POSSIBILITIES OF WATER CONTENT MEASUREMENT, IN COMBINATION WITH SUBSTRATE PROPERTIES AND DRAINING SYSTEM

Measuring the water content directly in the substrate with dielectric measurements gives relevant information to improve the interpretation of the effects of substrate type, irrigation amount and -frequency, and draining system on the water buffer in the stone wool slab.

The correlation between the water content measured with the used dielectric method and the traditional gravimetric method was shown, as was the correlation between the dielectric EC measurement and the traditional one.

A hand-held water content meter is now almost two years available, recently an improved stand alone apparatus was developed, which can log the data.
It shows interesting measuring results of water content and EC during the day night cycle.

Water content measurements were done on tomato crops on stone wool substrates, during several seasons.
The results are discussed in relation with the water content strategy.
In the first trials the water content/EC meter was coupled continuously to the normal glasshouse climate/water control computer.
The results showed that substrates with a steep water retention characteristic were very appropriate to regulate the water content and EC of the root medium.

International Symposium on Growing Media & Plant Nutrition in Horticulture

J.F. de Groot

Active draining system, mineral wool, irrigation strategy, EC measurement, glasshouse climate computer

https://doi.org/10.17660/ActaHortic.1995.401.59