TITLE:
Effect of Crop Root on Soil Water Retentivity and Movement
AUTHORS:
Kozue Yuge, Keiki Shigematsu, Mitsumasa Anan, Shinogi Yoshiyuki
KEYWORDS:
Water Consumption; Soil Water; Heat Transfer; Numerical Model; Irrigation Water Saving
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.3 No.12A,
December
31,
2012
ABSTRACT: The objective
of this study was to clarify the effect of crop root on soil water retentivity
and movement to improve the crop growth environment and irrigation efficiency.
To simulate soil water movement considering the crop root effect on the
physical properties of soil, a numerical model describing the soil water and
heat transfers was introduced. Cultivation experiments were
conducted to clarify the effect of the crop root on soil water retentivity and verify
the accuracy of the numerical model. The relationship between soil water
retentivity and the root content of soil samples was clarified by soil water
retention curves. The soil water content displayed a high value with increasing
crop root content in the high volumetric water content zone. The experimental
results indicated that the saturated water content increased with the crop root
content because of the porosity formed by the crop root. The differences of the
soil water retentivity became smaller when the value of the matric
potential was over pF 1.5. To verify the accuracy of the numerical
model, an observation using acrylic slit pot was also conduced. The temporal
and spatial changes of the volumetric water content and soil temperature were
measured. Soil
water and heat transfers, which considered the effect of the crop root on the
soil water retentivity clarified by the soil water retention curves, were
simulated. Simulated volumetric water content and temperature of soil agreed
with observed data. This indicated that the numerical model used to simulate
the soil water and heat transfer considering the crop root effect on soil water
retentivity was satisfactory. Using this model, spatial and temporal changes
of soil water content were simulated. The soil
water condition of the root zone was relatively high compared with the
initial conditions. This indicated that the volumetric water condition of the root
zone increased with the soil water extraction and high soil water conditions was
maintained because the soil water retentivity of root zone increased with the
root effect.