Hemp production: what should be considered and how can agricultural plastics help

The industrial production of hemp is an activity that has been carried out for decades, although today there are those who, perhaps due to their lack of knowledge regarding the subject, consider that it is illegal and should not be implemented.

With a little bit of information about what this new “cash-crop” is all about could help clarify some doubts such as understanding what it is used for and what are some of its multiple applications. In this post, we will provide information that can be very useful for those dedicated to the world of agriculture and for the general public as well. 

A little history about the origin of hemp…

Some accounts indicate that the industrial production of hemp, also known as “Cannabis Sativa L,” has a long history with human beings. In the beginning hemp was sown to obtain the fibre used in the production of ropes, grain bags, wagon covers and clothing. Between the 1700s and 1800s there were more than 100 water factories to process hemp fibre only in the County of Lancaster, State of Pennsylvania, in the United States.

The seeds were also used to obtain the oil that was used in the production of inks, paints, varnishes and oil for lamps. Most of the types cultivated in temperate climates had a minimum content of tetrahydrocannabinol (THC), a substance that until the 1960s had not been determined as the component that is responsible for the psychological effects on humans, the typical “high”, which explains why there was no way to differentiate the production of low THC industrial hemp from varieties with high THC content such as those that were used in medical marijuana, according to information obtained from the website Penn State Extension. 

Restrictions on hemp production

Over the years, there were certain restrictions on the production of hemp due to the emergence of certain varieties of marijuana with a higher degree of THC that were linked to drug trafficking, so its cultivation was banned for years.  However, with a change in legislation the States have been allowed to resume the production of hemp with some limitations and very rigorous supervision. 

It is worth mentioning that, although these crops are biologically linked and belong to the same species, industrial hemp and marijuana are different. For example, industrial hemp is cultivated to obtain its fibre and seeds for different purposes: food, fuels, personal care and industrial products, while marijuana is cultivated to obtain high levels of THC.

What should be considered in hemp production?

Regarding its production it is necessary to consider certain conditions for the cultivation of hemp, for example, the fact that it does not grow well in soils with high humidity or with a lot of clay, so it is better to locate soils that are well drained and that have a pH level between 6.0 and 7.0.

According to information published by PennState Extension “hemp is sensitive to soil crusting and soil compaction…ideally, hemp should be planted in May to early June…Some Canadian varieties are short season and could be planted through mid-to-late June and still mature before frost.”

 

How do agricultural plastics help hemp production?

Since hemp is a short-day plant and doesn’t need a lot of sunlight, it begins to mature when the day lasts less than 12 hours. In the case of areas where you want to cultivate it but there is excessive sunlight, farmers can implement a system of tunnels covered by  agricultural plastics to regulate the necessary entry of light, thus creating the ideal scenario for the crop to thrive. Typically specific IR block and light diffusing plastic covers are recommended to avoid variations in temperature or stress to photosynthetic activity of the plant since both factors have direct influence in possible spikes of THC in the crop. 

If you are specifically considering seed production, the hemp to be cultivated is usually the medium to shorter variety, which must be purchased in other countries, as shipping seeds between States is not allowed. The varieties chosen should be those with the lowest THC levels (less than 0.3%) in order to meet hemp production specifications.

Currently there are no herbicides labelled specifically to be used in the production of hemp, and for that precise reason, greater control is needed in case of the emergence of weeds. It is recommended that hemp is always in rows, such as in the cultivation of corn or using seedbeds such as those used for forage crops (herbaceous, gramineous or leguminous plants) to keep it firm and levelled.

Depending on the variety chosen, it is recommended to cultivate an average of 25 to 35 pounds per acre with a depth of about ½ to ¾ of an inch, i.e. having a dense and perforated support that allows better control of weeds. We invite you to read more information about how to do weed management in crops.

To know which fertilizer to use it is necessary to test the soil. For example, in the case of soils with good levels of phosphorus and potassium, with a yield potential of 1,500 pounds, the ideal would be about 150 pounds of nitrogen, 30 pounds of phosphate and 20 pounds of potash, according to information publish on the website Penn State Extension. 

Pests and insects that can compromise hemp cultivation

Like any other crop, insect pests or diseases that end up compromising crop quality can affect hemp. Among the most common are grey and white mould, bacterial leaf spots, viruses and rot among others, as well as the presence of cutworm, grubs, flea beetles, grasshoppers, larvae and aphids.

In terms of prevention, the idea is to avoid cultivating in lands with a history of any of these diseases and pests, since that increases the risk of compromising hemp production significantly. We invite you to read a post related to the importance of monitoring crops.

 An alternative to prevent the emergence of weeds or undesirable pests is to use mulch plastics based on the specific needs of the land, either to maintain moisture at optimal levels or to prevent crops from having greater contact with the soil where they may be housed. Typically white/black mulch plastics are recommended to control soil temperatures and provide extra light radiation to the plants. Some references:

White/black mulch-Solplast

White/black mulch Sotrafa

Depending on the quality of the fibre, hemp should be harvested when the plants are between the early flowering and seed production. Once hemp is cut it should go through the debarking process to break the ties between the outer long fibres and the inner short ones. The most common process is the removal from the field, which consists on leaving the crop in the field for a period of five weeks, so the decomposition of the field takes place.

When it comes to row crops a good recommendation is to rake them at least 2 or 3 times before harvesting to dry and remove the materials of the leaves, so they can finish drying to be later packed in bales that can be stored until they are needed.  

Hemp production as a rotational growing alternative

The production of industrial hemp can be an excellent alternative when it comes to rotation crops, since it eliminates weeds and reduces insect outbreaks and disease problems. Also, it can help rebuild and prepare soils by replacing organic matter and giving it some sort of oxygenation thanks to its root system. Learn more about the importance of crop rotation to maintain soil health.