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

ABSTRACT. Zone subsoiling on irrigated land has been successfully used to improve potato (Solanum tuberosum L) yield and quality. Zone subsoiling under furrow irrigation may disrupt water flow and influence infiltration and soil erosion. We hypothesized that zone subsoiling, done appropriately, will maintain integrity of irrigation furrows, improve small grain and dry bean (Phaseolus vulgaris L.) growth and yield, and not adversely affect water flow, infiltration, or erosion on furrow—irrigated soils. The experiment was conducted at the USDA—ARS Northwest Irrigation and Soils Research Laboratory in Kimberly, Idaho. The soil is a Portneuf silt loam (coarse—silty, mixed, superactive, 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 differences among treatments were largest at the 0.15 to 0.20—m depth, and bulk density 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 belonged 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 MPa). Cone index versus bulk density relationships 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 (r2 = 0.60). Subsoiling can be accomplished on furrow—irrigated lands with no adverse effects on runoff, infiltration, and erosion, but under our conditions did not improve crop growth and yield