Zone-subsoiling relationships to bulk density and cone index on a furrow-irrigated soil

Zone subsoiling on irrigated land has been successfully used to improve pot ato (Solanum tuberosum. L.) yield and quality. Zone subsoiling under furrow irrigation may disrupt water flow and influence infiltration and soil eros ion. We hypothesized that zone subsoiling, done appropriately, will maintai n integrity of irrigation furrows, improve small grain and dry bean (Phaseo lus vulgaris L.) growth and yield, and not adversely affect water flow, inf iltration, or erosion on furrow-irrigated soils. The experiment was conduct ed at the USDA-ARS Northwest Irrigation and Soils Research Laboratory in Ki mberly, Idaho. The soil is a Portneuf silt loam (coarse-silty, mixed, super active, mesic Durinodic Xeric Haplocalcids). Tillage treatments were disk, disk + paratill, paratill, and no-till. There were no differences in water infiltration, runoff, or soil erosion among treatments. Bulk density differ ences among treatments were largest at the 0.15 to 0.20-m depth, and bulk d ensity was about 16% to 18% greater on disk and no-till treatments than on paratill treatments. The highest frequency of low cone index (CI) values be longed to paratill treatments (65% to 80% frequency of CI values less than 2 MPa); the lowest frequency of low CI values belonged to no-till treatment (20% frequency less than 2 Wa). Cone index versus bulk density relationshi ps depended on soil water content with a slope of 5.81 (r(2) = 0.70) in the wetter year of 1997, and 2.90 in the drier year of 1995 (r(2) = 0.60). Sub soiling can be accomplished on furrow-irrigated lands with no adverse effec ts on runoff, infiltration, and erosion, but under our conditions did not i mprove crop growth and yield.