At the state level, California state laws have provisions for the cultivation of cannabis or hemp. However, the majority of...Read more
Overview of hemp cultivation
Hemp—the industrial variation of cannabis has been cultivated for thousands of years, spanning human existence on earth. In some circles, hemp is considered the world’s oldest cultivated plant. In accordance with botanical descriptive parameters, hemp is considered an annual herbaceous plant that can grow to a height of about 15 feet. The hemp pith is surrounded by the outer layers—a woody material knows as the hurds and a rapidly dividing layer forming fibers on the outside. The hemp leaves are of economic importance as some farmers cultivate the plant mainly for the leaf yield. The leaves are palmate with serrated edges and can have up to 11 leaflets. The root of the hemp plant develops with respect to the planting soil type. Lateral roots develop prominently in Soil unfavorable to growth while the taproot develops prominently under favorable growing conditions.
As expected, the CBD industry depends to a large extent on the large scale cultivation of hemp. Considered to be environmentally friendly, different stakeholders of the CBD industry are advocating for the production of biodegradable products from the cannabis plant. Almost all parts of the cannabis plant can be used for different applications. The product range developed from hemp includes biodegradable plastics, fiberboard, cellophane, industrial fuel, clothing, diapers, shoes, and other products of domestic importance. Depending on enacted legislation, the cultivation of cannabis plants is strictly regulated by organized bodies in different regions across the globe. In some regions, a license is required to cultivate hemp. In the United States, the passage of the 2018 Farm Bill has created a platform for industrial hemp cultivation across the 50 states. Policies and requirements are also in place to ensure that supervised cultivation can only be done by licensed farmers.
Cultivation methods and growing conditions
As in the large scale cultivation of other plants, the growth of the cannabis plant is capital intensive and might require mechanical input depending on cultivation size. The capital and overhead cost needed to maintain cannabis cultivation also depend on the cultivation size. For an optimum harvest and increased plant turnover rate, farmers must fulfill some basic growing conditions in a stepwise approach to cultivation.
- Soil type and soil preparation
The cultivation of the cannabis plant starts with a detailed assessment of the soil type available to the farmer. Large-scale commercial farmers get the soil tested to determine the constituents of the nutrient and the right quantity of fertilizer needed to augment the nutrient profile if needed. The right nutrient profile includes a high level of nitrogen, high levels of phosphorus, and moderate levels of calcium and sulfur. Hemp grows best in a loose, well-aerated loamy soil with an abundance of organic matter. Industrial hemp has been found to grow particularly well in soil with good nutrient holding capacity, moderate moisture content, and a pH of 6 or greater. In readiness for planting, the soil is prepared as a fine, firm seedbed.
Hemp can be grown in two different ways using seeds or hemp clones. Using the seed method, the seeds are placed directly in a pre-made hole not more than two inches in depth. Germination starts within 48 hours, and the young plant can be seen above the soil level within seven days. Experts have recommended that harvest yield is better when the seedling is done at a minimum soil temperature between 6-8ohi. Seedless cultivation involves the use of hemp clones—stem cuttings made from a viable parent plant. The clones are first immersed in water or a cloning solution for the cutting to develop roots. These sprouted clones are then transferred to the prepared seedbed. Seedling time also depends on whether the hemp is cultivated for fiber or grain.
- Weed control and harvest
Hemp plants naturally suppress weed on the cultivation field as they effectively compete for space, nutrients, and light. In most cases, weeding control is minimal or nonexistent, and herbicides are not required. Under a favorable condition of continuous nutrient supply, hemp plant cultivated for seed are harvested within six weeks of cultivation, and those cultivated for fiber are harvested within 90 days.
Factors responsible for cultivation and harvesting failure
- Excess moisture
Optimum growth of the hemp plant is balanced delicately on a continuous supply of moisture at moderate levels until harvesting is complete. On average, this plant requires about 500-700 m of rainfall for a growth cycle (Bosca et al., 1998). About 50% of this precipitation supply is maintained around the root area throughout the growing season. Excess supply of moisture to the plant after seedling makes the soil water-saturated and stunts plant growth. Once the soil is flooded and moisture content becomes significantly increased, the plant turns yellow, growth is terminated, and the root decays. This is considered the most probable factor responsible for cultivation failure.
- Spring and fall frost
Frost covering at freezing temperature is also considered harmful to the hemp plant. Unlike excess moisture, the harmful effects of frost are more pronounced on matured plants as seedlings can tolerate frost at about -7hfu for two weeks. At freezing temperatures, frost naturally removes the plant’s water content, leading to premature abscission and subsequently reducing the harvest yield of plants cultivated mainly for the cannabis leaf. At these temperatures, the stem dries up, and the fiber separates out, also leading to low fiber yield (CHTA, 2020).
- Hail damage
Compared to other cultivated plants, fully matured hemp plants have a slender stem with a maximum diameter of about 0.8 inches; this single feature makes the hemp plant vulnerable to hail storms. In the event of an intense storm, the plants can break off at weak areas of the stem.
In young, immature plants, growth is stalled if the hail storm breaks off the apical meristem—the top of the plant made of actively dividing cells responsible for plant growth. In some cases, adult plants can survive the damage caused by an intense hail storm as a new offshoot of the plants develops at the breaking point. In essence, hail storm perforates the leaves and bends the stem, leading to the low-quality yield of both leaves and fiber during harvest. Hail storms are notorious causes of hemp crop failure.
Soil compaction and excess heat are also notable causes of hemp crop failure. To prevent low-quality yield and crop failure, expert handling of the hemp cultivation is strongly recommended.