Without the process of photosynthesis, light energy would not be able to transform carbon dioxide into oxygen, an essential element for the life and growth of our crops. CO₂ enrichment promotes plant development, particularly in vegetables, as it leads to higher yields and better quality. CO₂ levels must be continuously monitored with a CO₂ analyser to ensure both greenhouse crop productivity and harvest quality. By controlling CO₂, growers can expect increased yields and improved product quality.
How to ensure accurateCO2 control?
Did you know that in addition to oxygen, our plants also produce sugar?
Photosynthesis is the source of the oxygen we breathe, as well as the food we eat.
Without this process, light energy could not transform carbon dioxide into oxygen.
Photosynthesis takes place in the presence of light, water, carbon dioxide and nutrients, all of which are essential for plant growth.
The effectiveness of this mechanism can vary according to several parameters, including the concentration of carbon dioxide in the surrounding air.
In addition to carbon dioxide, the plant needs sugar to grow. And the key point is that it produces this sugar itself.
Other essential elements include minerals, water, nutrients and light.
Photosynthesis reaction is then as follows:
CO₂ + H₂O + Light → Sugar + O₂
More precisely, the plant uses this sugar as fuel. It enables it to generate new cells and, in a way, to "breathe".
The answer is simple: to optimize the photosynthesis process, thereby stimulating plant growth and helping to control it.
Monitoring CO2 in greenhouses is also essential for managing exposure levels for both plants and workers, ensuring safety by keeping CO2 concentrations within recommended limits.
Greenhouse crop production is now a growing and global reality with an estimated 405 000 ha of greenhouses spread throughout Europe.
The last 20 years have seen a revolution in greenhouse cultivation and technologies.
Just a few years ago, a tomato yield of 100 tonnes/ha in a greenhouse was considered a good performance. Today, a harvest of 600 tonnes/ha is not unusual in high-tech greenhouses.Hans Dreyer, Director of Plant Production and Protection Division at Food and Agriculture Organization of the United Nations
You’d think that regions of the world with abundant sunshine wouldn’t need greenhouses. But this is not the case.
Depending on the plant cultivated, here again, CO2, as well as temperature and air speed, is a key parameter, and its optimal level varies.
The availability of CO2 is crucial for optimizing plant growth, as it directly affects the rate of photosynthesis and yield.
The CO2 concentration in ambient air, is famous for increasing dramatically since the industrial revolution, and faster and faster nowadays. While the average level is currently around 400 ppm (parts per million) which means 0,04% of the air we breathe, higher levels of CO2 can enhance plant growth up to a certain point.
Whereas, for instance, under adequate light and temperature conditions, tomatoes grow best at 900 ppm and cucumbers at 700 ppm.
It appears then obvious that CO2 controlled the atmosphere, thus greenhouses are to be developed at any place in order to meet the challenge of human nutrition in the coming years.
The Netherlands are well known as the pioneer country for crop growth in climate-controlled houses. With the huge and still growing number of 9000 large greenhouses, which occupy 0.25% of the total land area, this market represents a significant part of the country’s GDP. 150 000 workers are employed and 80% of the products are exported.
Spain is also famous for having one of the largest greenhouses in the world. This is in Almeria, where greenhouses cover almost a 200km2 area.
Supplementary CO₂ should be used during periods of sunny weather, but not in cloudy weather or at night.
CO₂ can be extracted from burners using fuel oil or natural gas. In such cases, care must be paid to avoid the presence in the greenhouse of toxic gases – whether for plants (SO2, ethylene etc.) or humans (carbon monoxide). CO2 generators that use combustion can also provide heating for the greenhouse, making them efficient for large-scale operations.
Another option is to use pure liquid CO₂, purchased from specialist suppliers.In this case, pressure regulation in CO2 tanks and delivery systems is essential for controlling CO2 flow and maintaining safety.
The most common method of CO2 enrichment for greenhouse applications is the combustion of fossil fuel. And the most used fuel for CO2 enrichment is natural gas.
With the combustion of 1 m3 of natural gas, approximately 1.8 kg CO2 is generated.
Then supplying CO2 may lead to local variations in CO2 concentration throughout the greenhouse. Horizontal, and vertical gradients in environmental conditions are disadvantageous but inevitable. The most important thing is toavoid a reduction in the homogeneity of plant growth and production.
For instance, with a distribution network, a high CO2 concentration is found near the distribution tubes and a low level close to the ridge, or near the opened ventilation windows. It is then recommended to place the CO2 distribution lines on a low level near the crops.
In this way, the natural diffusion of carbon dioxide towards the top of the greenhouse will ensure uniformCO2 enrichment along the vertical axis.
The horizontal distribution is also a challenge since the whole surface of the greenhouse should also contain the same amount of CO2, so that all plants grow at the same speed and the maturity and quality are homogeneous throughout the whole culture.
To ensure a volumetric (both horizontal and vertical) homogeneity of CO₂ concentration in the greenhouse, the best strategy is to measure it at several places in the greenhouse.
This can be done with several analysers and/or making a multipoint sampling with one single analyser, depending on the greenhouse size, and the available budget.
In the case of a large greenhouse, several CO2 monitors will be used to cover the whole volume. And to ensure the best representativity of all plants' atmosphere, each monitor will measure simultaneously several (usually 4 or 6) smaller areas.
This optimised strategy allows controlling that the CO2 is equally spread to all crops.
Fuji Electric's CO₂ sensor is a reliable device specifically designed for greenhouse applications. Key features include adjustable parameters, alarms and connectivity options, making it versatile and easy to integrate into different greenhouse environments.
The Fuji Electric ZFPCO2 controller for greenhouses is a dedicated NDIR (Non-Dispersive Infra-Red) gas analyser . It was designed years ago for this purpose and has been improved with experience. The CO2 sensor offers rapid response to variations in CO₂ concentration, enabling real-time detection and alerts to maintain optimal air quality for plant growth.
More than 10,000 ZFPCO2 monitors are currently in use across Europe to optimize our food production by enhancing photosynthesis throughCO2 fertilization.
Equipped with its internal filter and internal pump, this Infrared analyser is able to suck the ambient air around its own position, but also from remote areas through a network of sample pipes. A usual strategy like illustrated below consists in sucking the air from several areas to ensure the homogeneity of CO2 in the targeted area.
Installation of the CO₂ ZFP controller is straightforward, and its unique stability allows an annual calibration frequency.
The Fuji Electric CO2 monitor's non-dispersive infrared technology has been renowned since the 1960s for its robustness and signal stability in the harshest weather conditions.
The sensor works by an infrared (IR) lamp directing waves of light through a tube filled with a sample of air. This air moves toward an optical filter in front of an IR light detector.
The IR light detector measures the amount of IR light that passes through the optical filter.
The band of IR radiation also produced by the lamp is very close to the 4.26-micron absorption band of CO2.
Because the IR spectrum of CO2 is unique, matching the light source wavelength serves as a signature or "fingerprint" to identify the CO2 molecule.
As the IR light passes through the length of the tube, the CO2 gas molecules absorb the specific band of IR light while letting other wavelengths of light pass through.
At the detector end, the remaining light hits an optical filter that absorbs every wavelength of light except the wavelength absorbed by CO2 molecules in the air sample tube.
Finally, an IR detector reads the remaining amount of light that was not absorbed by the CO2 molecules or the optical filter.
The difference between the amount of light radiated by the IR lamp and the amount of IR light received by the detector is measured.
Since the difference is the result of the light being absorbed by the CO2 molecules in the air inside the tube, it is directly proportional to the number of CO2 molecules in the air sample tube.
This data is then treated by the internal DSP board and then output, most usually as a 4-20 mA signal to be used for the process control: the CO2 enrichment system here in our case.
Fuji Electric has decades of experience in the manufacturing of advanced gas analysis equipment, ensuring high-quality and reliable performance.
The ZFP Gas Analyzer is also suitable for use in a grow room environment, providing reliable CO2 monitoring and control for optimal plant growth.
ApplicationDownload your application sheet and improve the productivity and quality of greenhouse production!
Effective water and nutrient management is essential for supporting robust plant growth and maximizing plant yield in greenhouses. Each type of plant has unique requirements, but a balanced nutrient solution with a pH between 5.5 and 6.5 is generally ideal for most crops. Using a flow meter allows growers to monitor water usage precisely and adjust irrigation schedules to match the needs of their plants, preventing both under- and over-watering.
Maintaining optimal environmental conditions - such as temperature and humidity - is equally important. High levels of carbon monoxide can be harmful to plant health, which is why it's important to ensure adequate ventilation and good air quality. By closely monitoring these parameters, growers can create an environment that promotes healthy growth, reduces the risk of nutrient deficiencies and helps prevent the appearance of pests and diseases.
Consistent attention to water and nutrient management not only boosts yield but also supports the overall health and resilience of greenhouse crops.
Protecting greenhouse crops against pests and diseases is essential to maintaining high yields and ensuring the long-term viability of your operation. Growers can combine biological, chemical and cultural control methods to limit threats. Regular monitoring of plants to detect the first signs of infestation or disease is essential, as swift action can prevent spread and major damage.
A CO₂ monitor can be a valuable tool in this process, as sudden variations in carbon dioxide levels can indicate the presence of pests or diseases affecting plant respiration. Maintaining a clean, well-ventilated greenhouse environment also reduces the risk of pest outbreaks.
y implementing a proactive pest and disease control strategy, growers can protect their investment, maintain healthy plants, and ensure consistent, high-quality production.
The design and layout of your greenhouse are critical factors that influence plant yield, efficiency, and overall operational costs. A well-planned greenhouse should provide optimal light intensity, precise temperature control, and effective ventilation to create the best possible environmental conditions for plant growth. When designing a greenhouse, consider the specific needs of your crops, the local climate, and the available space to ensure every plant receives the right amount of light and air circulation.
A sealed greenhouse offers enhanced control over carbon dioxide, temperature, and humidity, allowing growers to maintain the desired level of each factor for maximum productivity. However, this approach requires careful monitoring and management to prevent issues such as excessive humidity or CO2 buildup.
By investing in a thoughtfully designed greenhouse, growers can optimize plant growth, increase yield, reduce energy costs, and improve the overall efficiency of their operation.
Proper post-harvest handling and storage are essential steps in the greenhouse production process to maintain the quality and value of your crops. Gentle handling reduces the risk of damage, while storage in a cool, dry environment preserves freshness and extends shelf life. Using a CO₂ controller or CO2 monitor is a simple and affordable solution for maintaining optimum carbon dioxide levels during storage, which can further improve crop longevity.
Monitoring temperature and humidity is also crucial, as excess moisture can lead to spoilage and reduce the value of the crop. A flow meter can help track water consumption and prevent unwanted moisture build-up during storage.
By applying good post-harvest handling and storage practices, growers can reduce losses, maintain high product quality and increase customer satisfaction - ensuring that the work invested in production pays off all the way to market.
