Horizontal measurements

Details on water and Ec distribution in stone wool slabs.

Horizontal profiles of water and EC distribution provide a lot of useful information.

There are various methods for measuring moisture content and EC value in the substrate. In practice, weighing scales and sensors are used most. The ultimate purpose of these measurements is optimised irrigation control. Making horizontal profiles of stone wool slabs will show the differences between substrates and irrigation (dose size and frequency), which in turn will provide insight into improved use of the substrate system.

Cultilène’s Development department has worked with this intensive measuring method for many years in order to gain insight into the characteristics of substrates. Cultilène’s team also does a lot of horizontal measurements in practice; growers respond very positively to these new insights.

Method

Traditionally, sensor-based moisture measurements are performed by means of vertically measuring a number of slabs in one position from the top of each slab. The moisture percentage of that one position is then taken to be a representative value for daily water supply control. However, a one-point measurement  does not give any insight into the details of water and Ec distribution throughout the slabs.

Cultilène’s horizontal measuring method involves performing 27 measurements for every metre’s length of slab. The measurements are taken from the length of the slab and several slabs are used so that differences between slabs may also come into view.

Ultimately, these measurements are presented as in the below examples of water and Ec distribution and the effects of irrigation strategies and stone wool properties – in terms of root distribution and homogeneity – can be analysed.

In actual practice, this analysis has turned out to be very useful for determining changes in the watering strategy. By regularly performing horizontal measurements it becomes clear that the differences in water and EC distribution between various substrate slabs and watering strategies can be larger than is often assumed.