Air compressors are already used for spraying a wide variety of liquids, many of which have applications in agricultural industries.

But a newly developed all-natural antifreeze formulation could soon allow air compressors to be used to render plants frost-proof.

The recipe, according to University of Alabama professor David Francko, contains “either human food ingredients or [components] used in the human food production chain”.

Yet, once sprayed on to plants, it enhances their natural antifreeze capabilities to a degree comparable with moving them to a climate 200 miles further south.

The discovery is one more example of how sprays can have beneficial effects for agriculture beyond the classic applications of feeding and insecticide.

What’s more, the all-natural formulation could mean the frost-proof spray is suitable for organic farming methods.

For agricultural applications on all scales – from semi-professional vegetable gardens to extensive arable farms – there are air compressors suitable for use in powering plant sprays.

Compact, portable air compressors are ideal for smaller plots, while larger, more powerful alternatives are available for permanent or semi-permanent installation.

One of the principle components in any air compressor is the pump, and over years of development, two main types of pump have evolved. The simpler, but more reliable type of pump is known as the oil lubed pump. This type of pump has proven itself again and again over the years, since it is highly durable, reliable and long-lasting. The only drawback of the oil lubed pump is that the pressurised air that it produces is sometimes not of the best and cleanest quality, which may make the oil lubed pump inappropriate for more technical and exacting applications where extra-clean pressurised air is required.

By contrast, the other type of pump available for air compresssors is known as the oil-less pump. This type of air compressor pump involves a higher level of technical sophistication in order to overcome the lack of lubrication system within the component. However, it can have several drawbacks; it may well be more expensive, it may make a louder noise than an oil lubed pump – and it may last for less time than an oiled lube pump; in its favour, though, the air produced is of better quality.

Air compressors come in all shapes and sizes, but there are broadly two methods of compression, which are known as positive-displacement and negative-displacement. Positive displacement is a form of compression in which air is forced into a chamber whose volume reduces as compression takes place. Piston-driven air compressors use this principle – as do rotary screw compressors, where two helical screws guide air into the chamber and then compress the air as the screws turn. Vane compressors – another type of positive-displacement compressor – use a slotted rotor with varied blade placement to guide air into a chamber and compress it prior to use.

The other method of compression, known as negative-displacement, is used in centrifugal air compressors (which are designed mostly for very large applications). These compressors use centrifugal force generated by a spinning impeller to accelerate and then decelerate captured air. Broadly speaking, most air compressors are either reciprocating piston type, rotary vane or rotary screw.