This checklist of RHP EXPLAINS how the acidity behaves in an organic substrate and why it possibly deviates from the expected value
Each culture has an optimal pH value in which plants develop best. That's why it is important to adjust the pH of the substrate to the culture and to know the factors that influence the pH value. Clarity on the dynamics of the pH in the root zone is essential for achieving the best culture result. RHP has developed a checklist which explains how the pH behaves in an organic substrate and why it possibly deviates from the expected value.
At the start of the culture you order substrate for your specific crop. Together with your supplier you determine the desired specifications: pH, EC, N+P+K, water- and air content. The crop has a good start and the root system is developing as you wish.
Factors
But during the culture period, there are also various factors that influence the pH value. You can think of the properties of the substrate and the culture situation that you create yourself.
Substrate properties:
• Initial pH of the substrate
• EC decrease or increase in the culture
• buffering of the substrate, dependent on the percent of peat in the substrate
Culture situation:
• crop stadium
• ammonium/nitrate-ratio in the fertilisation
• specific fertilisers
• bicarbonate and acidifying
• watering system
The properties of the mixture and the various culture factors all have an own influence factor on the pH. Knowledge of pH and executing measurements in the growth season are important to gain insight and steer in time. RHP advises to have a 1:1,5 vv analysis executed regularly:
• for cultures in greenhouses: once every four weeks.
• for outdoor crops: once per eight weeks, more often after a heavy rainfall. In the winter season a lower frequency can be applied.
In the event of a deviating pH, an explanation and solution can be found by means of the mentioned factors. You can determine yourself with which you can steer the pH best.
In the event of deviating individual nutrient contents we gladly refer to the Fertilisation Advice Basis Pot plants (Wageningen University; Dutch document).
Which pH value is optimal for you?
Do you want a new substrate that is fully fit for your culture situation as regards pH? Or do you want to get knowledge for your current culture in the causes of pH change? One of the RHP certified companies gladly advises you.
Because every crop has a desired pH value in which it grows best, it is important to adjust new substrates to be developed on the culture as regards pH. Or do you want to translate the consequences of a chosen recipe to the culture situation? Various factors influence the pH during a culture: the uptake of elements by the crop, the crop stadium, liming and fertilisation. In an existing culture situation you can still steer the pH, so that it fits the culture optimally.
pH-buffer
Each substrate has a certain pH-buffer. Because of this buffer the pH changes less quickly at adjustments. The pH-buffer can strongly vary per growing medium.
Checklist
You can use the checklist ‘pH organic substrates’ that RHP has developed, when you want to compose a new substrate that has been adjusted to a culture as regards pH. You can also gain more insight which factors in a culture influence the pH and to which extent. Based on this knowledge you can examine how the pH can be steered to the optimal pH value for the culture situation.
To develop new substrates?
Do you want to develop new recipes that are adjusted better to a specific culture as regards pH? RHP gladly advises you and has also developed a pH-workshop for certified companies.
