The protected greenhouse environment The greenhouse environment is designed to allow plants to perform close to their genetic optimum so that the grower achieves maximum profit. A greenhouse is designed so that the plant converts sunlight, water and CO2 and minerals into marketable yield. Thus the protected greenhouse environment creates a "cozy" climate inside a [...]
Heating the nutrient solution of a NFT hydroponic system may sound like a lucrative option for early yields. Tampering with the nutrient solution temperature is expensive and return on investment low. It is as if the protected environment provides growers endless possibilities to manipulate the growth season of their crops. Unfortunately nature does not work [...]
Proportioner systems Open hydroponic systems lend themselves to two different automation systems i.e. proportioner and injector systems. First let look at what a proportioner does. A proportioner can either be electrical or mechanical device that adds liquid, coming from a tank or other source, into a main line in specific ratio’s. For instance, the ratio [...]
Most automated systems installed in closed hydroponic systems use injectors rather than proportioners. A simplified diagram of where to install such a system is provided below. Many advanced injectors such as the Priva® and Volmatic® systems use much more complex configurations. Most of the systems use two pH probes and two EC probes in case [...]
Greenhouse heating can be very expensive, especially if you greenhouse is not optimally set up for heating. There are factors that can be taken into account in order to reduce greenhouse heating cost or capital installation cost. (A lot more info is in The Polytunnel Book) Reduce air leakages It is estimated that 10-30% of heat in [...]
The effectiveness of a pad and fan system will not only depend on the design, but also on the wet bulb temperature outside the greenhouse. It is not the relative humidity, as many grower think that determine the effectiveness of the pad and fan system. The wet bulb temperature will determine to what temperature the [...]
Mechanical filtration is not an effective tool to prevent water borne diseases in NFT hydroponic nutrient solutions. It has been found that the total organic carbon content can reach 20 mg.L-1 for 2-3 months without affecting plant growth. There are many other compounds that attribute to the total carbon mass such as chelates and the [...]
The correct flow rate of closed hydroponic systems is critical for optimal growth of plants. The flow rates are important for all types of closed hydroponic systems such as pure NFT systems, gravel cultures and ebb-and-flow systems. Inadequate flow rate will result in: Reduced oxygen levels at root surfacesIncreased susceptibility of diseasePlants are under stress [...]
The pythium fungus is one of the serious diseases that growers can encounter in hydroponic systems. The disease can be kept at bay if the irrigation system can be closed of from the environment. The best method to control pythium and phytophtera is by maintaining a 2.5% concentration of hydrogen peroxide. It has been determined [...]
