Drip irrigation

AGRICULTURAL TECHNOLOGY

Drip irrigation

With more than 15 million hectares of land watered by drip irrigation globally, the technology’s agricultural potential remains enormous. Fertigation – the ability to manage and regulate both water and plant nutrients – is a key advantage helping drive worldwide growth.

Cucumber growing in a greenhouse environment.

PHOTO: BORK/SHUTTERSTOCK.COM

In June 2012, David Hillel, an Israeli scientist who pioneered an innovative way of efficiently delivering water to crops in arid and semi-arid regions, was awarded the World Food Prize. The method Hillel helped develop, drip irrigation, supplies water directly to plant roots in small amounts – dramatically cutting crop water requirements and at the same time boosting crop yields.

The development of drip irrigation is arguably one of the most important agricultural advances of the last 50 years. Although more than 15 million hectares of land is watered by drip irrigation globally, the technology’s agricultural potential, and its use as a vehicle for delivering water-soluble fertilizers, is still in its infancy.

Double-digit growth

The thriving commercial market for drip irrigation equipment, currently worth $4.9 billion, is expected to grow by around 10 percent annually to reach $8.5 billion by 2025. The rising popularity of drip irrigation is linked to the need for water efficiency in drought-prone regions, and is also being boosted by government support programmes and subsidies. The ability to efficiently manage and regulate both water and plant nutrients is another key advantage that is helping drive worldwide growth in drip irrigation.

Drip irrigation has long proved profitable for watering vegetables and perennial orchard crops, and also has a strong foothold in the turf & lawn market. The technology is now finding increasing favour in the cultivation of field crops too – particularly corn, sugarcane, and cotton. Its ability to precisely deliver inputs to field crops in the correct amounts helps reduce costs and improve profit margins by lowering both water and fertilizer requirements. China and India are two key markets being targeted by drip irrigation manufacturers due to their large agriculture sectors.

Drip irrigation

Most farmers still irrigate their fields by flooding or watering the furrows between crop rows. Unfortunately, less than half the irrigation water applied to fields in this way actually benefits crops. The excess water is not necessarily lost, as some it will return to rivers or groundwater sources to be used again. Nevertheless, unnecessary abstraction of water for irrigation purposes can deplete freshwater supplies and result in evaporation.

Drip irrigation, originally invented and developed by Simcha Blass and his son Yeshayahu in Israel in the late 1950s, is one of the most significant advances in modern agriculture. Due to its water- and fertilizer-saving abilities, drip irrigation – also known as micro-irrigation, trickle irrigation or localised irrigation – has since become an increasingly common irrigation method for growing crops in greenhouses and fields.

In drip irrigation, drops of water are supplied at or below the surface, close to plants at very low rates (2-20 litres/hour) via a pressurised system of small diameter plastic pipes connected to outlets called emitters or drippers. Enough water is applied at regular intervals, usually every 1-3 days, to wet the root zone and provide the favourable high moisture conditions plants need to flourish.

Drip irrigation is more efficient than other methods which saturate the whole soil profile, such as surface and sprinkler irrigation, reducing weed growth and the leaching of plant nutrients. The drip irrigation of 100-200 plants typically consumes 40-80 litres per day. In arid and semi-arid regions, particularly in Israel and around the Mediterranean, recycled wastewater is often used to supply drip irrigation.

Fig. 1: Schematic of a drip irrigation system

Drip irrigation systems are suitable for commercial crops grown in rows, including vines, vegetables, soft fruits bushes and fruit trees, with one or more emitters allocated to each plant. Installation is generally only economic for high-value crops due to the capital costs involved.

A typical drip irrigation system (Figure 1) is made up of the following components:

• Pump unit: this delivers water from the source to the pipe system under pressure.
• Control head: this uses valves to control the system’s flow rate and pressure and may also contain screen filters and sand filters to clear the water by removing finely-suspended matter. Some control head units are fitted with a nutrient tank for fertigation. This allows fertilizers to be added to water in measured doses – one of the major advantages of drip irrigation.
• Mainlines, submain lines and laterals: these pipes distribute water from the control head to the field. They are usually made from PVC or PE plastic hosing and are often buried to prevent degradation from the sun. Lateral pipes are usually 13-32 mm in diameter.
• Emitters (drippers): these devices control the release of water to plants. They are usually spaced along laterals at more than a metre apart. One or more emitters are typically used for a single plant such as a tree, although they are generally more closely spaced when used for row crops. Emitters are designed not to block easily and should discharge water at a constant flow even when the pressure varies.

Drip irrigation systems require regular upkeep to maintain their efficiency. Leaks may develop due to pipe damage, for example, and emitters can also become blocked, even with filtered water. The build-up of salinity also needs to be monitored carefully, as salt can accumulate in soil along the edge of the wetting front. Additional irrigation may be also necessary during crop establishment as wetting from drip systems may not be enough to trigger seed germination.

On sloping land, drip irrigation laterals are generally placed in parallel with crop rows planted along contour lines. This minimises any potential variation in emitter discharge due to land elevation. Water needs to be applied slowly during the drip irrigation of clay soils to avoid ponding and run-off. Higher emitter discharges are used on sandy soils to ensure wetting is sufficient.

Because drip irrigation saturates a relatively small volume of soil, plants develop their roots in a small localised zone nearest to the water emitter. This limited root system is not problematic as long as favourable soil conditions are maintained, particularly low salinity and adequate aeration.

Inexorable rise

Drip irrigation was adopted agriculturally on a large-scale during the 1970s for fruit and vegetable production in Australia, Israel, Mexico, New Zealand, South Africa and the US. Compared to conventional flood or furrow irrigation, drip irrigation has the potential to reduce water use by up to 70 percent and at the same time increase crop yields by 20-90 percent.

The global area covered by drip irrigation systems has risen more than fivefold in the last 20-25 years, rising from three million hectares in 1996 to 16 million hectares currently (Figure 2), based on the latest figures published by the International Commission on Irrigation and Drainage (ICID).

The most dramatic expansions have occurred in two of the world’s top irrigators, China and India, where the area under drip irrigation has grown exponentially over the last two decades. The area cultivated under drip irrigation has accelerated particularly quickly in China and currently stands above five million hectares. Three other countries globally, India, Spain, and the US, each have more than 1.5 million hectares devoted to cultivation by drip irrigation. California, due to the concentration of fruit and vegetable growing within the state, accounts for around two-thirds of the area under micro-irrigation in the US, with Florida and Texas coming a distant second and third.

The switch from traditional irrigation methods to drip irrigation makes most economic sense for high-value crops grown in water-scarce regions. The resulting water savings can be considerable. In northwest China, for example, furrow or flood irrigation methods have an annual water demand of 7,320 m3 /ha on average, compared to only 3,250 m3 /ha for drip irrigation1 .

Drip irrigation is used without fertigation in most developing countries, with fertilizer dressings being applied by broadcasting and banding instead. In other countries, particularly Israel, the integration of fertigation has been a key factor behind drip irrigation’s rapid adoption. The simultaneous delivery of water and nutrients directly to the root zone is known to be advantageous (see box) for a number crops – tomatoes and other salad vegetables, for example – and also helps minimise nitrate-leaching losses1 .

Drip irrigation has been rolled-out to cover three-quarters of the total land under irrigation in Israel. Its success there is also undoubtedly linked to the fact that the method was originally pioneered in Israel, and because of other factors such as limited water availability.

Bestowing benefits

Drip irrigation is water efficient because it wets the soil sufficiently to satisfy the transpiration demands of plants – yet keeps soil evaporation losses and the deep percolation of water to a minimum. Application efficiencies as high as 0.9 are possible with drip irrigation, compared to 0.6-0.8 for sprinkler systems and 0.5-0.6 for surface irrigation1 .

Fig. 2: Drip irrigation: (a) top ten countries by land area, 2018/19; (b) land area compared to flood & furrow and sprinkler irrigation

Switching from flood irrigation to drip irrigation – by enabling crops to be grown on sloping land that was impossible to water previously – has also enabled irrigated land area to double in some regions, sugarcane cultivation in Maharashtra, India, being one notable example1 .

Another advantage of drip irrigation is its ability to balance soil aeration with wetting. During furrow and flood irrigation, in contrast, soils become waterlogged at times, reducing the supply of oxygen to roots. Valuable plant nutrients are also partially removed as excess water drains from the soil.

Installing the drip system beneath the soil surface further reduces evaporation and delivers water and nutrients directly to the root zone. In the Middle East, the switch from furrow irrigation to sub-surface irrigation has doubled wheat yields in some instances1 . Significant yield and water use efficiency improvements have also been reported for tomato, cotton, alfalfa and cantaloupe.

Much higher water use efficiencies are also obtained in sub-surface irrigation (1.643.34 kg grain/m3 ) than is possible with furrow irrigation (0.46-1.2 kg grain/m3 ). Soil nitrogen release is also much higher under subsoil irrigation (11-216 kg/ha) compared to furrow irrigation (11 to 33 kg/ha).

Markets and companies

The commercial drip irrigation market globally was valued at around $4.9 billion last year. The US has traditionally been the world’s largest market for micro-irrigation systems. But the Asia-Pacific region – India and China in particular – became the largest consumers of drip irrigation equipment in 2019. It is this region that also looks set to dominate market growth over the next five years.

Key global manufacturers of drip irrigation equipment and systems include:

• India’s Jain Irrigation Systems Ltd and Mahindra EPC
• Israel’s Netafim Ltd, Elgo Irrigation Ltd, Metzer Group and Rivulis
• US-based Lindsay Corp, The Toro Company, Rain Bird Corporation, T-L Irrigation and Dripworks Inc
• China’s Chinadrip Irrigation Equipment Co Ltd and Shanghai Huawei Water Saving Irrigation Corp
• Spain’s Sistema Azud and Grupo Chamartin (Chamsa)
• Antelco Pty Ltd in Australia and Microjet Irrigation in South Africa.

Four major players, Netafim, The Toro Company, Jain Irrigation Systems Ltd and Rain Bird Corporation, were thought to collectively control more than half of the global market for drip irrigation systems, as of 2016. Rivulis has, however, greatly expanded its global presence by recently opening a massive new equipment production plant in Leon, Mexico. The plant, the largest drip irrigation factory in the Americas, was expected to reach full capacity (the production of half a billion metres of drip line annually) by the end of 2019.

The global leader

Netafim, the global market leader in drip irrigation, celebrated its 50th anniversary in 2015. The firm has 28 subsidiaries, operates 16 manufacturing plants and employs more than 4,000 employees worldwide, enabling it to deliver systems and components to some two million customers in 110 countries.

In 2014, Netafim’s Indian subsidiary won a $62 million contract with state-owned Krishna Bhagya Jala Nigam Ltd for reportedly the world’s largest micro-irrigation project in the southern state of Karnataka. This involved Netafim building an automated drip irrigation network covering 11,800 hectares of land cultivated by around 6,000 farmers in the Bagalkot area of Karnataka.

The government-owned Ethiopian Sugar Corporation awarded Netafim the world’s biggest sugarcane drip irrigation project in 2015. Designed to boost the country’s domestic sugar production, the 7,000 hectare project – based at the Wolkaite sugarcane plantation – is fed by a 65-kilometre water pipeline and required the installation of a staggering 40 million metres of driplines.

Also in 2015, Netafim signed a $17 million contract with Vingroup, a major Vietnamese food retailer, for a 30 hectare greenhouse project, one of the largest in Southeast Asia. Netafim was contracted to supply greenhouses, drip irrigation and climate control systems, and agronomic services as part of the deal. This project has enabled Vingroup to directly supply its supermarkets with highquality, domestically-produced melons and leafy greens, 365 days a year.

The installation of a Netafim sub-surface drip system in the Philippines has also increased sugar cane yields by 90 percent, compared with a conventional centre-pivot sprinkler system, and cut water consumption by 70 percent – a huge increase in water productivity. The sucrose content of the sugarcane crop was also boosted by five percent, according to Netafim.

Other notable Netafim projects include:

• Azerbaijan: Five hectare tomato-growing polyhouse project for GP Alpha. The project’s precision irrigation system uses renewable energy and water sources to produce high yielding and high quality tomatoes all year round – while consuming 40 percent less water and fertilizers, compared to conventional growing practices.
• South Africa: Four hectare poly-house project for soilless cultivation of blueberries. The Netafim-designed advanced precision irrigation and fertigation system delivers premium quality fruit at a yield of around 28 t/ha.
• Kazakhstan: Two hectare glasshouse project for Atyrau Sauda in the country’s frozen Atyrau region. This produces 110,000 tonnes of cucumbers, tomatoes and other fresh vegetables throughout the year.

Additionally, Netafim has expanded the use of drip irrigation for cotton cultivation globally, notably in Australia, Egypt, Israel and the US.

Indian market giant

Jain Irrigation Systems Limited (JISL) is India’s largest and the world’s second largest micro-irrigation company. The company manufactures drip irrigation systems and components at a plant at Jalgaon. These are targeted at farmers growing apples, grapes, banana, sugarcane, tea, coffee, cotton, mango, teakwood, vegetables and flowers. According to Jain, drip irrigation typically cuts water use by 70 percent compared to flood irrigation – allowing more land to be irrigated – and also increases fertilizer use efficiency by 30 percent. The company has grown dramatically in the past 20 years, expanding twenty-fold between 2003 and 2010, and continues to grow strongly today.

10.3 million hectares of India’s cropland is currently equipped with micro-irrigation systems, according to the country’s ministry of agriculture. This represents just 15 percent of the 79.8 million hectares of Indian agricultural land that could potentially be micro-irrigated. To encourage adoption, the Indian government currently subsidises the installation of both drip and sprinkler irrigation systems by around 50-80 percent, depending on the state and the project concerned.

Jain, which has more than a 50 percent share of the Indian micro-irrigation market, should be well-placed to take advantage of future domestic growth opportunities. The company’s hi-tech business unit – which includes micro-irrigation – is a key earner, accounting for more than half of company revenues. Sector earnings are highly dependent on state support, however, as around 46 percent of micro-irrigation revenues last year came from government turnkey projects.

However, debt worries have seen Jain’s share price collapse by more than two-thirds over the last 18 months. The company is currently weighing-up the options for paying down debt and restoring investor confidence, including the potential divestment of its overseas micro-irrigation assets.

Nevertheless, Jain’s market position is bolstered by a strong project pipeline. For example, the company recently received a letter of intent from the government of Madhya Pradesh to execute the INR 9.8 billion ($137 million) Mohanpura micro-irrigation project. This pressurised pipe project aims to bring more than 92,400 hectares of land under micro-irrigation within a scheduled 36 month period.

Jain is also executing an integrated INR 2.4 billion ($33 million) drip irrigation project in the Wardha district of Maharashtra in India’s Vidarbha region. Some 65 villages in Arvi Taluka and more than 10,000 farmers should benefit from the 8,400 hectare project. The project, which is scheduled to be completed within 24 months, uses a pressurised piped network to distribute water from canals to on-farm micro-irrigation systems. This is expected to improve agricultural water use efficiency in the district from 35 percent currently to up to 90 percent.

Jain has also received an $18 million export order from the Rwandan government for a 1,752 hectare irrigation and watershed development project. This is being financed by EXIM Bank of India. Jain is responsible for designing, providing equipment and constructing the project’s gravity-fed irrigation systems. These include a mix of sprinkler irrigation, centre pivot and pipe hydrant systems. Jain says it plans to complete the project in the next 18 months.

Jain strengthened its presence in the US market in 2015 by buying PureSense Environmental Inc, a Californian irrigation management and field monitoring technology company.

Jain has also championed solar powered drip irrigation systems for off-grid farming in recent years. It has been working with Harvard University since 2013 on a solar irrigation project for village rice farmers in Bihar. In September 2016, the firm also won a e18.7 million Eritrean government contract to supply and install solar photovoltaic drip systems at 14 different locations in Eritrea. The project, which was due to take around 18 months to complete, should benefit 2,000 small-scale African farmers.

Rice is a notoriously water-hungry crop. So it is unsurprising that Jain is targeting the 43.8 million hectares under cultivation in India. Almost 85 percent of the fresh water consumption in India is for agriculture, much of which, some 70 percent, is used in paddy cultivation.

Trial results have been encouraging. Drip irrigated fields in Tamil Nadu consumed two-thirds less water to yield 22 percent more rice per hectare, in comparison to conventional paddy growing. The switch from paddy growing to drip irrigation by a commercial rice grower in Rajasthan increased crop yield by 25 percent and reduced water and electricity consumption by 40 percent each. The water saved enabled this farmer to expand the area of rice under cultivation from 2.8 to 4.8 hectares.

Untapped potential

Drip irrigation’s agricultural potential, and its use as a vehicle for fertigation, is still in its infancy, as Rabobank makes clear: “Only 40-45% of existing irrigation systems possess water-saving technologies… such as micro-irrigation… Water-saving irrigation systems can also help improve the efficiency of fertilizers and agrochemicals.”

Although the majority of irrigated crops still use surface or sprinkler methods (Figure 2), drip irrigation will continue to replace surface irrigation on farms where the water supply is costly and/or limited due to low rainfall, drought or other reasons. Drip irrigation can also be economic in situations where farmers have to compete with urban users for their water supply – as improvements in crop yield and quality can more than offset the equipment costs involved.

The wish to conserve water and reduce labour costs have often been the main motivations for switching to drip irrigation in the past. But the economic gains from better crop yields and quality – and more efficient fertilizer use – look like becoming increasingly important deciding factors in future.

References

1. Drechsel, P. et al., 2015. Managing Water and Fertilizer for Sustainable Agricultural Intensification. IFA, IWMI, IPNI and IPI, Paris, France.

2. IPI, 2003. Fertigation. Fertilization through Irrigation. IPI Research Topics No 23. International Potash Institute, Basel, Switzerland.

3. Kafkafi, U. & Tarchitzky, J., 2011. Fertigation. A Tool for Efficient Fertilizer and Water Management. International Fertilizer Association/ International Potash Institute, Paris, France.

4. Kafkafi, U., 2008. Global aspects of Fertigation Usage. In: Imas, P & and Price, M. eds. Fertigation: Optimizing the Utilization of Water and Nutrients. International Potash Institute, Horgen, Switzerland.