Drip Irrigation to Save Water

Keeping up with watering your garden or farm can be a challenge. Chaotic and changing weather conditions can all leave flowers, veggies, and shrubs gasping for water. Tired of standing next to your planting beds, garden hose in hand? Concerned about getting too much water where you don’t need it and not enough where you do? The solution is simple: switch over to drip irrigation.

It prevents many problems that result from overwatering, including soil erosion and puddling, plant disease and fungus growth.

What is Drip Irrigation?

Drip irrigation is the most efficient water and nutrient delivery system for growing crops. It is an irrigation technique that reduces water consumption by about 50 per cent from the other traditional irrigation methods. 

It delivers water and nutrients directly to the plant’s roots zone, in the right amounts, at the right time, so each plant gets exactly what it needs, when it needs it, to grow optimally. 

Drip irrigation provides a more favourable moisture level for the plants to thrive, as the application of water is more. It is also known as micro-irrigation, trickle irrigation or localized irrigation. 

It involves dripping water onto the soil at meagre rates of about 2 litres to 20 litres per hour from a drip system of small diameter plastic pipes fitted with outlets called emitters or drippers, thereby avoiding under watering and overwatering. The purpose of the system is to conserve water. 

Water is applied very close to plants so that only a portion of the soil in which the roots grow gets wet. This is in contrast with surface and sprinkler irrigation, where the entire ground receives the water. In this method of irrigation, watering is frequent, about 1 to 3 days compared to other methods, thereby providing a favourable high moisture level in the soil for the plant. 

As long as the water supply rate is below the soil’s infiltration capacity, the soil remains unsaturated, and there is no free-standing water over the soil surface.

Nutrients and water are delivered across the field in pipes known as dripper lines which feature smaller units known as drippers. Each dripper emits drops containing fertilizers and water, thereby resulting in uniform application of nutrients and water directly to each plant’s root zone across an entire field.

Design of a Drip Irrigation System

Water is taken from the source by the pump unit and provides the correct pressure for delivery into the pipe system.

The pressure and discharge in the entire system can be controlled by valves that are located in the control head.

It may also have filters for clearing the water. The different types of filter include screen filters and graded sand filters which removes fine material suspended in the water. Some control head units contain a nutrient or fertilizer tank. A measured dose of fertilizer is slowly added to the water during irrigation. It is one of the significant advantages of drip irrigation as compared to the other methods.

Mainlines, sub-mainlines and lateral lines supply water from the control head into the fields. They are usually made from PVC or polyethene hose and should be buried below ground because they easily degrade when exposed to direct solar radiation. Water distribution to the plants is affected through lateral lines hosting the specific drip devices or emitters. In principle, there are two types of drip irrigation:

• Subsurface type irrigation – Water is applied below the soil surface.
• Surface type irrigation – Water is applied directly to the soil surface.

SubSurface Drip Irrigation

Sub-surface irrigation (SDI) is a more sophisticated and hence expensive and rare method, which employs narrow plastic tubes of about 2 cm diameter. These are buried in the soil at a depth between 20 and 50 cm, deep enough so as not to interfere with normal tillage or traffic. 

The tubes are either porous throughout or are fitted with regularly spaced emitters or perforations. If porous, the tubes exude water along their entire length. If fitted with emitters, they release water only at specific points. The released water then spreads or diffuses in the soil. 

The pattern of wetting depends on the properties of the surrounding soil, as well as on the length of the interval between adjacent emitters and their discharge rates.

A potential problem with this technology is that the narrow orifices of the emitters may get clogged by roots, particles, algae or precipitating salts.

Experience in Israel, California and elsewhere has shown that this method of subsurface irrigation is feasible in plantations of fruit trees and other perennial row crops. It may also be applicable to annual crops grown in regular beds when high maintenance intensity can be assured. 

The employment of modern subsurface type irrigation technology in developing countries is seldom and is often not feasible due to unfavourable framework conditions.

Surface Drip Irrigation

Surface type irrigation is more common, and it uses an extensive range of drip emitter devices. The lateral lines supplied from a field main are laid on the surface. They are about 10 to 25 mm in diameter and are either perforated or fitted with special emitters. 

The latter are designed for dripping water onto the soil at a controlled rate. The operating water pressure is usually in the range of 0.5 to 2.5 atmospheres. This pressure is dissipated by friction inflow through the narrow passages or orifices of the emitters, so the water emerges at atmospheric pressure in the form of drops rather than a jet or spray.

Emitters or drippers are devices used to control the discharge of water from the lateral to the plants. They are usually spaced more than 1 meter apart with one or more emitters used for a single plant such as a tree. The basis of design is to produce an emitter that will provide a specified constant discharge that does not vary much with pressure changes and does not block easily.

Commercial emitters are either in-line (spliced into the lateral supply tubes), or online (plugged onto the tubes through a hole punched into the tubing wall). Commercial emitters are usually precalibrated to discharge at a constant rate of 2, 4, 8 or 16 litres per hour. The discharge rate is always affected by changes in pressure, but less so in the case of pressure-compensated emitters. 

The frequency and duration of each irrigation period are controlled by means of a manual valve or a programmable automatic valve assembly. Metering valves are designed to shut the flow automatically after a pre-set volume of water is applied.

Why Does the World Need Drip Irrigation?

The world population is forecasted to cross 10 billion by 2050, and there will be 20% less agricultural land per person to grow food. On top of it, there is an increasing scarcity of water. This calls for a situation where we need to find a way to increase agricultural productivity and resource efficiency. In this scenario, irrigation using drip method is changing the global agricultural economics by allowing farmers to produce more and cubic meters of water and calories per hectare.

• Reduces the impact of drought and climate change on food production. 
• Avoids contamination of groundwater and rivers caused by leaching of fertilizer.
• Supports rural communities, reduces poverty and reduces migration to cities.

Water scarcity is due to depleting natural water resources and water contamination due to pollutants has turned into a critical concern. Agriculture alone consumes ~90% of freshwater withdrawal (FAO). Besides, reducing groundwater resources has added to the critical problem that has hampered agriculture largely.

The land is a finite and limited resource, and we cannot afford to lose it annually. Globally, there has been a consistent loss of arable land annually. This has turned into a significant challenge, considering the rise in food demand shortly. It helps utilize every inch of ground by bringing a larger area under the irrigation zone.

Drip Irrigation – Farmers Choice

Over the years, it has become the farmer’s choice. Why? The reason is very simple. This irrigation method delivers greater returns on investment compared to other irrigation methods. Additionally, it also offers home gardeners and farmers a simple and efficient way to operate farms. Drip irrigation garden can be highly productive and water-efficient for gardeners landscapers and farmers.

• Farmers get consistent higher quality yields.
• As there is no waste, evaporation or runoff. leading to huge water savings.
• There is 100% land utilization. Drip irrigates uniformly in soil type and topography.
• As it works on low pressure leading to energy savings.
• As there is no leeching, so efficient use of fertilizer and crop protection.
• There is less dependency on weather, greater stability and lower risks

Drip Irrigation – Plants Choice

Plants like to get their nutrients and water in a balanced manner. This is why it applies to water and nutrients frequently and in small doses, ensuring optimal growing conditions that help produce the highest yields possible.   

Here’s why plants are more productive with this irrigation:

• High availability of water and nutrients.
• Doses of water and nutrients tailored to plant’s development needs.
• No saturation and good soil aeration.
• Avoids high salinity caused by excessive fertilizer application.  
• No wetting of foliage can result in fungal diseases.

Learn more about Solar Power Irrigation Systems here.

Benefits of Drip Irrigation

• Water is used at the maximum optimum level.
• Minimised loss of fertilizers and nutrients as leeching is reduced and water is applied locally.
• Weeds cannot absorb water as no water is available for them and thus grow in less number
• Crop yield is maximum
• Fertilizers can be used with high efficiency.
• Minimum operating cost
• No soil erosion
• Increase in the soil infiltration capacity.
• Fertilizers and groundwater are not mixed.
• Seed germination is improved.
• We can use recycled water safely.
• Levelling of fields is not required.
• Irregular shaped lands can be irrigated.
• Reduction in wastage of fertilizers by 50%
• Reduced cost of energy as it is operated at a lower pressure than other irrigation methods.

Disadvantages of Drip Irrigation

• The initial cost is pretty high.
• If water is not filtered correctly, it may cause clogging
• Problems in moisture distribution.
• Salinity problem.

Bottom Line

Drip Irrigation helps farmers to produce higher yields while saving on water as well as fertilizers, energy and even crop protection products. It is transforming the lives of millions of farmers across the world. It is enabling higher yields to be produced from any land while saving water, fertilizer and energy.