Brady, N.C., and R.R. Weil. 2008. The Nature and Properties of Soils, 14th ed. Upper Saddle River, NJ: Prentice Hall.
Hill, R.L. 1990. Long-term conventional and no-tillage effects on selected soil physical properties. Soil Science Society of America Journal 54: 161–166.
Karunatilake, U., and H.M. van Es. 2002. Temporal and spatial changes in soil structure from tillage and rainfall after alfalfa corn conversion in a clay loam soil. Soil and Tillage Research 67: 135–146.
Kay, B.D. 1990. Rates of change of soil structure under cropping systems. Advances in Soil Science 12: 1–52.
Shepard, G., C. Ross, L. Basher, and S. Suggar. Visual Soil Assessment, vol. 2: Soil Management Guidelines for Cropping and Pastoral Grazing on Flat to Rolling Country. Palmerston North, New Zealand: Horizons.mw and Landcare Research.
Whitman, H., ed. 2007. Healthy Soils for Sustainable Vegetable Farms: Ute Guide. Clayton North, Victoria: Land and Water Australia, AUSVEG, Ltd.