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Take a look at some of our previous articles regarding the potential risks and rewards in the CBD market as well as agronomic considerations for successful industrial hemp production.

Today's Notebook features Harvest and Dry Hemp for CBD Production

What does low THC level have to do with CBD hemp?

Commercial Hemp Production is changing rapidly. There is a massive shortage of research-based info regarding the basic agronomic recommendations but we are making progress. Because of the great interest in hemp from farmers, industry, community leaders, and potential consumers of hemp products, we will summarize what has been learned from listening to numerous people working with this crop.

Hemp can be grown for seed, fiber, or flower (oil extracts). The majority of production is focused on growing hemp for flower, primarily the CBD market. CBD, or cannabidiol, is one of over 100 cannabinoids identified in hemp plants. Another cannabinoidis THC, tetrahydrocannabinol, which is the psychoactive ingredient in cannabis that gives a ‘high’ effect. The amount of THC in a cannabis plant determines whether it is hemp or whether it is marijuana. If the THC content is 0.3% or less, it is hemp. If the THC content is greater than 0.3% it is marijuana. Female hemp flower. Most (but not all) hemp cultivars are dioecious, meaning male and female flowers are found on separate plants. Hemp growers interested in CBD production want female plants.

Usually, growers must report when plants are flowering and, thus, are ready to be tested for THC, and state officials may visit the site and sample hemp 3-5 weeks into flowering. They usually take the top 3-5 inches of the plant and if you have multiple varieties you will need multiple tests. The growers pay for all testing. If the level of THC is above 0.3% you will have two options – destroy your crop or pay for a re-test of the THC . Growers need to be aware that plant stresses (drought, flooding, excessive nutrients, not enough nutrients, heat, cold, etc) can result in THC spikes. According to our national survey, 9% came back above 0.3% THC. Thus, 9% of hemp fields are ‘going hot’ – lingo used to describe a THC spike. This is a serious risk to hemp producers and there is currently no crop insurance to mitigate this risk.

We don’t have solid data on the causes of THC spikes but here are some considerations. In one research trial, nitrogen was applied at rates of 50, 100, 150, 200, 250, and 300 lbs per acre. While there was no advantage at putting out more than 100 lbs of nitrogen per acre there was no spike in THC. In fact, from just this first year of preliminary data, our research did not see any relationship between nitrogen and THC or CBD. In fact, if nitrogen deficiencies could result in plant stress, thus causing a THC spike. From just this first year of data the nitrogen recommendation would be 100 lbs of N per acre. If Northridge was growing hemp right now we would lean towards a higher nitrogen rate (120 lb/N per acre). Certainly, variety selection will play a role in THC content of the hemp varieties.

We are still gathering information for growers regarding variety performance. Ask for Report A14-2020.

Hemp Production – Market Opportunities and Risks

Industrial hemp markets are growing. In 2015, the US hemp-based product sales totaled $573 million. In 2016, sales grew to $688 million and in 2017 sales reached $820 million. Those sales include food products, industrial applications, fiber products as well as products from the CBD oil. The majority of hemp producers are interested in the CBD oil market.

We are review data from processors that accept wet hemp flower biomass (within 48 hours of harvest) and base pricing on total CBD content. Because of this type of processing the whole plant (stems included) they had many samples testing at 3% CBD. The flower may have CBD levels at 10% or higher but the very low CDB percent in the stem brings the overall CBD percent of the sample down. Another method are processor receiving dried (below 10% moisture) flower biomass without stems and usually. However, accept fresh-cut biomass with stems on. Prices vary with the market and how the processor will accept the biomass. A different processor described a scenario for the purchase of dried floral material without stems. Depending on the quality (cannabinoid spectrum, impurities, mold) of the material they would pay anywhere from $2 to $7 per percentage of CBD. If a farmer produced 1000 lbs of biomass (dried and stemless), with a CBD percentage of 10% and the highest quality cannabinoid spectrum with no contamination or impurities they could gross $70,000 per acre [($7) x (10% CBD) x (1000 lbs biomass)]. However, if that farmer produced that same biomass but with 5% CBD and lowest quality of cannabinoids and impurities that farmer could gross $10,000 per acre [($2) x (5% CBD) x (1000 lbs biomass)]. These figures represent the national average and are lower on in the Northeast.

There are significant risks with growing hemp for CBD. If the markets get saturated prices could drop quickly. Production costs are estimated at $13,000 to $15,000 per acre primarily due to the high cost of female clone plants ($5 to $10 per plant with 1200 to 1500 plants per acre). We advise all farmers to start small and begin talking with processors right away. Know your market before you plant the crop. Speaking of risk, did we mention that the farmer loses everything if the THC of their plant goes higher than 0.3% at any time?

Harvesting hemp is a critical stage for CBD production.

The presence of molds and mildews will lower the value of hemp floral biomass so a timely harvest is essential. There are visual clues on the hemp bud that growers should monitor. When trichomes on the hemp bud shift from white to milky white it may be time to harvest. Weekly testing of CBD content can inform the grower of when the harvest should be initiated. While some of the tests for CBD, cannabinoids, terpenes, pesticide residue, mold, and heavy metals can cost as much as $300 the return on investment can be significant. For example, if 1000 lbs of biomass will be harvested on one acre the difference between harvesting when the crop is at 6% CBD versus when the crop is at 7%CBD is equivalent to 10 pounds of CBD oil. Current prices for CBD oil are $5 per gram. With 454 grams per pound, a 1% discrepancy in CBD content on one acre can be a $20,000 crop value difference. Growers need to test frequently to make the right decision regarding harvest timing.

Weather will also be a key factor in determining when to pull the harvest trigger. Harvest time for hemp coincides with the hurricane season. Growers will have an easier time drying and curing their hemp floral biomass if they can bring it in before the arrival of a storm. This is the time when adequate labor is crucial. The vast majority of hemp growers for the CBD market are relying on labor to cut the stalk (the machete is the current tool of choice) and load the biomass. This takes a lot of time and physical exertion. I have heard reports of growers that had an excellent crop of hemp floral biomass but suffered massive losses because they could not harvest it in time (their two-person harvest team was not adequate). The importance of measuring the labor requirement is a big reason why we recommend that first-year hemp growers for the CBD market start with 1 acre or less. Growers need to keep track of the amount of man and woman hours that it takes to bring in the harvest. Maintaining sharp tools during the harvest process will also save time and effort.

Drying and Curing Hemp

Hemp biomass made from chipping the entire hemp plant. This biomass is of low quality and will receive a reduced price. Once hemp is harvested growers should immediately move the floral biomass to the drying facility. This could be a simple structure like a barn. The facility should be under roof, out of direct sunlight, and well ventilated. Growers need to set up several fans and have them blowing continuously. Significant ventilation is crucial! Ideal temperatures for drying and curing are 60 to 70 degrees F at 60% humidity. Some processors say that hemp growers should not dry their floral biomass at the same temperatures as flu-cured tobacco. Those temps are too high and dry the hemp too quickly. A slow drying with high airflow will cure the hemp, produce a higher quality end product (better cannabinoid and terpene spectrum), and fetch a higher price. It is difficult to estimate the square footage of the drying space needed per plant. Using flu-cured tobacco with 800 square feet a grower was able to dry 1 acre worth of plants (approximately 1350 plants) in 3 days. Another grower was able to dry approximately 1.5 acres worth of hemp (plant number not stated) in a 2500 square foot barn. Hanging entire plants upside down on wires in the drying barn is a common practice. Unfortunately, as those plants dry the branches droop down in the formation of a closing umbrella. That closing umbrella shape results in less airflow to the center of that entire hemp plant. Thus more mold and mildew will grow in that center portion. We advise growers to break off the individual branches from the hemp plant and hang branches on the drying wire, not whole plants. This step is more labor-intensive but will help minimize mold and mildew.

Keep track of our notebook articles and follow the suggests. Remember: time gives good advice.


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