Research has suggested that biochar soil amendments have the ability to improve soil water retention, but results have not been consistent or predictable across soil types. The objective of this project was to evaluate the potential for biochar soil amendments to mitigate agricultural drought by characterizing their impacts on soil hydraulics and plant growth across a range of agricultural soil conditions. This data set contains soil moisture retention curves and unsaturated hydraulic conductivities for four Oregon agricultural soils amended with biochar. Gasified biochars made from wheat straw (AgEnergy, Spokane, WA) and conifer wood (BioLogical, Philomath, OR) were tilled into soils at experimental stations in Madras (loam), Pendleton (silt loam), Aurora (sandy loam), and Klamath Falls (loamy sand). The biochars were incorporated by tillage in the fall to a depth of 12 cm at rates equating to 0, 9, 18, and 36 Mg/ha, with three replicate plots per treatment. Soil cores were collected the following spring and used to construct moisture retention curves using a combination of pressure plates, a WP4 water potentiameter instrument, and a HYPROP instrument.