Aug 3, 2022

10 min read

Precision agriculture: using less to grow more

Agriculture has in many places been regarded as a rather traditional sector. Yet, in the past couple of centuries, it has gone through a number of technology-driven revolutions, such as the ones fostered by mechanization, electrification and automation, the availability of chemical fertilizers or the emergence of biotechnology and genetic engineering. Now, with the explosion of new digital technologies and the Internet of Things (IoT) we are entering the era of so-called precision agriculture. This article will introduce the concept of precision agriculture, with particular emphasis on how smart sensors and wireless systems contribute to improving agriculture practices' sustainability while optimizing resource efficiency and productivity.

Agriculture is incontestably one of the most important and essential human occupations, providing most of the world's food and fabrics (cotton, wool and leather), as well as wood and paper products. The dawn of agriculture about 12.000 years ago, often called the Neolithic Revolution, is considered to have sparked the birth of the earliest civilizations, allowing the emergence of villages and cities and the growth of the human population. Today, agriculture is strongly challenged by the need to provide adequate food for a fast-growing world population - expected to increase by about 2 billion people, i.e., by about 25%, by 2050

On the other hand, today's intensity of agriculture means that it is one of the human activities that put immense pressure on the environment and the planet's resources. Agriculture involves the combined use of land, water, fertilizers, pesticides, herbicides, livestock and energy, among other production factors - occupying nearly 40% of the terrestrial area of the planet and using 70% of the freshwater consumed globally. The environmental and derived societal impacts range from soil, water, and air pollution, to reduced biodiversity, water depletion, and climate change. 

So, making the best possible use of the planet's resources and exploiting all the existing possibilities for optimizing agriculture practices is a must - bottom-line, towards "using less to grow more". This means optimizing water and energy use through rational and sustainable use of these precious resources. It also means reducing to all the extent possible inputs like fertilizers, pesticides, and herbicides - which are today used in excess, causing nutrient and chemical stresses in soils, as well as water and air pollution, with nasty consequences on biodiversity, climate change and, ultimately, on human health. Precision agriculture strives to solve this equation - balancing between preserving the planet's environment and the need to feed the world.

What is Precision Agriculture?

According to the International Society of Precision Agriculture (ISPA), precision agriculture is defined as "a management strategy that gathers, processes and analyzes temporal, spatial and individual data and combines it with other information to support management decisions according to estimated variability for improved resource use efficiency, productivity, quality, profitability and sustainability of agricultural production". The exact definition may vary depending on the source, but some common ingredients clearly emerge: data, along spatial and temporal axes; information systems to support management decisions; resource efficiency, sustainability and productivity. So, it becomes pretty evident that precision agriculture lies at the intersection of agro-sciences and new information and communication technologies (ICT). Let's then explore how ICT and digitalization are increasingly becoming critical ingredients in agriculture and farming.

Farming systems made smarter.

As in most other areas of human activity, technology and digitalization have an increasingly important role in improving agriculture. Technologies like satellite imagery, drones, IoT, smart sensors, cloud computing, machine learning, etc. are already transforming the sector and hold the potential for many further impacts in the near future. Smart technologies - sensors, IoT systems, machine learning - can play a key role in real-time monitoring of critical parameters for precision agriculture, namely soil properties, weather conditions, pests and insect attacks, plant nutrition and health. 

As such, agriculture IoT is now an established segment of its own right - with smart sensor systems, and in particular wireless sensor networks, placed as key enablers in the path for precision agriculture. An overall look into sensors for agriculture shows a market estimated in the order of $1.3 billion (2021) and growing at a CAGR of approximately 14%. The market is highly fragmented with numerous players offering diverse sensor types and system solutions - such as Acclima, Acquity Agriculture, CropX, Glana Sensors, Libelium, Monnit, Pycno, Sensoterra, Sentera, Sentek, etc. Sensors for monitoring soil parameters constitute the largest segment, with soil moisture sensors at the top - so let's focus our attention on these ones for a while.

Grounded in data straight from the soil 

Sensors have been used to monitor the principal soil parameters - i.e. moisture/humidity, temperature, pH and nutrient contents, especially nitrogen, phosphorus and potassium (so-called NPK). Other relevant soil parameters include organic matter, exhaled gases, salinity, concentration of pollutants, presence of pests and insects, etc. For each of these parameters, there are multiple sensing methods and off-the-shelf sensors. More information about soil sensors for smart agriculture applications, including the recent R&D progresses and systems commercially available, can be found in a few recent review papers on the topic - such as Yin et al. 2021Kashyap and Kumar 2021 or Nadporozhskaya et al. 2022.

Wireless soil sensor systems are particularly attractive. Nowadays, the market offers a choice of sensor systems and providers serving diverse contexts - from professional solutions for large deployments to budget options for home-use. For professional agriculture deployments, wireless systems enable large arrays of sensors communicating seamlessly with a reader infrastructure; the choice of the communication technology depends on the context - such as total area to be covered, density of sensors, required data bandwidth, urban vs. remote areas, etc. Today's options go from short range - Wi-Fi, Bluetooth, ZigBee or Ultra Wide Band - to long range prototocols - including cellular networks; low-power wide-area network (LPWAN) technologies, such as NB-IoT, LoRa, LTE-M, Sigfox, etc.; or even upcoming satellite IoT networks. On the other end of the spectrum, for small deployments - such as residential owners/managers monitoring soil moisture conditions of potted plants, vegetable gardens or lawns; urban gardens; urban farming - there are 

solutions based on simple sensors that the users stick in the soil and which communicate wirelessly, e.g. using Wi-Fi, Bluetooth or ZigBee protocols, with smartphones or simple gateways. 

Let's give a closer look at a couple of examples from each type.

CropX is an Israeli company founded in 2015 and focused on soil sensing for management of irrigation and fertilization in a precise, predictive and effective manner. The company offers sensors for continuous monitoring of soil conditions and a data and analytics platform (software) to assist farmers in planning and decision-making. The sensor units collect soil moisture, temperature and electrical conductivity (representing the soil salinity level) data at multiple depths. All data is geo-tagged, based on GPS coordinates, creating geospatial time series for all measured data. The sensor units transmit data through the cellular network (3G or 4G) to the cloud system. In addition to data from the soil sensors, CropX's platform integrates other types of data, namely weather, aerial imagery, topography, soil mapping, hydraulic models, crop models, and other user inputs. This data integration improves the analytics and management support services provided to the farmers.

Sensoterra is headquartered in the Netherlands and focuses on wireless soil and water optimization solutions. The company commercializes a sensor to measure soil moisture, communicating through LoRaWAN technology - using gateways that must be within 4 kilometers from the sensor units. The solution includes a mobile app and a cloud-based server that assist the user and provide data insights. Besides agriculture, Sensoterra focuses on water management, for instance within the scope of smart/green cities.

The Netro Whisperer is a smart sensor for home-use (indoor plants, outdoor gardens, etc.) measuring soil moisture, surface temperature and sunlight. It connects via Wi-Fi to a smartphone app that collects the data and gives notifications to the user about plant care.

Xiaomi launched the Mi Flower Care series for home-use, with different versions for indoor, large plants and outdoor. The sensors monitor soil moisture, temperature, nutrition and sunlight, connecting through Bluetooth to a smartphone app that gives care recommendations tailored to the user plant type, based on a collection of more than 6000 plants.

We have analysed products from a number of other vendors for professional use - namely Libelium, Monnit, Pycno, Sentek, Zimmer & Peacock - and for home use - such as Verdmo, Ecowitt, Sonkir, XLux. Overall, the professional solutions are complex and very costly. For instance, the sensor units from CropX have an upfront cost of minimum $600; Sensoterra sells at €150-200 per soil probe. In addition, most systems entail quite considerable costs with communication hardware (gateways, base stations, etc.) and subscription fees for connectivity, software tools, etc. - for instance CropX charges an annual subscription fee of $275 per sensor. And, many of the sensor units are bulky and rely on wired connections to electronic casings or gateways - hardly qualifying as true wireless solutions. The home-use solutions can be quite cheap - as low as $20 per sensor - but are meant for individual sensors or small arrays. 


Drilling into the pros and cons of existing solutions there are two challenges that clearly emerge across the board: batteries and cost. 

First, the vast majority of the existing sensors run on batteries: some are equipped with solar panels, but still integrated with internal batteries. So, there are no real batteryless solutions - apart from a couple of very simple home-use devices (such as Sonkir and XLux) which do not provide any kind of data connectivity. We have repeatedly battled against the use of batteries in IoT devices. But here we'd like to add a couple of evidences specific for agriculture applications. A recent study reported that batteries were the cause of more than half of the failures found in a wireless sensor network to monitor soil moisture - including low batteries, moisture in enclosures, and sensor nodes that froze and drained their battery in one shot. Also, in agriculture, batteries represent an increased risk of soil and water contamination due to direct leakage of harmful chemicals, such as lithium and lead. So, batteries are a no-go!

Second, as seen above, systems for professional use are very costly - which hampers the deployment of large sensor arrays.

Looking ahead is leading the way in ultra-low-power and energy harvesting technology, making it possible to deploy true wireless and batteryless sensor systems across IoT verticals. Agriculture is no different. is breaking sensors free from batteries and implementing an unprecedented level of on-chip integration - drastically reducing the number of electronic components for a functional sensor unit, with a parallel reduction in cost. And so the magic happens: batteryless, low-cost sensors and systems - where form factors and footprint are not determined by the electronics but rather by the sensory elements and use-case needs. This will unshackle the potential of precision agriculture - with wireless sensor arrays spreading faster than weed! The simplicity of the underlying technology will enable diverse use-cases and application segments - from high-end smart platforms tailored to farmers, to mid-range applications like urban farming and gardening and to consumer products for home use.

All of this is expected to come with deep respect to the environment: saving freshwater, using less energy, reducing deleterious inputs like excess fertilizers, pesticides and herbicides. Ultimately, minimizing the environmental footprint of agriculture - while providing a steady stream of healthy food to all on the planet! Agriculture and sustainability hand-in-hand!

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