Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 16, 1996
Publication Date: N/A
Interpretive Summary: Potatoes (Solanum tuberosum L.) are particularly sensitive to soil compaction problems. Compaction reduces root growth and can physically constrain developing tubers affecting both yields and external quality. Deep tillage by zone-subsoiling after planting can reduce compaction problems and improve yield and quality if no other production limits are present. The acceptance of this practice is partially dependent upon knowing the correct nutritional management strategy for its use. We found that the nitrogen fertilizer should be banded for greatest utilization by the growing plants under furrow irrigation. Normal fertilization rates should be increased approximately 10% to achieve the increased yield potential from zone-subsoiling. If soil compaction is present in the rooting zone and not reduced, higher fertilization rates will also need to be used to increase nutrient availabilities.
Technical Abstract: Deep tillage can improve potato (Solanum tuberosum L.) tuber yield and quality on compacted soils if no other production factors are limiting. We hypothesized that zone-subsoiling and N placement would affect tuber yields and plant nutrient concentrations and uptakes. Potatoes (cv. Russet Burbank) were grown after winter wheat (Triticum aestivum L.) in 1989 and after dry beans (Phaseolus vulgaris L.) in 1990 on a furrow irrigated Portneuf silt loam soil (coarse-silty, mixed, mesic Durixerollic Calciorthid). Fall tillage treatments (disking, chiseling, and moldboard plowing) were split with zone-subsoiling after planting. Nitrogen was broadcast before planting or banded adjacent to the seed piece at planting across all tillage combinations. We estimated plant nutrient status and uptake each year during tuber growth with two whole plant and three petiole samplings. Final tuber yield and quality were determined in early October on machine harvested samples. Fall tillage treatments did not influenced the nutritional relationships or tuber yield and quality. Zone-subsoiling increased average plant dry weights 9%, and total tuber yields 10% (4 Mg/ha) and quality. Banding N increased average plant dry weight 6.4%, total tuber yield 9%, and N uptake 28% compared with broadcast N. Nitrogen uptake was not affected by any tillage treatment, but zone-subsoiling increased P uptake 11.6% (1.8 kg P/ha) without appreciably changing P concentrations. Petiole nitrate, P, K and Zn concentrations were higher where N was banded. Growers should band fertilizer N under furrow irrigation for greatest plant utilization and reduce soil compaction in the rooting zone of potatoes.