Soil Water Limits Database

Accurate evaluation of the soil water reserves available for plant use is vital in developing optimum water management for crop production in marginally dry regions. Laboratory estimates of the upper and lower limits of soil water availability used to calculate the soil water reservoir often deviate significantly from the limits measured in the field. To make a unified and broad assessment of the accuracy of laboratory measurements for estimating field soil water, investigators obtained and evaluated a comprehensive database of field-measured upper and lower limits of the soil water reservoir available to plants. The methods used to define the in-situ upper and lower soil water limits were similar to those described by Franzmeier et al. (1973) and Ritchie (1981) (i.e., gravimetric sampling and neutron attenuation). At each in-situ study location, additional soil samples were collected at depth increments that coincided with the depth of water measurement and/or soil horizon. Samples are analyzed for percent sand, silt and clay following standard procedures (SCS, 1972).

The field-measured upper limit (DUL) was taken as the water content at which drainage from a prewetted soil had practically ceased. The lower limit (LL) was taken as the water content of the soil at which plants were practically dead or dormant. The potential extractable soil water (PESW) is the difference in water content between the upper and lower limits of the soil water reservoir.

The soil water limits database contains 401 soil samples collected from 15 states in the United States. The data set provided here is a subset of this database; it excludes 13 observations whose upper limit is higher than 90% of total porosity. The remaining 388 observations provide the following data variables: soil texture (% clay and % sand), bulk density (where available, in mg m-3), and DUL, LL, and PESW (in percent by volume).

References:

Franzmeier, D. P., D. Wiersma, S. H. Brownfield, J. M. Robbins, Jr., J. L. Shively, and R. C. Wingard. 1973. Water regimes of some Indiana soils. Indiana Agric. Exp. Stn. Res. Bull. No. 904.

Jagtap, S. S., U. Lall, J. W. Jones, A. J. Gijsmann, and J. T. Ritchie. 2004. Dynamic nearest-neighbor method for estimating soil water parameters. Trans. Am. Soc. Agri. Eng. 47: 1437-1444.

Ratliff, L. F., J. T. Ritchie, and D. K. Cassel. 1983. Field-measured limits of soil water as related to laboratory-measured properties. Soil Sci. Soc. Am. J. 47: 770-775.

Ritchie, J. T. 1981. Soil water availability. Plant and Soil. 58: 327-338.

Ritchie, J. T., A. Gerakis, A. Suleiman. 1999. Simple model to estimate field-measured soil water limits. Trans. Am. Soc. Agri. Eng. 42: 1609-1614.

Soil Conservation Service. 1972. Soil survey laboratory methods and procedures for collecting soil samples. Soil Survey Investigations Report no. 1. U. S. Government Printing Office, Washington, DC.