Testing & Sampling
Tissue testing for phytocannabinoids such as CBD and THC are important to monitor the crop for quality and to anticipate harvest timing. Since industrial hemp may not exceed 0.3% THC, tracking the level of the crop may be critical as you approach harvest to prevent crop loss due to noncompliance.
CBD levels may fluctuate during the season. A Certificate of Analysis (COA) will need to be provided to the state Department of Agriculture to document delta-9 tetrahydrocannabinol concentration if your crop is not among those randomly tested by the Department. You'll need to choose a lab that is ISO 17025 accredited.
For nutrient analysis of plant tissue:
Collect the newest, fully developed leaf from at least 30 plants in the problem area. It’s important to collect a sample that’s representative of the area of concern.
If there is a good area as well as a bad area, it’s a good idea to collect samples from both. This will allow for a comparison between the good and poor crop. That’s especially important in hemp, as there is little information on plant tissue interpretation.