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Proper rooting volume
(Source: Up to date No 2 September 2003)
The subject of this issue is substrate volume with answers bij Dr.Andy Lee.
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Why increase the volume of my stone wool?
The goal of any sound water management strategy is to equalize water distribution over the height of the substrate and thus maximise the water buffer and effective rooting volume per m2. When this goal is achieved, the growers’ risk of blossom-end-rot (BER), russetting, and fruit cracking is reduced, since the root system is optimised. The grower can match the irrigation start and stop times with the plant activity, not (over) reacting to the needs of the substrate.
What’s more, the maximisation of rooting volume may also lead to the optimisation of fruit size and increased yields. Research conducted at Horst Research Station in the Netherlands has indeed shown increased yield in tomatoes. Furthermore, grower trials in UK have shown better yields and an easier to manage substrate with a number of growers increasing their substrate volume in the coming season. |
How to calculate the volume of stone wool ?
First calculate the volume of an individual slab :
Length (m)x Width (m) x Height (m)=x Litres
Calculate area represented by one slab :
Size of 1 bay (m2) / number of slabs per bay=x m2
Slab volume /m2 :
slab volume (litres) / area represented by 1 slab (m2)
A slab volume calculator can be found at by clicking here. |
The recommended volume of rock wool?
Grodan makes the following recommendations, based on research results:
| < 9 l/m2 | Too little: inadequate for proper
water management | | 9-12 L/m2 | Recommended: optimum for a
strong water management strategy | | > 12 L/m2 | Too much: inefficient and may make
water management more difficult |
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What would be the advantages of increasing my substrate volume ?
• If the substrate volume is optimised, irrigation start can be delayed until the crop is active. Proper start times in the morning, after the crop is active, will prevent the plants from becoming too stiff too soon in the morning.As a result, fewer heads will be broken
during plant twisting.
• When working with the proper substrate volume, the stop time can be optimised to accurately control the day/night water content (WC) difference. The day/night WC difference is a powerful tool for controlling the generative and vegetative balance of the crop. Controlling this balance will have a significant effect on fruit quality, especially russetting and BER.
• The larger the rooting volume, the larger the irrigation volume. Research into the application of large irrigation volumes has shown to reduce the incidence of BER in tomato and pepper. The larger the rooting volume, the greater the waterbuffer. Which reduces the risks associated with low capacity irrigation systems or problems with breakdowns. A large water-buffer will reduce the impact on the crop of fluctuations in irrigation applications. |
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