Deficit Irrigation as a Method to Increase Water use Efficiency of Some Crops Produced in Ethiopia: A Review

Addisu Asefa

doi:10.36648/ipjpsar.7.3.114

Deficit Irrigation as a Method to Increase Water use Efficiency of Some Crops Produced in Ethiopia: A Review

Addisu Asefa^*

Department of Irrigation and Water Harvesting Research, Jimma Agricultural Research Center, Jimma, Ethiopia

*Corresponding Author:: Addisu Asefa
Department of Irrigation and Water Harvesting Research,
Jimma Agricultural Research Center, Jimma,
Ethiopia,
E-mail: adisujarc2016@gmail.com

Received date: August 14, 2023, Manuscript No. IPJPSAR-23-17705; Editor assigned date: August 17, 2023, PreQC No. IPJPSAR-23-17705 (PQ); Reviewed date: August 31, 2023, QC No. IPJPSAR-23-17705; Revised date: September 07, 2023, Manuscript No. IPJPSAR-23-17705 (R); Published date: September 14, 2023, DOI: 10.36648/ipjpsar.7.3.114

Citation: Asefa A (2023) Deficit Irrigation as a Method to Increase Water use Efficiency of Some Crops Produced in Ethiopia: A Review. J Plant Sci Agri Res Vol.7 No.3: 114.

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Abstract

Deficit irrigation is an optimization strategy in which irrigation is applied during drought-sensitive growth stages of a crop. In Ethiopia crop like maize, common bean, soybean, potato, wheat and onion were affected by severe moisture stress. In areas where water is the most limiting resource to production, maximizing water use efficiency may be more profitable to the farmer than maximizing crop yield. This is because the water saved when deficit irrigation is applied becomes available to irrigate more land.

Keywords

Deficit irrigation; Water use efficiency; Growth stage

Introduction

Irrigation improves crop production and productivity by contributing towards food security, self-sufficiency and export market. Thus, irrigation water is one of the important factors for crop production provided that other essential requirements like nutrient, climate and soil environment are sufficient. Nowadays, the government of Ethiopia is giving more emphasis to the subsector by way of enhancing the food security situation in the country. Efforts are being made to involve farmers progressively in various aspects of management of small-scale irrigation systems, starting from planning, implementation and management aspects, particularly in water distribution, operation and maintenance to improve the performance of irrigated agriculture. As a result, irrigation infrastructures are increasing year after year, which show nationwide positive development implications and experiences in small and large scale irrigation schemes. The expansion of irrigated agriculture to feed the ever-increasing population on one hand and the increasing competition for water due to the development of other water use sectors on the other hand, as well as increasing concerns for environment, necessitated the improvement of water productivity in irrigated agriculture to ensure sustained production and conservation of this limited resource [1]. Water is the major yield limiting factor in agricultural system. In the present era of climate change and colossal population pressure, drought is becoming a critical problem, thus making the water a sparse resource in the world [2]. The sustainable use of water in agriculture has become a big concern. The adoption of strategies for saving irrigation water and maintaining acceptable yields may contribute to the preservation of this ever more restricted resource [3]. This long-term use of water in irrigated agricultural systems, with an emphasis on reducing water use, requires careful planning and management.

Advantages of Deficit Irrigation in Arid and Semi-Arid Areas of Ethiopia

Deficit is one of the irrigation management practices which could result in irrigation water saving. It is a water-saving strategy under which crops are exposed to a certain level of water stress either during a particular developmental stage or throughout the whole growing season [4]. Deficit irrigation is strategies allow crops to sustain some degree of water deficit and with insignificant yield reduction. The classic Deficit Irrigation strategy (DI) implies that water is supplied at levels below full Evapotranspiration (ET) at some growth stages or throughout the growing season. The other two main deficit irrigation strategies based on the physiological knowledge of crops response to water stress, are regulated deficit irrigation and partial root zone drying [5]. In the past, crop irrigation requirements did not consider limitations of the available water supplies. Therefore practice of new irrigation technologies such as deficit irrigation is one of the water management strategies to conserve water resources in addition to increasing water use efficiency in agriculture [6]. This approach to the management of water has been reported to increase yields in a number of crops such as beans and other legume crops [7]. In semi-arid regions of Ethiopia, irrigation was affected by water scarcity. Moreover in Ethiopia, there is spatial and temporal variability of rainfall to meet the timely required amount of water application for plant growth except in some highland areas [8]. In arid and semi-arid of Ethiopia, moisture stress is a frequently occurring phenomenon which is climate related natural hazard minimizing agricultural production in the country from time to time. In low land areas where moisture stress is common in crop production, drought leads to major socioeconomic problems like food insecurity, poverty and low quality of life. Therefore, there must be appropriate technologies for enhancing the socioeconomic condition of farming community with locally available resources. In arid and semi-arid areas where moisture stress is the main challenge for crop production, the spatial and temporal variations intensify the problem. Moreover, design of irrigation schemes does not address the situation of moisture availability for crop and the competition between different sectors. For improving water use efficiency, there is a growing interest in decreasing irrigation water amount, where by water supply is minimized and stress is allowed with minimal effects on crop growth. Under conditions of scarce water supply and drought, deficit irrigation can lead to greater economic gains by maximizing water use efficiency.

Benefit of Increasing Water use Efficiency under Deficit Irrigation

Improving water use efficiency in agricultural sector was used for sustainability of irrigated agriculture, Improvement of the environment and ensuring food security [9,10]. Deficit irrigation is an optimization strategy in which irrigation is applied during drought-sensitive growth stages of a crop. Outside these periods, irrigation is limited or even unnecessary if rainfall provides a minimum supply of water. Water restriction is limited to drought-tolerant phonological stages, often the vegetative stages and the late ripening period. Total irrigation application is therefore not proportional to irrigation requirements throughout the crop cycle. By limiting water applications to drought-sensitive growth stages, this practice aims to maximize water productivity and to stabilize -rather than maximize yields [11]. In areas where water is the most limiting resource to production, maximizing water use efficiency may be more profitable to the farmer than maximizing crop yield. This is because the water saved when deficit irrigation is applied becomes available to irrigate more land. In the arid region, irrigation is the dominant factor influencing agricultural production [12].

Effect of Deficit Irrigation Some Crop Produced in Ethiopia

Maize ( Zea mays L.)

Severe water stress affects maize grain yield during tasseling, silking and early grain-filling stages. Hence other agricultural inputs need to be appropriately used to enhance productivity by maintaining improved water use efficiency since WUE has increased with decreasing water application which, however is also related to decreased grain yield [13]. Different authors [14-16] revealed that the maximum yield of maize was obtained when the entire crop water requirement is fulfilled, practicing deficit irrigation could increase the irrigated area as a result of high water use efficiency. Therefore, deficit irrigation technique is much important where a limited amount of water is available for irrigation and irrigation water management is very poor.

Wheat ( Triticum aestivum L.)

There is spatial and temporal competition for both quality and quantity of water due to human activities like population growth, urbanization, increased living standards, growing competition for water and pollution. “Wheat is one of the major food security crops in Ethiopia but its productivity is reduced due to water scarcity, especially during the off season. Addressing these problems might be essential to increase water use efficiency” [17]. Practicing deficit irrigation used to improve water use efficiency with insignificant wheat grain yield reduction that leads to save irrigation water volume under moisture stressed condition [18,19].

Common bean (Phaseolus vulgaris L.)

Common bean crop is an important commodity in the cropping systems of smallholder farmers for food and income generation in drought-prone areas of Ethiopia [20]. Extreme water deficit can affects agricultural production particularly, short season growing grain legume crops such as common bean. Different author’s described that, moderate to high drought stress can reduce biomass, number of pods and seeds, days to maturity, harvest index, seed yield and seed weight in common bean [21,22]. Ghassemi-golazani, et al., reports that percentage of ground cover and number of grain per plants are the most important traits for estimating yield potential of common bean cultivars under both well and limited irrigation conditions [23]. Heshmat, et al., reports that Leaf Area Index (LAI), Relative Leaf Water Content (RLWC) and grain yield decrease with increasing water stress [24]. Addisu, et al., reported that, practicing of deficit irrigation leads to increment of area irrigated with the water saved to compensate for the yield loss by improving water productivity of common bean crop [25].

Soybean ( Glycine max L.)

Soybean is one of the essential food crops of the world and is becoming an important industrial and multipurpose crop. In Ethiopia, soybean is a multipurpose most nutritionally rich crop as its dry seed contains the highest protein and oil content [26]. Precise knowledge of soybean response to water stress and investigation of drought tolerance varies by growth stage, cultivars needs to be conducted [27]. According to 65% of soybean evapotranspiration occurred during the seed filling period and showed a major sensitivity to moisture stress during this period [28].

Potato ( Solanum tuberosum L.)

Potato crop is one of the most essential crops in the world are frequently served whole or mashed as a cooked vegetable [29]. Potato is very sensitive to water stress and tuber yield may be considerably reduced by soil water deficits due to its sparse and shallow root system [30]. Therefore, irrigation is always needed for production of high yielding crops [29]. However, the increasing worldwide shortage of water resources requires optimization of irrigation management in order to improve Water Use Efficiency (WUE). Increase the efficiency of use of the water that is available is an important for higher yields per unit of irrigation water applied.

Onion ( Allium cepa L.)

Among horticultural crop onion is one of the most highly consumed than other vegetable crops in Ethiopia [31,32]. According to “when water deficit is imposed early in the growing season, maximum yields of onion could easily be sustained provided adequate watering conditions take place during the rest of the growing season” [33]. Further the authors concluded that, critical period for onion irrigation is the bulb formation growth stage. This period coincides with the highest irrigation requirement and the crop cannot withstand water stress without substantial reduction on yield. On the other hand described that higher water productivity can be obtained by stressing onion crop by one-quarter deficit at developmental and/or bulb formation stage than stressing by one-half [34].

Conclusion

Deficit irrigation is an optimization strategy in which irrigation is applied during drought-sensitive growth stages of a crop. Deficit irrigation techniques can be applied to several crops, like maize, common bean, soybean, potato, wheat and onion particularly in arid and semi-arid area in order to improve water use efficiency and save water. Better understanding on the vulnerability of each developmental phase of plants to water deficits as well as drought tolerance mechanism of crops are also important in order to set the most appropriate deficit irrigation level for each crops.