Before planting, it is necessary to adjust the pH value of the rockwool grow media to a certain range before it can be used. Do you know why the rock wool substrate needs to adjust the pH before planting?

What is the PH?

The pH value indicates the pH of the substrate itself: pH=7 is neutral, pH

Changes in pH are recorded in multiples of 10, which means that for every unit increase or decrease in pH, the acidity or alkalinity of the pH value increases or decreases by a factor of 10. For example, the alkalinity of pH9 (10-9 hydrogen ion equivalent per litre) is 10 times higher than that of pH8 (10-8 hydrogen ion equivalent per litre), and the alkalinity is 100 times higher than that of pH7 (10-7 hydrogen ion equivalent per litre).

CP S40 MINI Block

What effect does the pH of the substrate have on crops grown in hydroponic culture?

Different planting substrates show different acidity and alkalinity according to different substrate materials, including acidic, alkaline and neutral.

The pH of the substrate will indirectly affect the effective absorption of various elements in the nutrient solution by soilless crops, resulting in nutritional imbalances in crops,

such as:

①When the pH value in the substrate is too high (pH>7): it will lead to the precipitation of trace elements such as iron, manganese, copper and zinc in the nutrient solution, making it impossible for crops to effectively absorb such trace elements. It will lead to an increase in the solubility of aluminium and manganese in the nutrient solution, resulting in plant intolerance;

② When the pH value in the matrix is too low (pH < 5), due to the antagonism of hydrogen ions, the absorption of calcium by crops is blocked, causing calcium deficiency in plants.

The environment of over-acidity and alkaline will affect the balance and stability of the nutrient solution. Since the pH value inside the matrix of UPuper® rock wool is alkaline, in order to make the elements in the nutrient solution fully play their role and ensure the good growth of plants, it is necessary to let It is in a slightly acidic environment. Generally speaking, we adjust the pH value of the UPuper® rock wool substrate to pH 5.5-6.5 (most crops used in hydroponics cultivation in greenhouses like the weakly acidic environment of pH 5.5-6.5, but there are exceptions, such as Blueberries like an acidic environment, and spinach likes a neutral environment. Growers can adjust the pH value of the rock wool matrix according to the actual needs of planting crops)

UPuper® rockwool medium is an inorganic and inert planting substrate with a stable and uniform pH value. The rockwool produced in each batch can achieve basically the same physical and chemical properties of the substrate, and will not mix with the nutrient solution during the planting process of crops. Physical or chemical reactions occur in any of the ingredients, avoiding the influence of the healthy growth of crops due to changes in the internal pH value of the matrix.

Organic substrates such as coconut peat and peat are different from rock wool substrates in that they have certain nutrient adsorption and release capabilities, which means that these organic substrates may have a certain chemical reaction or ion exchange with the nutrient solution. During the process, it is easy to cause the pH value of the crop nutrient solution to change, especially in the long-term planting process, it is easy to cause a large change in the EC and pH of the rhizosphere of the crop root, which will lead to an increased risk of premature ageing of the crop, which is not conducive to the second half of the crop. In the production management of the planting cycle, there will be problems including but not limited to crop yield reduction and product quality degradation.