Subsurface Drip Irrigation (SDI) for Sugarcane: Why should farmers adopt it?

What is Subsurface Drip Irrigation (SDI)?

1. SDI in simple terms : Subsurface Drip Irrigation means that the drip irrigation is done by subsurface pipes. In drip irrigation, the water is delivered to the root zones of the plants. In subsurface drip irrigation, the pipes are placed a few centimetres below the soil surface to better access the root zone. This works exceptionally well for plants with a larger, deeper root zone, such as sugarcane.
2. How it works : The subsurface drip irrigation system works by attaching pipes to the main waterline pipes and then burying them in the ground a few centimetres below the soil surface. This increases the reach of the droplets delivered by emitters or drippers and helps the plant receive the required amount of water. Drip irrigation systems can also be fully automated, so the water can be delivered directly to the root zones on schedule.
3. Comparison : Traditional irrigation methods, such as flood irrigation or being dependent on seasonal rains, are systems that cannot be controlled, nor can they be managed easily. Surface drip systems, on the other hand, are far easier to use and operate, enabling the farmer to save money on water, power, fertilisers, and labour. It is also a significantly smarter investment for a sugarcane farmer.

Why Sugarcane Needs Efficient Irrigation

1. High water requirement of sugarcane : Sugarcane is usually categorised as a thirsty plant, requiring a high amount of irrigation throughout its long duration of growth. Sugarcane can take anywhere between 10 and 18 months at a time to reach full maturity. It also needs 1,100 mm to 1,500 mm of annual rainfall to meet all its requirements. That is a lot of water for a long period of time. Efficient irrigation methods, such as drip irrigation, help ensure that plants receive sufficient water and meet their nutritional needs.
2. Common issues with traditional irrigation methods : There are certain common issues that any farmer is going to face is they use traditional irrigation methods, such as flooding or depending only on the rainy season.

• Water wastage : Since the root zone of a plant can absorb only so much water and nutrients at a time, flooding the whole field does not actually increase their absorption rates. Rather, quite a bit of the water is completely wasted and cannot be reused.
• Uneven distribution : The system of flooding or manually watering the plants with pipes or buckets can lead to uneven distribution. There is no calculation or measurement of how much water one portion of the field receives compared to another, nor is there a maintained grid system to ensure every plant is irrigated.
• Soil erosion : Repeated flooding can lead to soil erosion, which can effectively dismantle the topsoil of any farm or field, depleting the nutrients already present in the soil. It can even change the field's topography, creating pits that collect water where it shouldn't or eroding soil on the other end of the field. If you are a modern farmer, precision irrigation is a must.

How SDI Works in Sugarcane Fields

1. Layout of pipes below the soil : SDI have lateral pipes that lie along the rows of the crops and are usually buried 4-8 inches below the surface. This is mostly because sugarcane has a larger, deeper root system than most other row crops, and placing the lateral pipe below the soil surface helps better reach the root zone.
2. Role of emitters in water distribution : Emitters are placed along the lateral pipes, which can be controlled via automation and digital links. The water will be delivered at the appropriate time, at the appropriate speed, at the appropriate depth, using these emitters or drippers, and will properly irrigate the whole field.
3. Depth and spacing for sugarcane crops : The lateral pipes are usually placed under 4-8 inches in the soil, and spacing between the rows will depend on whether the pipes are applicable for one row or twin row. One lateral is placed beside each row in a single row, and for a twin row, one single pipe can support two rows. Pipes are spaced approximately 1.5 meters apart.
4. Importance of proper design and installation : The kind of soil that is present in a field, what is the water source, the kind of filter required, and whether the land is elevated, whether there is requirement of pressure compensating pipes due to the area of the farm, all of these thing need to be kept in mind to install a system with the proper design. If the design and the actual land do not align, the plants will not be irrigated properly.

Suitability of SDI for Indian Farming Conditions

1. Relevance in water-scarce regions : Using SDIs for regions that are already facing water scarcity and are making cultivation or farming of any kind very difficult is a smart investment on the part of the farmer. Using an SDI ensures that the farmer reduces his operational costs while increasing his yield with less water.
2. Works well in different soil types : Sugarcane grows the best in loamy soil. This could be clay loam, sandy loam, or another type of loam, with a fixed moisture level and amenable to fertigation at different growth stages. They also tend to grow well in tropical and subtropical climates, and many Indian states meet this requirement.
3. Government support and subsidies : The government offers subsidies that cover the purchase of a drip irrigation system, whether that be a surface one or a subsurface one. Installation teams are also available from reputable companies, such as Netafim, and there is additional state-specific support for farmers.
4. Growing adoption among progressive farmers : More and more farmers are taking on SDI to farm their sugarcane. Sugarcanes are long-duration crops that require support through different growth stages, each with distinct nutrient and irrigation requirements. An SDI makes the whole experience far less taxing and helps the farmer save money. In water-scarce areas, it is particularly important to use.