*How to Fix Nitrogen Toxicity in Plants
Nitrogen toxicity in a flowering cannabis plant.
Using sawdust as a mulch will help decrease the amount of nitrogen contained in the soil. Nitrogen toxicity can be corrected by:
- Flushing the growing medium with pure water or a flushing agent
- Correcting the pH level
- Making certain plants are not fed excess nitrogen
- Removing excess nitrogen from the soil
The most important step is determining if the plant is affected by nitrogen toxicity as quickly as possible. The medium should be flushed as soon as the issue is identified. Providing plants with fresh water will eliminate all excess nutrients present in the growing medium. The plants are then able to recover as the nutrients remaining are absorbed.
A flushing agent containing a specialized mixture can be used successfully as a flushing agent. Pure water is usually the most effective. Once the issue has been resolved, plants should resume the regular schedule for nutrient feedings. Sometimes, the issue is caused by too much nitrogen within the soil. The best way to treat this is by planting something the nitrogen in the soil will bind to.
How Long Does It Take for a Plant to Recover from Nitrogen Toxicity?
In most instances, excess nitrogen can be treated in the growing medium or removed from the soil in approximately five to seven days.
https://www.trifectanatural.com/problem-identifier/nitrogen-toxicity-in-plants/
*From a High Times Article
Applying straw or mulch to the top of the soil does not lock up nitrogen because they stay away from the root zone. These ground covers hold onto water and reduce water loss through evaporation, but are detrimental if mixed into the soil. On the other hand, never add sawdust to the top or any part of the soil. Sawdust has such a high ratio of carbon to nitrogen (C/N ratio of 50:1 or more) it will lock up nitrogen no matter what. Wood chips, twigs, branches and sawdust alike all need long amounts of time (two to three years) to decompose enough so they don’t lock up nitrogen.
So the answer is ...yes, sawdust locks up Nitrogen if mixed into the soil or put on top of the soil but will keep locking Nitrogen for years, it is best to flush with water for de-Nitrification.
The leeching process should take 5-7 days.
Be aware that not all PPM's are the same!
There are several scales and this is where over feeding can easily happen by reading a bottle in one scale and reading it on another scale with your meters.
Sometimes less is more, stick to the bottle instructions and use accurate measuring devices and calibrate your meters.
There are videos on meter calibration on youtube!
not fresh sawdust and wood chips to start a carbon cycle decay that does pull N out of the soil. I have used wood in double dig beds for half a century. It is in the first year of a five year soil plan. I don't know how fast that process can work? 
Night everyone I'm just raffling the night away
