Potential of Deficit and Supplemental Irrigation under Climate Variability in Northern Togo, West Africa

In the context of a growing population in West Africa and frequent yield losses due to erratic rainfall, it is necessary to improve stability and productivity of agricultural production systems, e.g., by introducing and assessing the potential of alternative irrigation strategies which may be applicable in this region. For this purpose, five irrigation management strategies, ranging from no irrigation (NI) to controlled deficit irrigation (CDI) and full irrigation (FI), were evaluated concerning their impact on the inter-seasonal variability of the expected yields and improvements of the yield potential. The study was conducted on a maize crop (Zea mays L.) at a representative site in northern Togo with a hot semi-arid climate and pronounced dry and wet rainfall seasons. The OCCASION (Optimal Climate Change Adaption Strategies in Irrigation) framework was adapted and applied. It consists of: (i) a weather generator for simulating long climate time series; (ii) the AquaCrop model, which was used to simulate the irrigation system during the growing season and the yield response of maize to the considered irrigation management strategies; and (iii) a problem-specific algorithm for optimal irrigation scheduling with limited water supply. We found high variability in rainfall during the wet season which leads to considerable variability in the expected yield for rainfed conditions (NI). This variability was significantly reduced when supplemental irrigation management strategies (CDI or FI) requiring a reasonably low water demand of about 150 mm were introduced. For the dry season, it was shown that both irrigation management strategies (CDI and FI) would increase yield potential for the local variety TZEE-W up to 4.84 Mg/ha and decrease the variability of the expected yield at the same time. However, even with CDI management, more than 400 mm of water is required if irrigation would be introduced during the dry season in northern Togo. Substantial rainwater harvesting and irrigation infrastructures would be needed to achieve that.

Download Full-text

An Economic-Based Evaluation of Maize Production under Deficit and Supplemental Irrigation for Smallholder Farmers in Northern Togo, West Africa

Resources ◽

10.3390/resources8040175 ◽

2019 ◽

Vol 8 (4) ◽

pp. 175

Author(s):

Agossou Gadedjisso-Tossou ◽

Tamara Avellán ◽

Niels Schütze

Keyword(s):

West Africa ◽

Smallholder Farmers ◽

Irrigation Management ◽

Management Strategies ◽

Irrigation Scheduling ◽

Yield Response ◽

Exceedance Probability ◽

World Population ◽

Supplemental Irrigation ◽

Aquacrop Model

While the world population is expected to reach 9 billion in 2050, in West Africa, it will more than double. This situation will lead to a high demand for cereals in the region. At the same time, farmers are experiencing yield losses due to erratic rainfall. To come up with a sound and effective solution, the available but limited water should be used to achieve high yields through irrigation. Therefore, full and deficit irrigation management strategies were evaluated. The expected profit that can be obtained by a smallholder farmer under a conventional irrigation system in the short-term of investment was also assessed considering rope and bucket, treadle pump, and motorized pump water-lifting methods. The study focused on maize in northern Togo. The framework used in this study consisted of (i) a weather generator for simulating long-term climate time series; (ii) the AquaCrop model, which was used to simulate crop yield response to water; and (iii) a problem-specific algorithm for optimal irrigation scheduling with limited water supply. Results showed high variability in rainfall during the wet season leading to significant variability in the expected yield under rainfed conditions. This variability was substantially reduced when supplemental irrigation was applied. This holds for the irrigation management strategies evaluated in the dry season. Farmers’expected net incomes were US$ 133.35 and 78.11 per hectare for treadle pump and rope and bucket methods, respectively, under 10% exceedance probability. The motorized pump method is not appropriate for smallholder farmers in the short run.

Download Full-text

Using every drop: rainwater harvesting for food security in Mbale, Uganda

Water Practice & Technology ◽

10.2166/wpt.2020.019 ◽

2020 ◽

Vol 15 (2) ◽

pp. 295-310 ◽

Cited By ~ 3

Author(s):

Oludare Sunday Durodola ◽

Joash Bwambale ◽

Victo Nabunya

Keyword(s):

Food Production ◽

Rainwater Harvesting ◽

Dry Season ◽

World Health ◽

Yield Response ◽

Cost Ratio ◽

World Population ◽

Aquacrop Model ◽

Rain Season ◽

The World

Abstract The world population is expected to increase with corresponding increase in food production and water withdrawals. To ensure continuous food production throughout the year, increasing irrigation is inevitable. However, the water available for agricultural use is inadequate due to the limited water resources globally and climate change challenges threatening water availability. The economy of Mbale, Uganda, mainly depends on rainfed agriculture. The rain season is from April to October whilst the dry season is from November to March. Therefore, this study examines the potential of rainwater harvesting for domestic and agricultural uses in Mbale. The AquaCrop model was adopted for the yield response of crops to water during the dry season. The study reveals that comparing the resulting rainwater harvesting potential with the water consumption, up to 186% of the annual water demand for domestic use, according to the World Health Organization (WHO) standard, can be provided. Thus, the excess harvested water from a 200 m2 rooftop was simulated for irrigation purposes, which shows that it can be used to cultivate areas of 269, 429, 125 and 388 m2 for cabbage, tomato, maize and potato respectively during dry periods. The economic analysis shows a benefit cost ratio of 1.99 over 10 years. It concludes by recommending RWH as an alternative water supply source for domestic and agricultural uses.

Download Full-text

Weighing Lysimeters for Developing Crop Coefficients and Efficient Irrigation Practices for Vegetable Crops

HortScience ◽

10.21273/hortsci.45.11.1597 ◽

2010 ◽

Vol 45 (11) ◽

pp. 1597-1604 ◽

Cited By ~ 29

Author(s):

David R. Bryla ◽

Thomas J. Trout ◽

James E. Ayars

Keyword(s):

Potential Evapotranspiration ◽

Irrigation Management ◽

Quadratic Function ◽

Ground Cover ◽

Soil Surface ◽

Irrigation Scheduling ◽

Yield Potential ◽

Vegetable Crops ◽

Soil Water Conditions ◽

Crop Coefficients

Large, precision weighing lysimeters are expensive but invaluable tools for measuring crop evapotranspiration and developing crop coefficients. Crop coefficients are used by both growers and researchers to estimate crop water use and accurately schedule irrigations. Two lysimeters of this type were installed in 2002 in central California to determine daily rates of crop and potential (grass) evapotranspiration and develop crop coefficients for better irrigation management of vegetable crops. From 2002 to 2006, the crop lysimeter was planted with broccoli, iceberg lettuce, bell pepper, and garlic. Basal crop coefficients, Kcb, defined as the ratio of crop to potential evapotranspiration when the soil surface is dry but transpiration in unlimited by soil water conditions, increased as a linear or quadratic function of the percentage of ground covered by vegetation. At midseason, when groundcover was greater than 70% to 90%, Kcb was ≈1.0 in broccoli, 0.95 in lettuce, and 1.1 in pepper, and Kcb of each remained the same until harvest. Garlic Kcb, in comparison, increased to 1.0 by the time the crop reached 80% ground cover, but with only 7% of additional coverage, Kcb continued to increase to 1.3, until irrigation was stopped to dry the crop for harvest. Three weeks after irrigation was cutoff, garlic Kcb declined rapidly to a value of 0.16 by harvest. Yields of each crop equaled or exceeded commercial averages for California with much less water in some cases than typically applied. The new crop coefficients will facilitate irrigation scheduling in the crops and help to achieve full yield potential without overirrigation.

Download Full-text

Studying Crop Yield Response to Supplemental Irrigation and the Spatial Heterogeneity of Soil Physical Attributes in a Humid Region

Agriculture ◽

10.3390/agriculture9020043 ◽

2019 ◽

Vol 9 (2) ◽

pp. 43 ◽

Cited By ~ 2

Author(s):

Amir Haghverdi ◽

Brian Leib ◽

Robert Washington-Allen ◽

Wesley Wright ◽

Somayeh Ghodsi ◽

...

Keyword(s):

Spatial Heterogeneity ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Soil Texture ◽

Temporal Variability ◽

Irrigation Management ◽

Yield Response ◽

Supplemental Irrigation ◽

Plant Available Water

West Tennessee’s supplemental irrigation management at a field level is profoundly affected by the spatial heterogeneity of soil moisture and the temporal variability of weather. The introduction of precision farming techniques has enabled farmers to collect site-specific data that provide valuable quantitative information for effective irrigation management. Consequently, a two-year on-farm irrigation experiment in a 73 ha cotton field in west Tennessee was conducted and a variety of farming data were collected to understand the relationship between crop yields, the spatial heterogeneity of soil water content, and supplemental irrigation management. The soil water content showed higher correlations with soil textural information including sand (r = −0.9), silt (r = 0.85), and clay (r = 0.83) than with soil bulk density (r = −0.27). Spatial statistical analysis of the collected soil samples (i.e., 400 samples: 100 locations at four depths from 0–1 m) showed that soil texture and soil water content had clustered patterns within different depths, but BD mostly had random patterns. ECa maps tended to follow the same general spatial patterns as those for soil texture and water content. Overall, supplemental irrigation improved the cotton lint yield in comparison to rainfed throughout the two-year irrigation study, while the yield response to supplemental irrigation differed across the soil types. The yield increase due to irrigation was more pronounced for coarse-textured soils, while a yield reduction was observed when higher irrigation water was applied to fine-textured soils. In addition, in-season rainfall patterns had a profound impact on yield and crop response to supplemental irrigation regimes. The spatial analysis of the multiyear yield data revealed a substantial similarity between yield and plant-available water patterns. Consequently, variable rate irrigation guided with farming data seems to be the ideal management strategy to address field level spatial variability in plant-available water, as well as temporal variability in in-season rainfall patterns.

Download Full-text

Evaluation of irrigation scheduling and yield response for wheat cultivars using AquaCrop model in an arid climate

Water Science & Technology Water Supply ◽

10.2166/ws.2021.246 ◽

2021 ◽

Author(s):

E. Amiri ◽

A. Bahrani ◽

S. Irmak ◽

N. Mohammadiyan Roshan

Keyword(s):

Water Balance ◽

Winter Wheat ◽

Grain Yield ◽

Irrigation Scheduling ◽

Yield Response ◽

Yield Reduction ◽

Wheat Cultivars ◽

Study Region ◽

Arid Conditions ◽

Aquacrop Model

Abstract Yield, soil water balance components and evapotranspiration-based water productivity (WPET) of three winter wheat cultivars were investigated using AquaCrop model under arid conditions in Shiraz, Iran, for two consecutive years. The irrigation treatments were non-stressed (I1) and post-anthesis water stress (I2) with three wheat cultivars. Evaluation of the model was performed using the coefficient of root mean squared error (RMSE) and normalized RMSE and R2. The AquaCrop model performed well in simulating grain yield and final biomass production with R2 > 0.90, RMSE and normalized RMSE values less than 10. The I1 treatment resulted in higher grain yield and biomass productivity than I2 treatment. The I2 irrigation resulted in yield reduction of 21 and 24% in 2006–2007 and 2007–2008 growing seasons, respectively, as compared with I2. Using the measured grain yield and AquaCrop-simulated water balance, the amount of WPET varied from 0.68 to 0.95 kg m−3. The AquaCrop model was able to predict winter wheat biomass and yield production with a good accuracy in arid conditions of this study and especially its ability to simulate these variables for different wheat cultivars' was notable. The AquaCrop model can be used to explore management scenarios to improve wheat water management in the study region.

Download Full-text

Citrus Irrigation Management

EDIS ◽

10.32473/edis-ss660-2017 ◽

2017 ◽

Vol 2017 (5) ◽

Author(s):

Davie Mayeso Kadyampakeni ◽

Kelly T. Morgan ◽

Mongi Zekri ◽

Rhuanito Ferrarezi ◽

Arnold Schumann ◽

...

Keyword(s):

Water Stress ◽

Physiological Activity ◽

Irrigation Management ◽

Fruit Size ◽

Irrigation Scheduling ◽

Leaf Expansion ◽

Tree Canopy ◽

Limiting Factor ◽

Irrigation Frequency ◽

Citrus Production

Water is a limiting factor in Florida citrus production during the majority of the year because of the low water holding capacity of sandy soils resulting from low clay and the non-uniform distribution of the rainfall. In Florida, the major portion of rainfall comes in June through September. However, rainfall is scarce during the dry period from February through May, which coincides with the critical stages of bloom, leaf expansion, fruit set, and fruit enlargement. Irrigation is practiced to provide water when rainfall is not sufficient or timely to meet water needs. Proper irrigation scheduling is the application of water to crops only when needed and only in the amounts needed; that is, determining when to irrigate and how much water to apply. With proper irrigation scheduling, yield will not be limited by water stress. With citrus greening (HLB), irrigation scheduling is becoming more important and critical and growers cannot afford water stress or water excess. Any degree of water stress or imbalance can produce a deleterious change in physiological activity of growth and production of citrus trees. The number of fruit, fruit size, and tree canopy are reduced and premature fruit drop is increased with water stress. Extension growth in shoots and roots and leaf expansion are all negatively impacted by water stress. Other benefits of proper irrigation scheduling include reduced loss of nutrients from leaching as a result of excess water applications and reduced pollution of groundwater or surface waters from the leaching of nutrients. Recent studies have shown that for HLB-affected trees, irrigation frequency should increase and irrigation amounts should decrease to minimize water stress from drought stress or water excess, while ensuring optimal water availability in the rootzone at all times.

Download Full-text

Irrigation Scheduling with Soil Gas Diffusivity as a Decision Tool to Mitigate N2O Emissions from a Urine-Affected Pasture

Agriculture ◽

10.3390/agriculture11050443 ◽

2021 ◽

Vol 11 (5) ◽

pp. 443

Author(s):

Camille Rousset ◽

Timothy J. Clough ◽

Peter R. Grace ◽

David W. Rowlings ◽

Clemens Scheer

Keyword(s):

Irrigation Management ◽

Irrigation Treatment ◽

Irrigation Scheduling ◽

Soil Gas ◽

N2o Emissions ◽

Irrigation Frequency ◽

Water Demands ◽

Gas Diffusivity ◽

Matter Production ◽

Access To Water

Pastures require year-round access to water and in some locations rely on irrigation during dry periods. Currently, there is a dearth of knowledge about the potential for using irrigation to mitigate N2O emissions. This study aimed to mitigate N2O losses from intensely managed pastures by adjusting irrigation frequency using soil gas diffusivity (Dp/Do) thresholds. Two irrigation regimes were compared; a standard irrigation treatment based on farmer practice (15 mm applied every 3 days) versus an optimised irrigation treatment where irrigation was applied when soil Dp/Do was ≈0.033 (equivalent to 50% of plant available water). Cow urine was applied at a rate of 700 kg N ha−1 to simulate a ruminant urine deposition event. In addition to N2O fluxes, soil moisture content was monitored hourly, Dp/Do was modelled, and pasture dry matter production was measured. Standard irrigation practices resulted in higher (p = 0.09) cumulative N2O emissions than the optimised irrigation treatment. Pasture growth rates under treatments did not differ. Denitrification during re-wetting events (irrigation and rain) contributed to soil N2O emissions. These results warrant further modelling of irrigation management as a mitigation option for N2O emissions from pasture soils, based on Dp/Do thresholds, rainfall, plant water demands and evapotranspiration.

Download Full-text

Response of tomato cultivars to irrigation management strategies employed by emerging farmers in the Greater Giyani Municipality

South African Journal of Plant and Soil ◽

10.1080/02571862.2021.1913767 ◽

2021 ◽

pp. 1-13

Author(s):

Tebogo J Lebea ◽

Nebo Jovanovic ◽

Mapotso Kena ◽

Kwabena K Ayisi ◽

Wisani G Mushadu

Keyword(s):

Irrigation Management ◽

Management Strategies ◽

Tomato Cultivars

Download Full-text

Soil moisture assessment based on Sentinel 1/2 and in-situ data: The vineyard case study

10.5194/egusphere-egu21-16507 ◽

2021 ◽

Author(s):

Maria Paula Mendes ◽

Ana Paula Falcão ◽

Magda Matias ◽

Rui Gomes

Keyword(s):

Soil Moisture ◽

Climate Models ◽

Root Zone ◽

Irrigation Management ◽

Management Strategies ◽

Winter Period ◽

Classification Algorithms ◽

Precipitation Regime ◽

Terrain Attributes ◽

Sentinel 2

Vineyards are crops whose production has a major economic impact in the Portuguese economy (~750 million euros) being exported worldwide. As the climate models project a larger variability in precipitation regime, the water requirements of vineyards can change and drip irrigation can be responsible for salt accumulation in the root zone, especially when late autumn and winter precipitation is not enough to leach salts from the soil upper horizons, turning the soil unsuitable for grape production.The aim of this work is to present a methodology to map surface soil moisture content (SMC) in a vineyard, (40 hectares) based on the application of two classification algorithms to satellite imagery (Sentinel 1 and Sentinel 2). Two vineyard plots were considered and three field campaigns (December 2017, January 2018 and May 2018) were conducted to measure soil moisture contents (SMC). A geostatistical method was used to estimate the SM class probabilities according to a threshold value, enlarging the training set (i.e., SMC data of the two plots) for the classification algorithms. Sentinel-1 and Sentinel-2 images and terrain attributes fed the classification algorithms. Both methods, Random Forest and Logistic Regression, classified the highest SMC areas, with probabilities above 14%, located close to a stream at the lower altitudes.RF performed very well in classifying the topsoil zones with lower SMC during the autumn-winter period (F-measure=0.82).This delineation allows the prevention of the occurrence of areas affected by salinization, indicating which areas will need irrigation management strategies to control the salinity, especially under climate change, and the expected increase in droughts.

Download Full-text

Use of geographic information systems and remote sensing as automated tool for variable rate irrigation prescriptions

10.32469/10355/79549 ◽

2019 ◽

Author(s):

◽

Anh Thi Tuan Nguyen

Keyword(s):

Remote Sensing ◽

Real Time ◽

Regression Models ◽

Field Data ◽

Irrigation Management ◽

Irrigation Scheduling ◽

Crop Growth ◽

Variable Rate ◽

Water Application ◽

Center Pivot

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Economic as well as water shortage pressure on agricultural use of water has placed added emphasis on efficient irrigation management. Center pivot technology has made great improvement with variable rate irrigation (VRI) technology to vary water application spatially and temporally to maximize the economic and environmental return. Proper management of VRI systems depends on correctly matching the pivot application to specific field temporal and areal conditions. There is need for a tool to accurately and inexpensively define dynamic management zones, to sense within-field variability in real time, and control variable rate water application so that producers are more willing to adopt and utilize the advantages of VRI systems. This study included tests of the center pivot system uniformity performance in 2014 at Delta Research Center in Portageville, MO. The goal of this research was to develop MOPivot software with an algorithm to determine unique management areas under center pivot systems based on system design and limitations. The MOPivot tool automates prescriptions for VRI center pivot based on non-uniform water needs while avoiding potential runoff and deep percolation. The software was validated for use in real-time irrigation management in 2018 for VRI control system of a Valley 8000 center pivot planted to corn. The water balance model was used to manage irrigation scheduling. Field data, together with soil moisture sensor measurement of soil water content, were used to develop the regression model of remote sensing-based crop coefficient (Kc). Remote sensing vegetation index in conjunction with GDD and crop growth stages in regression models showed high correlation with Kc. Validation of those regression models was done using Centralia, MO, field data in 2016. The MOPivot successfully created prescriptions to match system capacity of the management zone based on system limitations for center pivot management. Along with GIS data sources, MOPivot effectively provides readily available graphical prescription maps, which can be edited and directly uploaded to a center pivot control panel. The modeled Kc compared well with FAO Kc. By combining GDD and crop growth in the models, these models would account for local weather conditions and stage of crop during growing season as time index in estimating Kc. These models with Fraction of growth (FrG) and cumulative growing degree days (cGDD) had a higher coefficient of efficiency, higher Nash-Sutcliffe coefficient of efficiency and higher Willmott index of agreement. Future work should include improvement in the MOPivot software with different crops and aerial remote sensing imagery to generate dynamic prescriptions during the season to support irrigation scheduling for real-time monitoring of field conditions.

Download Full-text