poster - International Conference of Agricultural Engineering

water contents were almost greater than 12%. The surface soil water content reached about
34% (vol. %). The low water contents centered at the depth 10–50 cm and radial distance 0–
60 cm illustrated that the root water uptakes were intensive in this area. The agreement
between the simulations and measurements was excellent.
Radial distance from the trunk (cm)
0 20 40 60 80 100 120 140 160
0
Radial distance from the trunk (cm)
0 20 40 60 80 100 120 140 160
44 0
40
44
40
Soil depth (cm)
20
40
60
80
Soil water content (vol. %)
36
32
28
24
20
16
12
8
Soil depth (cm)
20
40
60
80
Soil water content (vol. %)
36
32
28
24
20
16
12
8
100
August 26 - Measured
4
100
August 26 - Simulated
4
Radial distance from the trunk (cm)
0 20 40 60 80 100 120 140 160
0
Radial distance from the trunk (cm)
0 20 40 60 80 100 120 140 160
44 0
40
44
40
Soil depth (cm)
20
40
60
80
Soil water content (vol. %)
36
32
28
24
20
16
12
8
Soil depth (cm)
20
40
60
80
Soil water content (vol. %)
36
32
28
24
20
16
12
8
100
September 2 - Measured
4
100
September 2 - Simulated
4
FIGURE 1: Two-dimensional maps of measured and simulated water content values.
Consequently, most of the tree root activity, as indicated by temporal and spatial changes in
soil water, was also concentrated in the surface soil layer. Water content profiles also
revealed that deeper/younger parts of the root systems did not extract water as efficiently as
shallower/older roots, suggesting a significant axial resistance could exist in deeper roots
(Pierret et al. 2006). All these observations converge and indicate that a precise description
of root water uptake requires the integration of data about soil and root hydraulic properties
as well as root spatial distribution. In order to study all these aspects of soil–root interplay on
water uptake, modeling can help, in conjunction with experimental work, to test these
hypotheses on water transfer in the soil–root system (Garrigues et al. 2006).
References
Clothier, B. E., & Green, S. R. (1994). Rootzone processes and the efficient use of irrigation
water. Agric Water Manag 25:1–12.
Clothier, B. E. (1989). Research imperatives for irrigation science. J Irrigation Drainage Eng
115(3):421–448.
Coelho, E. F., & Or, D. (1999) Root distribution and water uptake patterns of corn under
surface and subsurface drip irrigation. Plant Soil 206: 123–136.
Green, S., & Clothier, B. (1999). The root zone dynamics of water uptake by a mature apple
tree. Plant Soil 206: 61–77.
Kjelgren, R., Goldhamer, D. A., Uriu, K., & Weinbaum, S. A. (1985). Almond tree response to
variable nitrogen fertilization rates through low volume sprinklers. In: Proceedings of the
3rdInternational drip/trickle irrigation congress, Fresno, vol 2.