IMPROVING WATER USE EFFICIENCY IN AGRICULTURE

By DR. AMAN ULLAH CUAUDHRY
Department of Agronomy, University of Agriculture,
Faisalabad Pakistan. Email uaf_amanullah@yahoo.com

Jan 17 - 30, 2005

For water resources sector, the country should adopt the theme crop per drop. All of our policies, projects, development and thought should be addressed toward this theme. The water resources development agenda may be that one-half of the increase in the demand for water by 2025 should be met by increasing the effectiveness of irrigation. While the remaining water needs should be met by dams and the conjunctive use of aquifers. For effectiveness of irrigation, lining of canals, watercourses, construction of water storage at farm level and research, development, and joint venture in sprinkler, drip, trickle, micro-spray, center pivot irrigation and hydroponics green house production is necessary. This strategy will result in creating employment opportunities and for reduction of poverty in the country.

Future water scarcity presents the single biggest threat to food production. As the world population has increased since the 1960s, irrigated land has remained relatively stable at about 0.045 hectare per person. In contrast, arable land area per capita decreased from 0.38 hectare to 0.28 hectare per person in 1990. Irrigated land comprises 15 percent of the arable land in the world and produces 36 percent of the food. Two-thirds of the world's irrigated area is in Asia. Nearly 70 percent of the grain in China and almost 50 percent of the grain in India is harvested from irrigated lands. The FAO estimated that almost two-thirds of the increase in crop production that is needed in developing countries in the upcoming decades must come from an increased yield per unit of land area; one-fifth must come from increased arable land area and one-eight from increasing cropping intensity.

Water being lifeblood for agriculture, industry and domestic activities has become a dwindling natural resource on this contemporary globe. Developed and developing countries are striving hard to harvest and develop new water resources for future needs. It is anticipated as a major reason for future wars among nations. Per capita availability of surface has been gradually dwindling in Pakistan from 5400 cubic meters in 1951 to 1300 cubic meters in 2002. It has been projected that by 2005 per capita availability of surface water may hit 1000 cubic meters, which is a threshold for defining a water short country.

The Indus river basin system has multipurpose dams and reservoirs, nineteen barrages and headwork's, forty five independent main canals and twelve link canals covering about 90,000 villages and stretching over 40,000 miles in the country. The water entering the rivers aggregates to about 145 million acre feet per annum. Of this, about 109 million acre is transferred to canals annually and remaining 40 million acre feet flows down into sea, because of lack of storage capacities. The volume of water entering irrigation watercourses from canal amounts to 78 million acre feet per annum. Water obtained from 70,000 public and private tube wells for irrigation purposes has been estimated at 44 millions acre-feet annually. Thus the total water from both canals and tube-wells is about 122 million-acre feet. The agriculture sector was never able to make optimum advantage of the available water resources mainly due to the inefficient water management. Of the 109 million acre feet water entering the canals each year, about 28 million acre feet is lost in transit due to a number of factors. Besides about 45 million acre is lost within the watercourses.

The three rivers now with Pakistan Jehlum, Chenab and Indus water only flows from 70 to 100 days. If we don't store this water, it will flow to the sea. If this water is stored in dams it may be used throughout the year. For storage purpose we have three main dams namely, Terbela, Chashma and Mangla. Sedimentation is reducing their storage capacity day by day. Our neighboring countries like India and China have built 4200 and 22,000 large dams since 1948 respectively. So there is need of immediate construction of new dams.

As a result of global warming, intensity of precipitation is decreasing every year. More than 80 per cent area of Pakistan receives on average annual rainfall of less than 15 inches, which is insufficient for sustainable agriculture.

Domestic waste should be used in the country for irrigation only after treatments. At present the use of this water as such for producing vegetables around cities is causing problem to human health.

There is substantial loss of water from irrigation system. We need improvement of a farm water management system, improvement of water supply from surface and ground water, operation, maintenance, management and rehabilitation of canals and watercourses.

In projecting global water demands one international study concluded that one-half of the increase in the demand for water by 2025 could be met by increasing the effectiveness of irrigation. While small dams and the conjunctive use of aquifers could meet the remaining water needs, medium dams will certainly be needed.

PROMOTING IRRIGATION EFFICIENCY

One study offered four options for enhancing water use efficiency in irrigated agriculture. This study pointed out that focusing on only one category will likely to be unsuccessful. The four options are:

AGRONOMIC

Crop management to enhance precipitation captures or reduces water evaporation (e.g. crop residues, conservation till, and plant spacing): improved varieties; advanced cropping strategies that maximize cropped area during periods of lower water demands and/or periods when rainfall may have greater likelihood of occurrence.

ENGINEERING:

Irrigation systems that reduce application losses, improve distribution uniformly or both; cropping systems that can enhance rainfall capture (e.g., crop residues, deep chiseling or Para tilling, furrow diking, and dummer-diker pitting).

MANAGEMENT:

Demand-based irrigation scheduling; slight to moderate deficit irrigation to promote deeper soil water extraction; avoiding root zone salinity yield thresholds; preventive equipment maintenance to reduce unexpected equipment failures.

INSTITUTIONAL:

User participation in an irrigation operation and maintenance; water pricing and legal incentives to reduce water use and penalties for inefficient use; training and educational opportunities for learning newer, advanced techniques.

Different countries are carrying out a range of programs to improve their use of irrigation water. Below is a selection of successful projects now in operation.

KOREA

In Korea fertigation is practiced as a method of enhancing the efficiency of water use and fertilizer application. Irrigation efficiency through fertigation is measured using hardware and software management tools. The recently developed Korean auto-irrigation system covers a number of plots, and can irrigate several plots at the same time. It uses an electronic tensiometer to measure the level of soil moisture, and an electric flow meter as a watering gauge. This system provides accurate and uniform application of water and fertilizer at a lower labor cost.

JAPAN

Japan taps its biggest river in Kyushu Island, the Chikugo River, for irrigating diversified cropping system through water re-use and recycling. This is made possible through the canal-reservoir network systems that can be found in the river's downstream portion. In these lowland areas, water demand for irrigation is higher than potential water supply because of the river's relatively small basin.

Farmers practice the Ao-intake method as a means of maximizing the amount of stored water. During high tide, water pours in through the intake gate. Use of available water is maximized by a massive system of pipelines and pumps, as well as open canals. The main pipeline and pump systems are managed by Water Agency. Newly organizes Land Improvement Districts and the Local Government Units manage the operation of creeks, lateral canals and drainage systems. Coupled with these developments is the transformation from rice-based farming to multiple cropping. The area planted in soybean and wheat is expanding, in contrast with the area planted in rice.

PHILIPPINES

The National Irrigation Administration in the Philippines has implemented a number of projects to enhance irrigation efficiency. The focus is on the establishment and capability development of Irrigators Associations Improvements in the performance of irrigation systems can be attributed, not only to improved infrastructure and facilities, but also to the involvement of farmer-beneficiaries, from project planning to operation and maintenance of irrigation facilities. To effectively tap farmers' participation, pilot learning laboratories have been established. It has been policy to help farmers organize into Irrigation Associations. A common practice now in the Philippines is the pressurized irrigation system, which uses drip and sprinkler systems. More than 21, 600 hectares are now irrigated in this way, mainly in Mindanao, much of which is planted in high-value crops such as banana and mango. Pressurized irrigation system reduces non-beneficial evaporation, applies water uniformly to crops, reduce stress in plants, and helps increase the economic productivity of water. Pressurized irrigation system is appropriate in high-value production and other intensive cultivation. Irrigation systems for rice paddies depend partly on the scale of production. Paddy farms in Taiwan, Korea, and Japan are fairly small. However, irrigation and drainage practices are sophisticated, and considerable labor is needed to control gate operations. This become economically inefficient when labor coats are high. Rather independent management of irrigation water by farmers, the focus now is on rotational block irrigation. With ditches to recycle the overflow. This system helps reduce labor costs, and promote the use of mechanization.

UNITED STATES

In USA the types of irrigation systems used have changed dramatically through the years. Surface irrigation (various gravity methods) decreased from 63 percent of the total in 1979 to 50 percent in 1994, while low-pressure systems (e.g., drip, trickle and micro sprays) increased from 0.6 percent of the total in 1979 to almost 4 percent in 1994. One of the larger and more obvious changes was to center pivot sprinklers, which increased from 16.83 percent in 1979 to 30.27 percent in 1994.

OTHER COUNTRIES

Middle eastern countries and China have adopted high efficiency system. In Turkey sprinkler irrigation is used instead of flood irrigation.

TRANSFER OF WATER-SAVING TECHNOLOGIES

The international Rice Research Institute is conducting project on "Technology Transfer for Water Savings". The project aimed at developing a mechanism to bring water-saving technology to farmers. This involved selecting a pilot site, and assessing the needs and opportunities. A public seminar is then held to discuss water-saving technologies, and appropriate technology was selected. Demonstration on farms were set up, where two years of validation was carried out. This included regular collection and analysis of data, not only about the soils and crops, but also the economic returns and other socio-economic aspects. Regular discussion took place with farmers, and the technology was adopted according to feed back from farmers. Regular field days were held for farmers, to teach them about the technology. Finally, the technology was applied on a large scale, and extension materials were developed.

Some of the promising techniques to be tested at a pilot scale are as follows:

A. An important concept in deep-water irrigation cultivation technique.

This means providing the rice crop with surface irrigation when precipitation is plentiful. With this practice, less irrigation is needed and irrigation efficiency is improved. The water depth is increased gradually to 25 cm in keeping with the growth of the crop. The paddy field becomes a natural reservoir, which keeps recharging groundwater and continuously returning water to the system.

In Pakistan irrigation efficiency is low, as in Pakistan one kg of rice is produced with 3750 liter of water, while in China the same quantity of rice is produced with 1000 liter of water.

B. After Egypt, Pakistan is the second country, which has largest irrigated area. In Egypt and Pakistan 100 and 76 percent of the cultivated area is under irrigation. Experiments in Egypt have successfully reduced water budget for wheat by 70 percent.

C. The rain gun is pressure driven portable device that helps irrigate large tracts of cultivable land. The rain gun when compared to flood irrigation saves water by 50 percent. It also makes available the land use as water channels for cultivation. When compared to a sprinkler the throw and discharge of water is higher, thereby reducing the time consumed in irrigation. This saving in time translated into reduction in cost of irrigation when electricity is charged. Rain guns can be effectively used in irrigating crops such as sugarcane, tea, coffee, banana, turmeric, and ginger etc. The rain gun comes with a three different types of nozzles, 12mm, 16mm and 20mm. Nozzles can be fit as per the water requirements for the crop concerned. Te minimum pressure required is 2Kg/sq. cm.

The cost of production of sugar in Pakistan is very high as compared to other sugar producing countries. That is why sugar is not exported from Pakistan. The cost of production is largely determined by sugarcane yield, the sucrose content and sugar processing costs. Sugarcane yield in Pakistan are among the lowest in the world. In Pakistan climatic is not idle, since this is tropical plant. The rain gun method of irrigation may be tried on this crop to simulate tropical environment.

D. Hydroponics growing plants in sand, gravel or liquid without adding soil with nutrients, would help reduce freshwater consumption by using roughly one-hundredth the fresh water customarily needed for plants. This would leave the rest for human consumption, as well as for residential and industrial uses.

Water saving is of particular interest in New Mexico, Southeast America, Mexico and other water parched regions, including the Middle East and certain lands between India and Pakistan and northern China where the underground water supply is fast dipping. In all these places, the majority of water use is for irrigated agriculture rather than direct human consumption and other productive uses.

The US government is working with Mexico to develop on hydroponics and its uses. Survey have shown that 80 percent of New Mexico water use is agricultural, more than half of which goes into growing forage, mostly alfalfa. Preliminary indications are that hydroponics greenhouses in New Mexico could reduce the current 800,000 acre-feet of water used for agriculture to 11,000 acre-feet. In addition they can reduce the land used from 280, 000 acres of alfalfa to less than 1,000 acre.

ROLE OF FARMERS AT THE COMMUNITY LEVEL

The farmers' role development is crucial in enhancing water use efficiency. One example that exemplifies this is the San Benito Irrigators' Association in Victoria, Laguna, Philippines. Farmers in this area organized themselves through the assistance of the local office of the National Irrigation Administration. A continuous education program made members conversant with the operations and management of irrigation service. Farmers were able to adopt new technologies and increase their productivity. All members were given access to post harvest facilities.

A core project was the rehabilitation of old irrigation facilities. A participatory approach was followed. Farmers were given training and were involved in the project from planning and conceptualizing program and projects, up to implementation. To increase production income and maximize land use, farmers are practicing crop diversification (rice-watermelon). One policy of the irrigation association was that no water was supplied to farmers who did not have an official irrigation service fee receipt.

PROBLEMS

The problem can be categorized into technical, economic, institutional, social and political, and environmental. Some technologies that have been developed are not acceptable under local conditions. This is because of several factors, including lack of funds for large infrastructure projects, a lack of technical skills to automate irrigation system, and lack of adequate rainfall as one source of irrigation water. In developed countries, where funding is less of problem, the issues related to costs and benefits of large infrastructure projects are still under discussion. When governments make a large capital investment, there may be less concern to assess its cost effectiveness. Common among developing countries with small farms is the problem of collecting irrigation service fees. Most, if not all, experience a low rate of payment of fees. This low rate of collection leads to another problem, of poor infrastructure and irrigation facilities due to lack of funds. This in turn reduces the productivity of farms. The impact of intensive agriculture on the environment is another concern for almost all countries. The growing public awareness of the deteriorating water quality and widespread water pollution makes it imperative to develop a more holistic approach to water resources management.

CONCLUSION

There should be an integrated, holistic approach to irrigation management for positive impacts. Water use efficiency involves a wide range of factors such as farm size, soil condition, cropping patterns, agronomic crops, as well as the interplay of socio-political and economic aspects of allocation, management, and utilization of water.

Farmer's participation in the planning, implementation, monitoring and evaluation of irrigation projects is important. Also, a well-organized water users group or irrigation association must be in place to enable members to undertake operations and maintenance.

Pakistan should harvest ad develop new water resources for present and future needs. Pakistan should develop storage facilities at rivers, streams in form of large, medium and small dams. There is also a need for building water storage facilities at the farm level, so that water can be used by high technology irrigation system throughout the year. This will result in increasing the intensity and productivity of crops.

The agricultural and industrial sector should be able to make the optimum advantage of the available water resources by efficient water management i.e., by reducing water losses in canals, watercourses and at field level.

There should be project for rain harvesting and use of domestic wastewater.

Pakistan can learn from the successful high technology projects in operation in other countries. Our private sector should come forward and have joint venture with other countries for development of drip, trickle, micro spray, and center pivot sprinkler and rain gun irrigation. In Pakistan, farmers to meet the increasing water demand of crops are using brackish water, which is resulting in the destruction of national soils. Pakistan should encourage the farmers by giving incentives to adopt efficient advanced irrigation technology, which will result increase in crop productivity and intensity. These Technologies can be immediately used for high value crops such as fruit crops and intensive agriculture.

For enhancing water use efficiency there should be equal focus on options such as agronomic, engineering, management and institutional.

Pakistan should invest in research and development and joint ventures in drip, sprinkler and hydroponics greenhouse production, particularly in parts of country with severe water shortage. The development and use of these technologies will be important for creating employment and reduction in poverty.