UNRAVELLING CROP WATER PRODUCTIVITY OF TEF (ERAGROSTIS TEF (ZUCC.) TROTTER) THROUGH AQUACROP IN NORTHERN ETHIOPIA

2011 ◽  
Vol 48 (2) ◽  
pp. 222-237 ◽  
Author(s):  
ALEMTSEHAY TSEGAY ◽  
DIRK RAES ◽  
SAM GEERTS ◽  
ELINE VANUYTRECHT ◽  
BERHANU ABRAHA ◽  
...  
Keyword(s):  
Water Stress ◽  
Goodness Of Fit ◽  
Field Experiments ◽  
Root Zone ◽  
Water Productivity ◽  
Eragrostis Tef ◽  
Coefficient Of Determination ◽  
Northern Ethiopia ◽  
Statistical Parameters ◽  
Canopy Development

SUMMARYAt various locations in North Ethiopia (Tigray), field experiments were conducted from 2006 to 2009 to assess the crop response to water stress of tef (Eragrostis tef (Zucc.) Trotter) under rainfed, fully irrigated and deficit irrigation conditions. Observed soil water content (SWC), canopy cover (CC), biomass production (B) and final grain yield (Y) were used to calibrate and validate AquaCrop for tef. Data from an experiment in a controlled environment in 2008 were also considered in the calibration process. Simulations of SWC, CC, B and Y were evaluated by determining the index of agreement, the root mean square error, the coefficient of determination and the Nash–Sutcliffe efficiency. The statistical parameters showed an adequate fit between observations and simulations. The model was able to simulate for tef growing under rainfed condition the observed fast drop in SWC and CC when the rains ceased. The overall goodness of fit between the observed and simulated CC and SWC indicated that the thresholds for root zone depletion at which water stress (i) affects canopy development, (ii) induces stomata closure and (iii) triggers early canopy senescence were well selected. The normalised biomass water productivity (WP*) for tef was 14 g m−2 for the local variety and 21 g m−2 for the improved variety, which is a lot smaller than the WP* expected for C4 plants (30–35 g m−2). The results revealed an increase of 27% in reference harvest index (HIo) of tef in response to mild water stress during the yield formation of up to 33%. However, severe water stress causing stomata closure had a negative effect on HIo. Once it is properly calibrated, AquaCrop can provide room to improve the water productivity of tef by developing guidelines for good agricultural management strategies.

scholarly journals SOWING STRATEGIES FOR BARLEY (HORDEUM VULGARE L.) BASED ON MODELLED YIELD RESPONSE TO WATER WITH AQUACROP

2012 ◽  
Vol 48 (2) ◽  
pp. 252-271 ◽  
Author(s):  
BERHANU ABRHA ◽  
NELE DELBECQUE ◽  
DIRK RAES ◽  
ALEMTSEHAY TSEGAY ◽  
MLADEN TODOROVIC ◽  
...  
Keyword(s):  
Hordeum Vulgare ◽  
Rainy Season ◽  
Crop Production ◽  
Goodness Of Fit ◽  
Field Experiments ◽  
Water Productivity ◽  
Coefficient Of Determination ◽  
Yield Response ◽  
Northern Ethiopia ◽  
Shallow Soils

SUMMARYAquaCrop, the FAO water productivity model, is used as a tool to predict crop production under water limiting conditions. In the first step AquaCrop was calibrated and validated for barley (Hordeum vulgare L.). Data sets of field experiments at seven different locations in four countries (Ethiopia, Italy, Syria and Montana, USA) with different climates in different years and with five different cultivars were used for model calibration and validation. The goodness-of-fit between observed and simulated soil water content, green canopy cover, biomass and grain yield was assessed by means of the coefficient of determination (R2), the Nash–Sutcliff efficiency (E), the index of agreement (d) and the root mean square error (RMSE). The statistical parameters indicated an adequate accuracy of simulations (validation regression of yield: R2 = 0.95, E = 0.94, d = 0.99, RMSE = 0.34). Subsequently, sowing strategies in the semi-arid environment of northern Ethiopia were evaluated with the validated model. Dry sowing had a probability of 47% germination failure attributable to false start of the rainy season. On the other hand, delay sowing at the start of the rainy season to eliminate germinating weeds should be kept as short as possible because grain yields strongly reduce in the season due to water stress when sowing is delayed on shallow soils. This research demonstrates the ability of AquaCrop to predict accurately crop performance with only a limited set of input variables, and the robustness of the model under various environmental and climatic conditions.

scholarly journals THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF SUGAR CANE (SACCHARUM OFFICINARUM): A REVIEW

2011 ◽  
Vol 47 (1) ◽  
pp. 1-25 ◽  
Author(s):  
M. K. V. CARR ◽  
J. W. KNOX
Keyword(s):  
Water Stress ◽  
Water Relations ◽  
Sugar Cane ◽  
Root Zone ◽  
Water Productivity ◽  
Crop Coefficient ◽  
Saccharum Officinarum ◽  
Irrigation Scheduling ◽  
Background Information ◽  
Technology Choice

SUMMARYThe results of research on the water relations and irrigation needs of sugar cane are collated and summarized in an attempt to link fundamental studies on crop physiology to irrigation practices. Background information on the centres of production of sugar cane is followed by reviews of (1) crop development, including roots; (2) plant water relations; (3) crop water requirements; (4) water productivity; (5) irrigation systems and (6) irrigation scheduling. The majority of the recent research published in the international literature has been conducted in Australia and southern Africa. Leaf/stem extension is a more sensitive indicator of the onset of water stress than stomatal conductance or photosynthesis. Possible mechanisms by which cultivars differ in their responses to drought have been described. Roots extend in depth at rates of 5–18 mm d−1 reaching maximum depths of > 4 m in ca. 300 d providing there are no physical restrictions. The Penman-Monteith equation and the USWB Class A pan both give good estimates of reference crop evapotranspiration (ETo). The corresponding values for the crop coefficient (Kc) are 0.4 (initial stage), 1.25 (peak season) and 0.75 (drying off phase). On an annual basis, the total water-use (ETc) is in the range 1100–1800 mm, with peak daily rates of 6–15 mm d−1. There is a linear relationship between cane/sucrose yields and actual evapotranspiration (ETc) over the season, with slopes of about 100 (cane) and 13 (sugar) kg (ha mm)−1 (but variable). Water stress during tillering need not result in a loss in yield because of compensatory growth on re-watering. Water can be withheld prior to harvest for periods of time up to the equivalent of twice the depth of available water in the root zone. As alternatives to traditional furrow irrigation, drag-line sprinklers and centre pivots have several advantages, such as allowing the application of small quantities of water at frequent intervals. Drip irrigation should only be contemplated when there are well-organized management systems in place. Methods for scheduling irrigation are summarized and the reasons for their limited uptake considered. In conclusion, the ‘drivers for change’, including the need for improved environmental protection, influencing technology choice if irrigated sugar cane production is to be sustainable are summarized.

Changes in water flows and water productivity upon vegetation regeneration on degraded hillslopes in northern Ethiopia: a water balance modelling exercise

2009 ◽  
Vol 31 (2) ◽  
pp. 237 ◽  
Author(s):  
Katrien Descheemaeker ◽  
Dirk Raes ◽  
Jan Nyssen ◽  
Jean Poesen ◽  
Mitiku Haile ◽  
...  
Keyword(s):  
Water Balance ◽  
Biomass Production ◽  
Water Conservation ◽  
Root Zone ◽  
Water Productivity ◽  
Annual Rainfall ◽  
Northern Ethiopia ◽  
Water Balance Components ◽  
Water Flows ◽  
Vegetation Regeneration

The establishment of exclosures (i.e. areas closed for grazing and agriculture) is a common practice to reverse land degradation through vegetation regeneration in the semiarid highland areas of northern Ethiopia. In order to assess the effect of exclosures on water flows, the water balance components for different vegetation regeneration stages were assessed through field measurements and modelling. Successful model calibration and validation was done based on soil water content measurements conducted during 2 years in 22 experimental plots. In the protected areas, vegetation regeneration leads to an increase in infiltration and transpiration and a more productive use of water for biomass production. In areas where additional lateral water (runon) infiltrates, source–sink systems are created. Here, up to 30% of the annual rainfall percolates through the root-zone towards the groundwater table. Increased biomass production in exclosures leads to possibilities for wood harvesting and cut and carry of grasses for livestock feeding. Together with water conservation and more productive use of water, the latter contributes to increased livestock water productivity. At the landscape scale, the creation of vegetation filters, capturing resources like water and nutrients, reinforces the rehabilitation process and healthy landscape functioning.

Modeling Evapotranspiration and Crop Growth of Irrigated and Non-Irrigated Corn in the Texas High Plains Using RZWQM

2018 ◽  
Vol 61 (5) ◽  
pp. 1653-1666 ◽  
Author(s):  
Huihui Zhang ◽  
Robert Wayne Malone ◽  
Liwang Ma ◽  
Lajpat R. Ahuja ◽  
Saseendran S. Anapalli ◽  
...  
Keyword(s):  
Water Stress ◽  
Soil Water ◽  
Crop Production ◽  
Root Zone ◽  
Potential Evapotranspiration ◽  
Water Productivity ◽  
Stress Factors ◽  
Irrigated Agriculture ◽  
High Plains ◽  
Area Index

Abstract. Accurate quantification and management of crop evapotranspiration (ET) are critical to optimizing crop water productivity for both dryland and irrigated agriculture, especially in the semiarid regions of the world. In this study, four weighing lysimeters in Bushland, Texas, were planted to maize in 1994 with two fully irrigated and two non-irrigated for measuring crop ET. The Root Zone Water Quality Model (RZWQM2) was used to evaluate soil water balance and crop production with potential evapotranspiration (PET) estimated from either the Shuttleworth-Wallace method (PTSW) or the ASCE standardized alfalfa reference ET multiplied by crop coefficients (PTASCE). As a result, two water stress factors were defined from actual transpiration (AT) and were tested in the model against the lysimeter data, i.e., AT/PTSW and AT/PTASCE. For both water stress factors, the simulated daily ET values were reasonably close to the measured values, with underestimated ET during mid-growing stage in both non-irrigated lysimeters. Root mean squared deviations (RMSDs) and relative RMSDs (RMSD/observed mean) values for leaf area index, biomass, soil water content, and daily ET were within simulation errors reported earlier in the literature. For example, the RMSDs of simulated daily ET were less than 1.52 mm for all irrigated and non-irrigated lysimeters. Overall, ET was simulated within 3% of the measured data for both fully irrigated lysimeters and undersimulated by less than 11% using both stress factors for the non-irrigated lysimeters. Our results suggest that both methods are promising for simulating crop production and ET under irrigated conditions, but the methods need to be improved for dryland and non-irrigated conditions. Keywords: ET, RZWQM modeling, Stress factor, Weighing lysimeter.

scholarly journals Water-Saving Irrigation Strategies in Potato Fields: Effects on Physiological Characteristics and Water Use in Arid Region

Agronomy ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 172 ◽  
Author(s):  
Tarek Zin El-Abedin ◽  
Mohamed Mattar ◽  
Hussein Al-Ghobari ◽  
Abdulrahman Alazba
Keyword(s):  
Field Experiments ◽  
Root Zone ◽  
Water Productivity ◽  
Net Photosynthesis ◽  
Water Saving ◽  
Physiological Characteristics ◽  
Growth And Yield ◽  
Irrigation Amount ◽  
Chlorophyll Contents ◽  
Potato Growth

In this study, field experiments were conducted to investigate the effects of two water-saving practices—partial root-zone drying (PRD) and deficit irrigation (DI)—on potato growth and yield in comparison with full irrigation (FI). The required FI amount was applied to the potato plants to enable 100% crop evapotranspiration, and the plants received 70% and 50% of the irrigation amount of FI for DI (DI70 and DI50) and PRD (PRD70 and PRD50), respectively. The physiological characteristics of the potatoes during the 2014–2015 seasons indicated that the relative chlorophyll contents were not significantly higher for the DI and PRD treatments than for the FI treatment. The DI50 had the lowest net photosynthesis rate (p < 0.05) while DI50 and PRD50 had significantly lower stomatal conductance (gs) values in both years. Meanwhile, the values of the PRD treatments were lower than those of DI treatments based on the transpiration rates. The xylem (abscisic acid) based on PRD50 had an average increase of 0.38 mol/m2 s due to decreasing gs values compared with other water-saving irrigation treatments. However, the FI and DI treatments had increased fresh tuber yields compared with the yields of PRD treatments. Furthermore, the PRD70 and PRD50 treatments significantly reduced the water productivity (WP) values by 30.16% and 41.32%, respectively, relative to that of FI.

The response of cassava to water deficits at various stages of growth in the subtropics

1989 ◽  
Vol 40 (3) ◽  
pp. 517 ◽  
Author(s):  
GR Baker ◽  
S Fukai ◽  
GL Wilson
Keyword(s):  
Water Stress ◽  
Leaf Area ◽  
Field Experiments ◽  
Total Biomass ◽  
Water Deficits ◽  
Canopy Development ◽  
Stages Of Growth ◽  
Storage Organs ◽  
Tuber Crop ◽  
Final Yield

Cassava is a potential tuber crop for northern Australia where water stress is likely to occur during some stages of growth. Field and glasshouse experiments were conducted to examine the response of cassava to soil water deficits which developed at various stages. The field experiments, covering 10-month growth durations from planting in spring to harvesting in winter, showed that water stress occurring in summer or winter had small effects, but in autumn severely reduced the final yield. Autumn was the time of maximum bulking of underground storage organs in well-watered plants, and water stress which reduced assimilate production also reduced bulking. Temperature at this time was suboptimal for canopy development, and leaf area which was reduced during the stress did not increase after its relief, affecting further the growth of storage organs. Similarly, in the glasshouse experiment, plants recovered rapidly during early stages of growth, but when stress occurred later leaf area was reduced greatly, and recovery after its termination was poor. In all experiments, water deficits affected yield of storage organs but not the pattern of assimilate distribution, resulting in similar harvest indices among the plants of different watering treatments. It is concluded that the reduction in cassava yield (cv. M Aus 7) is caused by the reduction in total biomass production, and that stress occurring later in the season is most detrimental to yield because of the additional effect of reduced ability of old plants to recover leaf area after the stress is relieved.

Thin-Layer Drying Characteristics and Modeling of Paper Sludge

2012 ◽  
Vol 190-191 ◽  
pp. 575-580
Author(s):  
Han Min Xiao
Keyword(s):  
Goodness Of Fit ◽  
Effective Diffusivity ◽  
Empirical Models ◽  
Coefficient Of Determination ◽  
Paper Sludge ◽  
Mean Square ◽  
Statistical Parameters ◽  
Drying Characteristics ◽  
Thin Layer Drying ◽  
Drying Conditions

In this paper, the drying experiments of paper sludge were performed at different drying conditions. The drying kinetics and phenomena of paper sludge were investigated. The effective diffusivity and the activation energy of the paper sludge during drying had been evaluated. At the same time, seven empirical models were used to model the experimental data, such as Newton, Page, Modified Page, Henderson and Pabis, Logarithmic, Two term, Two Term exponential et al. Three statistical parameters (The coefficient of determination (R2), root mean square error (RMSE) and the residual sum of square (RSS) ) were used to evaluate goodness of fit of the tested models.

Evaluation of the FAO Aqua-Crop model for Durum wheat (Triticum durum Desf.)on the eastern Algeria under semi-arid conditions

2017 ◽  
Vol 51 (04) ◽  
Author(s):  
Guendouz Ali ◽  
Maamri Khalifa ◽  
Moumeni Lyes ◽  
Hafsi Miloud
Keyword(s):  
Water Stress ◽  
Durum Wheat ◽  
Field Experiments ◽  
Water Productivity ◽  
Relative Yield ◽  
Crop Model ◽  
Maturity Stage ◽  
Management Options ◽  
Aquacrop Model ◽  
Cropping Seasons

The relative yield decline that is expected under specific levels of water stress at different moments in the growing period is estimated by integrating the FAO Ky approach in the soil water balance model BUDGET. FAO recently developed a water-driven model (Aqua-Crop) for use as a decision support tool in planning and scenario analysis in different seasons and locations. The Aqua Crop model was evaluated with experimental data collected during three cropping seasons; the field experiments were conducted in Setif, Algeria. The objective of the study is to quantify the water stress based on estimation of evapo-transpiration by Aqua Crop model in Durum wheat under stressed conditions.The results of this study proved the efficiency of the Aqua Crop model to quantify the water stress. Total water stress during three cropping seasons (2010-2013) ranged between 0.15 (15%) at Double ridges to anthesis stage to 0.56 (56%) at Anthesis to maturity stage. The AquaCrop model can adequately quantify water stress and can be used to explore management options to improve wheat water productivity.

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