Kanika singh, Alex McBratney, Brian Murphy and Brett Whelan
Soil carbon variability within individual fields
Abstract
This work reports on a dynamic sampling and monitoring strategy to measure soil carbon at
the field scale. The current method in NSW for estimating soil carbon is given in McKenzie et
al. (2000). The current method does not allow incorporation of ancillary spatial data which
are now becoming available for fields. This soil carbon sampling design presented here aims
to take into account the spatial variability of soil carbon at the field scale. A systematic grid
sampling strategy was carried out to obtain the carbon data for the whole field and to study
the factors accounting for the carbon variability. A part of this bigger study is to devise a
more efficient and accurate sampling scheme using ancillary information such as crop yield,
soil and landscape information (soil ECa, terrain parameters, radio gamma data). Intensive
sampling and compilation of ancillary data on one field will facilitate a trail for future
sampling methods on different fields. There is a decrease in soil carbon content with depth
and it becomes less spatially variable with depth. Thus a 25 m x 25 m square can give the
estimate of carbon in just that square but is not pertinent to monitor soil carbon of the whole
paddock.