Water use efficiency and productivity for rice (oryza sativa) in the Bontanga irrigation scheme of northern region of Ghana.

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1 Agricultural Science Research Journals Vol. 2(7), pp , July 2012 Available online at ISSN-L: International Research Journals Full Length Research Paper Water use efficiency and productivity for rice (oryza sativa) in the Bontanga irrigation scheme of northern region of Ghana. *Abdul-Ganiyu S, Amaanatu MK and Korese JK Department of Agric. Mech. and Irrigation Technology, Faculty of Agriculture, University for Development Studies, P. O. Box TL 1882, Tamale. *Corresponding Author s sruad@yahoo.com Abstract Rice is one of the most important cereal crop cultivated in the Bontanga Irrigation Scheme during dry season. The crop performance is sensitive to irrigation practices; however, there is no adequate information on water productivity for the crops cultivated by the Scheme. The study was therefore conducted to determine the water use efficiency and productivity of rice cultivated during the dry season. Data on the yields of dry season rice and crop management practice information were obtained from the Scheme while climatic data was obtained from the Meteorological Agency of Tamale for the determination of crop water requirement and productivity. The results indicated that, mm of water was required for its growth, development and maturity. The average yield of paddy rice was 3.6 tons/ha while the average water productivity was 0.43 kg/m 3 in the Scheme. Application of proper irrigation schedule by the management would bring about better water use efficiency for improved rice yield. Key words Irrigation scheme, water productivity, irrigation schedule, crop water requirement, rice. INTRODUCTION Water is essential for agricultural production. The moisture needs of crop are fulfilled by water stored in the soil through precipitation received at the surface or applied as supplemental irrigation. Precipitation and snow melts are the only sources of fresh water that is stored in above-ground reservoirs or groundwater aquifers below the surface. More than 80 90% of the stored water is used for agricultural production (Jensen, 1984). The growing world population requires increased food production, while less water resources are available for agriculture. This alarming situation can only be resolved if water is managed more efficiently, so that crop yield per unit of water consumption increases (World Bank, 2003). Water productivity is defined as the ratio of the net benefits from crop, forestry, fishery, livestock, and mixed agricultural systems to the amount of water required to produce those benefits (Steduto et al., 2007). In its broadest sense it reflects the objectives of producing more food, income, livelihoods, and ecological benefits at less social and environmental cost per unit of water used, where water use means either water delivered to a use or depleted by a use. Put simply, it means growing more food or gaining more benefits with less water. Physical water productivity is defined as the ratio of the mass of agricultural output to the amount of water used, and economic productivity is defined as the value derived per unit of water used (Steduto et al., 2007). Water productivity is also sometimes measured specifically for crops (crop water productivity) and livestock (livestock water productivity). To feed a growing and wealthier population with more diversified diets will require more water for agriculture on an average annual basis. Evapotranspiration from agricultural land is estimated at 7,130 cubic kilometers and without increases in water productivity could increase by 60% 90% by 2050 (Steduto P, Kijne JW, Hanjra MA, Bindraban PS, 2007). Improving physical water productivity in agriculture reduces the need for additional water and land in irrigated and rain fed systems. Thus a critical response to increasing water scarcity, including

2 Abdul-Ganiyu et al. 363 the need to leave enough water to sustain ecosystems and to meet the growing demands of cities and industries. Water productivity, is an accurate indicator of agricultural productivity in relationship to the crop s consumptive use of water (World Bank, 2003). Evapotranspiration is the term used for total water consumption of the crop; it includes water loss due to evaporation and plant transpiration. Water productivity (kg/m 3 ) is defined as crop yield (kg) per accumulated actual evapotranspiration for the growing season (m 3 ) (World Bank, 2003). Deficit irrigation is a strategy that allows a crop to sustain some degree of water deficit in order to reduce costs and potentially increase income. It can lead to increased net income where water costs are high or where water supplies are limited (Kirda C, Moutonnet P, Hera C, Nielsen DR, 2002). Analysis of agricultural yield must include the crop water consumption, especially in semi-arid and arid zones. Crop yield per unit of water consumed, or water productivity, is a key element in successful water resource management (World Bank, 2003). Optimization and minimization of water to be applied to crops is essential in irrigation system. Yields of crops are adversely affected with excess or inadequate water supply. Yields can be considerably increased by adopting proper irrigation management. For proper irrigation management, scheduling of water is essential as said by Tan (1980). Irrigation scheduling is the process by which an irrigator/farmer determines the timing and quantity of water to be applied to the crops. According to Tan and Lanye (1981) for proper irrigation management the challenge is to estimate crops water requirement in the context of growth stages and climate.the amount of water required by plants depends upon the crop water requirement. Allen RG, Pereira LS, Raes D, Smith M (1998) refers water requirement as the amount of water that is lost through evapotranspiration. So the evapotranspiration is an important parameter in scheduling. Irrigated rice-based cropping systems are among the major water users globally and account for around half of all diverted freshwater in Asia. Rice is usually irrigated with 2 to 3 times more water than other irrigated cereals (Tuong TP, Bouman BAM, Mortimer M, 2005). The increasing scarcity of water and competing claims on water by other sectors (CA, 2007; FAO, 2003) require that agriculture uses water resources more efficiently than in the past. According to Mobil and Okran (1985), rice has been cultivated in Ghana for a long time. The irrigated rice schemes contribute about 25% of the total national rice production (Manful JT, L Hammond, 1998). Rice is important to Ghana s economy and agriculture, accounting for nearly 15% of the Agricultural Gross Domestic Product (Day G, P Oldham, J Achampong, A Opoku-Apau, A Langyintuo, 1998). The rice producing area represents about 45% of the total area planted to cereals in Ghana. The rice sector is an important provider of rural employment. Rice is now an important staple food for many Ghanaians. Its consumption increased from 11.5~26.7 kg/person/year between 1980 and 1995 (FAO, 2000). Rice production in Ghana has increased from 1970 to 2000 metric tons, but it is still far below the consumption needs. Presently, the country imports much of its rice needs. It is estimated that 64% (120 million U.S. Dollars) of Ghana s rice needs of 520,000 metric tons is imported (Kwame O, Asubonteng, Benjamin A, Tsugiyuki M, Toshiyuki W, 2006). The average rice yield obtained by most small-holder rice farmers in Ghana is still very low ( tons ha -1 ). The yield sharply contrasts with the irrigated rice yields which vary from 3.5 to 7 tons ha -1 with an average of 4.6 tons/ha and the mean yield of sawah rice without fertilizer application estimated between 2 and 2.5 tons/ha (FAO, 2005). Although Ghana, like many sub-saharan African (SSA) countries is projected to experience economic rather than physical water scarcity by 2025 (IWMI, 2000), geographically disadvantaged settings within Ghana such as the Northern Regions where the Bontanga Irrigation Scheme is located often face severe physical water scarcity far beyond what is suggested by national average per capita water resources figure. A country with adequate water resources but lacking capacity to develop water infrastructure to supply water is referred to as economically water scarce, whereas a country with water resources insufficient to support its population, experiences physical water scarcity (IWMI, 2000). Cook et al. (2006a) point out that most water-scarce regions coincide with regions where most of the poor and foodinsecure people live. The Northern Region (NR), one of Ghana s northern regions is a typical case. Improving water productivity (WP) is one important strategy for addressing future water scarcity, which is driven particularly by increasing human population and potential climate changes. Although an understanding of WP is required to develop improved water management strategies, little is known about WP in irrigated systems in sub-saharan Africa (SSA) and the Northern Region (NR), Ghana, in particular. To address this problem, this study was conducted in the NR during the dry season to determine the water use efficiency and productivity for rice, and to assess the factors contributing to the variation in yield and water productivity of the crop in the Bontanga Irrigation Scheme. MATERIALS AND METHOD Study Area Bontanga irrigation scheme is located in the Northern Region of Ghana, in the Tolon Kumbungu district, it lies

3 364 Agric. Sci. Res. J. Figure 1. Map of Bontanga Irrigation Scheme between latitude and N and longitude and W (GIDA, 2011). Figure 1 shows the study area. The cropping area is divided in to two, upland and lowland, the upland is free draining soil and plots are designed for furrow irrigation. The upland area is for vegetables production and the lowland for rice production because of the nature of the soil that is heavily textured and irrigated by flooding. The system works under gravity from the dam through the canals, laterals and to the various farms. The maximum, minimum and dead storages of the reservoir are 25 million m 3, 20 million m 3 and 5 million m 3 respectively, two (2) canals and twenty eight (28) laterals aid in the distribution of water to the farms. Thirteen (13) villages benefits from the dam which includes Tibung, Kumbungu, Kpasogu, Dalun, Wuba, Kukuo, Kpong, Saakuba, Yiplegu, Voggu, Kushibo, Zangbalwe and Bagli. Source of Data Primary data was collected by means of observations, semi-structured questionnaires from the management at the project site. Data was also collected from key informants. Secondary data of dry season and average yields of pepper were collected in tones from the Bontanga Irrigation Scheme. Climatic records of over 30 years from

4 Abdul-Ganiyu et al. 365 Figure 2. Variation of Yield of Rice at the Bontanga Irrigation Scheme Table 1.Crop Water Requirement for Rice at Bontanga Irrigation Scheme Month Decade Stage Kc ETc ETc Eff rain Irr. Req. coeff mm/day mm/dec mm/dec mm/dec Dec 2 Initial Dec 3 Initial Jan 1 Initial Jan 2 Development Jan 3 Development Feb 1 Development Feb 2 Mid Feb 3 Mid Mar 1 Mid Mar 2 Mid Mar 3 Mid Apr 1 Mid Apr 2 Late Apr 3 Late May 1 Late May 2 Late Source: Field survey, 2011 Meteorological Services of Tamale. These were monthly averages for the minimum and maximum temperature, relative humidity (minimum and maximum), sunshine, wind speed, rainfall and geographic coordinates (altitude, latitude, longitude) for the period The CROPWAT 8.0 software was used to calculate crop water requirements (maximum evapotranspiration ETM), effective rainfall, reference evapotranspiration (ETo), and irrigation needs. This software uses monthly averages of the climatic parameters mentioned above. The ETo was calculated using the Penman-Monteith method, whiles the actual

5 366 Agric. Sci. Res. J. Table 2. Crop Water Productivity for Rice at Bontanga Irrigation Scheme Crop Year Yield (Kg/ha) ET act (m 3 ) CWP(Kg/m 3 ) 1996/ / / / / / / / / / / / / / Average Source: Field survey, 2011 crop water requirement was also computed using equation 1. Where ETc is crop evapotranspiration (mm/day), Kc is crop coefficient a ETref is reference evapotranspiration (mm/day). The crop water productivity also expressed by the equation (Molden, 1997; Ahmad et al., 2004): Where CWP is the crop water productivity (Kg m -3 ), Y, is the actual yield (Kg ha -1 ), ET act is the actual evapotranspiration (mm) and C is the conversion factor, 0.10 (ha/mm/m -3 ). RESULTS AND DISCUSSIONS Crop Water Requirement for Rice Table 1 show that, the total water requirement of rice grown in the irrigation field for days is mm with peak value of 7.77 mm/d, due to the climate of Northern Region. The cultivated varieties of rice at the scheme are the Jasmine 85 (140 days) and Tox (150 days) and all are cultivated once in the cropping year using floods irrigation with an irrigation interval of 5-7 day. (1) (2) Variation of Yield of Rice (Oryza sativa) The variation in yield of rice from 1996/ /10 is shown in figure 2. There was a sharp decline of yield below average in 1999/00 and 2004/05(2.5 t/ha) and an increase above average in 2006/ /10, with 1997/98 recording the highest yield of 4.3 t/ha. The low yield of rice could be attributed to farmers inability to apply the right quantity of fertilizers. According to the management, rice crops were attacked by birds which contributed to the low yields of 2.5 t/ha in 1999/00 and 2004/05, FAO (1999 & 2011). This indicated that, irrigated rice yield varies from 3.5 to 7.0 tons/ha with an average yield being 4.6 t/ha and the mean annual yield in Sawa without fertilizer application was estimated to be between 2.0 t/ha to 2.5 t/ha. However, the highest yield of rice in Bontanga Scheme falls within the range but does not meet the average yield of 4.6 t/ha. As indicated, the yield of 2.5 tons/ha fell below the average as shown in Figure 1 and could be attributed to lower amount of fertilizer application, late planting and overused of seeds. Since some of the farmers used seeds from their previous harvest, rice blast (fungus) and colour rot which were known to be the major diseases also attacked the rice at their booting stage in the irrigation scheme. Crop Water Productivity for Rice The crop water productivity of Rice was expressed using equation 3, (Molden, 1997; Ahmad et al., 2004; Rashidi et al., 2008). The crop water requirements was calculated from table 1 to be mm and with the yield data of the

6 Abdul-Ganiyu et al. 367 dry season collected from management at Bontanga Irrigation Scheme as shown in table 2 the value (9399 m 3 ) was then used as the actual evapotranspiration (ETact) in determining the crop water productivity (CWP) of Rice for the whole cropping seasons as shown in Table 2. The average crop water productivity for rice was 0.40 kg/m 3 in 1996/ /10 farming season, and this is in the range as researched by Cia and Rosegrant (2003), that, the average water productivity of rice will increase in from kg/m 3 in developing countries and from kg/m 3 in developed countries, as seen in table 2.0. There was a decline below average in 1999/ /01and 2004/ /06 cropping year and increased above average in 1996/91997/98, 2001/ /04 and 2007/ /10. However, it falls in line with the average in 1998/99 and 2006/07. This variability could be attributed to the irrigation practices, climatic conditions, late planting, overused of seeds, pest pressure, weeds and the inherent characteristics of the soil among others. NPK , urea or Ammonium Sulphate are the recommended fertilizers applied to rice by the farmers at the scheme. The recommended rate is as follows: for farmers cultivating rice in the Irrigation Scheme: NPK is supposed to be applied as basal fertilizer two week after planting at the rate of 300 kg/ha. The remaining N (Urea) should be applied at the rate of 100 kg/ha, as topdressing at panicle initiation stage. The farmers applied fertilizers by broadcasting. However, some of the farmers were not able to meet this recommendation for their crops, and as such used much lower rates of fertilizers than the recommended rate, which affected the productivity of rice in the scheme. For optimum and quality yield of rice, seeds should be purchased from accredited centers, early planting, control of weeds and pest, plant resistance varieties and timely application of fertilizer in right quantity and at the right stage. CONCLUSION The water requirement of rice for days was mm with peak application rate of 7.77 mm/d. The average yield was 7.3 t/ha and the crop water productivity also found to be 0.38 kg/m 3 in the Bontanga Irrigation Scheme. RECOMMENDATION For crop water productivity to improve in Bontanga Irrigation Scheme, there is the need for the management to adopt efficient water management strategies by training farmers and the water users association on irrigation water management so as to avoid wastage of water by farmers. REFERENCES Ahmad MD, I Masih, H Turral, (2004). Diagnostic Analysis of Spatial and Temporal Variations in crop Water Productivity: A Field Scale Analysis of the Rice-Wheat Cropping System of Punjab, Pakistan J. 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