L. Zhang et al., Growth and ground water uptake responses of lucerne to changes in groundwater levels and salinity: lysimeter, isotope and modelling studies, AGR WATER M, 39(2-3), 1999, pp. 265-282
Shallow saline water tables underline large areas of the Riverine Plains of
the Murray Basin of southern Australia. It is believed that deep-rooted pe
rennial plants in these areas are able to reduce recharge and use shallow g
roundwater, thus controlling groundwater levels. Lysimeters represent the b
est experimental technique for investigating capillary upflow from shallow
water tables and the associated processes of salt accumulation, plant water
use, and growth response. Techniques involving stable isotopes of water he
lp determine the components of upflow due to vegetation. When combined with
models that stimulate salt and water movement in the soil zone and the pla
nt water use and growth, we can thoroughly test our understanding of salini
ty processes and the ability of plants to control water tables. Results fro
m WAVES simulations of plant growth, evapotranspiration, groundwater uptake
, salt accumulation, and the impacts on lucerne growth are compared against
measurements made in lysimeters at Griffith, NSW, Australia. With minimal
calibration, WAVES was able to reproduce both the daily and seasonal variat
ion in evapotranspiration, upward flux from the groundwater table, plant gr
owth in terms of leaf area development, soil water profiles, soil water sal
inity, and root water extraction patterns. There was a decline of 36% in tr
anspiration, 42% in leaf area growth, and 67% in upward flux after the sali
nity of the water table increased from 0.1 to 16 dS m(-1). Although the upw
ard flux of water was large, lucerne used little of it (< 20%), preferring
'fresher' rainfall and irrigation water near the surface. Given the tests p
resented in this work, we think WAVES is applicable to irrigated agricultur
al systems. (C) 1999 Elsevier Science B.V. All rights reserved.