 91 cm (30, 32, 34, and 36 in.)) indicated that row widths <86 cm had several advantages over those ≥86 cm. The protocol and methods were refined and a larger study conducted between 2013 and 2015. Russet Norkotah, Chieftain, and Teton R. were planted with the four varieties mentioned above into 71, 76, 81, and 86 cm (28, 30, 32, and 34 in.) row-width treatments; in-row seed piece spacing was 25.4 cm (10 in.). When data were averaged across years and varieties, a quadratic regression provided the best fit for total yield and adjusted gross return; the values for each peaked at 79 cm and 80 cm, respectively. Row widths of 76 and 81 cm produced 6 and 7 t ha−1 higher yields, respectively, than the 86 cm industry standard. The 81 cm treatment produced 7.3% higher adjusted gross than the industry standard. Compared to the industry standard, plants from the 71 cm rows performed poorly; this 15 cm (6 in.) reduction in row width caused a 9.3% loss of adjusted gross income. Tuber weight and number per plant and were maximized when rows were ≥81 cm wide. These data suggest that the industry standard row width of 86 cm is an inefficient use of land and that an inter-row spacing of 80–81 cm (31.5–32.0 in.) could improve economic return to Columbia Basin growers by as much as $937 ha−1.