Tunnel farming is an agriculture technique in which the crop is grown in a long row or block under row covers, where it is protected from environmental factors such as rain, hail, snow, wind, frost, and pests. It can be done on both a commercial or subsistence level. Subsistence farmers, who are generally poorer than farmers in industrialized countries, can use the technique to improve their food security by producing crops that would normally fail under open field conditions. They can sell any excess produce at a higher price than they would get for the normal crop.
Commercial tunnel farming is usually done on farms with greenhouses using electric lights and plastic film coverings instead of row covers. It is used more frequently in areas where growing seasons are short or cool climates exist during half of the year. In some cases, crops are grown exclusively in tunnels such as melons and tomatoes while other crops may be more appropriate for both field and tunnel production such as cucumbers or peppers. In this case, it’s important to understand which pests affect which stage of the crop. For example, cucumber beetles are more likely to damage transplants if they are first grown in a greenhouse before being tunnel planted.
Types of Tunnel farming
1. Low Tunnel Farming
A low tunnel or hoop house is an unheated, partially covered structure with a nearly flat roof, typically no more than 3 feet (0.91 m) high (although some are taller), that extends the growing season for many crops by protecting them from cold and frost. Low tunnels can be built on sloped terrain where there is not enough space to use vertical supports like other types of greenhouses. The structure itself can be made of wire mesh (to allow maximum sunlight penetration), plastic (for durability), rigid plastic or vinyl piping, natural materials such as branches or bamboo poles, or other suitable material which will allow airflow while also blocking damaging UV radiation. It covers roughly half of the planting area allowing sunlight to reach the plants inside.
Low tunnels can be used to grow vegetables such as lettuce, spinach, carrots, and peas early in the season or later into fall or winter. In tropical climates, low tunnels are commonly employed using either concrete reinforcing wire mesh which allows more sunlight penetration from above or black polyethylene plastic sheeting which provides a high degree of shade and insulation. A small portion of one end may be left open to allow entry.
Low Tunnel farming is also known as “hoop house” farming because even though they are unheated structures, they prevent damage from cold and frost by utilizing buried plastic film-covered hoops for structure. These types of tunnels are mainly intended for the production of cool-season vegetables, but they may be used to grow warm-season vegetables as well if enough heat can be provided. Low tunnels provide protection against cold temperatures, which allows gardeners to start vegetable plants earlier in the spring and harvest them later into fall or winter. These low tunnels are typically plastic hoops covered by plastic sheeting that is clear on one side and black on the other to absorb solar radiation. With these structures, it is possible to create an environment that closely mimics the natural growing conditions of specific plants without the use of supplemental heat sources. It is important not to leave any portion open unless there is a way of covering it at night so no heat is lost. The covering can be removed during the day to allow for pollination and water evaporation
2. High Tunnel Farming
A high tunnel, also called a ridge house, hothouse, or sun tunnel is an agricultural greenhouse structure with a sloped roof and tall, vertical walls that allow sunlight to penetrate deep into the interior of the building. High tunnels are often used in conjunction with sprinklers or drip irrigation systems because of their high soil temperatures and humidity levels, which inhibit evaporation. In addition to extending the growing season, high tunnels have been found to play a significant role in suppressing weed growth without using herbicides. It was estimated that there were over of high tunnels in the United States, with 10% using some type of mechanization.
3. Walk-in Tunnels (Rigid Frame)
A walk-in tunnel or grower house is a low, unheated, partially covered structure that utilizes a rigid frame for support. These tunnels are typically at least 10 feet (3.0 m) wide and 25 to 100 feet (7.6 to 30.5 m) long with sloped roofs supported by center posts. Walk-in tunnels have 3 to 6 inches (7.6 to 15.2 cm) of soil covering the floor, which reduces heat loss from the soil in early spring when nighttime temperatures still pose a threat.
These structures are often used by growers who want protection from cold but also desire some natural airflow through the structure because they do not require supplemental heat. The low tunnels are often used with high tunnels to create an optimal microclimate in which specific plants thrive. Walk-in tunnels are ideal for both spring and fall production because they offer some protection from the elements while also allowing natural air movement
Advantages of tunnel farming
- It is a way to help with the control of pests and diseases by excluding insects, slugs, snails, birds, etc. from access to the crop. This can be done by using one or more types of protection such as nets, tunnels made from shade cloth or polypropylene plastic sheets that keep insects off the plants while allowing light and water through; these materials also protect against frost and hail damage in colder climates.
- Growing vegetables under row covers are a good way to plant them earlier in the season due to their ability to allow for some heat retention during cold weather and protection from both wind and snow. Row covers (plastic-based) also provide excellent weed control, of particular benefit in organic farming.
- It is used to extend the season of harvest for certain crops by protecting them during cold weather or drought periods, sometimes allowing multiple cropping of the same field over one season. This allows more income from the same amount of land due to an extended growing time and can allow some vegetables that cannot tolerate high heat (such as carrots) to be harvested late into summer without risk of damage due to extreme temperatures. Some tunnels are able to provide gentle heating using technologies such as a geothermal heating system, a biomass/biofuel source or solar thermal energy in combination with a propane or natural gas heater in colder climates, all of which provide heat in addition to that provided by passive solar heating.
- It is a means of recycling otherwise unusable or vacant land by growing food for local consumption on that land, thus preventing the high costs of importing it from elsewhere. This is often accomplished with cover crops in areas where food crops are not possible. For example, products such as salad greens may be grown in cooler parts of greenhouses that have redundant capacity during colder periods using hydroponics or soil-less production techniques to avoid the cost of maintaining a constant temperature outdoors during these times. The use of permaculture designs can allow wide varieties of produce to be grown even in areas with cold winters where other methods would require more specialized design elements. In the summer, when there are few insects and diseases, the tunnel coverings may be removed to allow bees and other pollinators to visit the plants for food, while also allowing bigger fruits to develop.
Disadvantages of Tunnel farming
- The main disadvantage is that it takes up valuable space which could otherwise be used for conventional farming or other purposes (such as housing or industry). This problem can be mitigated by using greenhouses attached to existing buildings, using temporary geodesic domes over field crops during ripening periods, or simply not planting any other crops in the unused land while the tunnel covering is off.
- Another difficulty is that row covers are usually installed when there is no crop planted yet; thus, you cannot determine how much waste got covered and how much seed got wasted. The whole purpose of tunnel farming is to protect your investment and not waste it if possible. There are ways you can reduce this type of loss such as using drip irrigation systems where the water will get to each plant without major losses.
- Poor installation techniques such as improper tensioning or sagging over time will also cause problems with the function of your equipment, so take care when assembling these components that they are fitted correctly and that all connections are secure and water tight. Problems like this can lead to collapse and damage/destruction (both financially and functionally) of key pieces if precautions aren’t taken at installation stage under a competent tradesperson.
- You need access to power tools, machinery and other equipment as well as PPE (personal protective equipment) such as gloves, eye protection and dust masks to avoid contaminants that may cause harm to you or damage your covers if not used correctly.
- The ground under the tunnels must be properly prepared for installation of the row cover, so take care when removing the soil to avoid any obvious problems with root contact or other obstacles which can restrict your cover’s performance.
- While a greenhouse is a useful way of extending a growing season, it comes with several disadvantages from ordinary outdoor farming. In an indoor environment there is no weather beside what you’re controlling, so certain crops will need to be coddled carefully or they won’t survive. For example: If there isn’t enough light during winter months, plants will not produce flowers (which is the part you want to eat). That will make it impossible for them to bear fruit.
- Uncontrolled light can also damage plants or cause problems with aspects of growth such as budding . If your cover is mobile then wind may become a problem for plants where they sway back and forth too much (and eventually break), which means you need some way of controlling that motion if you’re relying on natural ventilation
Crops suitable for tunnel farming
1. Crops for low tunnel farming:
low tunnel farming is suitable for heavy individual fruit-bearing crops, i.e. melons, watermelons, pumpkins, round gourds, squashes etc
2. Crops for High Tunnel Farming
Tomatoes, Chilies / Hot pepper, Cucumber, Brinjal, Sweet peppers, Ridge-gourd and Bitter-gourd can be cultivated using high tunnel technology
3. Crops for walk-in tunnel farming
Tomatoes, Chilies, Cucumber, Brinjal, Hot pepper, Sweet peppers, Watermelon, Muskmelon, Pumpkin, Ridge-gourd and Bitter-gourd etc can be cultivated using walk-in tunnel technology
Is tunnel farming profitable?
Tunnel farming is profitable because crops such as lettuces and tomatoes, which typically have a short shelf life, can be produced locally for consumers instead of having to be transported from long distances. In addition, tunnel farming allows farmers to grow out-of-season fruits and vegetables all year round without losing too much money due to spoilage. Furthermore, the use of natural watering sources in tunnels greatly reduces water consumption and many times enables year-round irrigation where traditional surface irrigation techniques would not work. In most cases, tunnel farms are economically sustainable when they produce enough food to offset operation costs. However, it may require significant capital investment to construct these tunnels; this is especially true if the soil needs to be moved or if the concrete needs to be poured.
Factors affecting Tunnel Farming
When grown in a tunnel, plants that are normally killed by frosts, such as tomatoes and cucumbers, can be grown to maturity even when the temperature outside dips below 32°F. This allows for fresh fruit production during colder months, which is especially beneficial if the area lacks a consistent growing season.
Fertile soil is important for healthy plant growth. However, since most of the nutrients needed for photosynthesis are provided by artificial fertilizer or organic matter (such as animal manure), there is no need for fertile soil inside of high tunnels; this allows farmers to grow food on land that would otherwise be considered infertile.
Rainfall can affect crop success by either promoting or inhibiting plant growth. In general, light rainfall will not harm a tunnel farm’s plants as long as the soil is dry enough for them to be dug into. However, if heavy rainfall occurs while the soil is wet, it may cause damage to the greenhouse structure.
Wind affects high tunnel farms in two ways. On one hand, wind can cause significant damage if it knocks over the tunnels or damages the greenhouse covering. On the other hand, strong winds can actually benefit crops by adding coolness and reducing humidity inside of greenhouses.
High-tunnel farms are usually built with south-facing sides that allow sunlight through but prevent heat from entering. This allows producers to maximize their growing season and protect sensitive plants from unusually hot temperatures. Additionally, the shade created by a high tunnel’s greenhouse structure can reduce weed growth and potential disease .
High tunnels trap heat during hot summer months but block out cold air in winter. These structures are important because they allow farmers to grow crops that would otherwise be impossible due to extreme weather conditions. For example, many plants cannot be grown properly during winter due to low temperatures and heavy winds. However, crops such as lettuce, tomatoes, cucumbers, peppers and chilies have been shown to thrive even when grown inside of a high tunnel with minimal supplemental light or heat.
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