Technological revolutions play a vital role in agriculture systems to be more productive. Sensors are one of those revolutions used in agriculture. The use of sensors in modern agriculture is increasing rapidly which provides higher yield, growth, and reduced cost of production as well.
Sensors are a simple and small device that measures, detects, and accumulates information of real-world conditions such as heat, light, or motion and converts it to electrical signals, analog and digital representation, or other forms of output. The advantages of using sensors are their reduced size, versatility, and lower mass-production cost. That’s why the application of sensors in agriculture has increased rapidly.
There are different kinds of sensors available. We are discussing here the top five most common sensors used in agriculture farming systems that can monitor different stages of plant growth and conditions.
Soil monitoring is one of the major factors to manage smart farming to ensure food safety and security. So, it is important to have a quantitative understanding of soil conditions for optimizing crop production.
Electrochemical sensors can provide the most important type of information for precision agriculture and measure soil chemistry by testing pH and nutrient content in the soil. Two types of electrochemical sensors are used commonly to detect the activity of ions in the soil i. ion-selective electrode (ISE) sensors and ii. ion-selective field-effect transistor (ISEET) sensors. These electrodes are able to detect the activity of specific ions nitrate, potassium, or hydrogen in the case of pH in the soil. By monitoring the availability of ions in both plant and soil enables farmers to design fertilizer applications properly that optimize production.
Monitoring the nitrogen ions and the concentration of ions like iodide, chloride, fluoride, sodium, potassium, and cadmium in soil and plant by using ISE sensors can help to investigate the soil fertilizer management, plant metabolism, nutrition status, and toxicological effects of heavy metal on plants accordingly.
Some companies such as Horiba, Hanna Instruments have introduced low-cost nitrate sensors which can measure nitrate and other soil nutrients in solution form. GPS Sensor
The Global Positioning Systems (GPS) has advanced significantly in the recent past and has numerous applications in precision agriculture industries which provide producers to manage their large land and crop production in a more effective way.
One of the most common uses of these GPS sensors to track the livestock is to monitor animals movement with a simple push of buttons by attaching a sensor and tracking device which is capable of recording the behavior of the livestock, animal detection, heat detection, health supervising, and these systems send alerts to the farmer’s smartphone.
For example, using a collar with built-in movement sensors and microphones in cow livestock, the farm allows the farmers to enhance milk production, reduce birth risks or observe cow health status and save precious time.
In addition, GPS applications in farming include guidance of equipment such as a sprayer, fertilizers applicators, tillage implements to reduce excess overlaps and skips and map the field. It can also be used for soil sampling, map to weed by using linear sampling techniques, disease, insect in the field by operating GIS (geographic information systems) computer programs and to apply variable-rate crop inputs, yields monitoring, reduced crop yields in the fields with a mass flow sensor for continuous measuring of the harvested weight of the crops.
Moreover, precision crop input by GPS receiver, computer controller and regulated drive mechanisms mounted on the applicators, locate yield map by GPS receiver, farm mechanics and data collector.
The optical sensor uses light to characterize soil properties by measuring the different frequencies of light reflectance in mid-infrared, polarized and near-infrared light spectrums.
Optical sensors can be placed on vehicles, drones, and satellites that record plant color and soil reflectance, and collected data can be processed and analyzed for scientific conclusions.
The close-range substance, vehicle-based optical sensors can be used in a similar way to electromagnetic sensors and can provide more information about single data points since reflectance can be measured in more than one portion of the spectrum at a time.
Optical sensors have been developed to determine the clay, organic matter, moisture content of the soil. Several optical sensors such as light curtain imaging, laser distance sensors, 3D Time-of-Flight cameras, hyperspectral imaging, and color imaging are integrated and used.
In addition, a three-sensor system is used to monitor the amount of nitrogen uptake based on the canopy spectral reflectance. The chlorophyll fluorescence sensor helps to determine plant physiological activities such as photosynthesis because the chlorophyll is excited by light sources.
Additionally, pest control has consistently been one of the most significant challenges in agriculture. Farmers now utilize smart cameras for real-time pest detection and monitoring to effectively seek action against pests without harming agriculturally helpful non-target insects. Smart cameras can also replace semi-legacy sensing devices such as ambient light monitoring, which enables system simplification and a reduction in the component count.
Companies such as Blue River Technology, a division of John Deere have implemented smart camera technology to detect weeds and other plant locations to automatically and accurately dispense herbicides and fertilizer. This optimizes chemical utilization and increases overall productivity while decreasing chemical usage.
A recent 2018 study discussed the development of a novel PAR sensor based on an array of silicon diodes that accurately measured, recorded, and stored information on the light intensity, which proved its promising commercial viability in the future.
The temperature and humidity sensor can monitor the changes in air temperature and humidity in the agriculture planting environment, which is designed in two major variations.
In one variation, the sensor acts as a trigger when a certain level of temperature or humidity is reached and a specific circuit is activated. Other variations are used to measure the actual temperature or humidity in the ambient air and it has a different analog response to the level of those two atmospheric readings.
A simple temperature sensor relies on the metallic expansion principles of thermodynamics where the complex one, especially for electronic circuits, relies on the voltage drop across a transistor to determine the current temperature. On the other hand, the humidity sensors also have a way of measuring the temperature in the air since it is related to the moisture in the air to the current air temperature. These sensors typically rely on a capacitor to determine moisture content.
The temperature sensors play two key roles in the smart agriculture-ambient conditions of physical space and mechanical asset monitoring. Such as, ice wine harvesting happens within the narrow temperature when the ambient temperature first reaches between 10⁰C and -120⁰ C. So, the accurate temperature and humidity sensors and precise forecast of temperature are very important to this industry.
Besides, temperature and humidity sensors can help to improve the agriculture process. The plant needs water to survive and measures relative humidity of how much water in the air can hold at any given temperature. Temperature and humidity sensors are used to control and monitor the relative humidity and temperature in a controlled environment like climate chambers and a greenhouse.
The sensors are wall-mounted in a greenhouse. In a shading place with good air circulation in the environment during outdoor monitoring, a sensor can be installed in a louver box together with an agrometeorological station.
For example, the Renke temperature and humidity sensor adopt a temperature and humidity movement unit which imported from Switzerland and a built-in industrial-grade imported US. The microprocessor chip used in the sensors has the characteristics of accurate measurement with table communication.
Large-scale greenhouse management is getting easier because it is now possible to measure the exact conditions of the growing environment or even in automated processes. By operating smart sensors coupled to responsive automation systems which can perform functions such as regulate the temperature and humidity of the greenhouse, growers can leave these basic functions to the technology.
Mechanical sensors measure soil compaction or mechanical resistance of the soil. Compacted soil can be formed by the natural soil-forming process or caused by the heavyweight of field equipment which leads to soil degradation and affects crop production negatively.
The sensor penetrates the soil by inserting a probe in the soil to measure the resistance force through the use of load cells and strain gauges. When a mechanical sensor cuts through the soil, it records the resistance forces of soil which result from the cutting, breaking, and displaying of soil. This mechanical resistance is measured in a unit of pressure
Soil mechanical resistance is measured in a unit of pressure and represents the ratio of the force required to penetrate the soil medium to the frontal area of the tool engaged with the soil.
In large tractors, a similar form of this technology is used to predict the pulling requirements for ground-engaging equipment. Tensiometers, such as Honeywell FSG15N1A can detect the force that is used by the plant roots in the soil for water absorption and is very useful for irrigation interventions.
The smart agriculture industry is growing and expanding continuously and using sensors is growing rapidly to optimize the agriculture farming process. Sensors are simple and easy to install, cheaper as well equipped with wireless chips that can be used remotely.
Author: Sanzida Akhter Anee (Co-founder of AgriBioTechX)
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