Characterization of spatial variability of soil physicochemical properties and its impact on Rhodes grass productivity

Characterization of soil properties is a key step in understanding the source of spatial
variability in the productivity across agricultural fields. A study on a 16 ha field located in the
eastern region of Saudi Arabia was undertaken to investigate the spatial variability of selected soil
properties, such as soil compaction ‘SC’, electrical conductivity ‘EC’, pH (acidity or alkalinity of
soil) and soil texture and its impact on the productivity of Rhodes grass (Chloris gayana L.). The
productivity of Rhodes grass was investigated using the Cumulative Normalized Difference
Vegetation Index (CNDVI), which was determined from Landsat-8 (OLI) images. The statistical
analysis showed high spatial variability across the experimental field based on SC, clay and silt;
indicated by values of the coefficient of variation (CV) of 22.08%, 21.89% and 21.02%, respectively.
However, low to very low variability was observed for soil EC, sand and pH; with CV values
of 13.94%, 7.20% and 0.53%, respectively. Results of the CNDVI of two successive harvests
showed a relatively similar trend of Rhodes grass productivity across the experimental area
(r =0.74, p= 0.0001). Soil physicochemical layers of a considerable spatial variability (SC, clay,
silt and EC) were utilized to delineate the experimental field into three management zones
(MZ-1, MZ-2 and MZ-3); which covered 30.23%, 33.85% and 35.92% of the total area, respectively.
The results of CNDVI indicated that the MZ-1 was the most productive zone, as its major