scholarly journals Estimating Soil Water Content and Evapotranspiration of Winter Wheat under Deficit Irrigation Based on SWAP Model

2020 ◽  
Vol 12 (22) ◽  
pp. 9451
Author(s):  
Xiaowen Wang ◽  
Huanjie Cai ◽  
Liang Li ◽  
Xiaoyun Wang

Deficit irrigation strategy is essential for sustainable agricultural development in arid regions. A two−year deficit irrigation field experiment was conducted to study the water dynamics of winter wheat under deficit irrigation in Guanzhong Plain in Northwest China. Three irrigation levels were implemented during four growth stages of winter wheat: 100%, 80% and 60% of actual evapotranspiration (ET) measured by the lysimeter with sufficient irrigation treatment (CK). The agro−hydrological model soil−water−atmosphere−plant (SWAP) was used to simulate the components of the farmland water budget. Sensitivity analysis for parameters of SWAP indicated that the saturated water content and water content shape factor n were more sensitive than the other parameters. The verification results showed that the SWAP model accurately simulated soil water content (average relative error (MRE) < 21.66%, root mean square error (RMSE) < 0.07 cm3 cm−3) and ET (R2 = 0.975, p < 0.01). Irrigation had an important impact on actual plant transpiration, but the actual soil evaporation had little change among different treatments. The average deep percolation was 14.54 mm and positively correlated with the total irrigation amount. The model established using path analysis and regression methods for estimating ET performed well (R2 = 0.727, p < 0.01). This study provided effective guidance for SWAP model parameter calibration and a convenient way to accurately estimate ET with fewer variables.

1993 ◽  
Vol 118 (5) ◽  
pp. 580-586 ◽  
Author(s):  
J. Girona ◽  
M. Mata ◽  
D.A. Goldhamer ◽  
R.S. Johnson ◽  
T.M. DeJong

Seasonal patterns of soil water content and diurnal leaf water potential (LWP), stomatal conductance(gs), and net CO2 assimilation (A) were determined in a high-density peach [Prunus persica(L) Batsch cv. Cal Red] subjected to regulated deficit irrigation scheduling. The regulated deficit irrigation treatment caused clear differences in soil water content and predawn LWP relative to control irrigation treatments. Treatment differences in midday LWP, gs, and A were also significant, but not as distinct as differences in predawn LWP. Leaves on trees subject of the deficit irrigation treatment were photosynthetically more water-use-efficient during the latter part of the stress period than were the nonstressed trees. Midday LWP and gs, on trees that received the regulated deficit irrigation treatment did not recover to control treatment values until more than 3 weeks after full irrigation was resumed at the beginning of state III of fruit growth, because of water infiltration problems in the dry soil caused by the deficit irrigation. The regulated deficit irrigation treatment caused only a 8% reduction in trunk growth relative to the control, but resulted in a 40% savings in irrigation requirements.


Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 425 ◽  
Author(s):  
Fairouz Slama ◽  
Nessrine Zemni ◽  
Fethi Bouksila ◽  
Roberto De Mascellis ◽  
Rachida Bouhlila

Water scarcity and quality degradation represent real threats to economic, social, and environmental development of arid and semi-arid regions. Drip irrigation associated to Deficit Irrigation (DI) has been investigated as a water saving technique. Yet its environmental impacts on soil and groundwater need to be gone into in depth especially when using brackish irrigation water. Soil water content and salinity were monitored in a fully drip irrigated potato plot with brackish water (4.45 dSm−1) in semi-arid Tunisia. The HYDRUS-1D model was used to investigate the effects of different irrigation regimes (deficit irrigation (T1R, 70% ETc), full irrigation (T2R, 100% ETc), and farmer’s schedule (T3R, 237% ETc) on root water uptake, root zone salinity, and solute return flows to groundwater. The simulated values of soil water content (θ) and electrical conductivity of soil solution (ECsw) were in good agreement with the observation values, as indicated by mean RMSE values (≤0.008 m3·m−3, and ≤0.28 dSm−1 for soil water content and ECsw respectively). The results of the different simulation treatments showed that relative yield accounted for 54%, 70%, and 85.5% of the potential maximal value when both water and solute stress were considered for deficit, full. and farmer’s irrigation, respectively. Root zone salinity was the lowest and root water uptake was the same with and without solute stress for the treatment corresponding to the farmer’s irrigation schedule (273% ETc). Solute return flows reaching the groundwater were the highest for T3R after two subsequent rainfall seasons. Beyond the water efficiency of DI with brackish water, long term studies need to focus on its impact on soil and groundwater salinization risks under changing climate conditions.


1988 ◽  
Vol 39 (1) ◽  
pp. 11 ◽  
Author(s):  
WS Meyer ◽  
HD Barrs

Transient waterlogging associated with spring irrigations on slowly draining soils causes yield reduction in irrigated wheat. Physiological responses to short-term flooding are not well understood. The aim of this experiment was to monitor above- and below-ground responses of wheat to single waterlogging events during and after stem elongation and to assess the sensitivity of the crop at these growth stages to flooding. Wheat (cv. Bindawarra) was grown in drainage lysimeters of undisturbed cores of Marah clay loam soil. A control treatment (F0) was well-watered throughout the season without surface flooding, while three others were flooded for 96 h at stem elongation (Fl), flag leaf emergence (F2) and anthesis (F3), respectively. Soil water content, soil O2, root length density, leaf and stem growth, apparent photosynthesis (APS), plant nutrient status and grain yield were measured. Soil water content increased and soil O2 levels decreased following flooding; the rate of soil O2 depletion increasing with crop age and root length. Leaf and stem growth and APS increased immediately following flooding, the magnitude of the increases was in the order F1 >F2>F3. A similar order existed in the effect of flooding which decreased the number of roots. Subsequently, leaf and stem growth decreased below that of F0 plants in F1, and briefly in F2. Decreases in APS of treated plants compared to F0 plants appeared to be due to their greater sensitivity to soil water deficit. There was no effect of flooding on grain yield. It is suggested that, while plant sensitivity to flooding decreased with age, flooding at stem elongation had no lasting detrimental effect on yield when post-flood watering was well controlled.


2021 ◽  
Author(s):  
fawen li ◽  
chunya song ◽  
hua li

Abstract To examine whether the use of default CO2 database affected the simulation results, this paper built the AquaCrop models of winter wheat based on the measured CO2 database and the default CO2 database, respectively. The models were calibrated with data (2017–2018) and validated with the data (2018–2019) in the North China Plain. The residual coefficient method (CRM), root mean square error (RMSE), normalized root mean square error (NRMSE) and determination coefficient (R2) were used to test the model performance. The results showed that the accuracy of simulation under the two CO2 database were both good. Compared with the default CO2 database, the simulation accuracy under the measured CO2 database had higher accuracy. In order to verify the model further, the simulated values of evapotranspiration, soil water content and measured values were compared and analyzed. The results showed that there were some errors between the measured evapotranspiration and the values of simulation in the filling and waxing period of winter wheat. In general, the simulation values of evapotranspiration were consistent with the measured value at different irrigation levels. The simulated values ​​of the soil water content at the three levels of irrigation were all higher than the measured values, but the simulated results basically reflected the dynamic changes of soil water content throughout the growth period. The model adjustment value of WP*(the normalized water productivity) were a difference under the two CO2 databases, which is one of the reasons for the difference in the simulation results. The results show that in the absence of measured CO2 data, the default CO2 database can be used, which has little influence on the model construction, and the accuracy of the model constructed meets the actual demand. The research results can provide a basis for the establishment of crop models in North China Plain.


2016 ◽  
Vol 61 (No. 5) ◽  
pp. 213-219 ◽  
Author(s):  
K. Copec ◽  
D. Filipovic ◽  
S. Husnjak ◽  
I. Kovacev ◽  
S. Kosutic

2020 ◽  
Vol 46 (3) ◽  
pp. 279-288
Author(s):  
Mohmed A. M. Abdalhi ◽  
Zhonghua Jia ◽  
Wan Luo ◽  
Osama O. Ali ◽  
Cheng Chen

2000 ◽  
Vol 40 (1) ◽  
pp. 37 ◽  
Author(s):  
S. J. Lolicato

Fortnightly soil water content measurements to a depth of 2.1 m under 4 cocksfoot cultivars, 2 phalaris cultivars, 2 lucerne cultivars and 1 Lotus corniculatus cultivar were used to compare soil profile drying and to define seasonal patterns of plant water use of the species over a 3-year period, on a duplex soil. Cultivars were also selected, within species groups, for varying seasonal growth patterns to assess this influence on soil water dynamics and growth. Over the 3-year period, treatments with the highest and lowest measures of profile soil water content were used to derive and compare values of maximum plant extractable water. Plots were maintained for a further 3 years, after which soil water content measurements in autumn were used to assess long-term effects of the treatments. The effect of seasonal growth patterns within a species was negligible; however, there were significant differences between species. Twenty-one months after pasture establishment, lucerne alone had a drying effect at 2.0 m depth and subsequently it consistently showed profiles with the lowest soil water content. Maximum plant extractable water was greatest for lucerne (230 mm), followed by phalaris (210 mm), Lotus corniculatus (200 mm) and cocksfoot (170 mm). Profiles with the lowest soil water content were associated with greater herbage growth and greater depths of water extraction. The soil water deficits developed by the treatments in autumn of the fourth year were similar to those measured in autumn of the seventh year, implying that a species-dependant equilibrium had been reached. Long-term rainfall data is used to calculate the probabilities of recharge occurring when rainfall exceeds maximum potential deficits for the different pasture species.


1994 ◽  
Vol 119 (3) ◽  
pp. 383-388 ◽  
Author(s):  
Horst W. Caspari ◽  
M. Hossein Behboudian ◽  
David J. Chalmers

Five-year old `Hosui' Asian pear (Pyrus serotina Rehder) trees growing in drainage lysimeters and trained onto a Tatura trellis were subjected to three different irrigation regimes. Weekly water use (WU) was calculated using the mass-balance approach. Soil-water content of control lysimeters was kept at pot capacity, while deficit irrigation was applied before [regulated deficit irrigation (RDI)] and during the period of rapid fruit growth [late deficit irrigation (LDI)]. Soil-water content was maintained at ≈50% and 75% of pot capacity for RDI and LDI, respectively. Deficit irrigation reduced mean WU during RDI and LDI by 20%. The reduced WU was caused by lower stomatal conductance (gs) on deficit-irrigated trees. RDI trees had more-negative diurnal leaf water potentials (ψl). The ψl, gs, and WU remained lower for 2 weeks after RDI was discontinued. RDI reduced shoot extension and summer pruning weights, whereas winter pruning weights were not different between treatments. Except for the final week of RDI, fruit growth was not reduced, and fruit from RDI grew faster than the control during the first week after RDI. In contrast, fruit volume measurements showed that fruit growth was clearly inhibited by LDI. Final fruit size and yield, however, were not different between treatments. Return bloom was reduced by RDI but was not affected by LDI.


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