Advanced Micro Irrigation Techniques

Abstract

Problem statement: Indian agriculture’s food basket has grown like a giant elephant with the advent of the green revolution, and later on, the micro irrigation task force came into existence in India. With the growing population, food requirement has to shoot up. Hence, productivity should be increased. With the advent of micro irrigation techniques, the area under irrigation increased enormously, and the footprint of the crop yields reached a pinnacle, ranging from horticultural to field crops, etc. Objectives: Micro irrigation techniques are trekking towards doubling the farm income by increasing productivity, i.e., doubling the farmer’s income, and increasing water use efficiency in a bi-directional mode as resource enhancement and judicious use of resources on the other. Traditional micro irrigation methods cost more for farm installation, which is a big financial task that hinders adoption and leaves farmers looking for government policy support. There is a dire need to address this issue; alternate, best, and most effective systems must be facilitated for the farmer at an affordable price. In this context, rain port irrigation and laser irrigation viz., are innovative, highly efficient conveyance systems with higher water use efficiency and are available in an affordable price range for small and marginal farmers to bring more area under micro irrigation to achieve more harvest in a wide range of crops. Critical numerical findings: These systems have an edge-cutting advantage over the existing micro irrigation systems (sprinkler and drip) in terms of cost, ease of operation, water use efficiency, etc. Furthermore, they can be adopted for a wide range of crops, like both agriculture and horticulture, and other micro irrigation systems with single-man handling operations. This type of system has advantages over other micro irrigation systems in terms of increasing the harvestable basket, water use efficiency, and water conservation. Conclusion: The laser irrigation and rain port irrigations are alternate to drip and sprinkler irrigations, respectively. They could be used in a wide range of crops with precise water delivery system, easy to handle, one farmer can irrigate the entire field, unlike in sprinkler irrigation where carrying and installation require 2–3 man labourers. The droplet size and the pressure with which it exerts on ground are less compared to sprinkler irrigation leads creating lower bulk density and high porosity, causing better root growth and nodule formation in groundnut. The availability of nutrients is higher in laser spray irrigation followed by rain port mini sprinkler system and sprinkler irrigation.

1. Introduction

Micro irrigation was an untapped potential during the early twentieth century in the Indian agriculture scenario. The productivity of rainfed crops is always dictated by the quantity and pattern of rainfall received during the crop season. A farmer’s livelihood is invariably linked with rain, particularly in drought-prone arid districts of Andhra Pradesh [1]. In the present scenario, the irrigation of the crops has changed to feed the root, not the crop, and in the future, the definition may change in a new direction [2]. However, a National Task Force Committee, appointed by the Government of India in 2003, has recommended that 69 million ha of the area be suitable for micro irrigation in India. A target of 14 million ha has been suggested for the Eleventh Five-Year Plan [3]. Initially, irrigation was done through flooding from 1950 to 2000, then it moved to micro irrigations such as drip and sprinkler, which ruled over a period of two decades, viz., 2006 to 2020. Now, the concept of irrigation has become more precise with the advanced methods of irrigation such as rain port irrigation (micro jet sprinkler), laser irrigation, and so on [2]. Precision farming practices, along with plasticulture technologies such as micro irrigation techniques, have proven to be a driving force for the enhancement of farmers’ income through increased productivity and optimum utilization of various inputs.

With the advent of the task force on micro irrigation and government incentives, the area under micro irrigation has increased enormously in India, especially in a few other states like Andhra Pradesh, Maharashtra, Tamil Nadu, etc. In districts like Ananthapuramu of Andhra Pradesh, the harvested water can be given as supplemental irrigation to the crops to enhance yields. However, in the recent past, many studies have revealed that drip and sprinkler irrigation deepened the water table depth in a few parts of Maharashtra and southern states due to the free power supply and automated irrigation switching systems. Hence, an alternate method of micro irrigation must be addressed to sustain micro irrigation in the long run. The best alternate method of micro irrigation is laser irrigation, to drip and sprinkler irrigation methods. Micro irrigation technologies (MI) are being expanded horizontally in vast stretches across the length and breadth of the country, covering 3.56 million ha of the area under micro irrigation in the sampled 13 states [4]. The micro irrigation techniques expanded vertically from orchards to ornamental crops too. These technologies are promoted primarily as: (1) a means to save water in irrigated agriculture; (2) a strategy to increase income and reduce poverty; and (3) to enhance the food and nutritional security of rural households. Despite the reported significant economic advantages and the concerted support of the government and non-governmental organizations (NGOs), the current area under micro irrigation is expanding on a large scale, but the water use efficiency has not improved much across the country. Still, there is a dire need to develop advanced micro irrigation systems with higher water use efficiency.

Different advanced micro irrigation systems are to be discussed here under with ease of operation and improved water use efficiency.

2. Journey of Indian irrigation concept

The Vedas first reported about irrigation in mythology, and the earliest mentions of irrigation were found in the Rig Veda. It has mentions of “kupa” and “avata” wells from where the water is drawn by “varatra” (rope strap) and “chakra” (wheel) pulling “kosa” (pails) of water. Later on, a few of the experts quoted in the 1980s said about nurturing the soil with nutrients and water to harvest more.

3. Sprinkler irrigation

Sprinkler irrigation is a method of applying irrigation water that is similar to rainfall. Water is distributed through a system of pipes, usually by pumping. It is then sprayed into the air and irrigated across the entire soil surface through spray heads so that it breaks up into small water drops that fall to the ground. Sprinklers provide an efficient coverage for small to large areas and are suitable for use on all types of properties. It is also adaptable to nearly all irrigable soils since sprinklers are available in a wide range of discharge capacities.

3.1 Practical layout and applicability of the sprinkler for groundnut crop as example

1. Any pipe with ISI marking having a length of 6 m or 20 feet is sufficient for a sprinkler pipe.

2. Each sprinkler’s raised head discharges approximately 1800 L of water per hour (lph).

3. The throwing radius of each sprinkler raised head is 12 m (operates at 2.5 kg cm⁻² pressure normally).

4. In sprinkler irrigation, the arrangement should be placed in a triangular pattern to achieve higher uniformity, as depicted in Figure 1.

5. Each sprinkler covers an area of 144 m². Ten sprinklers could cover an area of 1440 m² (144 m² × 10 sprinklers), approximately one third of an acre.

6. To achieve 95% uniformity in a 1440 m² area, 16 pipes and 8 raisers are required. The irrigation requirement for groundnut is 450–500 mm on varied crop coefficients, evapotranspiration (ET), and plant water demands depending on the conditions.

7. The number of irrigations required for the groundnut is 8–9, approximately. (9 irrigations × 50 mm each through flooding = 450 mm), such as sowing before flowering (30–35 days after sowing (DAS)) and pegging to pod formation (around 35–90 DAS). Six irrigations are required based on evapotranscription (ET), rainfall, and soil conditions; finally, one irrigation is required 15 days before harvest.

8. With the same principle and nine irrigations through sprinkler irrigation of 40 mm each, by maintaining the acibenzolar-S-methyl (ASM) in the root, we can save around 100 mm of water for one hectare.

Figure 1.

Laser spray irrigation system at the ARS Research farm, Ananthapuramu.

3.2 SWOT in Sprinkler irrigation

See Table 1.

Strengths	Weakness
Wide adoptability	Difficulty in conveyance to other fields
Less automatization	More leakages in conveyance
More flexibility	Operated at few stages only
	Less precise
	Not suitable to operate at all stages
Opportunities	Threats
More scope to adopt in large areas	Excess discharges may cause ground water depletion
Well accepted and adopted in farming community	Clogging is the major problem

Table 1.

Strengths, weakness, opportunities and threats of drip irrigation system.

4. Drip irrigation

Drip irrigation is a type of micro irrigation system that has the potential to save water and nutrients by allowing water to drip slowly to the roots of plants, either from above the soil surface or buried from below the surface. The goal of the said irrigation is to place water directly into the root zone and minimize evaporation. Two important things need to be known before the application of drip irrigation are how much water is to be applied and how much time is required to discharge the desired quantity of water.

4.1 SWOT in drip irrigation

See Table 2.

Strengths	Weakness
Suitable for a wide range of crops	More cost of installation
Automation can be adopted in wide range	Requires a sand filter
Premium quality of harvests can be reaped	Clogging is problematic
Easy to install, replace, and repair	Requires frequent maintenance
Opportunities	Threats
More scope to adopt in large areas	Excess discharges may cause groundwater depletion
High value crops yield more	More power consumption due to automation
Grow more with less
Wider acceptance and adoptability

Table 2.

Strengths, weakness, opportunities and threats of drip irrigation system.

5. Laser drip irrigation

Laser drip irrigation, also known as precision or targeted irrigation, is an advanced technique of punching holes on the pipe by laser technology at definite intervals for the discharge of minute droplets to the plant roots. It involves the use of lasers to precisely deliver water directly to the plant roots, thus minimizing water wastage and ensuring efficient water use. Laser irrigation is an innovative alternative to drip irrigation.

Laser irrigation can significantly reduce water consumption by delivering water only where it is needed, unlike sprinkler irrigation, thus conserving water resources. The precise and uniform water distribution eliminates overwatering or underwatering issues. It requires less energy compared to sprinkler systems because it does not rely on pumping large volumes of water. Laser irrigation targets the plant roots, minimizing water availability to weed seeds and reducing weed growth.

5.1 Specifications of laser drip irrigation system

The available length for laser drip irrigation is 54 m, the available diameters are 16 and 20 mm, and the available thicknesses are 5, 8, and 0.4 mm. It can work at ultra-low pressure, i.e., 0.1–0.2 kg cm⁻². The laser hole discharge is 4 liters per hour (lph), and the spacing between the laser holes is 40 cm. Row-to-row lateral drip spacing is 1.2 m (approximately 4 feet). The depth of application per hour is 8.33 mm. The time required for running 1 acre through laser drip is 36 min. In a laser drip system, there are no drippers; hence, there is less chance of clogging (Table 3).

	Laser drip	Traditional drip irrigation
Operating pressure required at dripper discharge point (kg cm^2)	0.1–0.2	1
Dripper discharge (lph)	4	4
Dripper spacing in the lateral (cm)	40	40
Row-to-row spacing of lateral (m)	1.2	1.2
Depth of application (mm hr.^−1)	8.33	8.33
Clogging	Negligible	High
Maintenance	Low	High
Pump horsepower (Hp) required	Low	High
Electricity consumption	Low	High
Cost	Highly economical	Expensive

Table 3.

Comparison of laser drip versus traditional drip irrigation system.

5.2 Durability and cost of laser irrigation material

5.2.1 Suitability of the crops

It is suitable for wide-spaced crops to narrow-spaced crops, i.e., groundnut, greengram, blackgram, maize, cotton, soybeans, vegetable crops, horticulture crops, etc.

Laser drip irrigation offers several advantages over traditional drip irrigation methods. Here are some key points:

1. Very fine droplets and precise water delivery to the root zone.

2. Increased water use efficiency by significantly reducing water loss due to evaporation, runoff, and deep percolation.

3. Installation and removal are easy compared to drip irrigation.

4. Improves nutrient availability in the soil and increases nutrient uptake.

6. Laser spray irrigation

It is a revolutionary new irrigation system that is an alternative to sprinkler irrigation. Later pipes are punched with minute holes for the discharge of water in the form of sprays, which simulate light rainfall during the operation and run at low pressure. Micro-sprinkling hose irrigation has the unique advantage of reducing labour and input costs. The irrigation system uses low pressure to deliver water to micro-spray emitters through water pipes and tapes and adopts grouped multiple holes to emit water to soils, which markedly saves electricity costs in irrigation [5].

6.1 Specifications of laser spray system

The laser spray system consists of lateral laser pipes and subline from the main line of water discharge. The available lateral diameters of the laser line are 32 and 40 mm and it has a roll size of 100 m length. The wall thickness of the lateral line is 0.3 mm. The discharge of each lateral line is 172–175 lph per metre length. The wetting diameter of each laser punch is 12 m; however, the best results can be obtained at a 10 m distance with 100% overlapping. It can drizzle up to 5–6 feet (1.5–1.8 m) height depending on the operating pressure. The droplet size is minute to very minute and the pressure it exerts on the ground is less (0.5–1.0 kg cm⁻²) compared to the sprinkler irrigation droplet size. Hence, the bulk density and porosity of the soil are not changed during crop season (Table 4).

	Laser spray irrigation	Sprinkler irrigation
Spacing between laterals	6 × 6 m	12 × 12 m
Discharge (lph)	170	1500
Pressure (kg cm^−2)	0.7	1.5–2
Depth of application (mm h^−1)	28–32	10
Cost per acre (INR acre^−1) approx.	20,000	25,000
Radius of operation	4–5 m	10–12 m

Table 4.

Comparison of laser spray versus traditional sprinkler irrigation system.

6.2 Durability and cost of laser spray material

Laser spray accessories are very cheap (approximately 16,000–20,000 INR acre⁻¹) compared to drip and sprinkler irrigation, can be affordable by every farmer, and have a life span of 3–5 years depending on the usage and maintenance of the farmer.

6.3 Suitability of the crops

Laser irrigation can be adopted for a wide range of crops, from leafy vegetables to onions, because it enhances the humidity and alters the microclimate for better yields in the summer. In the hilly terrains of the Western Ghats, viz., Ooty and Munnar areas, temperatures reach a little higher and require cool climates and higher humidity. In that context, laser spray lowers air temperatures by altering the microclimate. Laser irrigation is suitable for a wide range of field crops, viz., cereals, pulses, and oilseed crops. Sprinkler irrigation may affect flowering, pollination, fruit set, etc., in certain crops and may be replaced with laser irrigation. Even for horticultural crops and greenhouses, it can be useful. As the droplet size is finer and discharge is just like drizzle, it infiltrates to more depth compared to sprinkler irrigation. The bulk density of soils under this system of irrigation will be less when compared with sprinkler irrigation, facilitating for easy penetration of pegs into soil.

Micro-spraying irrigation has great advantages in realizing the high efficiency and water saving of pipe irrigation systems. In recent years, the micro-spraying irrigation system has been widely adopted in cereal crops such as wheat and maize (Figures 2–5) [5].

Figure 2.

Laser pipe with punched laser holes.

Figure 3.

Saddle fitting.

Figure 4.

Laser spray pipe fitting to subline with saddle fitting.

Figure 5.

Laser end cap.

6.4 Feasibility for adoption

1. The cost is a bit cheaper compared with the other micro irrigation systems.

2. It can be easily laid out and can be wound up too in off seasons.

3. Mostly, it was manufactured with high-density polyethylene/low-density polyethylene (HDPE/LDPE), which is easily flexible in operation.

4. The rusting problem can be avoided.

5. Higher water uses efficient and better alternate conveyance system.

6. Damages/repairs can be done or rectified through puncture kit.

7. It can be operated at low pressures with high water use efficiency.

8. As the droplet size is minute, it has a greater efficiency and more water savings.

9. In short time, more discharge can be grounded.

10. Clogging problem can be avoided and even the runoff surface collection can be used for the conveyance in this system.

11. Can be utilized in all stages of the crop including flower and pod development stages also as the water jet does not force much.

6.5 Shortfall in adoption

1. Being manufactured with HDPE/LDPE, it can be prone to damages.

2. The HDPE material is so thin that it can face the rodent’s damage

3. Lack of government policy on this system for the rapid adoption.

6.6 SWOT in laser irrigation

See Table 5.

Strengths	Weaknesses
Operated at lower pressures	New innovation—Difficulty to adopt
Higher water use efficiency
Lower cost than other micro irrigation systems
Easy to lay and windup
Opportunities	Threats
Feasible to operate at all stages of crop	LDPE is prone to damage easily
No damage to fruit and flowering	Requires more skills to operates
Operates at lower pressures with high discharge
No issue of clogging
Extra filters are not required
Less maintenance
Any type of water can be used

Table 5.

Strengths, weakness, opportunities and threats of laser spray irrigation system.

7. Rain port Irrigation system

A rain port system is an advanced version of sprinkler irrigation with a discharge rate of 800 liters per hour and uniformity of 90–95%. It is made with polyvinyl chloride (PVC) or HDPE at a low cost. Rain port sprinkler systems are mini-irrigation systems, i.e., laterals and sprinklers can be easily shifted from one place to another. Reinstallation of the system is also easy and consumes less time and labour. Depending on the pressure and recharge capacity of a bore well, the laterals are spaced at a distance of 6–10 m.

It overcomes all the limitations of conventional sprinkler irrigation systems and yet meets the high standards of effective irrigation principles such as

1. High distribution uniformity.

2. Controlled application rate.

3. Gentle precipitation, low droplet impact on soil structure, and no damage to foliage.

4. Short irrigation cycles to provide optimal growing conditions with highly accessible water and nutrients in a controlled wetted and aerated soil profile.

In a rain port irrigation system, flexible polyethylene tubes are used as laterals, and high-performance, low-weight plastic sprinklers are connected to these tubes using easily detachable connectors. Sprinklers are fixed on mild steel (MS) raiser rods or bamboo sticks can also be used to reduce the cost of raiser rods.

7.1 Specifications of rain port system

1. Rain port system is made with the linear low-density polyethylene materials and is easily flexible and suitable to transport and layout.

2. The operating pressure required for the rain port system is 1.5 kg cm².

3. Throwing radius of each rain port sprinkler is 10 m (operates at 1.5 kg cm²)

4. The distance between each rain port sprinkler for the effective uniformity is 8 m × 8 m

5. Each rain port sprinkler covers around 64 m² area × 10 sprinklers = 640 m²). For 1 acre with the rain port system with 8 m × 8 m spacing, it requires 63 rain port mini sprinklers.

6. The discharge of each rain port sprinkler is around 540 L h⁻¹.

7. Depth of irrigation achieved with one rain port sprinkler is 2.7 mm h⁻¹.

8. The available diameter sizes of the rain port sprinklers are 25 and 32 mm.

9. The minimum and maximum operating pressures required for the rain port irrigation system are 2–4 kg cm² (Table 6).

Parameter	Rain port irrigation	Sprinkler irrigation
Spacing between laterals	9 × 9 m	129 × 12 m
Discharge (lph)	540	1500
Pressure (kg cm^−2)	1.5	1.5–2
Depth of application (mm h^−1)	8	10
Cost per acre (INR acre^−1) approx.	20,000	25,000
Radius of operation	10 m	10–12 m

Table 6.

Difference between the rain port and sprinkler irrigation system.

Compared to the sprinkler system (10 m), the throwing radius is a little bit lower, i.e., 9 m in the rain port system. The discharge rate of each rain port came down to one third of the sprinkler discharge to increase the water use efficiency and also to operate even under low water availability. The operational pressure for the rain port system is 1.5 kg cm², which is 0.5 kg cm² lower than that of the normal rain port sprinkler system. Though the discharge is lower than the sprinkler irrigation system, the depth of application is 8 mm per hour compared to the sprinkler, i.e., 10 mm per hour. In the rain port system, the distance between the laterals is 9 m, whereas in the sprinkler irrigation system, the spacing between the laterals is 10 m.

Rain port is more efficient with water saving up to 33% across the cropping season in different crops including dry seeded rice when compared with surface irrigation techniques.

7.2 Suitability of crops

Rain port irrigation system can be suitable for the wide range of crops, i.e. groundnut, greengram, blackgram, bengalgram, and sesamum to green forage crops, etc., where sprinkler irrigation is suitable except at flowering.

7.3 Feasibility for adaption

1. The cost is a bit cheaper compared with the other micro irrigation systems.

2. These are made with LDPE/HDPE which eases the conveyance operation from one farm to others.

3. Higher uniformity can be achieved with lower operation pressure and low power consumption.

4. One person can install the system easily unlike sprinkler jet.

5. Can be operated at wide ranges of discharges with low power consumption.

6. Costly materials like brass/bronze can be avoided for the raiser rods/discharge guns.

7.4 Shortfall in adoption

1. Being manufactured with HDPE/LDPE, it can be prone to damages.

2. The HDPE material is so thin that it can face the rodent’s damage.

3. Lack of government policy on this system for the rapid adoption.

7.5 SWOT in rain port irrigation

See Table 7.

Strengths	Weakness
Lighter in weight, handling, and installation	New innovation—Difficulty to adopt
More precise discharge and more water saving
Easy to lay and wind up compared to sprinklers
Opportunities	Threats
One man can install and operate	LDPE prone to damage easily
Operates at low pressures	Requires more skills to operate
More areas can be covered with available pressure

Table 7.

Strengths, weakness, opportunities and threats of laser spray irrigation system.

See (Figures 6–10).

Figure 6.

Saddle.

Figure 7.

Flash cap.

Figure 8.

High-density polyethylene (HDPE) 32 mm lateral with mini sprinkler raisers.

Figure 9.

Rain port irrigation system in groundnut.

Figure 10.

Rain port irrigation system in sesamum.

8. Conclusion

Laser irrigation is in an infant stage in India. It can be studied in depth for a wide range of crops. The area under laser irrigation may be increased by the policy decision imparted to the existing micro irrigation methods, viz., drip and sprinkler irrigation. Furthermore, it is high time to adopt better micro irrigation techniques, such as laser irrigation, for a wide range of crops to upgrade the farmer’s economic status by increasing productivity. The rain port irrigation system has the advantages over the sprinkler system by way of ease of operation, field shifting, higher water use efficiency, lower discharge rates, and lower cost. It is the best system to be promoted in the future.