Agrofrost is a company that makes only machines for frost protection. Agrofrost has two directors: Marc Polleunis has been the director of Ferti-Systems in Kortenaken, for more than 20 years. Because of his long experience in the fruit business, he knows very well the needs of fruit growers. He founded Agrofrost in 2000 and started the production of the first Frostbusters. Several years ago, he sold Ferti-Systems so he could concentrate 100 on the production of frost protection systems. Marc is responsible for the development and the production of our machines and for sales in some countries. Patrik Stynen has been the director of Eropak NV for more than 20 years, and was an importer of agricultural machinery and spare parts. In 2002 he sold the spare parts division to the company Kramp. In order to concentrate 100 on the sales and development of the Agrofrost machines, he also sold the machine division in 2005 to Agropak.
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- Business Type:
- Industry Type:
- Market Focus:
- Globally (various continents)
- Year Founded:
- $1,000,000 US - $10,000,000 US
How Does It Work ? –> Phase Changes Or Phase Transitions
The working principle is, unlike all other frost protection systems, not based on raising the temperature above the critical values but on phase transition. Or in this case by controlling the forming of hoarfrost. Where our machines are used, we notice a significantly lower formation of hoarfrost. We all know that hoarfrost is the biggest enemy for the flowers and buds. But there is a way to use the enemy for protection.
The transformation of vapour into hoarfrost is called desublimation or deposition and liberates a lot of energy. This energy is transferred to its surroundings, in this case the surrounding air but above all into the leaves and flowers themselves. We know that it’s precisely the hoarfrost that normally causes most damages. This is because the ice crystals extract energy and humidity from the flower. Without protection, the layer of hoarfrost will increase and finally cause damages by dehydration and under-cooling.
But not with our system. Because we pass with a hot air stream, every 7 to 10 minutes, part of the ice evaporates (called sublimation) and the remaining ice gets energy from the passing air. The higher the humidity, the more energy that is transferred. After a few minutes, the air cools down again, the relative humidity increases and some new rime will be formed. This liberates again energy and gives again energy to the flowers. This allows us to create an optimal protection with only a fraction of the energy input that is needed by other systems.
What Can You Expect ?
We believe that it’s very important that you know what you may expect from our machines (Frostbuster and FrostGuard). What can we protect, what not? Until which temperatures does it work? For which kind of fruits?
First of all, we have to make a distinction between flowers and fruits. It’s easier to protect flowers than to protect small fruits. The bigger the fruits, the more difficult to protect. Good to know: most frost damages occur on flowers.
Another very determining factor is the relative air humidity (RH). During a night frost, the RH is normally high, very high. This causes white frost or hoarfrost. And this is mostly the reason for damages. Our machines work better with a high RH then with a low RH. Or, the higher the risk (caused by RH), the better the results. On the other hand, the results might be poor when the RH stays below 85%. Good to know: RH is higher than 95% during most frosts.
Further, there are differences between all the kinds of fruits, vines, etc.
Not to forget the length of the frost period: when a frost of -5 °C lasts 4 hours, damages will be less compared to a frost of -4° that lasts 10 hours.
Also wind is a dangerous factor. Most systems do not work in case of wind. Our machines will still give a positive result if the wind is not too strong.
Every year and all over the world, farmers have severe losses because of frosts. More than 90% of all damages are caused by frosts on flowers with temperatures between -2 and -5 °C, and with an relative air humidity higher than 95%. Which means that we can provide a good protection in more than 90% of the cases. We cannot guarantee 100% protection at all time. Nobody or no protection system can. Now and then, weather conditions are extreme and not matter what you do, damages are inevitable. However, a success rate of minimum 90%, with a system that has less disadvantages than others, is more environmental friendly and above all, is cheaper in use and purchase… we believe it’s not bad, not bad at all.
Most protection systems have a lot of disadvantages. No one else can offer you similar results as ours, with a minimum of disadvantages at the same time. Furthermore, our machines can improve fruitsetting.
For all these reasons, we can tell that we have the best protection system on the market.
On the next page – Protection Limits – you find a table that shows you what you may expect from our protection systems.
Another page – Improving Fruit Set – shows you how you can use our machines for improving the fruit set.
The temperatures in the table below are the minimum temperatures where our machines still had good results. The data in the table below are not “absolute” values. We regularly adapt these values, based upon new experiences from our customers and from some Research Centres.
The critical temperatures also depend on the stage of flowering and the size of the fruits. For example: we had good results at -8 to -9 °C in pears in the stage “white bud”, while the table here shows -5,5 °C for “full flowering”. So in certain flowering stages, the minimum temperatures where we can provide protection are lower.
* = the capacity of a wind machine depends a lot on the temperature, the eventual use of an extra heating system, the hight of the trees and of course of the quality of the inversion layer. The protected area from our wind machine varies between 2 to 4 ha at -5 °C and 6 to 7 ha at -3 °C. In case of negative inversion, the wind machine should not be used because it will create even more damage.
** = depends a lot on the phenological stage of the plants: the smaller the buds, the more difficult to protect. We advise to combine the Frostbuster and FrostGuard with paraffin candles, certainly in the stage of bud burst or first leaves.
*** = also depending on the type of fruits, the size of the fruits, humidity, wind. Small fruits are very difficult to protect.
**** = in case of wind frost or a combination of wind frost with radiation frost, always put paraffin candles around the area that needs to be protected.
****** = put paraffin candles on the wind side to improve results, certainly with the FrostGuard.
Guidlines For Use
The correct use of the Frostbuster and FrostGuard is very important to achieve good results. Therefore, we give some guidelines that, when followed, will improve the results.
When to start up?
It‘s very important that our machines are started up in time. They should be started before the wettemperature drops below 0 °C. Therefore, we recommend to start at + 0.5 °C (wet temperature). That’s the reason why we set the alarm temperature of our alarm systems at + 0,5 °C for the wet bulb sensor.
The temperature of the blown out air has to be around 80 to 85 °C. It’s important that you do not exceed 90 °C. Especially in vineyards and when humidity is low (< 80%), it’s better to work with lower temperatures (70 to 80 °C).
Our machines work only with propane gas. Butane gas bottles will freeze. Also LPG cannot be used. LPG (or GPL, LP Gas) stands for Liquefied Petroleum Gas, and is mostly a mixture of propane and butane gas. Because it contains too many butane, it will freeze. Always open all gas bottles because otherwise, the consumption per bottle is too big and even the propane bottles will freeze.
Guidelines for the Frostbuster
- You have to drive a circuit through the orchard that does not lasts longer than 10 minutes. (between 7 and 10 is ideal) If intervals between passages are shorter than 7 minutes, results will be less. We know it sounds weird but tests has clearly shown this.
- The ideal distance between the passages in the rows is between 60 and 90 meters. It’s important that these distances are respected. Our intuition tells us that making these distances shorter would increase the efficiency. But it’s the opposite and the results might be less.
- If you have to change the gas bottles, make sure it does not lasts longer than 10 minutes. Therefore, we advise that 2 people are present for changing the bottles.
- Do not change your gas bottles just before sunrise. This is the coldest moment of the night, at which you cannot afford to stand still. If you notice that you will have to change the bottles at this moment, stop 1 hour before and do the change 1 hour earlier.
- We also advise that there are 2 drivers that can alternate.
- Make sure you have spare bottles of propane gas, and that they are stored in the orchard where you need them. Avoid extra driving in order to make the switch of the gas bottles as fast as possible. Keep the bottles stored vertically. If you store them horizontally, put them vertically into the machine and start using them immediately, dirt might enter the gas system and might cause obstructions in the gas circuit.
- If you have a Frostbuster and you have not received a drawing with the ideal circuit to drive, or you have doubts about it, please send us a map of your orchard and we will calculate for you the ideal circuit.
Guidelines for the FrostGuard.
- The capacity of the FrostGuard depends a lot of the density of the plants. For example: in orchards where trees are planted 5 x 5 m, we can protect approx. 1 ha. In orchards where trees are planted 3,3 x 0,5 m, the protected area will be approx. 0,6 to 0,7 ha.
- If you put more machines in one orchard, the distance between the machines will depend also on the density of the plants. If you have FrostGuards and you have not received a drawing with the ideal positioning, or you have doubts about it, please send us a map of your orchard and we will calculate for you the ideal positions of the machines.
- Make sure the grass is mowed as short as possible. The airstream passes close to the ground. If the grass too long, it will slow down the airstream and reduce the range of the machine. Another reason to keep you grass short is that it will allow the soil to take in more heat by radiation during the day. This will result in a better emission of warmth during the night so temperatures will drop less at night.
- If you have to start up several machines and you have to do it alone, make sure you start in time. It takes at least 5 minutes per machine so if you have to do 12 machines, it will be one hour before you get to the last one. Therefore, we advise that one person should start up not more than 8 to 10 machines. (A solution for this problem: Auto Start System. Equipped with this, the FrostGuard starts automatically when a preset temperature is reached.)
- If you have to change the gas bottles, make sure it does not lasts longer than 10 minutes. Therefore, we advise that 2 people are present for changing the bottles.
- Do not change your gas bottles just before sunrise. This is the coldest moment of the night, at which you cannot afford that the machine stands still. If you notice that you will have to change the bottles at this moment, stop 1 hour before and do the change 1 hour earlier.
- Make sure you have spare bottles of propane gas, and that they are stored in the orchard where you need them. Keep the bottles stored vertically. If you store them horizontally, put them on the support and start using them immediately, dirt might enter the gas system and might cause obstructions in the gas circuit.
Improving Fruit Set
Our machines (Frostbuster and FrostGuard) were developed for frost protection. Some of our customers noticed an improved fruit setting when they used the machines during full flowering. So this extra advantage was discovered by clever users during practice.
Meanwhile, also the people from the Research Centre in Gorsem (PCF) have done several tests to see what the results can be if the machines are used for fruit set improvement. With very positive results.
We have customers with big orchards (+ 100 ha) who bought a few Frostbusters for frost protection and bought some extra machines later, just to be able to use it in all of their orchards for fruit set improvement.
How to use the Frostbuster and FrostGuard for fruit set improvement?
FrostGuard: just start the machines early afternoon (13h00-14h00) and let them run for 3 to 4 hours.
Frostbuster: drive with the machine through the orchard early afternoon (13h00-14h00) and pass through every third row.
In both cases, the burner does not have to work when weather conditions are good (dry and warm). Only when temperatures are low and/or the humidity is high, it’s better to run the machines with the burner activated.
Agrofrost Versus Science
Frost protection with our Frostbuster and FrostGuard is a new and revolutionary system. Since 2001, when the Frostbuster was introduced on the European market, tests has been done and results have been analyzed. It was easy to found out that the machine was very effective, but it was difficult to find out why it was so effective.
Most scientists first look at the energy input of our system. Based on that, they conclude that our system cannot work. This is because all other frost protection systems are based on raising the temperature above the critical values. And this demands a huge input of energy. Because we only use a fraction of that energy, most people will say that the energy input is too low and that it’s impossible to create a good frost protection with such little energy input.
But practice has proven that these people are wrong. So there must be another explanation why our systems is so effective, using such low energy input.
Let’s take a look at some facts and experiences.
- The hot air stream of our machines passes and provides energy where it’s needed: on the flowers and buds.
- The outlets of the machines make sure that the air stream remains horizontal as far as possible.
- Air with a high humidity has more latent heath (=energy) than air with a low humidity (at the same temperature).
- Air with a high humidity transfers more heath (=energy) to its surroundings than dryer air.
- Wet flowers freeze easier than dry flowers. So if we can dry the atmosphere, damages will be less. (a wet flower freezes at -2°C, a dry flower freezes at -5 °C)
EXPERIENCES FROM TESTS AND EXPERIENCES FROM OUR CUSTOMERS
- It’s very important to start the machines before the wet temperature becomes negative.
- It’s very important to start the machines before flowers and leaves are covered with hoarfrost.
- Where we use our machines, the forming of hoarfrost in the protected orchard is less compared to not protected areas.
- Contradiction 1: it’s necessary to pass with the machines on the same spot with intervals between 7 and 10 minutes. In this way, we create a temperature fluctuation. At every passage of the machine, the temperature rises and drops again after a few minutes. This fluctuation is important. We have done tests, passing every 2 to 3 minutes on the same spot, so putting in 3 times the energy, and avoiding the temperature to drop between passages. So there was no fluctuation. Result: the flowers were not protected as good as passing every 10 minutes. This was also for us a complete surprise, but practice showed very clearly that the results were much better if the temperature could go down between 2 passages. Why? We will see this later.
- Contradiction 2: normally, the risk of damages due to frost will be greater when air humidity is high. When we use our machines, we see that the results are better when the humidity is high and get worse when humidity gets very low. So, in general, the bigger the risk, the better our machines perform.
- Contradiction 3: tests done in the south of France has shown that during the use of the Frostbuster, while the instantaneous temperature becomes lower than the average temperature of the 30 previous minutes and of the next 30 minutes, the air humidity of the ambient air drops at the same time, where it normally should rise. (See article of Jean-François Berthoumieu)
BASED ON ALL ABOVE FACTS, CONCLUSIONS, TESTS AND EXPERIENCES, WE HAVE FOUND OUT WHAT GIVES US THE GOOD RESULTS.
The forming of hoarfrost liberates energy. The transformation of vapor into hoarfrost gives energy. This energy is transferred to its surroundings, in this case the surrounding air but above all into the leaves and flowers themselves. The warm air stream of our machines, that passes every 7 to 10 minutes, gives energy to the ice. A part of the ice evaporates. After the surrounding air has cooled down again, some new rhyme will be formed, giving again new energy to the flowers. This explains why we need the temperature fluctuation.