Trying to look for a reference and this kinda explains it better than I can.
Iβm growing organically and my readings are way off!
Yeah, this gets a little complicated. PPM are a straightforward measure for hydroponic or standard, synthetics-based growing. Thereβs a set number thatβs ideal for each stage of growth, and thatβs it. Organic growing is a little different. Part of the philosophy of organic growing is that the nutrients donβt just come from some refined, synthetic fertilizer. The soil itself should be fortified and made nutritious for your plants using natural, organic ingredients. Why does this affect PPM readings?
Rich, healthy organic soil is more complex than artificially fertilized soil or hydroponic solutions. The nutrients are stored in more complex molecules than with artificial fertilizers, that are released slowly over time. EC meters work by measuring the electrical conductivity of salts in water; organic nutrients havenβt yet broken down into simple salts. Itβs like the difference between complex carbohydrates found in whole grains and refined white sugar. The organic nutrients get broken down by microorganisms over time, much like complex carbs get broken down by our digestive system. Therefore, the PPM readings you get from organic soil wonβt reflect the actual nutrients that soil contains.
However, they may not be lower, as you might expect them to be. Why? There are plenty of non-nutrient solubles found in organic fertilizers that can confuse your readings. Remember how we talked about solubles in tap water earlier? This is a similar concept; many organic soil additives can end up adding acids and carbohydrates that are electrically conductive, thus throwing off your TDS meterβs EC readings.
Is it worth testing organic soil for PPM?
Good question. Due to the complex nature of organic soil, EC readings will be too inaccurate to determine whether the appropriate amount of nutrients are present in the soil. To determine if organic soil is well-balanced for your growing system, youβll need to carefully monitor pH, watch the plant for signs of nutrient deficiency or imbalance, and learn from experience. If you have the resources, you can send a soil or plant matter sample to a lab for analysis. Alternatively, you could always rely on our simple four-step process for growing flavorful and potent organic cannabis