Effective and Economical Anti-Frost Systems
There are different types of anti-frost systems. Please refer to the FAO guide on this subject, FAOHome, where the different methods are discussed in detail.
Among them, one of the most effective methods of frost protection, with the lowest equipment cost and the lowest energy consumption, is an overhead sprinkler system. This system uses the latent heat contained in water to protect plants. This amount of energy is very high — approximately 81 kilocalories from 1 litre of water — and, unlike the fuel energy used in heating systems, it is essentially free. For more information on this subject, please see the FAO guide and ProAgro’s earlier blogs.
Overcoming frost requires a large quantity of water. For the frost conditions we can expect locally, around –3°C to –5°C, approximately 25–40 m³/hour per hectare may be required. If this amount of water is not available, we need to consider how to reduce the required quantity.
Of course, we cannot bypass the laws of nature and physics, but water savings can be achieved by using a more efficient sprinkler. One such sprinkler is the Wobbler.
Wobbler – Oscillating Sprinklers
Conventional impact sprinklers rotate and distribute water over the area in this way. The potential problem is that, before the water jet reaches the plant again, the water already on the plant may freeze.
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For this reason, such sprinklers must discharge a relatively large amount of water to prevent this from happening. If fast-rotating sprinklers specifically designed for frost protection are used, water consumption can be reduced. This is also stated in the FAO guide.
Sprinklers commonly used on center-pivot irrigation systems are known as oscillating sprinklers, or Wobblers.
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With these sprinklers, water is distributed simultaneously in all directions. This means they can be even more effective for frost protection than very fast-rotating sprinklers. As a result, the amount of water required can be minimized.
Anti-frost systems designed with Wobbler sprinklers are among the most efficient solutions in terms of both water and energy consumption. The overall project budget can also be more economical than with other systems. This advantage is particularly significant in crops planted at high density, such as blueberries, vineyards, and similar crops.
In addition, the same system can be used during hot summer days for plant cooling.
ProAgro supplies these systems and represents Wobbler sprinkler manufacturers as a dealer in Georgia. With us, you can receive the correct hydraulic calculations, a properly designed system, and full project implementation. The project budget can also be adapted to fit within the limits of the state co-financing program.
Strip Sprinklers and Individual-Plant Sprinklers
Another approach is to use sprinklers that distribute water not in a circular pattern, but in a narrow strip.
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Such a sprinkler can cover only the crop row while leaving the inter-row area dry. Naturally, this can reduce water consumption.
Another approach is to install a small-radius sprinkler above each individual plant.
However, there are several points that need to be considered:
- Cold air can also reach the plant from the sides, reducing the effectiveness of frost protection.
- If plant density is high, as in blueberry plantations, a very large number of sprinklers will be required. As a result, the project becomes much more expensive, and total water consumption may eventually become similar to that of a Wobbler-based system.
For this reason, this method may be more suitable for orchards where plants are established at relatively low density.
Based on our assessment, and also on information we have received from farms in South America, localized spraying may still involve a certain level of risk. Its frost-protection effect may not always be sufficient to fully neutralize frost conditions.
Nevertheless, if the available water quantity is limited, this method can still be considered, and we can also supply such systems.
It should also be taken into account that, where a large number of sprinklers and individual supports are required — for example in blueberry and vineyard projects — the total project cost may exceed the limit defined under the state co-financing program.