Crop diversification is an important tool for reducing the negative environmental impacts of cannabis cultivation. It can improve soil fertility, suppress weeds and increase the resilience of crop varieties against pests and diseases.
However, research on the effects of crop diversification in cannabis cultivation is still limited. Therefore, further studies are needed to fill the existing gaps in knowledge.
1. Crops with Different Needs
Among the many factors that influence cannabis cultivation, water and climate are two important ones. Outdoor cannabis cultivation is generally less water-intensive than other commodity crops, but this isn’t always the case, especially in arid or drought-stricken growing regions.
The high demand for water induced by cannabis cultivation leads to soil and groundwater pollution and divertion (Moyle 2002). A study of irrigated agriculture in California, for example, found that surface water diversions reduced flows, dewatered streams and caused a decline in the quality of irrigation water, which negatively affected crop yields [63]. In addition, irrigation systems require energy resources and water to pump large amounts of water from afar.
Aside from water, energy consumption also plays a crucial role in the environmental impacts of cannabis cultivation, which is particularly problematic when indoor cultivation is involved. Lighting, HVAC (heating, ventilation, and air conditioning) and dehumidification account for a major portion of energy use in the production of cannabis. Moreover, the CO2 emissions of lighting and precise microclimate control contribute to a substantial carbon footprint in indoor cannabis cultivation (Mills 2012).
In addition to water, temperature is another limiting factor for indoor cannabis growth, especially for tropical varieties that require higher temperatures to thrive. Generally, temperatures should range between 25-30 degrees Celsius to maximize plant yields.
However, the optimal growing temperature for different strains of cannabis varies widely, and it is important to choose the right strain that will thrive in your climate conditions. For example, leafy greens prefer colder temperatures to promote growth and maximize yields; fruiting and flowering crops, on the other hand, tend to grow best in warmer climates.
Hence, crop diversification is an important way to minimize the environmental impact of cannabis cultivation by increasing its productivity. Some of the most common crop diversification methods include increasing the density of plants, promoting canopy growth, and supplementing light. These methods can significantly increase yields and reduce costs.
Crop diversification is also a way to decrease the environmental impact of cannabis cultivation through reducing energy consumption, using less water, and decreasing CO2 emissions. In addition, crop diversification can help to alleviate the pressure on available land by increasing production and reducing demand.
2. Crops with Different Growing Conditions
Crop diversification can be a good way to increase cannabis cultivation production. Several factors contribute to this practice: crop availability, genetic diversity, and agronomic knowledge. These factors can be used to select the best cultivars and manage them in a more efficient manner, promoting the maximum yield of phytocannabinoid compounds.
As a result, diversification can help to reduce the risks associated with cannabis cultivation. In addition, it can allow for the development of more advanced techniques to improve quality and productivity.
The cultivation of cannabis is a complex process that involves different stages in plant life cycles. The first stage is germination, which occurs in early spring and results in the emergence of new plants in the soil or in a controlled environment. The second phase is the growth period, which begins in late summer and ends in early autumn when the plant is harvested.
Cannabis is grown in a variety of growing environments, such as hydroponics, in pots and directly in the soil. When a plant is large enough, it is usually transplanted into larger containers.
Many growers also use supplemental light to promote the growth of their plants. This can be achieved by using a high-pressure sodium lamp, a fluorescent lamp or an LED light. The choice of lamp type is important to maximize yield and phytocannabinoid production.
Aside from the light supply, a greenhouse-like atmosphere with a stable temperature is also necessary for optimal cannabis growth. This is particularly important for flowering stages, when temperatures in the range of 35 degC are needed to achieve sufficient CO2 assimilation rates.
Studies have shown that a temperature above 35 degC can reduce the yield of secondary metabolites and the overall flowering rate in some cultivars [133]. This is due to an increased risk of root diseases, which reduce nutrient availability and exacerbate apical deterioration in plants.
In the greenhouse, it is recommended to install a temperature control system that maintains the ideal growing conditions. This is especially important during the flowering phase, when it is necessary to produce large amounts of phytocannabinoid compounds and flowers in a short time frame.
3. Crops with Different Pests
Crop diversification is a useful tool in cannabis cultivation to reduce the risk of pests and diseases. Moreover, crop diversification can also be used to enhance yields and improve quality.
In addition to weeds, cannabis crops also are susceptible to various insect pests and diseases. Hence, it is necessary to take precautions and apply pesticides to protect the plant and the final product.
Among the most common insect pests that affect marijuana plants are aphids and whiteflies. These pests are known to attack both the leaves and the stems of the plant, making them one of the most problematic pests for cultivators. They can spread to other plants in the area, so it is important to identify them and eliminate them before they destroy the entire crop.
Another insect pest that is often found in marijuana is thrips. These insects are very small, so they can be difficult to detect and treat early on. However, they can cause serious damage to the plant and are one of the most costly insect pests for growers.
There are several species of thrips that can infest marijuana plants, including greenhouse thrips, western flower thrips and onion thrips. Depending on the specific species of thrips, they can damage the plant by eating the leaves or extracting the chlorophyll from the leaf tissue.
Some thrips are more common than others, but they can all be controlled using a variety of insecticides. These include BT spray and spinosad, which can kill spider mites, thrips, and whiteflies on contact.
Many of the insecticides available for marijuana plants can be diluted with water and applied to the soil, but the best solution is prevention. A quarantine area and strict sanitation rules are important to prevent these pests from infesting the plant.
The cultivation of marijuana plants requires a high level of water availability to ensure that the plants receive enough moisture, especially in dry periods. This water requirement depends on the growing conditions and is affected by factors such as temperature, CO2 concentration, and fertilization. The amount and frequency of irrigation must be adjusted to the optimum water level for each genotype and crop.
4. Crops with Different Diseases
The cultivation of cannabis sativa has become a key livelihood strategy in southern Africa, enabling rural households to generate income from a small amount of land. This strategy has been highly effective in combating poverty, reducing the incidence of HIV/AIDS and increasing household food security. However, there are many challenges to maintaining these livelihoods.
The rapid expansion of cannabis production in rural Lesotho, for example, has led to an increased pressure on available land and a decrease in soil fertility. This decline in soil quality, in turn, has resulted in an increase in erosion rates. Despite the decline in cannabis prices and a reduction in remittances from South African mineworkers, the majority of households are still unable to afford to purchase additional land to expand cultivation.
In some cases, cannabis farmers have been forced to encroach on marginal lands or steep slopes in order to increase their crop area. This may have resulted in soil degradation and erosion, although it is difficult to determine the exact cause of this.
Crop diversity in cannabis cultivation can be a major source of disease resistance. This is particularly true in outdoor cultivation, which has a greater risk of exposure to pathogens than indoor systems, but it can also be beneficial for avoiding disease problems in greenhouses.
A recent study by a team from the University of Connecticut found that cannabis plants grown on substrates using coconut fiber in soilless culture exhibited higher THCA and CBGA yields than those grown on other substrates (Figure S1). This indicates that substrate selection can improve the productivity of cannabis crops, allowing more room for plant growth and maximizing secondary metabolite production.
As with many horticultural crops, the presence of pests or diseases in greenhouse-grown cannabis has resulted in an increased need for disease control strategies. These strategies are generally based on a combination of physical barriers, chemical controls and biological control agents.
While most of the pathogens that can affect greenhouse-grown cannabis crops have been well-characterized, there are still many gaps in our understanding of how and when they attack this crop. Therefore, research on these issues is vital for the development of efficient and sustainable management strategies that maximize yield and product quality.
