Plot Numbers Required to Determine Infiltration Rates and Sediment Production on Rangelands in South Central New Mexico

Abstract

Many studies have been made, and continue to be conducted, to determine infiltration rates and sediment production on rangelands. Most of these studies use small sample plots (<2 m2). This study determined the number of sample plots required to achieve confidence intervals of +/- 10, +/- 20 and +/- 30% of the sample mean at 80, 90, and 95% probability levels. For 80 and 90% probability levels, 20% of the mean could be achieved with 1 to 5 plots for infiltration rates, and as low as 1 or as many as 263 plots for sediment production. For dry soil moisture conditions, infiltration rates could be estimated with 4 or 5 plots, with 10 to 12 plots needed for field capacity conditions to achieve 10% of the mean with 95% confidence. Achieving 10% of the mean with 95% confidence was not considered practical for sediment production.