Tillage and Cultural Management of Irrigated Potatoes¹

Abstract

Many intensively row‐cropped, irrigated soils are compacted and have slow water infiltration rates. This study was conducted to evaluate the relationship among soil compaction, water infiltration rates, and potato (Solanum tuberosum L.) yield and quality; and to determine the influence of tillage and other practices on soil compaction, water infiltration rates, and potato response. Twenty‐two commercial, irrigated potato fields were monitored and several tillage practices evaluated on soils from seven great groups. Soil compaction was evaluated by measuring penetrometer resistance. Although penetrometer resistance and water infiltration rates showed a large amount of variation in the 22 fields, they were not significantly correlated with each other. The correlation coefficient between penetrometer resistance 0.2 m below furrows and tuber yield was −0.38. Water infiltration rate was not associated with tuber yield nor quality. In the 18 fields with less than 600 g kg−1 sand, soil texture had little association with water infiltration rates, however, soil organic matter greater than 12 g kg−1 was positively associated with water infiltration rates. In the 22 fields, number of years between successive potato crops accounted for 33% of the variation in tuber yield with greatest yields when at least 4 years occurred between potato crops. In replicated tillage experiments, chiseling reduced penetrometer resistance to a deeper depth than moldboard plowing. Chiseling did not result in greater water infiltration rates, tuber yield, nor tuber quality than plowing. Chiseling and plowing in combination showed no advantage over either practice alone. Additionally, chiseling bed centers showed no yield advantage over an unchiseled check in fields that were previously plowed even though penetrometer resistance was reduced by chiseling. This study indicates that with proper irrigation management some deep tillage operations can be eliminated by many growers.

Soil compaction problems and subsoiling effects on potato crops: A review

“…Depending on the soil type, axle load, and cultivation practices, plow pans can be found at different depths ranging from 8 to 20 inches (Bishop & Grimes, 1978; Miller & Martin, 1987). Subsoiling can reduce bulk density at depths ≥12 inches (depth) but tends to have little to no influence on bulk density at shallower depths compared with conventional tillage implements (Buxton & Zalewski, 1983; Pierce & Burpee, 1995; Sojka, Westermann, Brown, & Meek, 1993). However, the effectiveness of subsoiling varies with the depth of the compaction layer.…”

“…Therefore, it is very likely that the water use efficiency will also increase and the irrigation water requirement will be reduced (Miller & Martin, 1990). These effects on irrigation requirements are expected in potato, since it is a water‐stress‐sensitive and shallow‐rooted crop (95% of the root system lies within the 10‐inch depth) that is commonly cultivated in compaction‐prone sandy soils with low water holding capacity (Buxton & Zalewski, 1983, Miller & Martin, 1990, Westerman & Sojka, 1996).…”

“…However, just as many studies have shown that both tuber yield and quality were either unaffected or slightly reduced by subsoiling, even in severely compacted soils (Buxton & Zalewski, 1983; Copas et al., 2009; Henriksen, Mølgaard, & Rasmussen, 2007; Holmstrom & Carter, 2000). Such results are often attributed to clod formation, reconsolidation, high moisture content during bedding, topographic variations, and compaction variation among wheel‐trafficked and non‐trafficked furrows.…”

“…The ideal soil conditions for a potato seedbed are low bulk density, low shear strength, good aeration, a crust-free soil for adequate herbicide activity, and adequate ambient temperature (>39 • F) for sprout growth, root respiration, and tuber growth (Stalham, Allen, & Herry, 2005). Potato also requires high water availability with minimum fluctuations between irrigation events to maximize yield and quality (Buxton & Zalewski, 1983). The high water requirement is partially due to the relatively shallow root system of potato (<24 inches) that limits the plant's capacity to extract water from deep within the soil profile (Porter, Bradbury, Sisson, Opena, & McBurnie, 1999).…”