Definition - What does Nutrient Lockout mean?
Nutrient lockout is a term that simply means a plant is unable to access a particular nutrient or group of nutrients from the soil or grow medium around it. More specifically, nutrient lockout is a situation in which the roots of your plants are unable to take up the nutrients present, and additional fertilizer applications will not help.
Symptoms of nutrient lockout are similar to nutrient or leaf burn and nutrient deficiencies: stunted growth, and lifeless, yellowing leaves.
Note that in a nutrient lockout situation, the nutrients are present, but are unable to be taken up by the roots.
MaximumYield explains Nutrient Lockout
In order to grow healthy and strong, your plants need access to the right nutrients in the soil. Accurate soil testing can tell you want nutrients are missing, and how you need to amend the soil to ensure healthy growth. However, in some instances, this may not work.
Nutrient lockout can be caused by several different factors. One of the most common is pH imbalance. If your grow medium is either highly acidic or highly alkaline, nutrient lockout can occur. Note that most plants have some tolerance for pH imbalance, but severe imbalances can create a lockout situation. In order to grow healthy plants, you will need to address the imbalance (soil testing should reveal whether your soil is too acidic or too alkaline).
In order to change your pH and encourage plant growth, you will need to flush your soil or grow media. This is best done with pure water and no other additives. It is also easiest to do with plants grown in containers, but in-ground plants can be flushed as well. Use twice the amount of water as soil (two gallons of water for one gallon of soil). Flush again within three hours of the first flushing.
After flushing, test your soil’s pH constantly to ensure that you have the right level and the right balance of nutrients in the soil or hydroponic grow medium for plant growth.