Due to the long degradation time of sponge substrate, not good for environmental protection. In order to find an alternative to sponge substrate that is easy to degrade, #Trinog Agro-team is trying to have a new rock-wool for testing, use Batavia lettuce as the test variety for #NFT #hydroponics.
The different between #rock-wool and sponge substrates as follows:
The seedling emergence rate was approximately the same, but rock-wool showed more capping, which affected the seedling emergence rate.
The rock-wool retained water better and was irrigated less than the sponge substrate. At day 17, it was found that the plants rooted better in the sponge and the plant bodies were upright, while rock-wool plants floated on the surface and had less roots rooted out.
With sufficient irrigation and fertilizer, rock-wool plants with long and large leaves, the base of the stem cannot support the weight of collapse, bending. The rock-wool seedling time should not be too long, or the leaves torn will affect the efficiency of transplanting. We recommend to plant with three leaves a heart. In the Sponge substrate, the leaf size is moderate, four leaves a heart do not appear collapse phenomenon.
The two substrates pre-growth rate is roughly the same, the rock-wool leaf number began to more than the sponge substrate when it when it has three leaves a heart.