There are two main ways that farmers and ranchers use agricultural water to cultivate crops:
- Rain fed farming
Rain-fed farming Irrigation Rain-fed farming is the natural application of water to the soil through direct rainfall. Relying on rainfall is less likely to result in contamination of food products but is open to water shortages when rainfall is reduced. On the other hand, artificial applications of water increase the risk of contamination.
Irrigation is the artificial application of water to the soil through various systems of tubes, pumps, and sprays. Irrigation is usually used in areas where rainfall is irregular or dry times or drought is expected. There are many types of irrigation systems, in which water is supplied to the entire field uniformly.
Types of irrigation
- Surface irrigation
- Drip irrigation
- Sprinkler irrigation
- Center pivot irrigation
- Lateral move irrigation
- Manual irrigation
Surface irrigation is mainly divided in basin, border, and furrow systems. It is widely utilised and therefore a well-known system, which can be operated without any high-tech applications. In general, it is more labour intensive than other irrigation methods. Proper design of surface irrigation systems takes into account the soil type (texture and intake rate), slope, levelness of the field, stream size, and length of run. It is generally more difficult to obtain high uniformity of water distribution in long fields on coarse textured soils (gravel and sands) than on fine textured soils (loams to clay). Levelling the fields and building the water ditches and reservoirs might be expensive, but once this is done, costs are low and the self-help capacity is very high.
The advantages of surface irrigation are as follows:
- Because it is so widely utilised, local irrigators generally have at least minimal understanding of how to operate and maintain the system.
- Surface irrigation systems can be developed at the farm level with minimal capital investment.
- The essential structural elements are located at the edges of the fields, which facilitates operation and maintenance activities.
- Surface irrigation systems are less affected by climatic and water quality characteristics.
- The gravity flow system is a highly flexible, relatively easily managed method of irrigation.
Although surface irrigation is one of the most popular irrigation system but it has some disadvantages:
- The soil, which must be used to convey the water over the field, has properties that are highly varied both spatially and temporally.
- Surface irrigation systems are typically less efficient in applying water than either sprinkler or trickle systems.
- The need to use the field surface as a conveyance and distribution facility requires that fields be well graded if possible.
Drip irrigation is the most efficient water and nutrient delivery system for growing crops. 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. Thanks to drip irrigation, farmers can produce higher yields while saving on water as well as fertilizers, energy and even crop protection products.
Water and nutrients are delivered across the field in pipes called ‘dripperlines’ featuring smaller units known as ‘drippers’. Each dripper emits drops containing water and fertilizers, resulting in the uniform application of water and nutrients direct to each plant’s root zone, across an entire field.
Farmers prefer drip irrigation because of following reasons:
- Higher consistent quality yields
- Huge water savings: no evaporation, no run off, no waste
- 100% land utilization – drip irrigates uniformly in any topography and soil type
- Energy savings: drip irrigation works on low pressure
- Efficient use of fertilizer and crop protection, with no leaching
- Less dependency on weather, greater stability and lower risks
Sprinkler irrigation system allows application of water under high pressure with the help of a pump. It releases water similar to rainfall through a small diameter nozzle placed in the pipes. Water is distributed through a system of pipes, sprayed into air and irrigates in most of the soil type due to wide range of discharge capacity.
Advantages of sprinkler irrigation are as follows:
- Eliminates water conveyance channels, thereby reducing conveyance loss.
- Suitable in all types of soil except heavy clay.
- Water saving up to 30% – 50 %.
- Suitable for irrigation where the plant population per unit area is very high.
- Helps to increase yield.
- Reduces soil compaction.
- Mobility of system helps system operation easy.
- Suitable for undulating land.
Center pivot irrigation
A center pivot irrigation system is a movable pipe structure that rotates around a central pivot point connected to a water supply. Center pivot irrigation systems are the most popular sprinkler irrigation systems in the world because of their high efficiency, high uniformity, ability to irrigate uneven terrain, and low capital, maintenance, and management costs. The history of center pivot irrigation systems began in Nebraska in the 1950s, and there are now hundreds of thousands of center pivot irrigation systems in the world. Center pivots are “perhaps the most significant mechanical innovation in agriculture since the replacement of draft animals by the tractor” (Splitter, Scientific American). The systems move through the field by electrically powered tractor wheels. Sprinkler flow rates increase toward the outer end of the pivot because the end of the pivot travels faster. The primary design constraint is the prevention of runoff at the end of the pivot, where application rates are highest.
Lateral move irrigation
The Lateral Move is best known for what the name suggests; lateral moving. The channel feed system is a labour and energy saver; no hose shift, and minimum operation pressure (no friction loss through drag hose and underground mainline. This solution is well suited for a high flow Lateral Move when the grade of the paddock is relatively level allowing the construction of an open air channel.
Sub irrigation system
In commercial landscaping and container gardening, a sub-irrigation system is located at the bottom of the box or container. During sub-irrigation, water is applied to the bottoms of the plants and allowed to travel upwards to the roots and stems through capillary action. Because it does not require a lot of space, this type of irrigation system is often used in urban settings or high-rise buildings.
A sub-irrigation system is essentially a series of pipes and drip emitters buried beneath a plant’s growing medium, and water is pumped to the bottom of the container, where roots find it and uptake it. This is opposed to traditional overhead watering systems, where water is applied to the tops of roots, and flows downwards.
While it has been shown to have quite a few advantages, sub-irrigation systems can encourage an accumulation of soluble salts. This is because the soluble salts cannot escape into the lower soil profile. An accumulation of soluble salts can have a significant impact on the plant’s growth and development.
Despite this one disadvantage, sub-irrigation systems can be labor-saving while encouraging both water and nutrient conservation because water doesn’t leach out of the container or planting box. Additionally, because plants receive water directly through their roots, this type of irrigation system prevents powdery mildew and other forms of diseases that form when the stems or leaves of the plants are overly exposed to water.
Manual irrigation systems are very simple, but effective methods for making water available to crops. Manual irrigation systems are easy to handle and there is no need for technical equipment. But it is important that they are constructed correctly to avoid water loss and crop shortfall. The systems allow for high self-help compatibility and have low initial capital costs. They can be used in almost every area, but they are especially adapted for arid areas where evaporation rates are high.
Advantages of this irrigation system are as follows:
- Improved water-use efficiency (reduced loss through evaporation)
- Well directed, selective and targeted irrigation
- Ensures constant water supply in the crucial phase of germination
- Higher yields, better quality, higher germination rate, lower incidence of pest attack
- Facilitates pre-monsoon sowing
- Can be constructed with locally available material
- Low investment costs
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