The nonlimiting water range (NLWR) is defined as the range of soil water content in which water, oxygen, and mechanical resistance do not limit plant growth. Our research objectives were to (1) refine the methodology of measuring NLWR and (2) determine the utility of NLWR as a soil quality index for soils treated with conventional 4-year rotation, conventional 2-year rotation, low-input, and organic farming systems at the Sustainable Agricultural Farming System (SAFS) in Davis, CA. Undisturbed soil core samples were collected from the plots of 4 farming system treatments that had the same crop cover at the time of sampling. Eight cores (5-cm dia x 5-cm height) from a depth of 2-7 cm were taken from each of the 16 plots (4 treatments x 4 replications), resulting in a total of 96 samples. The core samples were used for measuring bulk density, saturated hydraulic conductivity, water retention, mechanical resistance (MR), and oxygen diffusion rate (ODR). Bulk soil samples were collected from the same plots to determine particle-size distribution and pH values. Results showed that the MR and ODR values were not significantly different among the treatments. None of the 4 treatments had a mean MR greater than the critical value of 2 MPa at the wilting point, or ODR values below the limiting value of 2 mg cm^-2 min^-1 at the field capacity. Water contents at field capacity and wilting point determine the NLWR for soils from each treatment. Soil from the organic farming system had the highest volumetric water content at saturation, but water content at 0.01 MPa (field capacity) and 1.5 MPa (wilting point), and the resultant NLWR were not significantly different among the four treatments.