The soil moisture requirements for warm season turfgrasses such as Cynodon spp. and Zoysia spp. has previously been well documented. More recent research has revealed that some of the previous data on the turfgrass plant requirement is based on work of the time or the 'best guess' principal.

In suggesting that some of the previous information was perhaps inaccurate conjures up that perhaps a 'slight' is being made at some well recognized 'experts'. This is not so, indeed as mentioned, the results of this previous research was only produced by way of instruments and knowledge available at that time. Although in some cases, in order to produce a result on schedule, the 'best guess' or observation technique may have been used.

The broadly available data when referring to soil moisture requirement was based greatly on the 'by observation' technique, which resulted in such outcomes as terms such as dry, damp and wet being the best description.

From there technology moved rapidly toward the next stage of moisture by weight. That is, to weigh the soil containing 'Y' amount of water, then oven drying it and weighing the soil again. This would show 'saturation' level and from there, by simple mathematics, it became possible to determine the soil moisture content by soil weight, in a general sense.

Technology advanced to the next stage of determining soil moisture content by way of using a gypsum block, which produced an electrical charge when wet at differing degrees. By using this form of sensing, coupled with 'observation' and plant biology a more realistic measurement of of the content was produced. These results were for that time believed to be as accurate a required for the conservation of water and optimization of plant production.

At the same time as the 'gypsum' method was being developed, so to was the pursuit of measuring evapo-transporation of the plant, which was also determined to be the most logical way of determining the plants moisture requirement. Both methods were used either separately or in conjunction, to produce some of the documentation still used today when determining turfgrass soil moisture requirements.

Turfgrass research has again advanced since then, with more than three (3) most commonly accepted methods of soil moisture measurement being used. These being the use of in-ground thermal sensing devices, the neutron probe and remote sensing.

Thermal Sensing Devices.

At this time there are many thermal probes in the market, perhaps a short description of one of the earlier soil moisture sensing systems is applicable.

In early 1980's, a relatively small electronics design company in Sydney, Australia began to investigate ways of reliably and accurately measuring soil moisture conditions, with a view to creating a fully automated irrigation system that would provide selected plants with optimum moisture conditions.

After some time was dedicated to evaluating available moisture probes it became apparent that there was not a suitably accurate and easy to use moisture probe monitoring system available in the marketplace, that could automatically schedule irrigation.

The company, Cambrone Pty. Ltd, decided it would have to develop its own system and after much research established that the best method of determining soil moisture would be thermal conductivity. After 8 years of research and development Australian and world patents were received for Cambrone soil moisture probe.