Future Food Growing NOTES

Those in the community who are involved with growing plants or encouraging others to grow food locally should be aware of new techniques that make this more efficient. The growing season usually means the days between last and first frost, or approximately the last and first occurrence of 32° F (freezing) overnight low temperature. In the northern regions this is roughly May to October, in southern-southwestern-Californian regions it is roughly March to November or longer.

A simple covering for plants is now known as a frost blanket, A floating row cover is usually constructed from an ultra-thin layer of spunbonded polyester. (Not the greenest material out there,. It lets light through, it's permeable to rain, and it's breathable, and yet it provides a degree of protection from frost, and a slightly warmer micro-climate for plants to thrive. It is usually simply layed over a crop, with pegs in the corner to hold it down, but you can also lay it over a frame if you are concerned about weighing plants down. According to gardening.com, a floating row cover will offer 2-4 degrees of frost protection in the spring and a bit more in the fall, because the soil is warmer. On unexpectedly cold nights, you can always double-up your layers for a little added protection.

One family wanted to find an environmentally-friendly way to heat their Greenhouse. A SE CERT grant allowed them to conduct a feasibility study that led them to install a ground source heat pump in their greenhouse. So far, the results have been promising.

Norm and Mary Erickson of Hazelnut Valley Farm retired and started a hazelnut farm in Lake City, MN. installed a solar-heated greenhouse

Students at Willmar High School in Willmar, MN decided that they wanted to fix up an old greenhouse, update it by adding renewable energy source to heat it and provide out-of-season produce for local school food services and food pantries. They asked the West Central CERT to help them out and were granted the funds to help install a solar water heater and biomass boiler, which keeps the inside of the greenhouse warm enough to grow produce all the way through the bitter Minnesota winters.

For something residential instead of rural, take a look at the Hunt Utilities Group (HUG) sustainable building research facility outside of Pine River in central Minnesota. HUG’s researchers wanted to explore the possibilities of taking the greenhouse out of the garden and attaching it to the home. Paul Hunt, the Project Coordinator explains, “A greenhouse that is part of a residence seems to have a lot of functions going for it. It gathers huge amounts of solar heat in the winter. Even at night, it buffers the south side of the house from losing heat. It adds wonderful space to a house. It helps clean and humidify the air. It helps feed the occupants.

Pelletizing On-Farm Perennials to Heat a Greenhouse In 2010, CERTs provided a seed grant to Pork and Plants LLC focusing on the biomass that can be harvested from native perennial grasses and wildflowers (also called “forbs”). While corn stover is already harvested for biofuel, growing corn is very energy intensive; unconventional biofuels such as prairie grass may help bridge the gap between sustainable farming practices and renewable energy. In addition, it provides an opportunity to create a locally-supplied fuel source for rural communities.

On the cutting-edge research side of things, meet Phil Rutter of Badgersett Research Farms and his revolutionary “woody agriculture” practices. For over thirty years he has been hybridizing several varieties of woody plants: chestnuts, hazelnuts, hickory nuts and butter nuts without ever having to plow his land. This saves precious topsoil. Another remarkable thing about the farm is that it is completely off the grid; his greenhouse is powered by photovoltaic cells. “We estimate the greenhouse, which is deep earth sheltered glass and concrete, and designed as a 4 season structure, uses on the order of 1/50th of the energy that other commercial greenhouses do; including heating, cooling, and water management.”

Cornell researchers are working to extend the growing and selling seasons by as much as 10 weeks. Their method is a so-called high tunnel project using unheated greenhouses to grow various crops to see how practical they are for New York state growers. Growing tomatoes is easy. These structures are often called hoop houses because they are made of pipr or wooden hoops covered with plastic. An article in the march 25 Macomb Daily by Maryanne MacLeod tells about them. She states that they are different than Green houses because they are not heated and they grow plants directly in the ground where warmth is held in better than in a greenhouse where plants sit on tables. It is like bridges which ice over because the cold air cools both from the top and bottom. The ground keeps heat in better. In Michigan farmers can begin planting summer crops such as Tomatoes in April and winter crops such as kale and spinach nearly year round. Heaters could be used for year round use but they bring the cost way up. They can allow farmers to harvest and market crooups year-round giving farmers year-round income. This may be better than trying to buy seeds and pay heop in the spring after a winter of no income.

Hoop housed also reduce pests and weeds and protect plants from fungal outbreaks stemming from heavy rains and moisture. Incentives may be avail from agencies. About 400 Michigan farmers have begun using these houses as of 2012. One farmer stated he will have fresh local tomatoes by the 4th of July. That is 4 to 6 weeks earlier than those outside. Joe Kutchey in Macomb Township has just started using these hoop houses.


Hydroponics is a method of growing plants using mineral nutrient solutions, in water, without soil. Most Terrestrial plants may be grown with their roots in the mineral nutrient solution only or in an inert medium, such as perlite, gravel, mineral wool, or coconut husk. In natural conditions, soil acts as a mineral nutrient reservoir but the soil itself is not essential to plant growth. When the mineral nutrients in the soil dissolve in water, plant roots are able to absorb them. When the required mineral nutrients are introduced into a plant's water supply artificially, soil is no longer required for the plant to thrive. This is important as one of the most common errors when growing is over- and under- watering; and hydroponics prevents this from occurring as large amounts of water can be made available to the plant and any water not used, drained away, recirculated, or actively aerated, eliminating anoxic conditions, which drown root systems in soil. In soil, a grower needs to be very experienced to know exactly how much water to feed the plant. Too much and the plant will not be able to access oxygen; too little and the plant will lose the ability to transport nutrients, which are typically moved into the roots while in solution.

"Bubbleponics" is the art of delivering highly oxygenated nutrient solution direct to the root zone of plants. While Deep Water Culture involves the plant roots hanging down into a reservoir of water below, the term Bubbleponics describes a top-fed Deep Water Culture (DWC) hydroponic system. In this method, the water is pumped from the reservoir up to the roots (top feeding). The water is released over the plant's roots and then runs back into the reservoir below in a constantly recirculating system. As with Deep Water Culture, there is an airstone in the reservoir that pumps air into the water via a hose from outside the reservoir. The airstone helps add oxygen to the water. Both the airstone and the water pump run 24 hours a day.

The biggest advantages with Bubbleponics over Deep Water Culture involve increased growth during the first few weeks. With Deep Water Culture, there is a time where the roots have not reached the water yet. With Bubbleponics, the roots get easy access to water from the beginning and will grow to the reservoir below much more quickly than with a Deep Water Culture system. Once the roots have reached the reservoir below, there is not a huge advantage with Bubbleponics over Deep Water Culture. However, due to the quicker growth in the beginning, a few weeks of grow time can be shaved off.[15]

With pest problems reduced, and nutrients constantly fed to the roots, productivity in hydroponics is high, although plant growth can be limited by the low levels of carbon dioxide in the atmosphere, or limited light exposure. To increase yield further, some sealed greenhouses inject carbon dioxide into their environment to help growth (CO2 enrichment), add lights to lengthen the day, or control vegetative growth, etc.

A number of hydroponic experts are now promoting hydroponic solutions as cheap ways of producing food in areas with bad soil. As hydroponic systems use less water to grow than traditional farming it is also a more efficient use of resources. Above from Wikipedia

The following is a direct quote from http://www.androidworld.com/prod26.htm

Hydroponic and greenhouse yields are commonly 5 times the field yield for a two crop per year field harvest and 10 times the field yield for a one crop per year field harvest. In one case the Whittaker Corporation's Agri-Systems division in Somis, CA. Has achieved an absolutely astounding 100 times the field yield of Bibb lettuce in their 2.5 acre facility [57, p.147-151]. The normal field yield is about 30,000 heads per acre, but they grow an amazing 3.2 million heads per acre per year [57, p.150]. Sometimes the roots are allowed to hang down in the air and sprays or mists are used to wet the roots with the nutrient mixture.

The interested reader is referred to "Hydroponic Food Production" by H.M. Resh published by Woodbridge Press, third edition in 1987 [Ref 57]. In any case, the roots are periodically soaked in a water-based nutrient mixture which contains a very carefully selected blend of dissolved chemicals which provide the food elements that the crop needs. Of course different plants require somewhat different nutrients, but the common elements are needed by all. The following 16 elements

are considered essential to the growth of higher plants [84, p.194]. \

* Element Atomic Atomic % of dry Symbol Weight plant tissue

Carbon C 12.01 45 Oxygen O 16.00 45 Hydrogen H 1.01 6

Nitrogen N 14.01 1.5 Potassium K 39.10 1.0 Calcium Ca 40.08 0.5

Magnesium Mg 24.30 0.2 Phosphorus P 30.97 0.2 Sulfur S 32.06 0.1

Chlorine Cl 35.45 0.01 Iron Fe 55.85 0.01 Manganese Mn 54.94 0.005

Boron B 10.81 0.002 Zinc Zn 65.38 0.002 Copper Cu 63.55 0.0006

Molybdenum Mo 95.94 0.00001

Sources: [84] F.B. Salisbury, C.Ross, "Plant Physiology", Wadsworth, 1969, p.194. ( except atomic weights ) [70] "The 1990 Information Please Almanac", 1990, p.532-533. ( atomic weights )

Why are the yields are so much greater for hydroponic or greenhouse produce than for field crops.

The most important factor is plant spacing or plant density. Plant density is increased in one or more of the following ways: (1) grow plants closer together, (2) eliminate extra walk space between rows, (3) train plants to grow vertically instead of horizontally, and (4) grow plants in layers. It appears that Whittaker Corp has employed methods (1),(2), and (4). They tested up to 5 layers but settled on two [57, p.147]. They do not use articifial light so that means the density could be increased without limit through the use of artificial light and more layers. Given that an acre contains 43,560 square feet, it is clear that a field yield of 30,000 heads per crop (which is only about 2/3 of the crop planted) is about one head per square foot. That is a spacing of 12 inches in each direction. By reducing the spacing to 6 inches in each direction you multiply the density by four. And by adding a second layer you multiply the density by eight. Gurney's gives the spacing for tomatoes as 4 feet between rows and 4 feet between plants 78, p.4.Tomatoes grown in greenhouses in AbuDhabi and elsewhere are trained to growvertically A spacing of 24 inches in each direction gives an increase in density of 2 times 2 or a factor of 4.

Crop Density increase factor Bibb lettuce 8 Cucumbers 6 Tomatoes 4 Squash 16

The second most important factor in increasing yields is the number of crops per year. Many field crops have only one harvest per year. A few crops have two harvests per year, such as broccoli or carrots, but rare is the crop with more than two harvests per year (radishes 3 to 4 or bean sprouts - many). The obvious reason for this is the weather. Frost either late in the spring or early in the fall will kill most fruits and vegetables. Since greenhouse and hydroponic crops are grown indoors, their crops can be grown all year long. This means that you can have four 90 day crops per year or five 70 day crops or twelve one-month crops etc. Let us summarize these results.

Crop Crops per year Yield factor

Bean sprouts 26.0 2-3

Radishes 12.0 2-3

Bibb lettuce 8.0 4-8

Beets 6.0 3-6

Peppers 5.0 2-5

Tomatoes 4.0 2-4

Parsnips 3.0 2-3

Thus, depending upon your local growing season, this can mean an increase in the yield by a factor of from two to eight or perhaps more.

The third most important factor in increasing yields is the particular variety of crop you plant. This has at least three effects: (1) the amount of produce per plant per crop, (2) the number of crops per year (i.e. faster maturing crops allow more crops per year), and (3) the space required by each plant. Clearly these effects may not all work in your favor in the same crop. For example, Gurney's 1990 catalog offers over a dozen varieties of tomatoes [78, p.16-17]. The time to maturity varies from 45 to 90 days. Obviously this means twice as many crops per year with the former variety. One variety is claimed to produce 50 pounds of tomatoes per plant! That variety grows 10 to 15 feet tall. Together these effects may produce a yield multiplier of two to four. Future research

may double the yields again by producing higher yielding crop varieties. The next most important factor is the carbon dioxide concentration in the air around your crops. Resh suggests twice to five times the normal amount may be optimal [57, p.297]. He further states that tomato yields were increased by 20 to 30% and cucumber yields were increased by up to 40% [57, p.297]. Carbon dioxide enrichment also produced faster growth rates in lettuce and thus permitted an extra crop each year [57, p.297]. Propane or fuel oil can be burned to provide both carbon dioxide and heat. Dry ice may also suffice. Since the carbon dioxide in the air is the plants only source of carbon, which as we saw above amounts to 45% of the plant's dry weight, it is not surprising that this factor is so important. Research in Canada has also shown that carbon dioxide enrichment produces a 15 to 20% increase in plant growth [83, p.7]. Thus we conclude that the carbon dioxide multiplier will be in the range of 1.2

to 2. The temperature of the plant and its surroundings are quite important to plant growth. Table 2.1-1 given below was produced by J.F. Harrington of the Department of Vegetable Crops at the University of California at Davis. It shows the very significant effects of temperature on the germination time of various seeds. You can see that the germination time is weeks faster at the optimal temperature. Each crop has its preferred growing temperature and that temperature also varies depending upon what growth phase the plant is in. Most plants prefer 75F to 85F for optimal growth - and that applies to their roots as well! "Growing Greenhouse Vegetables" states that the increase in leaf and flower initiation is about 10% for each degree Centigrade increase [83, p.4].

* Table 2.1-1 Days for Seed to Emerge at Different Temperatures

Temperature in degrees Centigrade

Crop 0 5 10 15 20 25 30 35 40

Asparagus 52.8 24.0 14.6 10.3 11.5 19.3 28.4

Bean,lima - 30.5 17.6 6.5 6.7 - -

Bean,snap 16.1 11.4 8.1 6.4 6.2 -

Beet - 42.0 16.7 9.7 6.2 5.0 4.5 4.6 -

Cabbage 14.6 8.7 5.8 4.5 3.5 - -

Carrot - 50.6 17.3 10.1 6.9 6.2 6.0 8.6 -

Cauliflower 19.5 9.9 6.2 5.2 4.7 - -

Celery - 41.0 16.0 12.0 7.0 - - - -

Corn - 21.6 12.4 6.9 4.0 3.7 3.4 -

Cucumber 12.0 6.2 4.0 3.1 3.0 -

Eggplant 13.1 8.1 5.3 - -

Lettuce 49.0 14.9 7.0 3.9 2.6 2.2 2.6 - -

Muskmelon 8.4 4.0 3.1 - -

Okra 27.2 17.4 12.5 6.8 6.4 6.7

Onion 135.8 30.6 13.4 7.1 4.6 3.6 3.9 12.5 -

Parsley 29.0 17.0 14.0 13.0 12.3 - -

Parsnip 171.7 56.7 26.6 19.3 13.6 14.9 31.6 - -

Pea 36.0 13.5 9.4 7.5 6.2 5.9 - -

Pepper 25.0 12.5 8.4 7.6 8.8 -

Radish - 29.0 11.2 6.3 4.2 3.5 3.0 - -

Spinach 62.6 22.5 11.7 6.9 5.7 5.1 6.4 - -

Tomato 42.9 13.6 8.2 5.9 5.9 9.2 -

Turnip 5.2 3.0 1.9 1.4 1.1 1.2 -

Watermelon 11.8 4.7 3.6 3.0 -

Source: J.F.Harrington, Dept of Vegetable Crops, UC Davis, Agricultural Extension Leaflet, 1954.

. Light itself is also a very important factor. We assume that the grower exposes his crops to sunlight whenever possible even though it may be diminished by passing through plastic or tinted

glass. Obviously cutting off the light to your crops will reduce your yield to zero (unless you are growing mushrooms or bean sprouts). In multi-layered greenhouses artificial light may be needed. In space we may have unlimited sunlight although it may require some cleverly placed mirrors to utilize it. A graph is given in [89, p.235] which shows the effect of light level on the growth of corn, tomatoes, and collards. It shows that a reduction in the ambient light level to about half of the normal noonday level of 10000 foot candles reduces the plant growth by about 20%. Further reductions below that amount of light cause a dramatic drop off in plant growth. Plants prefer light of wavelengths in the range of 360 - 760 nm (nanometers) [89, p.237]. Plant photosynthesis is especially responsive to blue light (around 430 nm) and red light (around 660 nm). Plant germination, flower growth, and

stem growth are especially responsive to red light (around 660 nm) and far red light (around 735 nm) [89, p.237]. Cool white flourescent lights provide a light spectrum which covers these perferred wavelengths [89, p.237]. Clearly ample water is critical. This is not generally a problem in greenhouses, but in the fields drought can be devastating. Plants can also be drowned in too much water in as little as a few hours. Generally more than 90% by weight of your vegetable crop is water [79]. Fruits average about 86% water [79]. Another very important factor is fertilizer. In greenhouse and hydroponic operations the fertilizer is dissolved in the water to create a nutrient solution and then pumped to the plants. Clearly if the plants don't get the nutrients they need, they will either die or grow sub-optimally. In either case your yield will be less than it could have been. Other factors which effect plant growth include: relative humidity, the PH of the nutrient solution, the amount of oxygen the plant roots receive, nighttime temperature, number of hours of illumination per day, pollination considerations, and believe it or not, the sounds your plants "hear". The impact of each of these factors is not easy to pin down, but they are still very important. What happens if your plants are not pollinated? Obviously you get no harvest unless you are using selfpollinating crops or crops which don't require pollination. Crop yields are also effected by plant diseases, pest damage, and bad weather. The latter two problems can be nearly eliminated by indoor growing and this is truly a fundamental advantage of greenhouse or hydroponically grown crops. The losses in field crops due to insects, birds, mammals, weeds, and pathogens is about 33% [90, p.25] and rises to 40% without pesticides [90, p.25]. Even greenhouse growers must fight off pests. In space or at a lunar base we don't anticipate any pest problems because we will simply insure that none is taken with us. Bad weather won't stop either of course, but unless your buildings are damaged or destroyed, the only impact on you will be higher bills for heating or cooling. Plant diseases are another story. This is one area where indoor crops can be devastated. In hydroponic operations, the same nutrient solution is used to nurish bed after bed of crops. If that water contains some kind of water-borne disease, you can lose a whole crop. In nearly all indoor operations, the growing medium is sterilized after each crop to try to eliminate carryover of diseases from one crop to the next. In many places around the world, human waste is used to fertilize crops. This often leads to dysentery in the consumers. Clearly this problem is completely eliminated through the use of nutrient solutions in hydroponic growing facilities. There are probably many more factors of which I am unaware, but

this list should give you an idea of how yields can be improved. Now let us give a grand summary of these factors. Factor Yield multiplier Plant density 4-16 Crops per year 2-8 Crop variety 2-4 Carbon dioxide level 1-2 Fertilizer 1-2 Light level 1-2 Pollination 1-2 Temperature 1-2 Water 1-2 Others 1-2 each .

If you multiply all these factors together, you can easily exceed 100 times the field yield.

2.2 Analysis of vegetables The following table [2.2-1] of vegetable data was assembled

from a variety of sources which are listed at the end of the table. These data form the basis from which we project our results. Perhaps a few words are in order about how these data were selected. The pricing information was collected over a period of about three years (1989-1991). It was collected only from large stores in my geographical region which is eastern Pennsylvania, USA. The prices represent the lowest common price for each product. The prices shown are generally one half to one

third of the highest price recorded over the period. The germination data were obtained from references 75 and 76. Where the data were not broken down by variety, the data were simply

duplicated for each variety as in onions, peppers, and squash. The time to maturity data were obtained from references 76 and 78. Here the absolute minimum was not selected, but rather the lowest common time. We felt that the absolute fastest growing crop might not have the best taste, the factor which we consider most important. We did select a short time however, because we want to increase yields which is done by using fast growing crops. The plant spacing was obtained from references 77 and 78. The spacing was changed for those crops which can be trained to grow vertically such as cucumbers, tomatoes, and squash. The yield information came primarily from Gurney's spring

1990 catalog [Ref 78]. Again, where the data were not broken down by variety, they were simply duplicted. One major problem with this data is the following. Many crops such as tomatoes, squash,

cantaloupes, and (snap) pole beans take a long time to grow to maturity and then they produce continuously until they are killed by frost. In the case of indoor crops there will be no frost so

what then will be their yield? And also how many crops will you get per year? Crop heights and crop consumption information came from references 80 and 81 which are "Fruit and Vegetable Facts & Pointers" and "Supply Guide" both published by United Fresh Fruit and Vegetable Association of Alexandria Va. It is clear that if we have no meat in space, then we will have vegetarian diets. This

will obviously change our consumption figures drastically. We anticipate that people will desire as much variety as possible so that even those crops which presently show low consumption figures will become popular. Table 2.2-1 Data for Selected Common Vegetables

Vegetable price germ grow total spc yield harv ht #/p

cents days days days inch lbs index ft /yr

Artichoke 67 7 365 372 60 100 0.05 4 0.4

Asparagus 149 10 1000 1010 30 30 0.20 4 0.5

Beans,-snap-bush 69 7 50 57 4 48 0.20 2 1.1

Beans,-snap-pole 69 7 60 67 12 128 0.20 10 0.0

Beans,-sprouts 133 6 6 12 1 10 1.00 1 0.0

Beets -20 5 55 60 4 100 1.00 1 0.1

Bok-Choy 89 4 45 49 8 150 0.67 2 0.5

Broccoli -79 4 60 64 18 100 0.33 2 3.2

Brussel-sprouts 172 4 80 84 18 60 0.50 2 0.1

Cabbage,-green 29 4 65 69 12 150 0.67 1 5.4

Cabbage,-red 39 4 70 74 12 200 0.67 1 0.0

Carrots 35 6 60 66 2 75 0.80 1 8.0

Cauliflower -99 5 55 60 15 -80 0.33 2 2.5

Celery -69 7 90 97 6 -200 0.75 2 7.2

Collards 69 5 65 70 12 100 0.67 3 0.0

Corn, sweet -15 4 60 64 8 -150 0.05 12 7.4

Cucumbers 33 3 55 58 18 400 0.20 2 4.4

Eggplant 59 6 75 81 18 -167 0.33 4 0.6

Escarole 59 5 45 50 6 100 0.67 1 0.4

Kale 59 6 55 61 8 75 0.67 2 0.0

Leeks 149 19 80 99 4 75 0.75 2 0.0

Lettuce,-Iceberg 69 3 70 73 10 -120 0.67 1 21.2

Lettuce,-leaf 99 3 45 48 6 100 0.67 1 1.5

Lettuce,-Romaine 59 3 80 83 6 100 0.67 1 1.4

Onions,-green 133 6 70 76 2 50 0.80 1 0.8

Onions,-red 59 6 105 111 4 100 0.67 1 0.0

Onions,-spanish 49 6 105 111 4 100 0.67 1 0.0

Onions,-white 59 6 100 106 4 100 0.67 1 12.4

Onions,-yellow 39 6 100 106 4 100 0.67 1 0.0

Parsnips 99 14 100 114 4 100 1.00 1 0.0

Peas 369 6 65 71 4 64 0.25 2 0.1

Peppers,Cubannel 89 8 65 73 12 -800 0.25 3 0.0

Peppers,-green 59 8 60 68 12 -600 0.25 3 3.4

Peppers,-hot 89 8 78 86 12 -1000 0.25 2 0.0

Peppers,-orange 129 8 65 73 12 -600 0.25 3 0.0

Peppers,-yellow 129 8 65 73 12 -600 0.25 3 0.0

Potatoes,-Idaho 28 9 90 99 10 240 0.25 2 47.2

Potatoes,-red 28 9 100 109 10 240 0.25 2 0.0

Potatoes,-sweet 49 7 100 107 12 240 0.50 2 4.8

Radishes 49 3 23 26 2 20 0.67 1 1.0

Snow Peas 169 6 60 66 4 64 0.25 2 0.0

Spinach 79 5 45 50 4 10 0.67 1 0.8

Squash,-acorn 49 4 85 89 18 -667 0.50 8 0.0

Squash,butternut 39 4 85 89 18 -667 0.50 8 0.0

Squash,spaghetti 39 4 85 89 18 -667 0.50 8 0.0

Squash,-green 69 4 50 54 18 -2000 0.50 8 0.8

Squash,-yellow 69 4 50 54 18 -2000 0.50 8 0.0

Squash,-zucchini 69 4 50 54 18 -2000 0.50 8 0.0

Tomatoes,-cherry 139 6 55 61 18 500 0.50 3 0.8

Tomatoes,regular 49 6 90 96 18 1000 0.50 10 15.6

Turnips 29 2 45 47 4 100 1.00 2 0.3

Column Sources:

2,5,8 Author

3 Ref 75 and Ref 76

4 Ref 76 and Ref 78

6 Ref 77 and Ref 78

7 Ref 78 and Author

9 Ref 80 and Author

10 Ref 81 Column Notes: 2 This is a retail price in cents per pound.

A negative price means the price is per piece.

3 The number of days for the seed to germinate.

4 The number of days for the crop to mature.

6 The spacing between plants in inches.

7 Yield is for a single 100 foot row of plants.

A negative yield means the yield is a piece count.

8 This is fraction of the plant which is edible, also

called the harvest yield. This is basically a SWAG.

9 Height of plant in feet.

10 US consumption in pounds per person per year.

Where consumption is 0, that means either that there

were no data or that it was very small. In some cases

such as potatoes and onions the data were not broken

down by variety and thus one variety has all of it.

These data were read in by one of my programs and used to calculate the data presented in table 2.2-2. These data are my projections of expected yields and income from the various crops if they were grown in greenhouses or hydroponically. This table shows vividly the vast potential of

greenhouse or hydroponically grown crops. The second column shows the number of plants per acre in thousands. Remembering that one acre has 43,560 square feet, it can be seen that "44" means one plant per square foot and "174" means 4 plants per square foot and so on. Clearly the very high density crops are radishes, carrots, green onions, and highest of all - bean sprouts. The number in this column is for each crop. The third column shows the expected harvest in tons per acre per crop. This was calculated by scaling up the expected harvest of 100 feet of each crop (table 2.2-1 column 7) to a whole acre. It was then divided by 2000 pounds per ton to give the answer. The fourth column is the retail value of each crop in thousands of dollars. This is basically the product of the yield in pounds

times the value per pound. The fifth column is the number of crops per year. This was calculated by dividing 365 by the sum of the germination time and the time to maturity. The sixth column is the yield per acre per year which is simply the product of the yield per crop and the number of crops per year. The seventh column is the growers share of the total retail value of the crop. It represents the growers "gross" income per acre per year for each crop. Clearly the percent of retail that the grower receives will vary from crop to crop, but we have used 30% throughout. Reference 80 gives figures varying from 34% to 37% for the growers share, but those figures are from the early 1970's.

The last column shows the number of grams of edible food product which is grown per square meter per day. This is the same data as in column six, but in different units. We give this data

because it is of special interest in space grown crops. From it you can estimate the growing area required to support the crew of your spaceship.

* Table 2.2-2 Projected Yields from Hydroponic Crops at Minimum Spacing

Vegetable P/A T/A/C $/C C/YR Y/A/YR $/A/YR G/D

1000s 1000s 1000s

Artichoke 2 4.4 6 1.0 4.3 2 3

Asparagus 7 2.6 8 0.4 0.9 1 1

Beans,-snap-bush 392 31.4 43 6.4 200.8 83 123

Beans,-snap-pole 44 27.9 38 5.4 151.9 63 93

Beans,-sprouts 6273 26.1 70 30.4 795.0 634 488

Beets 392 65.3 105 6.1 397.5 191 244

Bok-Choy 98 49.0 87 7.4 365.0 195 224

Broccoli 19 14.5 31 5.7 82.8 52 51

Brussel-sprouts 19 8.7 30 4.3 37.9 39 23

Cabbage,-green 44 32.7 19 5.3 172.8 30 106

Cabbage,-red 44 43.6 34 4.9 214.9 50 132

Carrots 1568 98.0 69 5.5 542.0 114 333

Cauliflower 28 34.8 28 6.1 212.0 50 130

Celery 174 130.7 120 3.8 491.7 136 302

Collards 44 21.8 30 5.2 113.6 47 70

Corn, sweet 98 12.3 15 5.7 69.9 25 43

Cucumbers 19 58.1 38 6.3 365.5 72 224

Eggplant 19 24.2 29 4.5 109.3 39 67

Escarole 174 43.6 51 7.3 318.0 113 195

Kale 98 24.5 29 6.0 146.6 52 90

Leeks 392 49.0 146 3.7 180.7 162 111

Lettuce,-Iceberg 63 31.4 43 5.0 156.8 65 96

Lettuce,-leaf 174 43.6 86 7.6 331.2 197 203

Lettuce,-Romaine 174 43.6 51 4.4 191.6 68 118

Onions,-green 1568 65.3 174 4.8 313.8 250 193

Onions,-red 392 65.3 77 3.3 214.9 76 132

Onions,-spanish 392 65.3 64 3.3 214.9 63 132

Onions,-white 392 65.3 77 3.4 225.0 80 138

Onions,-yellow 392 65.3 51 3.4 225.0 53 138

Parsnips 392 65.3 129 3.2 209.2 124 128

Peas 392 41.8 309 5.1 215.0 476 132

Peppers,-Cubannel 44 32.7 58 5.0 163.4 87 100

Peppers,-green 44 49.0 58 5.4 263.0 93 162

Peppers,-hot 44 27.2 48 4.2 115.5 62 71

Peppers,-orange 44 57.2 148 5.0 285.9 221 176

Peppers,-yellow 44 57.2 148 5.0 285.9 221 176

Potatoes,-Idaho 63 62.7 35 3.7 231.3 39 142

Potatoes,-red 63 62.7 35 3.3 210.0 35 129

Potatoes,-sweet 44 52.3 51 3.4 178.3 52 110

Radishes 1568 26.1 26 14.0 366.9 108 225

Snow Peas 392 41.8 141 5.5 231.3 235 142

Spinach 392 6.5 10 7.3 47.7 23 29

Squash,-acorn 19 193.7 190 4.1 794.4 234 488

Squash,-butternut 19 96.8 76 4.1 397.2 93 244

Squash,-spaghetti 19 193.7 151 4.1 794.4 186 488

Squash,-green 19 145.2 200 6.8 981.4 406 603

Squash,-yellow 19 145.2 200 6.8 981.4 406 603

Squash,-zucchini 19 145.2 200 6.8 981.4 406 603

Tomatoes,-cherry 19 72.6 202 6.0 434.4 362 267

Tomatoes,-regular 19 145.2 142 3.8 552.1 162 339

Turnips 392 65.3 38 7.8 507.4 88 312

Column Notes: 2 P/A plants per acre (in 1000s)

3 T/A/C tons per acre per crop

4 $/A/C retail dollars per acre per crop (in 1000s)

5 C/YR number of crops per year

6 Y/A/YR total yield per acre per year in tons

7 $/A/YR farmer's gross share = 30% (in 1000s)

8 G/D edible plant growth in grams/sq meter/day

2.3 Are these numbers for real? The reader is probably wondering if these projections are really possible. The answer is that they definitely are! Look at table 2.3-1. This table compares the normal field yields of some selected crops (those for which I could find the data) with the projected greenhouse or hydroponic yields and also with actual yields of several greenhouse or hydroponic operations for which I was able to find data. Most of the "actual" data comes from the Abu Dhabi operation as reported by Resh [57, p.219-222]. The field yields come from references 80 and 82. These yields are significantly lower than the yields given by Gurney [78, p.4]. A small backyard garden receives more TLC than the average field crop. The projected yields are from table 2.2-2 column 3. The yield of 20 tons per acre of bush beans came from reference 80 and appeared in October 1976 in the report NRP 20020 of the Agricultural Research Service. Notice that some of the actual yields are much higher than the projected yields. Resh gives a yield of 300 tons per acre per year for a tomato crop [57, p.29], but he states that the

yield per plant was 18 to 20 pounds [57, p.28]. Perhaps if they used the variety offered by Gurney [78, p.16] which yields 50 pounds per plant, they could do twice as well. The leaf lettuce result was the Whittaker Corp in Somis, CA. [57, p.150]. The head lettuce result was from Hidroponias

Venezolanes, S.A., Caracus, Venezuela [57, p.248-9].

* Tabel 2.3-1 Comparison of Selected Vegetable Yields

Hydroponic Yields Vegetable Field Yield Proj Actual C/YR total source

T/A/C T/A/C T/A/C # T/A/YR

Artichoke 3.5 4.4

Asparagus 1.2 2.6

Beans,-bush 2.4 31.4 20.0 * 6.4 = 128 [80, UFFVA]

Beets 6.25 65.3

Broccoli 3.75 14.5 13.0 * 3.0 = 39 Abu Dhabi [57]

Brussel-sprouts 6.0 8.7

Cabbage 10.8 43.6 41.4 * 5.0 = 207 Abu Dhabi [57]

Carrots 6.25 98.0

Cauliflower 9.0 34.8

Celery 25.0 130.7

Collards 5.0 21.8

Corn,sweet 3.0 12.3

Cucumbers 5.4 58.1 65.7 * 6.3 = 414 Abu Dhabi [57]

Eggplants 7.5 24.2 42.7 * 4.5 = 192 Abu Dhabi [57]

Escarole 7.0 43.6

Lettuce,iceburg 10.8 31.4 28.5 * 5.0 = 142 [57, p.248]

Lettuce,-leaf 7.5 43.6 101.2 * 8.0 = 809 [57, p.150]

Onions,-green 48.0 65.3

Onions,-white 35.0 65.3

Parsnips 4.0 65.3

Peas 2.4 41.8

Peppers,-green 9.6 49.0

Potatoes,-idaho 13.5 62.7

Potatoes,-sweet 7.0 52.3

Squash,-summer 4.0 145.2

Squash,-winter 8.75 193.7

Spinach 3.6 6.5

Tomatoes,cherry 4.0 72.6

Tomatoes,regular 10.8 145.2 150.0 * 2.0 = 300 [57, p.29]

Turnips 10.0 65.3 45.4 * 7.8 = 354 Abu Dhabi [57]

Column Notes

1 Crop

2 Field yield in tons per acre per crop (T/A/C)

3 Projected yield in tons per acre per crop (T/A/C)

4 Actual yield in tons per acre per crop (T/A/C)

5 Number of crops per year

6 Total yield in tons per acre per year (T/A/YR)

7 Source

2.4 Analysis of fruits

Comparitively little work has been done on greenhouse or hydroponically grown fruits. The only fruit mentioned by Resh is strawberries. Two examples were given; one in the Canary Islands where strawberries are being grown in columns [57, p.278] and the other in Catania, Italy where strawberries are being grown in sacks which are hung from overhead supports [57, p.279-284].

The primary reason for this is the simple fact that most fruits grow on trees and those trees are fairly tall. This makes it quite expensive to grow them indoors. There are several fruits which could be grown indoors including: cantaloupes, honeydews, grapes, kiwis, pineapples, strawberries, and possibly raspberries. The first four are vine crops whereas the latter three are individual plants as opposed to trees. Unfortunately raspberries do not lend themselves well to greenhouse operations because of their thorns and heavy labor requirements. Too bad, they are one of my favorites. The crew of a spaceship will want fruit in as wide a variety as possible. They will desire it not only for its taste but also to fight the boredom of constant vegetarian meals. Gurney's offers some dwarf fruit trees which are one half to one third of the height of ordinary fruit trees [78, p.36-41]. Of course the

yield is one half to one third as well. Significant additional research needs to be done to determine

the optimal growing conditions for each of these fruits and to discover which ones we could economically raise in space.

The following table [2.4-1] shows the nutrient value of some of the more common fruits.

Table 2.4-1 Nutrient Value of Fruits (All quantities are 1/2 pound)

Fruit water E Prot Carb Na K P Ca Fe

Cost % cal gm gm mg mg mg mg mg

Apples 79 84 131 0 35 0 261 16 16 0.3

Apricot 79 86 107 2 26 2 672 43 32 1.3

Bananas 37 74 209 2 54 2 897 46 14 0.8

Cantaloupe -169 90 81 2 19 20 701 38 25 0.5

Cherry 99 81 167 3 37 0 507 43 33 1.0

Coconuts -57 47 806 5 35 45 806 257 30 5.5

Grapes 129 81 159 0 41 5 422 32 27 0.5

Grapefruit 40 91 76 2 19 0 316 19 26 0.2

Honeydew 69 90 79 2 21 23 615 23 14 0.2

Kiwi -24 83 134 3 33 12 752 90 60 0.9

Lemon -25 91 56 1 5 1 74 8 14 0.3

Lime(juice) -25 90 60 1 20 2 247 16 20 0.1

Oranges -25 87 104 2 26 0 410 31 90 0.2

Peaches 99 88 91 3 26 0 446 26 10 0.3

Pears(Anjou) 79 84 136 1 34 0 283 25 25 0.6

Pears(Bosc) 89 84 137 2 34 0 283 26 26 0.6

Pineapple -177 87 110 1 28 3 256 16 16 0.9

Plums 129 85 120 3 31 0 392 24 10 0.3

Raspberries 400 87 111 2 26 0 345 28 50 1.3

Strawberries 169 92 68 2 15 2 376 43 32 0.9

Tangerines -33 88 94 3 24 3 356 22 32 0.3

Watermelon 39 92 73 1 16 5 263 20 18 0.4

Fruits have no cholesterol and less than 1 gram of fat. Sources: Column 2 (Author's research) retail cost in cents per pound; A negative cost means price per piece.

Remainder of table from:

[79] "Nutritive Value of Foods", by S.E. Gebhardt,

R.H. Mattews, USDA Home and Garden Bulletin #72, USGPO, 1981. Notes: Na - Sodium E - energy in calories K - Potassium gm – grams P - Phosphorus mg – milligrams Ca - Calcium % - percent by weight of water Fe - Iron Prot – protein Carb - carbohydrate

2.5 Nutrient value of vegetables

Table 2.5-1 shows the nutrient value of some of the more

common vegetables. The data were extracted from "Nutrient Value of

Foods" by S.E. Gebhardt and R.H. Mattews, USDA Home and Garden

Bulletin #72, 1981. All data were scaled up to 1/2 pound servings.

* Table 2.5-1 Nutrient Value of Vegetables

(All quantities are 1/2 pound)

Vegetable water E Prot Carb Na K P Ca Fe

Cost % cal gm gm mg mg mg mg mg

Artichoke 67 87 104 6 23 149 597 136 89 3.0

Asparagus 149 92 57 8 11 8 703 140 53 1.5

Beans,snap-bush 69 89 82 4 18 7 679 89 105 2.9

Beans,sprouts 133 90 65 7 13 13 338 122 31 2.0

Beets -20 91 68 7 16 111 708 70 25 1.4

Bok-choy 89 96 27 4 4 77 842 65 211 2.4

Broccoli -79 91 60 6 12 62 737 150 108 2.0

Brussel sprouts 172 87 88 6 19 48 718 127 82 2.8

Cabbage,-green 29 93 49 3 13 42 557 52 107 1.3

Cabbage,-red 39 92 65 3 13 26 467 94 117 1.0

Carrots 35 88 94 3 22 79 734 101 60 1.3

Cauliflower -99 92 57 5 11 34 805 104 66 1.4

Celery -69 95 28 0 6 198 646 57 79 1.1

Collards 69 96 30 2 6 43 211 23 177 1.0

Corn, sweet -15 70 250 9 56 38 566 233 6 1.5

Cucumbers 33 96 40 0 8 8 340 40 32 0.8

Eggplant 59 92 59 2 14 7 562 50 14 0.7

Endive 59 94 45 5 9 50 712 64 118 1.8

Kale 59 91 70 3 12 52 516 63 164 2.1

Leeks 149 83 140 4 31 44 410 79 131 4.8

Lettuce,iceberg 69 96 29 2 5 21 359 45 43 1.1

Lettuce,romaine 59 96 40 4 8 20 599 57 154 3.2

Mushrooms 109 92 65 3 10 10 839 237 13 2.9

Onions,-green 133 92 76 8 15 8 582 76 136 4.5

Onions,-white 59 91 78 3 17 4 352 65 57 0.9

Parsnips 99 78 182 3 44 23 833 157 84 1.3

Peas 369 89 92 7 16 9 544 125 95 4.5

Peppers,green 59 93 61 3 12 6 441 49 12 2.8

Peppers,hot 89 88 101 5 20 15 771 106 40 2.5

Potatoes 28 71 247 6 57 18 948 129 22 3.0

Potatoes,sweet 49 73 229 4 56 22 790 125 64 1.0

Radishes 49 95 63 0 13 50 529 38 50 1.3

Snow peas 169 89 92 7 16 9 544 125 95 4.5

Spinach 79 92 41 8 8 177 1266 111 223 6.2

Squash,-winter 49 89 89 2 20 2 991 45 32 0.8

Squash,-summer 69 94 44 3 10 3 436 88 62 0.8

Tomatoes 49 94 46 2 9 18 470 52 17 1.1

Turnips 29 94 44 1 12 113 307 44 49 0.4

Vegetables have no cholesterol and less than 1 gram of fat. Sources: Column 2 (Author's research) retail cost in cents per pound; A negative cost means price per piece. Remainder of table from:

[79] "Nutritive Value of Foods", by S.E. Gebhardt, R.H. Mattews, USDA Home and Garden Bulletin #72,

USGPO, 1981. Notes: Na - Sodium E - energy in calories K - Potassium gm - grams

P - Phosphorus mg – milligrams Ca - Calcium % - percent by weight of water

Fe - Iron Prot – protein Carb – carbohydrate 2.6 Financial considerations

According to the "Greenhouse Vegetable Guide" published by Texas A&M [Ref 120], the cost of building a greenhouse varied from $1.90 per square foot to over $30 per square foot with the weighted

average at $6 per square foot [120, p.105]. That works out to $261,360 per acre - obviously beyond the means of the average person - and that doesn't include the cost of the land. Including

other necessary equipment, the total average cost was $6.52 per square foot or $284,011 per acre [120, p.106]. In addition the average yearly production costs (for growing tomatoes) was about

$3.92 per square foot or $170,755 per acre [120, p.107]. About half ($1.95 psf) of this cost is interest and depreciation. The cost of labor is included in the remainder and 25% of that is assumed

to be paid to the owner/operator for his labor. On the other hand, total revenue was $4.77 per square foot or $207,781 per acre [120, p.108]. This yields a net profit of $0.85 per square foot or $37,026 per acre. Not counting interest and depreciation, the profit would be $2.80 per square foot or about $122,000 per acre. This analysis is based on a yield of 20 pounds of top grade tomatoes (at $0.80 per pound) and 7 pounds of salable culls (at $0.40 per pound) or 27 pounds per plant ($18.80 per plant) - which is only about half of what they could be getting according to Gurney's [78, p.16].

Another detailed cost outline was given in "Florida Greenhouse

Vegetable Production Handbook", published by the University of Florida's cooperative extension service [Ref 128]. Their very detailed cost breakdown gives a total construction cost of about

$298,000 per acre or $6.84 per square foot [128, p.93]. Further (five year) fixed costs of $47,800 per acre are given. Variable costs were estimated to be $122,460 per acre [128, p.94]. The gross revenue

was estimated to be $179,150 per acre based upon 4 square feet per plant, 22 pounds of tomatoes per plant, and a price of $0.75 per pound or $16.50 per plant [128, p.97]. That works out to $4.11 per

square foot. The expected profit was $67,295 per acre or $1.54 per square foot, not counting interest or depreciation [128, p.97]. The Ontario Ministry of Agriculture and Food [83] gives some

interesting data on Canadian greenhouse production. They state that 450 acres of Ontario greenhouses had a grower value of $45 - $50 million in 1986 [83, p.3]. That works out to at least $100,000 per acre or $2.29 per square foot.

In summary we have: Area Profit (psf) Profit per acre Florida $1.54 $67,295

Ontario $2.29 $100,000 Texas $2.80 $122,000

. 2.7 Financial summary Cost will be: $300,000 per acre for construction Years 1 - 7 : $50,000 per acre profit, $50,000 loan repayment Years 8 + : $100,000 per acre profit.

. That is a 16.67% return on investment for the first 7 years and a 33.3% return thereafter. Most people would consider that a good investment. We believe that $300,000 per acre for construction is

very high. If the cost could be brought down to $100,000 per acre, then the facility could be doubled every two years with no additional investment. This estimate is for tomatoes, but we can't all grow tomatoes. Other crops offer as good or better possible returns (see table 2.2-2). 2.8 Political summary 1. The yields of hydroponic crops can be 100 times as high as that of field grown crops. 2. Hydroponic or greenhouse production of vegetable crops will provide a more reliable source of food due to its year round growing season and lower susceptability to bad weather and pest damage.

3. Low quality and therefore low cost land can be used for hydroponics since the soil is not used. Since the government owns lots of land, the land cost should be almost nothing. 4. The construction of the facilities will create jobs in the construction industry. 5. Facilities could be constructed in center cities. That would save on transportation costs between the growing facilities and the market. Unemployed people could be hired to pick and pack the harvest.

REFERENCES This article was extracted from my book called "JOBS for the 21st Century". This book is now available online at the following URL: http://www.androidpubs.com/space_book.htm

The hydroponics chapter is located at the following URL: http://www.androidpubs.com/Chap02.htm#2.0 The complete biography is located at the following http://www.androidpubs.com/awrefs.htm#bib Comments? Email me at crwillis@androidworld.com