Water balance of centre pivot irrigated pasture in northern Victoria, Australia

Qassim, Abdi; Dunin, F. X.; Bethune, Matthew

doi:10.1016/j.agwat.2007.12.009

Cited by 13 publications

(5 citation statements)

References 22 publications

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“…In the same region with this study, the K c of alfalfa in the 2nd and 3rd year under subsurface drip irrigation were 1.03 and 0.84 [46], while 1.13 and 1.31 under sprinkler irrigation in the same period, respectively [7]. In arid Northern Australia, the K c of alfalfa were 1.04 and 0.97 during two consecutive years [47]. These studies were similar to the results of our study.…”

Section: Daily Crop Coefficients and Et Componentssupporting

confidence: 88%

The Dynamic Yield Response Factor of Alfalfa Improves the Accuracy of Dual Crop Coefficient Approach under Water and Salt Stress

Kang

Ding

et al. 2020

Water

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The accurate quantification of crop water use or evapotranspiration (ET) under water and salt stress is needed for efficient water management and precision irrigation in water scarce regions. However, few studies were examined on alfalfa water use and its components under water and salt stress. We carried out two field experiments to quantify alfalfa water use through setting up different water and salt gradients, including two irrigation levels (full and deficit irrigation) and four soil salinity levels (0, 2‰, 4‰ and 6‰ salt of mass ratio) in an arid region of Northwest China. Electrical conductivity of soil saturation extract (ECe), soil water content (SWC), leaf area index (LAI) and soil evaporation (E) were measured. The SIMDualKc model, which uses the FAO56 dual Kc approach, was calibrated and validated using measured SWC and E. Model results show a good agreement between observed and simulated SWC and E without stress. The depletion fraction for no stress (p) and the percent yield reduction per unit increase in soil salinity (b) were 0.50 and 6.0%/(dS m−1), respectively, slightly lower than those of FAO-56 (0.55 and 7.3%/(dS m−1)). The difference indicates that alfalfa has a lower capacity of water use but a greater tolerance to salt stress after soil salinity reached its sensitivity threshold in the arid region. The model performed a reduced accuracy under water and salt stress and the differences tended to increase as stress increased, which was partly attributed to constant yield response factor (Ky) under different soil water and salt stress. The key parameter Ky dynamically increased with the increased degree of stress. Compared to constant Ky, the simulations of SWC and E showed improved accuracy with dynamic Ky. These results suggested that the response and acclimation of alfalfa to stress might be incorporated into the dual Kc model through the diversity of Ky.

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Section: Daily Crop Coefficients and Et Componentssupporting

confidence: 88%

The Dynamic Yield Response Factor of Alfalfa Improves the Accuracy of Dual Crop Coefficient Approach under Water and Salt Stress

Kang

Ding

et al. 2020

Water

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“…It could be observed that several papers reporting on the use of the grass reference ET o did not follow the concepts described above. A few authors directly compared ET obtained with eddy covariance, BREB, or a soil water balance with ET o but not searching for a K c value [20], or even assumed equality between grass ET and ET o [21]. Other authors just computed daily K c act values (often using different designations for that parameter) but did not search for a K c curve that would describe their seasonal variation [22,23], or just identified a mean seasonal K c act [24].…”

Section: Introductionmentioning

confidence: 99%

Evapotranspiration Partition and Crop Coefficients of Tifton 85 Bermudagrass as Affected by the Frequency of Cuttings. Application of the FAO56 Dual Kc Model

Paredes

Rodrigues

Petry

et al. 2018

Water

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Abstract:This study aims to model the impacts of the frequency of cuttings of Tifton 85 bermudagrass on the dynamics of evapotranspiration (ET c ) and to derive crop coefficients appropriate for grass water management. Two seasons of experimentation were used with four different cutting treatments which provided field data for calibration and validation of the soil water balance model SIMDualKc for all treatments. Cuttings were performed after the cumulative growth degree days (CGDD) attained 124 • C, 248 • C and 372 • C, thus from short to very long intervals between cuttings. SIMDualKc adopts the Food and Agriculture Organization (FAO) dual K c approach for partitioning ET into crop transpiration and soil evaporation, thus providing for an assessment of their dynamics. All treatments were irrigated to avoid water stress. Grass ET c was modelled adopting a K cb curve to describe the ET variation for each cutting cycle, that is, using the FAO K c curve that consists of a series of K cb curves relative to each cutting cycle. Each individual K cb curve consisted of three segments constructed when knowing the K cb values at the initial, at the end of rapid growth, and at cutting, respectively K cb ini , K cb gro and K cb cut . These K cb values were first estimated using the equation relating K cb to the density coefficient (K d ), which is computed from the fraction of ground cover (f c ) and canopy height (h) at the same dates. The goodness of fit indicators relative to the calibration and validation of the SIMDualKc model were rather good, with the normalized root mean square error (RMSE) ranging from 4.0% to 6.7% of the mean available soil water. As an example, the standard K cb values obtained after model calibration relative to the cuttings treatment with CGDD of 248 • C are: K cb ini = 0.86, K cb gro = 0.91 and K cb cut = 0.96. K cb values were smaller when the frequency of cuts was larger because h and f c were smaller, and were larger for reduced cuttings frequency since h and f c were then larger. Because the soil was wet most of the time, the soil evaporation K e varied little but its value was small due to the combined effects of the fraction of crop cover and plant litter covering the soil. The values of K c = K cb +K e also varied little due to the influence of K e and the K c curve obtained a form different from the K cb curves, and a single K c value was adopted for each cutting frequency, e.g., K c = 0.99 for the treatment with CGDD of 248 • C. Results of the soil water balance have shown that, during the experimental periods, likely due to the effects of the El Niño Southern Oscillation (ENSO), runoff and deep percolation exceeded ET c . Moreover, the soil evaporation ratio was small: 14% in case of frequent cuttings and less for more spaced cuttings, thus with a transpiration ratio close to 90%, which indicates a very high beneficial consumptive water use, mainly when cuttings are not very frequent.

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“…They also concluded that leaching rates estimated from water balance approach were unrealistic, since it resulted in negative leaching rates (upward flow) throughout the monitoring period. Qassim et al (2008) used the WB to estimate the weekly leaching below the 40 cm soil depth of irrigated pasture. Greenwood et al (2009) applied a slight revised version of WB equation to estimate the leaching in different forage species, where they assumed leaching occurs when the soil water content exceeded a certain threshold value.…”

Section: Introductionmentioning

confidence: 99%

Uncertainties in leaching assessment in micro-irrigated fields using water balance approach

Kisekka

Kandelous

Sandén³

et al. 2019

Agricultural Water Management

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Leaching is an important aspect of irrigation water management, as it must be minimal to save available irrigation water resources, prevent shallow groundwater tables, and reduce nutrient loadings to the groundwater. However, at the same time, leaching should be sufficient to maintain root zone salinity levels below the threshold to prevent yield reduction. Therefore, monitoring leaching is the key component in evaluation and optimization of irrigation water management practices. Water balance (WB) is a common approach used to estimate leaching in agricultural fields and was applied in this study to assess field-scale leaching and the associated uncertainties for an almond orchard under drip and micro-sprinkler irrigation systems. In this study, we showed that change is soil water storage (ΔS) is highly influenced by the extent of monitoring depth, the location and number of monitoring points. Local measurement of WB parameters showed that leaching is highly variable across the field, thereby introducing considerable uncertainty on estimated leaching using WB approach. It was also shown that unknown input of water through fog interception added to the complexity of closing water balance at field scale.

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Water balance of centre pivot irrigated pasture in northern Victoria, Australia

Cited by 13 publications

References 22 publications

The Dynamic Yield Response Factor of Alfalfa Improves the Accuracy of Dual Crop Coefficient Approach under Water and Salt Stress

The Dynamic Yield Response Factor of Alfalfa Improves the Accuracy of Dual Crop Coefficient Approach under Water and Salt Stress

Evapotranspiration Partition and Crop Coefficients of Tifton 85 Bermudagrass as Affected by the Frequency of Cuttings. Application of the FAO56 Dual Kc Model

Uncertainties in leaching assessment in micro-irrigated fields using water balance approach

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