Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub
    Author(s): Youzhi Han; Jianwei Zhang; Kim G. Mattson; Weidong ZhangThomas A. Weber
    Date: 2016
    Source: Soil Science Society of America Journal. 80(3): 756-764
    Publication Series: Scientific Journal (JRNL)
    Station: Pacific Southwest Research Station
    PDF: Download Publication  (0 B)


    Characterizing forest soil properties with high variability is challenging, sometimes requiring large numbers of soil samples. Soil bulk density is a standard variable needed along with element concentrations to calculate nutrient pools. This study aimed to determine the optimal sample size, the number of observation (n), for predicting the soil bulk density with a precision of ±10% at a 95% confidence level among different soil types. We determined soil bulk density samples at three depths at 186 points distributed over three different 1-ha forest sites. We calculated n needed for estimating means of bulk density using a traditional method. This estimate was compared to a bootstrapping method n where the variance was estimated by re-sampling our original sample over 500 times. The results showed that patterns of soil bulk density varied by sites. Bootstrapping indicated 3 to 17 samples were needed to estimate mean soil bulk density at ±10% at a 95% confidence level at the three sites and three depths. Sample sizes determined by the bootstrap method were larger than the numbers estimated by the traditional method. Bootstrapping is considered theoretically to be more robust, especially at a site with more variability or for site measures that are not normally distributed.

    Publication Notes

    • You may send email to to request a hard copy of this publication.
    • (Please specify exactly which publication you are requesting and your mailing address.)
    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.


    Han, Youzhi; Zhang, Jianwei; Mattson, Kim G.; Zhang, Weidong; Weber, Thomas A. 2016. Sample sizes to control error estimates in determining soil bulk density in California forest soils. Soil Science Society of America Journal. 80(3): 756-764.


    Google Scholar


    Soil bulk density, Sample size, Bootstrapping, confidence interval, spatial variability

    Related Search

    XML: View XML
Show More
Show Fewer
Jump to Top of Page