Hybrid Irrigation Method for Improving Surface Irrigation

Efficiencies and Crop Water Productivity

Abdrabbo A. A. Shehata Aboukheira, Associate Research Professor,

Ahmed M. Abdel-Fatah, Researcher, Youssri Atta, Research Professor

Water Management Research Institute (WMRI), National Water Research Center (NWRC)

Address: NWRC’s Premises P. O. 13621/5, Delta Barrage, Kaliobiya, Egypt

Voice: (+202) 42189458, Fax: (+202) 42189561, E-mail: abdo23870@gmail.com

Executive Summary: Egypt has a large and growing population currently estimated at over 90 million and expected to rise to exceed 140 million by the year 2050 if present growth rates continue. The country is almost entirely desert with virtually no rainfall. The country’s renewable water resources are restricted to the flow of the Nile River, although there is limited exploitation of non-renewable underground water in the oases of the Western Desert. Egypt’s share of the Nile River flow is governed by a treaty signed with its southern neighbor Sudan in 1959 and set at 55.5 billion cubic meters per year. Since the national water supply is fixed at this amount, continued population growth inevitably means increasing national water scarcity, and Egypt is already well under the international standard of 1,000 cubic meters per person per year. Over 85% of the annual water supply is devoted to agricultural production, and Egyptian farmers practice on of the most intensified forms of irrigated agriculture in the world, achieving global records for yield per hectare in a number of major food crops. Despite impressive gains in the 1980s and 1990s, agricultural production has not kept pace with population growth, and Egypt has a net food import bill of over $6 billion.

In Egypt, under limited water supply conditions, providing additional resources will be an expensive option. Therefore, efforts in the optimal management of water resources should concentrate on the demand management side. As the agricultural sector is consuming the bulk of water supply, good management of irrigation water can be translated into significant amount of saving in the water resources. In addition, the agriculture sector will be most affected by water shortage and would be asked to give water to other uses such as the domestic and the industrial sectors. Consequently, increasing the efficient use of water in the agricultural sector would be an overarching goal in changing certain policies or adopting new technologies with the objectives of improving on-farm water management and maximizing agricultural return per unit of water.

In the 2.31 million ha of the old lands of the Nile Valley and Delta, most farmers still use primitive methods of irrigation, fertilization, and weed and pest control practices. The application of fertilizers is usually by hand with low efficiency, resulting in higher costs and environmental problems. Surface irrigation is typically practiced in short furrows surrounded by small basins for irrigating most crops, except those such as rice that are grown in ponded water. This method is inefficient in the following respects: (1) Water is

used excessively because flowrates are not uniform; (2) Labor is wasted in construction of checks, furrows and water manipulation; (3) 10 - 20% of land is wasted in borders, furrow ends and small canals; and (4) Poor uniformity and distribution of irrigation water results in waterlogging, salinization, and low distribution and application efficiencies of surface irrigation (35-65%) in the Nile Valley and Delta. In the last two decades, replacing surface irrigation with precise irrigation systems became the main interest of the decision makers and policy planners in Egypt. Land fragmentation, capital and operating costs, profitability, and the need to qualified labors are the main challenges of converting from surface to pressurized irrigation systems. Surface irrigation systems can be as efficient as most other irrigation methods. To achieve the high efficiency and uniformity of surface irrigation systems, all parts of an irrigated field should receive water for near equal period of time, with a minimum of water lost to runoff or to deep percolation below the root zone. In addition to several practices, land smoothing, reuse of tailwater (i.e., reuse of water that runs off the downstream end of surface irrigated fields), cutback irrigation, and surge-flow irrigation can be employed to improve the effectiveness of surface irrigation. Best management practices and strategies improved the efficiencies of surface irrigation but still below level compared with pressurized irrigation methods, so looking for innovative ideas and highly efficient improvements for surface irrigation modernization is an urgent need.

Rice is the staple food for nearly half the earth’s population. Irrigated rice cultivation claims more than half of the water extracted for human activities in different regions of the world. One kilogram production of rice in irrigated fields consumes 2 to over 5 m3 of water, while the theoretical minimum at the crop scale is as low as 0.6 m3. The traditional practice of permanently flooding rice fields increases breeding habitats for malaria vectors. Particularly, rice has become one of the most important Egyptian exports in the agricultural sector. Rice cultivated area is growing gradually in the Nile Delta. It increased from about 280,000 ha by the mid-70’s to about 0.8 million ha in 2013. This rapid increase in rice cultivation has resulted from increasing its profitability compared to other crops. The drastic increase in water use in rice cultivation is augmenting the pressure on water supplies; it consumes about 29-50% of the total water budget of Egypt, and threatens to undermine the availability of water for reclaiming new lands.

This case study presents the first findings of an ongoing research to develop and evaluate an innovative irrigation method named “hybrid irrigation method”. The new method is a compromised solution to overcome the disadvantages of surface and pressurized irrigation methods. These first findings are the optimum plot area per outlet for irrigating wheat, raised-bed management practices of rice and corn under hybrid irrigation method in clay soil of the east Nile Delta of Egypt, and the feasibility of using hybrid irrigation method for irrigating rice and vegetable gardens for food security and rural income sustainability in Mali and sub-Saharan Africa.

The theory of hybrid irrigation method is to maximize water distribution efficiency as much as of pressurized irrigation systems by using a network of pipelines which decrease water losses by eliminating evaporation, deep percolation, surface run-off, and seepage, that occurs under normal conditions of surface irrigation using earthen

ditches. Moreover, application efficiency was modified by delivering water under pressure inside the field plot to minimize advance time, which results in decreasing water losses and ensuring that the depths and discharge variations over the field are relatively uniform and, as a result, available soil water in the root zone is also uniform.

Hybrid irrigation is accomplished by causing water to flow under pressure over the land surface through the same components of sprinkler or microirrigation irrigation networks (mainlines, sub-mainlines, and manifolds; except the lateral lines and distributors which replaced by outlets, each outlet is designated for irrigating a certain field plot). The outlets are devices that release water from high-head pipelines into basins, borders, and furrows (i.e., in the multi-outlet hybrid irrigation system, the outlets consist of a riser pipe and one or more valves to control the flow). The outlets should release into fields without causing erosion. They may include alfalfa or orchard valves, various types of hydrants, gated pipes, perforated pipes, different sizes of hoses, etc. Seven irrigation systems could be classified as hybrid irrigation systems, which are multiple-inlet, multi-outlet, simulated LEPA (Low Energy Precision Application), low-head bubbler, micro-flood, perforated pipes, and gated pipes irrigation systems.

Hybrid irrigation systems design begin when the desired combination of irrigation time, stream size, inflow time, basin dimensions, and the number of basins irrigated per set have been identified. In this regard, a field experiment was conducted to examine the optimum irrigated area per outlet of the multi-outlet hybrid irrigation system for irrigating wheat in the clay soil of the east Nile Delta of Egypt during the winter season of 2007/2008. Three irrigated areas per outlet (350, 525, and 700 m2) were studied. The results revealed that increasing the irrigated area per outlet from 350 to 700 m2

increased advance time from 4.7 to 12.1 min/outlet, respectively. In addition, increasing the irrigated area per outlet by 100% from 350 to 700 m2 increased total applied water from 3580 to 3970 m3/ha and decreased crop water productivity from 0.99 to 0.86 kg/m3, respectively. In general, application efficiency modified for all treatments as much as the average application efficiency of sprinkler irrigation systems (82-84%). In particular, application efficiency decreased by increasing the irrigated area per outlet from 350 to 700 m2 (84-82%), respectively. The results concluded that the optimum irrigated area per outlet is 350 m2 because it decreased water losses in the root zone and optimized water use.

Two field experiments were conducted in clay soil of the east Nile Delta of Egypt to investigate the optimum raised-bed width using the multi-outlet hybrid irrigation system for irrigating corn and rice crops. First, a 2‐year field experiment (2005-2006) was conducted to examine the effect of raised-bed width (80 and 160 cm) compared with traditional furrow irrigation on corn production. The results revealed that water saving (30 and 54%), grain yield (6 and 9%), and crop water productivity (52 and 131%) were increased by increasing the width of the raised bed under the multi-outlet hybrid irrigation system (80 and 160 cm) compared with traditional furrow irrigation, respectively. Second experiment was conducted on rice cultivation with two different width of raised-bed (60 and 80 cm) compared with traditional furrow irrigation during two summer seasons of 2006 and 2007. The interactive effect of raised-bed and the multi-outlet hybrid irrigation system saved water by 33 and 38%, increased paddy yield by 4

and 6%, and, as a result, improved crop water productivity by 56 and 75% with the 60 and 80 cm width of the raised-bed technology compared to the traditional furrow irrigation. The results concluded that the wider raised-beds (160 and 80 cm) are the most efficient and profitable for corn and rice, respectively, due to improving soil water availability redistribution in the root zone.

A feasibility study was carried out to evaluate the profitability of applying the multi-outlet hybrid irrigation system for irrigating rice and vegetable gardens in Mali and sub-Saharan Africa in 2011. The study indicated that the advantage of the multi-outlet hybrid irrigation system over gravity irrigation system for rice production is about US $ 1062. On the other hand, the multi-outlet hybrid irrigation system increased the net income of producing onion by 80% compared to manual irrigation by jugs. Furthermore, for both crops, the multi-outlet hybrid irrigation system changed the opportunity of agricultural production from mono-crop to multi-crop system in three consecutive seasons per year by increasing the cultivated areas per family and controlling irrigation and drainage water.

In Egypt, the multi-outlet hybrid irrigation system was adopted by the irrigation sector of the Ministry of Water Resources and Irrigation and the Ministry of Agriculture and Land Reclamation to be implemented at large scale level and to be the new model of the Irrigation Improvement Project in the west Nile Delta of Egypt. The innovative system was implemented in about 504 ha on Neckla Canal at El-Beheira Governorate in the east Nile Delta and the plan is to use the multi-outlet hybrid irrigation system model in all ongoing and future irrigation improvement projects around the country. In addition, some orchard producers were adopted the system for irrigating about 3.8 ha of citrus trees in the east Nile Delta.

Ultimately, first findings of field experiments and the feasibility study concluded that the hybrid irrigation method is optimizing water use and maximizing yield compared with surface irrigation and pressurized irrigation methods. The hybrid irrigation method saves water, energy, fertilizers, and money; moreover, increases yield of rice, corn, and vegetables and farmer’s income; in addition, it protects the environment and decreases health risk. Therefore, the hybrid irrigation method should be adopted and expanded for achieving food security and rural income sustainability in arid and semi-arid areas, as well as depressed areas in Sub-Saharan Africa.

Keywords: Surface irrigation, distribution and application efficiencies, Mali, Egypt, raised-bed, rice, corn, wheat, feasibility study, vegetables, advance time, pressurized irrigation