The world has close to 7.53 billion people at present. A recent study found that, on average, 33% of the global population suffers from water scarcity in some form or the other. By 2030, this figure is likely to rise to 50% – clearly underlining the alarming rate at which the problem of water deficiency is expanding. Interestingly, ~70% of the total volume of water withdrawals in the world are used for irrigation, and that’s precisely where most of the water-wastage happens. Around 60% of the water meant to be used for irrigation is lost either due to evapotranspiration, or land runoff, or simply inefficient, primitive usage modes. This, in turn, brings to light the importance of smart irrigation – powered by the internet of things (IoT) – that can go a long way in managing the rising levels of water stress worldwide. In what follows, we will put the spotlight on some interesting facts about smart irrigation:
The need for automated irrigation
Smart irrigation is a key component of precision agriculture. It helps farmers avoid water wastage and improve the quality of crop growth in their fields by: a) irrigating at the correct times, b) minimizing runoffs and other wastages, and c) determining the soil moisture levels accurately (thereby, finding the irrigation requirements at any place). Replacing manual irrigation with automatic valves and systems also does away with the human error element (e.g. forgetting to turn off a valve after watering the field), and is instrumental in saving energy, time as well as resources. The installation and configuration of smart irrigation systems is, in general, fairly straightforward too – which helps the average user.
The IoT-based irrigation system architecture
A smart microcontroller (which serves as the ‘information gateway’) lies at the heart of the automated irrigation infrastructure. Soil moisture sensors and temperature sensors, which are placed on the fields, send data on a real-time basis to the microcontroller. Generally, a ‘moisture/temperature range’ is specified – and whenever the actual values are out of this range, the microcontroller automatically switches on the water pump (mounted on it with output pins). The microcontroller also has servo motors, to make sure that the pipes are actually watering the fields uniformly (no area gets clogged; no area is left too dry). The entire system can be managed by the end-user (farmer) through a dedicated mobile application. Smart irrigation makes it possible for growers to monitor and irrigate their fields remotely, without any hassles.
The use of internet
The flow of information to and from the centralized gateway (here, the microcontroller) has to be supported by stable internet services. Wireless low-power networks (e,g., LoRaWAN or Sigfox) can easily be used to power the sensors. These sensors send field information to the local computer of the user, or to a cloud network (as required). Over there, the system can combine the information with other inputs from third-party services (say, the local weather channel) to arrive at ‘intelligent irrigation decisions’. For example, if rain is in the forecast, water will not be released – even if the real-time data suggests that the field needs irrigation. Recalculations are done at regular intervals.
Note: Smart irrigation systems can save up to 45% water during the dry season, and around 80% water in the rainy season, compared to manually operated watering systems.
The cost advantages
In an automated irrigation infrastructure, there are no rooms for resource (read: water) wastage. As a result, there are cost benefits to be gained as well – by replacing the traditional watering system with a fully self-operating one. Chances of crops dying due to excessive (or insufficient) watering are minimal, which means that farmers will not have to worry about frequent plant replacement. Also, since smart agriculture in general, and smart irrigation in particular, is all about faster, healthier crop growth – the average crop cycle is shortened, and there are every chances of annual yields being higher. IoT-powered irrigation tools can be used in lawns, gardens and landscapes too.
Types of sensors used
Several types of sensors are used to parlay data to the irrigation multicontroller unit – each dedicated to capture and transmit specific data. The first are the soil moisture sensors (or SMS), which examine the dielectric constant of soil surfaces to estimate the volumetric water content in the surface (this moisture level is directly proportional to the dielectric constant reading). SMS controllers can either be ‘on-demand’ (with the capability of initiating and terminating irrigation sessions) or ‘bypass’ (with the capability to allow irrigation sessions (or bypass them), within pre-specified threshold levels). Next up are the temperature sensors, which typically use advanced Resistance Temperature Detector components (RTDs) to track soil temperature levels accurately. The ‘relay’ systems are made responsible for turning on or turning off the pump(s), as per the precise soil requirements at any time.
Note: Soil moisture sensors offer much more efficient on-field irrigation than traditional, timer-based sprinkler systems. There are no risks of overspraying or overwatering with the former.
Incorporating the climatic parameters
While there are many merits of the smart soil moisture sensors – they do not factor in weather-related factors in any way, and that remains a limitation. Significant amounts of moisture is lost due to evapotranspiration (ET; the total water lost from the plant leaves via transpiration, AND the soil via evaporation). Hence, crop-growers should ideally think beyond SMS controllers, and start using the ‘smarter’ evapotranspiration controllers or weather-based irrigation controllers (WBICs). These work with high-quality weather sensors – which receive real-time weather updates, and use the same for customizing the irrigation events. WBICs can also work with historical weather information and/or data received from satellites. Other unique characteristics of a particular crop field, right from types of plants and nature of the soil, to the ground slope and the amount of sunlight available, are taken into account – for determining the exact amount of watering a place needs at any point in time.
The role of LED lights
A smart irrigation unit, with microcontroller(s) at its core, also has pre-tested LED bulbs. When the on-field sensors report that the moisture level is has fallen below the recommended/threshold level – the bulb glows, indicating that an irrigation event has to be initiated (i.e., the sprinkler valves have to be turned on). LED lights are also an important part of ‘tank overflow control models’, which work with powerful ultrasonic sensors. As long as the pump motor is running and the water level in the tank is beneath the threshold level – the bulbs glow. In essence, the LED lights serve as handy tools to indicate the status of the pumps and sprinklers at any time. Readings from the SMS-es or the ultrasonic tank sensors can be displayed on a mobile app, for the convenience for farmers.
Note: Users can see the water level in a tank, or the soil moisture levels, on LCD screens.
The placement of sensors
It’s all very well to set up gateways and pumps and other tools, but unless the sensors are placed correctly in the fields – the ‘decisions’ taken by the smart irrigation network can very well be erroneous. Experts recommend users to make sure that the sensors remain in contact with the soil surface at all times (ruling out the presence of any ‘air gaps’), and are placed a minimum of 5 ft. away from irrigation heads, property lines, homes, and high-traffic zones. For best results, the sensors should be strategically placed in the area(s) that receive the maximum sunlight, and within the root zones of the plants (at a depth of ~3”). A soil moisture sensor has to be covered with soil, but the surrounding pressure should not be too high.
The rise of smarter sprinklers
One of the biggest advantages of switching over to a smart irrigation regime is the considerable volume of water savings. These savings can be increased even more (by around 20%), by ditching the outdated sprinkler systems, and using nozzles that can spray rotating water streams in multiple trajectories instead. The ‘smarter sprinklers’ go a long way in ensuring uniform distribution of water to all parts of the field (or a section of it), and offers much greater resistance to changes in weather conditions (wind speed, mist, etc.). The water released by these rotating-head sprinklers is mostly soaked in by the soil, thereby minimizing runoffs and other forms of wastage.
Note: Rain sensors have also already found widespread acceptance among crop-growers in different countries. These sensors double up as ‘shutdown devices’, sending signals to stop automated sprinklers at the time of (and just afterwards) heavy rainfalls.
10. More prompt fault detection and repair
Small leaks and cracks in traditional irrigation systems (in tanks, reservoirs, etc.) can lead to considerable water loss – adding to the already mounting global water crisis. What’s more, manually detecting the source of these problems is often difficult, and a potentially time-consuming affair. Installing smart irrigation tools is a great way to keep such problems at an arm’s length. With IoT-support, these controllers can detect existing problems in any irrigation unit real-time – which, in turn, makes it easy for users to do the necessary repairs immediately. In essence, an internet-enabled irrigation system can ‘supervise’ the condition of the tanks and pumps and other units – without the user having to stay in front of a computer at all times.
11. The cost factor
While some investment is required to implement smart irrigation solutions on a field, the sensor costs are far from being exorbitant. On average, the price of a soil moisture sensor lies in the $150-$160 range, while that of the more advanced WBICs is around $300. The rotating sprinklers (which, incidentally, are ideal for irrigating slopes) are priced on a per-unit basis (around $6 or $7). Large manufacturers also offer special rebates on the sensors and sprinkler units. Given the potential benefits of upgrading to a smart plant-watering system – the cost figures are relatively reasonable.
Note: SoCal WaterSmart is one of the leading manufacturers of irrigation controller systems. For crop-growers with minimum technical expertise, an IoT irrigation device like CropX (which reduces water wastage and helps in increasing yields) is ideal.
12. The challenges
The adoption of IoT in agriculture has gone up immensely in recent times – but even so, the concept of ‘smart irrigation’ remains a relatively new one. Most of the existing smart irrigation controllers have many complex features and capabilities – which, while perfectly suited for large-scale commercial usage (e.g., on a golf course), are way too elaborate for small farmowners and individual gardeners. The need of the hour is to raise the awareness about, and the familiarity with, these smart irrigation systems among people – particularly since user-inputs (type of crops, soil, surface slope, etc.) are critical for the performance of these systems. Also, it has to be kept in mind that the room for error in a ‘smart system’ is much lower than in a traditional set-up. A mechanical failure or a network snag can have serious consequences.
There are plenty of things to be said in favour of smart irrigation setups. For starters, they help in optimal utilization of water – ensuring uniform watering of plants, at the right times, and in the right amounts. With the help of high-end sensors, they can also factor in climatic parameters, to make the irrigation routine more efficient. Significant savings are to be had, both in terms of much lower water wastages, as well as the diminished need for manual labour. With intelligent ‘irrigation decision-making’ capacities, advanced IoT-supported smart irrigation controllers are changing the face of agriculture. The field is evolving rapidly, and it will be interesting to track further developments in this domain over the foreseeable future.
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