This article presents the potential improvement in agricultural production from the Northern State of Sudan's 4 million ha arable lands using the great underground reservoir of the Nubian Sandstone Basin for enhanced food security in the region. Review of literature on crop performance under the prevailing gravity irrigation system and potential achievements using sprinkler irrigation are addressed in this article.
According to Food and Agriculture Organization (FAO) the area of Sudan is 1.8 million square km putting it the third-largest country in Africa following separation of South Sudan in July 2011 with an estimated total population of more than 33 million people. Eighty percent of the population derive their livelihood from agriculture but Sudan's abundant agricultural potential is still largely untapped. The major agricultural commodities produced in Sudan are cereals, oilseeds, sugarcane, cotton, vegetables and animal products.
The Northern State of Sudan (16 ° -22 ° N, 30 ° -32 ° E) is one of the most important regions in the country for agricultural production especially of winter crops. Research findings reveal the potentiality of the state to produce winter crops as compared with other parts of the Sudan. This is favored by a relatively longer and cooler winter season that extends for six months from October to March. Total area of the Northern State is 347,000 km² and it is dominated by the desert climate. Annual rainfall ranges between zero in the north and 100 mm in the southern parts, with mean summer and winter temperatures of 40º C and 12 Cº, respectively. River Nile is the main source of water crossing the state from south to north with a total length of 600 km. Underground water in the Nubian Basin which covers 70% of the Northern state's area with water depth ranging from 100-300 feet. Plant vegetation is very poor except in a narrow strip along both sides of the river Nile. Total population of the state was 700,000 in 2008 and the population density was 1.9 persons / km². Rural inhabitants constitute 86% of the population and irrigated agriculture is their main activity. According to the Northern State's Ministry of Agriculture, total arable land area is estimated at 4,000,000 hectares with large variation in physical and chemical soil properties. Only 10% of this area is cultivated every year especially in the winter season in spite of the large efforts excreted by the government to construct new schemes and introduce vast areas within the National Wheat Program (NWP) which was initiated in 1992 to increase the domestic wheat production by shifting its cultivation from central to Northern Sudan where climate is more favorable.
The main challenge is to solve the problem of high cost of production and low productivity at the field level. Potential wheat productivity is much higher at research level and a wide gap exists between research and farmers yield gains. This situation necessitates implementation of effective extension and technology transfer programs to increase farmers productivity levels to bridge this gap.
2. Surface versus sprinkler irrigation in Northern Sudan
The cost of irrigation is one of the major items comprising the total cost of production in the Northern State of Sudan. High prices of diesel used for irrigation, low efficiency of irrigation units and other problems associated with pumping water from the Nile and underground water are the main reasons. Pumping irrigation water is the main cost item leading to the known high cost of agricultural production in the Northern State.
Irrigation process follows three farming systems in the State depending on the scheme size, production relations and other factors. These are;
a- Small private pump schemes which mostly use three or four inches discharge pumps to draw water from the Nile or underground water and are mostly located at the alluvial highly fertile soils along the Nile (low terrace soils).
b- Cooperative schemes which are collections of small holdings usually irrigated using 8 and 10 inches diameter pumps and located in the middle terrace soils but some at the fertile lower terrace soils near Nile banks.
c- Large government schemes which are located in the high terrace soils (Far from the Nile on both sides) using large size pumps (12 inches diameter or more). These soils are characterized by poor fertility problems which can be solved in a medium to long – run improvement programs ..
Some previous studies showed that more than 40% of the total money spent on agricultural production in winter season is paid for irrigation. However, this percentage tended to decline in 2011 due to the rising cost of inputs specially fertilizers and pesticides. The main cost item for pumping irrigation water was found to be the cost of diesel as proved by a joint study in 2008. A significant variation existed in the cost of pumping irrigation water among large schemes and cooperatives depending on the pumping unit and canal system efficiency , Labor and administrative costs were the most important sources of variability among these schemes. The effect of previous government subsidy of diesel price to encourage wheat production did not significantly reduce the cost of pumping irrigation water. It was found that the cost of diesel alone amounted to 91% of the total pumping cost with subsidy as compared with 76% without subsidy. This proportion of diesel cost to the total pumping cost signals the urgent need for an effective intervention to reduce it to an acceptable level. This, among other reasons urged the government to launch a program of using electricity as an alternative source of energy specially after construction of Merowe dam which avails a sufficient supply of electric energy to meet the expected demand in the agricultural sector.
Earlier studies to explore possibilities of reducing the cost of pumping irrigation water using electricity as a source of energy showed promising results. The average cost of irrigation per hectare was found to be 281 Sudanese pounds (SDG), ranging from SDG 182 to 393. This cost is relatively high as compared with the international average cost of irrigation and even with what is prevailing in the surrounding region.
Comparison of irrigation costs showed that the average cost of irrigation is SDG 293 and SDG 260 for the cooperative and large schemes, respectively. This variation in the costs of irrigation between different schemes was attributed to differences in the efficiency of irrigation units. Low efficiency leads to higher spending on diesel, oil and periodic maintenance resulting in higher cost of pumping irrigation water. Difference in labor wages among the surveyed schemes has a significant effect on variability of the cost of pumping irrigation water. Supplying schemes with electricity is not only important for the agriculture sector in the Northern State but also helps to greatly improve competitiveness of the agricultural products in the international markets. This will violate the most important single limiting constraint to invade outside markets which is the high cost of agricultural production. The Northern State lies within the animal disease – free zone which is a great privilege for it. Adopting the necessary and right measures to grasp the maximum possible benefits from these advantages necessitates also the work to reduce the high cost of agricultural production which will gear up the pace of general development in the State.
The average value of money spent for diesel is SDG 217 / ha with subsidized diesel prices and this is equivalent to about 19 gallons of diesel representing 76% from the total cost of pumped irrigation water. The proportion of diesel in the total cost of pumping decreases to 68% with subsidized diesel prices. Money spent on diesel per one hour ranges from SDG 8 to 232, depending on daily operation hours, number of operating irrigation units, pumping efficiency and irrigation canal system efficiency. These values are generally higher for big government schemes. A project to use electricity as a driving source of energy for irrigation water using sprinkler system in the Northern State is vital. Agricultural production is predominantly practiced in the State using surface irrigation to pump water either from the Nile or underground water through mostly inefficient canal system. The joint effect of deep percolation and evaporation results in significant losses in the amount of water due to high temperature and light soils. It is evidentfrom the literature that saving conveyance losses can lead to significant saving in water pumped for irrigation and using sprinkler irrigation is the most effective means to demolish conveyance costs totally.
Using pivot sprinkler irrigation showed remarkable successes in the State as proved by the few established pivot driven agricultural schemes. The effect of using sprinkler irrigation on improving soil properties is equally important as its effect on reducing the total cost of agricultural production. A thorough look into the detailed impacts of using electricity in pumping irrigation water is crucial. Different scenarios can be developed for different situations to increase the resource use efficiency. The expected economic, social and environmental impacts of using electricity and sprinkler irrigation should be clearly assessed.
A detailed plan of work within the project to develop the agricultural sector in the Northern State should include two important short – run milestones:
– An immediate transformation from diesel to electricity as a source of energy to pump irrigation water in the State. This requires a careful study of the technical aspects of electrification and setting the priority in supplying the agricultural schemes based on a careful assessment of the expected impacts.
– Detailed comparative studies on the effect of using electricity and sprinkler irrigation effect on the cost o pumping, productivity level, competitiveness and marketing of different crops specially with in the light of the WTO's arena.
– A well formulated government policy to gain the maximum possible benefits of using electricity and sprinkler irrigation system in the Northern State is vital.
Based on the above arguments, it is necessary in the course of realizing food security for Sudan and the region to transform from the current inefficient canal based surface irrigation system in Northern Sudan to use sprinkler irrigation system using electricity as an alternative source of energy to pump irrigation water for the known benefits which can be proved by sound research projects.
Elrashid A. Fageer
Agricultural economist ( Irrigation economics specialist) – Agricultural Research Corporation (Sudan)