TITLE:
Monitoring of Soil Bulk Density in Context with Its Small-Scale Spatial Heterogeneity
AUTHORS:
Miloš Širáň, Jarmila Makovníková
KEYWORDS:
Soil Monitoring, Soil Bulk Density, Spatial, Site and Time Variability, Significant Time Change
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.9 No.5,
May
31,
2021
ABSTRACT: The
main aim of soil monitoring system is to obtain the knowledge of the most
current state and development of soil properties according to concrete threats
to soil. To determine the significant changes of soil properties in time, it is
important to know spatial variability of concrete soil parameter for concrete
site. Only those time changes of the soil parameter are significant, which
exceed its spatial variability at the site. The main aim of the study has been focused
on the evaluation of small-scale site heterogeneity of equilibrium soil bulk
density and the integration of impact of this heterogeneity in evaluation of
degradation process of soil compaction in time. As site variation coefficients
have considerably varied at standard sampling with five repetitions during monitoring
period, one-time detail spatial variability mapping of soil bulk density was
realized at 17 repetitions on five selected monitoring sites with different
soil type, texture and use. This increase in the number of sampling points
helped us to specify and stabilize the values of variation coefficients
(between minimum and maximum by standard sampling) as well as the extent of
confidence intervals. Standard deviations at the chosen monitoring sites moved
from 0.039 to 0.118 g·cm-3 in topsoil and from 0.031 to 0.067 g·cm-3 in subsoil and expressed as variation coefficient 2.9% - 9.2% and 2.0% - 4.9%,
respectively. The intervals of significant time changes of soil bulk density
for the sites and depths were determined on the base of its site confidence
interval (95%) and uncertainty rate of its measure methodology. The time
changes of bulk density values between single year-to-year sampling were
overlapped by this interval of significant changes to obtain significant bulk
density changes in time. This method allowed us to distinguish significant time
changes in soil bulk density from insignificant ones. The bulk density value
changes on the monitoring sites were significant in the range of six to nine
years within observed period 2002-2014 in both depths.