4.3 Selecting the Best Crops and Cultivars for Soilless Production
4_Production-Systems-for-Various-Crops
7b - Leafy Crop Production in Small-Scale Soilless and Hydroponic Systems COPYRIGHTED
7c - Tomatoes, Peppers and Cucumbers in Small-Scale Soilless and Hydroponic Systems COPYRIGHTED
Exercise 7a Test Tube Hydroponics
Exercise 7b Hydroponic Design
SPECA grant- Greenhouse introduction handbook_2018 COPYRIGHTED
SPECA grant-Hydroponics introduction handbook_2018 COPYRIGHTED
Production Systems for Various Crops
Overview
Title image CropKing, Inc., Lodi, OH, used with permission from "Greenhouse Structures for Vegetable Production " by N. Bumgarner, University of Tennessee Extension. Copyright © UT Extension.
Did you have an idea for improving this content? We’d love your input.
Introduction
Lesson Objectives
Match specific crops with appropriate controlled environment production systems.
Identify common crops grown in a variety of controlled environment systems.
Key Terms
controlled environment systems - adjusts the environment around crops to provide conditions that optimize growth and productivity to enhance yield and/or quality of crops; heavily reliant on technology
What is Controlled Environment Agriculture?
Excerpt used with permission from "Greenhouse Structures for Vegetable Production" by N. Bumgarner, University of Tennessee Extension. Copyright © UT Extension.
Controlled environment agriculture (CEA) involves production systems that rely on some degree of technology to alter the conditions around crops. The goal of adjusting the environment around crops is to provide conditions that optimize growth and productivity to enhance yield and/or quality of crops. In order to consider investing the time, energy, and money in CEA, growers need to gain a production advantage, labor savings, crop quality enhancement or some benefit to their business. As compared to traditional open field agriculture, CEA is often referred to as intensive production, requiring larger inputs of labor and capital per unit of land as compared to the more traditional extensive production, which requires larger inputs of land per unit of labor and capital. There is a wide spectrum of CEA practices in use, so this discussion will begin with a brief overview of some the lower input or temporary methods, with the document then focusing on greenhouses and their use in CEA vegetable production.
[See Unit 7, Lesson 1: Controlled Environment Agriculture and Protected Culture Systems for more information about growing methods.]
The majority of this [unit] will be focused on greenhouse systems, but this overview will also provide an introduction to other types of CEA operations because CEA facilities are not limited to greenhouses and other structures that rely on natural light to support photosynthesis. Enclosed facilities can be managed to provide proper temperatures, humidity, carbon dioxide and light needed for plant growth. Such CEA operations are present in the United States, but are likely more prevalent in countries where population density is higher and there are more limitations to farm land. Japan is an example of a country that has focused on developing CEA facilities that are independent of natural light - often called plant factories. An example of such a facility that is pushing the field of completely enclosed production forward would be the CEA systems on the international space station.
Current Examples of Controlled Environment Agriculture
Excerpt used with permission from "Greenhouse Structures for Vegetable Production" by N. Bumgarner, University of Tennessee Extension. Copyright © UT Extension.
Innovators around the world are putting state of the art technology to the test to evaluate yield and crop quality with the intent of minimizing their environmental footprint while maximizing profitability. In the Atlanta, Georgia area, for example, leafy crops are growing year-round in a climate that would not be conductive to such production. PodPonics has converted shipping containers into a CEA and soilless (often referred to as hydroponic) growing system where all light for leafy crop production is artificial (Figure 7.4.1).
Across North America, the Houweling family has greenhouses in California, Utah and British Columbia, and provides an example of stewardship in the production of tomatoes and cucumbers. The family-owned business recently opened a 28-acre greenhouse farm location in Mona, Utah, that was built near a natural gas power plant to capture the waste heat and carbon dioxide from the exhaust stacks. Vertical farming, utilizing indoor stacked soilless production systems, is also a growing area of interest in some urban areas. Farmed Here is a business in Chicago in a 90,000 square foot facility utilizing all supplemental lighting that supplies greens to grocery stores and restaurants only a few miles from the suburban production facility.
Most crops produced in CEA facilities are high-value and many of these are leafy and fruiting vegetables as well as herbs. CEA production enables growers to sell local vegetables for longer periods of the year (or year round) and provides the opportunity for quality or production increases. Crops that were once limited to field cultivation and dependent on locally appropriate climates can be grown in greenhouses around the globe.
It is important to note that it may not be economically feasible for producers to grow all crops in CEA facilities. For example, growing wheat indoors would not be advantageous or possible on a large enough scale to feed the masses without exponentially increasing the cost of wheat and the many food products it is used in. The agriculture industry is instead striving to strike a balance in between innovatively producing high quality food for the population while reducing environmental impacts. The USDA, NASA and other government agencies are partnering with private and public agricultural business to fund research that implements and investigates these innovative practices.
While there is still much to learn about production in these facilities, CEA including soilless production is not merely a niche market as a wide range of vegetable produce on grocery store shelves already come from such operations. With an increasing population and decreasing arable land, greenhouse production will continue to play a vital role in providing vegetable and other crops. While CEA can be beneficial to our communities, health and environment, it is not meant to replace traditional field agriculture. The premise of this document is simply that providing high quality, sufficient, and accessible fresh produce will likely require a range of effective and efficient tools to provide for an increasing human population. In order to meet society’s present and future food needs, the CEA industry links chemists, biologists, engineers, farmers, marketers, and growers to explore and experiment with a range of food production systems.
Selecting the Best Crops and Cultivars for Soilless Production
Excerpt used with permission from "Soilless Growing Systems and Common Vegetable Crops" by N. Bumgarner, University of Tennessee Extension. Copyright © UT Extension.
Descriptions of the crops and cultivars are provided here to provide information on vegetable cultivars for non-commercial growers. While these comparisons can be used to inform educational and small-scale production, greenhouse and environmental conditions will dictate the performance of cultivars, so quality and yield may vary greatly by system and locations.
One of the most important aspects of growing vegetable crops in soilless system is making sure that the growing system itself and the management are likely to produce a successful crop. Consider the mature size of the plant and make sure that it will not outgrow the spacing in the growing system. Overgrown plants generally have reduced quality or increased chance of disease. This is true for shoot growth, but larger or older crops can also have large root masses that can create issues in NFT systems.
Also consider the nutrient needs of the crop. Many lettuces and leafy greens can be grown using a similar nutrient solution (Figure 7.4.2). However, some may need slight adjustments. For instance, basil can be grown with lettuce, but it may require additional iron in the solution. Similarly, some of the kale and other crops in the same family (collards, radish) may be deficient in some micronutrients when lettuce is still being successfully grown. The most sensitive crop often determines nutrient solution levels. Cilantro will often tipburn at lower EC levels than other leafy crops, so it must be grown separately or other crops must be produced at lower EC levels than may be needed for optimum growth. These are just some examples of considerations for crop selection in small-scale soilless systems.
Common Leafy Crops Grown in Soilless Systems
Excerpt used with permission from "Greenhouse Structures for Vegetable Production" by N. Bumgarner, University of Tennessee Extension. Copyright © UT Extension.
Head Lettuce
The most common leafy crop grown in most soilless systems is bibb or butterhead lettuce. Part of the reason is that tender bibb leaves do not ship as well as iceberg and romaine and are less common in large soil grown lettuce production areas. Another aspect may well be tradition and European influence combined with the fact that the majority of breeding efforts for controlled environment lettuce has been in bibb lettuce. So, the prevalence of this crop in soiless system is likely a combination of suitable cultivars that perform consistently well and the market niche. Discussions of crops and cultivars can be found in Chapter 4.
Romaine lettuce is increasingly popular in soilless production. It can be a bit more difficult to produce due to a slightly higher sensitivity to quality issues such as tipburn. However, the more open romaine heads often have a higher percentage of dark green leaves than romaine hearts often purchased. Oakleaf lettuce is a good option for beginning growers, and can often provide a reasonably consistent, high quality crop. Some of the lettuces typically thought of as leaf cultivars can be grown to a more mature stage and produce weights similar to bibb lettuces. Green leaf lettuces and the smaller serrated leaf lettuces, such as lolla rossa, can be good choices for variety and quality. They can also be harvested at a range of maturity stages. Iceberg lettuce is not often produced in soilless systems due to the specific environmental conditions needed to form heads as well as a longer production time and larger mature size that can create issues in NFT systems.
Mixed Lettuce - Immature Stages
Lettuce commonly referred to as leaf lettuce is often simply harvested at an immature stage (Figure 7.4.3). Many romaine, leaf, and oakleaf cultivars can be successfully produced for immature harvest. One important feature of immature harvest is the opportunity to produce multiple plants in the same growing space. These mixed cubes are essentially a mixed bag salad grown and harvested together. The opportunities for mixing colors and leaf shapes creates a tasty and visually appealing product that can be harvested at a range of sizes.
Kale and Other Brassica Crops
Kale, mustard, Pak choy, and mizuna are examples of other leafy crops that can thrive in small hydroponic systems. While many lettuces were bred and developed for soilless production, these crops and cultivars are more commonly developed for use in soil. Many of the crops and cultivars still do quite well in soilless production. Trying a range of crops and cultivars is one of the best means of determining what works well in the site and system.
Basil
After lettuce, basil is the second most widely grown leafy crop in hydroponic systems. While most lettuce crops are harvested once at maturity, basil is often harvested multiple times. Growing points and young leaves are harvested and the plant continues to branch and grow to produce more harvestable leaves and tender stems. Often basil plants can be grown and harvested for many weeks (longer than lettuce and other leafy crops). An important consideration is that basil is a warm season crop and prefers warmer temperatures and higher light levels than are typical for lettuce production. In fact, basil can also be grown in fruiting crop systems with fertilizer levels similar to those used for tomatoes and cucumbers.
Common Vine Crops Grown in Soilless Systems
Tomatoes
Tomatoes are the most commonly grown soilless vegetable crops. There are a wide range of tomato cultivars that can be grown in the soilless systems described here. Beefsteak tomatoes are generally the most common in the US, but there are a wide range of cherry, grape (Figure 7.4.4), plum, and roma or paste tomatoes that can be grown as well. Currently, cluster or tomato-on-vine (TOV) are a common tomato crop. You would recognize these as the cluster of 5 tomatoes sold in grocery stores.
There are many cultivars developed specifically for soilless systems in greenhouses. Even when growing in a small greenhouse where productivity may not be the main criteria, these cultivars would be good choices because they have more resistance to leaf molds and powdery mildew common in these environments. If the soilless system is used to grow tomatoes outdoors, some of the greenhouse tomato cultivar disease resistances may not be as useful.
Important factors in selecting tomato cultivars are taste preference, productivity and growth habit. Most greenhouse cultivars are indeterminate, meaning they continue to grow vertically while producing fruit. These cultivars have been developed to bear consistently for several months. Many home gardeners and commercial field producers grow determinate cultivars that bear over a shorter period of time and do not continue to produce vertical stem and leaf growth and flowers for the duration of the crop. Both indeterminate and determinate crops can be grown in soilless systems, but there will be differences in harvest duration and plant management (see "Soilless Growing Systems and Common Vegetable Crops" in Supplemental Reading for more detail).
There are two different cropping calendars for greenhouse tomatoes. The more northern schedule has transplants seeded in December or January that enables harvest to begin in mid to late spring. Fruit are harvested through the summer and the crop continues to produce into the fall. Low production, disease pressure or the need to remove the current crop to clean out the greenhouse for the next crop are the determining factors in how long the crop stays in the greenhouse in the fall. In more southern areas, seeds are sown in or around August and come into production in the late fall. They are harvested through the winter and spring and generally come out of the greenhouse in the hottest months of summer.
Cucumbers
Cucumbers are a rapidly growing and productive crop that can fit well in home soilless production systems. Additionally, cucumbers can be grown on the same fertilizer solution as tomatoes in small systems. Regular garden cucumbers can be grown in soilless systems if there are bees present to carry out pollination. However, greenhouse cucumbers are thin-skinned (skins are not bitter) and typically seedless, so they do not require fertilization. In fact, greenhouse cucumbers do not have male flowers.
So, if these cultivars are grown outdoors where bees can get to the flowers of the seedless and field cucumbers, they will no longer be seedless. In addition to the cultivars selected for greenhouse production, there are now a number of seedless cucumbers that were bred and developed for outdoor production, which can be grown in greenhouses.
Greenhouse cucumbers are typically grown in three to five crops per year. Sometimes plant spacing is reduced in the low light times of year to improve production potential.
Peppers
Colored bell peppers are high value crop often grown in soilless systems on a similar schedule to tomatoes. However, these large bells are considered a challenging crop. It can be difficult to precisely manage nutrients and environments to maintain good production over a long period of time. Small bells (Figure 7.4.5) and various types of hot peppers can be less challenging for the small-scale grower.
Eggplant
Eggplant can be a desirable mid-length crop for soilless systems. They will typically bear fruit at a younger age than tomatoes and peppers. While there are greenhouse eggplant cultivars, a range of cultivars for home production can be grown. One of the largest assets of greenhouse production of eggplants is the opportunity to limit pest damage (such as flea beetles), which can be a challenge in outdoor production.
Basil
Basil is an herb harvested for its leaves, and was presented as a possible crop in the leafy crop system. It should also be stated that basil can be grown under similar nutrient, light and temperature regimes as many of the vine crops discussed here. So, there is an opportunity to incorporate this common herb with vine crops. Buckets or bags may provide more rooting volume for the plants and enable basil crops to be grown and harvested for a longer period of time than may be possible in many recirculating systems.
Dig Deeper
"Leafy Crop Production in Small-Scale Soilless and Hydroponic Vegetable Systems" by N. Bumgarner & R. Hochmuth, University of Tennessee Extension. Copyright © UT Extension. Used with permission.
"Greenhouse Structures for Vegetable Production" by N. Bumgarner, University of Tennessee Extension. Copyright © UT Extension.
"Soilless Growing Systems and Common Vegetable Crops" by N. Bumgarner, University of Tennessee Extension. Copyright © UT Extension. Used with permission.
"Tomatoes, Peppers and Cucumbers in Small-Scale Soilless and Hydroponic Vegetable Systems" by N. Bumgarner & R. Hochmuth, University of Tennessee Extension. Copyright © UT Extension. Used with permission.
Unit 7 Lab Exercises
Exercise 7a: Test Tube Hydroponics
Students will set up a hydroponic system using test tubes to grow plants without soil and observe and document the growth and health of the plants over time.This exercise will help students grasp the basics of hydroponics and the importance of controlled environments in plant cultivation.
Exercise 7b: Hydroponic Design
Students will set up and operate various controlled environment systems. They will explore the principles of nutrient delivery in hydroponics, monitor plant growth, and understand the advantages and challenges of using hydroponic systems for plant cultivation.
Attribution
Excerpts used with permission from "Greenhouse Structures for Vegetable Production" by N. Bumgarner, University of Tennessee Extension. Copyright © UT Extension.
Excerpts used with permission from "Soilless Growing Systems and Common Vegetable Crops" by N. Bumgarner, University of Tennessee Extension. Copyright © UT Extension.
Title image CropKing, Inc., Lodi, OH, used with permission from "Greenhouse Structures for Vegetable Production " by N. Bumgarner, University of Tennessee Extension. Copyright © UT Extension.