The importance of the right substrate
A substrate is, in particular in greenhouse horticulture, an artificial soil for plant growth. Advantages of a substrate above ground are the controllability of the supplied nutrients and the easy way to disinfect the substrate. Horticultural substrates are often made of stone wool, which is also fully recyclable. The nutrients are supplied in liquid form, for which an installation is present in the greenhouse to mix the various nutrients in the correct proportion. The ingredients are manufactured by the chemical and fertilizer industry. Nowadays, plastics, such as polyurethane foam, are also used as a substrate. Other materials used are peat fiber, peat moss (Sphagnum), coconut fiber and the like.
Pumice grains and other porous stony material is also used as a substrate because of the ability to retain water. In dry, volcanic areas, such as the Canary Islands, pumice is used in open soil cultures to absorb the moisture present during the night hours that the plants can use during the day. The term is also used in horticultural mediums for the tailor-made mix soil that is supplied for their cultivation. With this, trays or pots are filled for the propagation of their plants. In this way the grower also has good control over the composition of his cultivation soil.
Function of substrate
Substrate is therefore a collective name for soil types such as soil, coconut, sand, clay etc. In short, substrate is the one where you put your plants. But what is the function of substrate and how do you choose the right kind? Substrate has the primary function to give your plants a place to fix or fix themselves. In addition, it still has a large number of functions where the three most important are providing oxygen, providing water and providing nutrients to the plant.
It may sound strange, but oxygen is the most important here because plants without oxygen do not absorb water or nutrients. In the root pack, oxygen is continuously exchanged with CO². The substrate must therefore be airy enough to allow CO² to escape and allow oxygen to pass through. Oxygen is an important building material when it comes to the development of the plant roots. When there are circumstances where oxygen can not be absorbed, it paralyzes the metabolic and respiratory activities which can affect vital processes in the plant.
A good substrate satisfies a number of basic characteristics for a good oxygen exchange and the amount of water that the substrate can hold which is important to get the nutrients to the plant and to let the roots “breathe”. If a substrate is too compact or has the tendency to retain too much water, there is a great chance of root rotting which does not benefit the plant development.
On the other hand, if the substrate dries too quickly, the water evaporates too quickly and the plant therefore does not take enough water for proper development. A good substrate should hold enough water for about 3 to 4 days to allow the plant to absorb the water. Maintaining wet / dry periods is essential for the plant. Since plants also perspire, watering too early can affect the perspiration of the plant.
Furthermore, knowing which substrate you work / will work with is important because the food for the plant is adjusted accordingly. Substrates exist in different types, depending on the desired properties. Physical examination of a substrate determines the amount of moisture in the substrate (%), the bulk density (weight / cubic meter), the shrinkage and the pore size; furthermore, the volume fraction of air (%) and the volume fraction of water (%) of the organic substance are determined