Sustainable Civilization: From the Grass Roots Up
Micro Environment Subsistence System (M.E.S.S.) Appendix
(Ok, so I tend toward corny names.) The purpose of this appendix is to look at the limits on closing the loop for the safe recycling of human effluents to a growing medium which is a micro-environment optimized for growth of food. Our present population of 6+ billion is dependent on the present global socio-economic-industrial infrastructure not only for economic purposes, but also for "life support" such as food. That infrastructure is itself dependent on cheap, abundant fossil fuels, in particular oil. It is becoming clear that we are approaching the peak of oil production. Prior to the point where oil ceases to be cheap, or abundant, we need alternatives. Organisms live in many different kind of habitats, which MUST contain a minimum of every life support limiting factor for each species. As the eagle’s habitat is more that a nest, including both land and air, so the habitat for a human is not just a house, it is the rest of the local ecosystem that provides the overall life support for not just the present generation of humans, but for the indefinite future.
The human food chain is the simple progression from plants that absorb sunlight, to the human table. A downward example of a food chain is: The human eats the dog, the dog ate several cats, the cats ate lots of mice, the mice ate fields of grass which grew by absorbing the sunlight. After the table though, all waste must somehow, eventually, become “food” for something else and be recycled. Small organisms such as insects, bacteria, mold, & mushrooms fill a vital niche in an ecology in that they eat dead biological materials and make the atoms and molecules again available as nutrients to grow plants. This takes us to the food web, which is the blend of the overlapping food chains in an ecosystem. A food web is from one celled organisms to bugs, to humans, and everything in-between.
Scientifically a community is all of the population that lives together in the same place and interacts. In reality a minimal human food production area is a specialized niche, requiring some particular mix of organisms and physical factors. What are the minimums for such?
If overall loss is minimized, a community of organisms, interacting with each other and the nonliving things in the environment can provide a long term localized ecosystem. A limiting factor is any living or nonliving part of an ecosystem that effects the survival of an organism, such as heat, light, particular atoms or molecules, and water.
As far as the physical atoms incorporated into living organizations are concerned, the Earth is essentially a closed system, with the energy of sunlight as the only input and the power source for essentially all life on the surface of the Earth. Much of this document is "generic", based on the theory that once the major nutrient loops are closed further augmentation should not be required. However, my personal focus is "high desert", in Arizona, USA, where water is a significant limiting factor. Every area will have it's on local limiting factor, potentially for most locations the limiting factor may be sunlight and growing season. I've also got to deal with the natural heat, and very low typical humidity.
The optimal human centered ecosystem is physically different from, and essentially incompatible with, any "natural" environment, and must be kept separate. This document combines personal theory, web research into programs such as NASA's CELESS, the Biosphere II project, the work of Ecology Action, and other closed loop food systems, as well as research on optimal food growing methods (hydroponics, aquaponics & aeroponics) and recycling of human effluent, and personal container garden experiments.The area needed to grow food for a fully grown human to survive should, logically, match the area which can be fertilized by human effluents (solid, liquid & gas). Urine, feces, and eventually our physical bodies can all be readily returned to the growing medium.
It is vital to ensure optimal growing conditions for crops, to include exclusion of plant pathogens, as well as those that may infect humans. The growing area will receive both gray water and black water, which must be handled in a safe manner.
Absent a sealed environment, we lose water vapor, CO2, and other gases. It is obvious that when we grow a crop of which humans eat only a portion, the rest of the plant must be recycled by animals or microorganisms before the nutrients are again available for plant growth. Think of the kernels eaten on an ear of corn, vs the total mass of the plant. This makes crop selection a critical element.
With a typical "first world" diet the upper fertilizing limit for humanure looks to be around 1600 ft. sq. and a potential "minimum" area of 600 ft. sq. as touched on below. Of course, our diets are horrible. If we ate food with greater vitamin content, we would excrete a greater concentration, which would fertilize a larger area. I solicit feedback on vitamin / nutrition standards and what the upper limit is for safe human consumption of various minerals if they are in high concentration in plants.
Every square yard (9 sq. ft.) on the earth's surface with direct, perpendicular un-shaded exposure to the sun receives energy at the rate of around 1kwh (3412 BTU or 859,845 heat calories). The value of a food calorie is 1,000 heat calories, so at 100% conversion each square yard could generate 859 "food" calories per hour. An "average" person needs 2,000 food calories per day. Therefore, if humans were directly solar powered with 100% efficiency, each of us would only need around 22 sq. ft. /hours per day of solar exposure. But of course, we are not directly solar powered, nor are our plants 100% efficient.
If limited to fertilizing 1600 ft. sq., and 6 hour/day of light, the garden must have an overall average efficiency of something just over .225%. But crops for nutrition rather than mere calories do not approach this level of efficiency.
Various health guides indicate humans should "aim" for having our daily calorie intake fulfilled by 40% carbohydrates (1 g = 4 calorie), 30% protein (1 g = 4 calorie), and 30% fats (1 g = 9 calorie).
OVERVIEW OF PLANT NEEDS Edit
The basic needs of plants are nutrients (certain atoms in certain forms), water, and light. On the scale of the Earth, our entire ecosystem is an essentially sealed environment. AIR
Plants need three primary gases from air.
Carbon Dioxide (CO2), which is used in their leaves in the photosynthesis process to combine hydrogen from water with carbon from CO2 to produce carbohydrates (sugars), with the oxygen being released. In normal seal level air, CO2 is at 350 parts per million (ppm), or .035%. Even this tiny amount is enough to support plant growth. Studies seem to show that the upper concentration limit for CO2 for plants is around 4%, which requires that all other growing conditions be optimized. But, plants cannot tolerate the 4% level unless there is sunlight present for photosynthesis. WARNING: In general, humans cannot breathe where the CO2 concentration approaches 3%.
Water will absorb it's own volume of CO2, and when evaporated will release the CO2. This seems nicely in tune with nighttime water condensation absorbing CO2, with daytime evaporation releasing the gas.
Oxygen for their roots. Roots can suffocate or drown without enough O2. Conversely, as aeroponics shows given access to nutrients and kept moist, roots and the plant will thrive when given lots of air. Aeroponics is cited as perhaps the most productive means of providing crops necessary nutrients. Aeroponics has plants suspended in holding material, in an air gap, which is kept in a spray of the liquid nutrient. The falling liquid also gains air which provides O2 for the roots in the liquid below. I continue experiments on a static means to approximate this. I’ve had modest success with containers set up with a bottom wick kept moist by an upturned bottle of water, several inches of perlite over the wick, then a tower of perlite up the center with compost around the tower. A WARNING: You may have heard that more houseplants are killed by overwatering than by underwatering." The problem with overwatering is not that the roots do not like to stay moist, but that if heavily watered, water fills most of the spaces ordinarily filled by air in dry soil. Plant roots require oxygen, but not all portions of a plant's roots require the same amount of oxygen. Plants can form what he calls oxygen (O) roots and water/nutrient (W/N) roots. Roots exposed to air specialize in taking up oxygen; those immersed in water specialize in taking up water and nutrients. When the water level drops in a plants growing medium, the W/N roots change into O roots, a process taking only 2-4 days. However, this is not reversible. If water returns to the original depth the plants wilt within a few hours and do not recover. You need to create a medium with such large air spaces that no matter how much water is around, the roots will still find plenty of air, but dense enough that water can move up by capillary action and keep the medium moist.
Nitrogen (79% of the air) to produce complex molecules. Most plants cannot absorb nitrogen directly from the air on their own, but must obtain it via their roots from a substance which embodies the gas atom.
The bulk of commercial nitrogen fertilizer is made using un-sustainable high energy chemical processes.
There are various methods to "fix" the gas into the soil, for example special bacteria, that can live in symbiosis with some plants:
Clover, alfalfa, select legumes, and select trees such as Neem and Russian Olive. Research what grows well in your area. It is the bacteria that make nitrogen available for absorption by plant roots. Fixing nitrogen takes energy. Every gram of nitrogen fixed requires 10 gram of glucose, with the plant feeding the bacteria growing on it's roots.
Blue-green algae can also absorb nitrogen and incorporate it into their cells, with the advantage it can be used as an animal (or human) food, or as fertilizer.
Lightning splits the N2 molecule, which can then combine with oxygen into a nitrogen oxide which can dissolve in rainwater, which was something that Tesla referenced in several of his papers.
In a free online pamphlet, Bill Mollison presents his "third world endless nitrogen fertilizer supply system." You will need a sand box, with a trickle-in system of water, and a couple of subsurface barriers to make the water dodge about. Fill the box with white sand and about a quarter ounce of titanium oxide (a common paint pigment). He indicates that in the presence of sunlight, titanium oxide catalyzes atmospheric nitrogen into ammonia, endlessly. You don't use up any sand or titanium oxide in this catalyic reaction. Ammonia is highly water soluble. You run this ammonia solution off and cork the system up again. You don't run it continuously, because you don't want an algae buildup in the sand. You just flush out the system with water. Water your garden with it. Endless nitrogen fertilizer. If you have a situation where you want to plant in sand dunes, use a pound or two of titanium oxide. You will quickly establish plants in the sand, because nitrogen is continually produced after a rain. This solution is carried down into the sand. If you are going to lay down a clover patch on a sand dune, this is how you do it.
Apart from the legumes and actinorhizal plants, there are a number of other systems involving nitrogen-fixing cyanobacteria, notably of the bacterial genera Azotobacter, Anabaena, and Nostoc. These systems involve the following:
1. Gunnera-Nostoc. Probably all Gunnera species display a localised infection of the stem by Nostoc bacteria.
2. Azolla-Anabaena. The aquatic plants of the Azolla family form a symbiosis with Anabaena bacteria.
3. Liverwort-Nostoc. The liverwort genera Anthoceros, Blasia and Cavirularia all form associations with Nostoc bacteria.
4. Lichen associations. About 7% of lichen species are not of the traditional fungi-algae symbiosis, but are instead formed of a fungi-cyanobacteria symbiosis. Nostoc in the bacteria genus is usually involved. The lichen genera Collema, Lobaria, Peltigera, Leptogium and Stereocaulon form this type of symbiosis. They are particularly important as nitrogen-sources in Arctic and desert ecosystems, where fixation rates may reach 10-20 Kg/ha/year.
5. Leaf surfaces (the phyllosphere). There is increasing evidence that free-living N-fixing species of bacteria are abundant on wet and damp leaves in predominantly moist climates.
6. Root zone (Rhizosphere). Free-living bacteria, for example Azotobacter species, may be more abundant in the areas immediately adjacent to plant roots and aid plant nitrogen nutrition.
7. Free-living. N-fixing bacteria thrive where the Carbon:Nitrogen ratio is high and there is sufficient moisture, for example on rotting wood, in leaf litter, the lower parts of straw and chipping mulches etc.
FACTORS AFFECTING NODULE DEVELOPMENT Edit
1. Temperature. Depends on the bacteria species and the host plants, for example 4-6 deg C is adequate in Vicia faba, whereas 18 deg C or more is necessary for most sub-tropical and tropical species.
2. Seasonality. For most species, fixation rates rise rapidly in Spring from zero, to a maximum by late spring/early summer which is sustained until late summer, then decline back down to zero by late autumn. In evergreen species, N-fixation occurs throughout the winter provided the soil temperatures do not fall too low.
3. Soil pH. The legumes are generally less tolerant of soil acidity than actinorhizal plants. which is reflected by Rhizobium species being less acid-tolerant than Frankia species. Of the actinorhizal plants, Alders (Alnus spp) and Bayberries (Myrica spp) are most acid tolerant. Of Rhizobium species, acid-tolerance declines in the following order: cowpea group (most acid tolerant) - Soya bean group - Bean & Pea groups - Clover group - Alfalfa group (least acid tolerant).
In poor soils which are low in Nitrogen, the introduction of N-fixing plants usually leads to considerable acidification (e.g., a fall in pH of up to 2.0 in 20 years for a solid stand), which itself will in time start to affect nodulation efficiency.
4. Availability of Nitrogen in the soil. If Nitrogen is abundant and freely available, N-fixation is usually much reduced, sometimes to only 10% of the total which the N-fixing plants use. In trials with Alders, at low soil N levels (under 0.1% total soil nitrogen), the majority of N used by the alder comes from N fixed from the air; when total soil nitrogen is as high as 0.5%, only 20% of the N used came from fixed N from the air.
5. Moisture stress. In droughts, bacterial numbers decline; they generally recover quickly, though, when moisture becomes available again. Some species (usually actinorhizal), for example Alnus glutinosa and Myrica gale, are adapted to perform well in waterlogged conditions.
6. Light availability. Nitrogen fixation is powered via sunlight and thus will be reduced in shady conditions. For most N-fixing plants, which are shade sensitive, N-fixation rates decline in direct proportion to shading, i.e. 50% shading leads to 50% of the N-fixed. The relationship for N-fixing species which are not so shade-sensitive is not so clear: they may well continue to fix significant amounts of nitrogen in shade.
Plants use water in the photosynthesis process, combining carbon from the air with the hydrogen from the water molecule, and releasing the oxygen from the water molecule. They also use water in their circulation system and to cool themselves when the temperature gets too high. The relative humidity has a large effect on plants evaporation of water, with plant water use varying 5x over a humidity range of 5% to 95%. A "ballpark" figure for plant transpiration is roughly 30g/hr/plant of H2O. A specific example is sorghum, which "consumes" water at the rate of 200:1 (water weight to dry weight sorghum) In addition to the water loss thru the plants, your soil/growing medium will have losses. Aeroponics have virtually no evaporative loss, but poor growth for some plants. In conditions of 50-75% relative humidity and average temperature of 75 F- good plant conditions, an open water surface may evaporate at a rate of 3.2 mm/day. Soil may start at around 4 mm/day until the top soil area is dry, around five days or less, with an eventual drop to around 1.5 mm/day. Different growing media have differing levels of per foot maximum holding of water, and the level of water that the medium will hold so tight that the plants cannot access it. Soil Available Moisture per foot General Description Texture Class Light, Sandy Coarse Sand 0.7 in. Fine Sand 0.9 Sandy Loam 1.2 Medium, Loamy Fine Sandy Loam 1.5 Loam 1.8 Silt Loam 2.0 Heavy, Clay Clay Loam 2.2 Clays; Peats/mucks 2.4 Source: "Water", The Yearbook of Agriculture, the USDA (1955) If you must provide the largest safety margin of water available for plant use per each foot of depth, you want something like silt or clay loam. If you can reliably replenish the water in your growing medium, and want to maximize air space then you want a growing medium something like medium sand. If you are using well water, city water, etc. rather than rain water, you are probably adding dissolved salts to your plant growing medium. A general guide is to leach - flood the plant and medium to wash out the salts, every 4 to 6 months. In example, a typical 6 inch pot will hold 10 cups of water, so 20 cups of water are used to leach a plant in such a pot. Keep the water running in a flow to wash out the salts. If the top of the soil has a salt crust, remove it before starting the rinse. The Arizona Master Gardeners Manual suggests as a watering rate, "…During dry periods, one thorough watering each week of 1 to 2 inches of moisture (65 to 130 gallons per 100 square feet) is usually enough for most soils. Soil should be wetted to a depth of 12 inches each time you water and not watered again until the top few inches begin to dry out. Average garden soil will store about 2 to 4 inches of water per foot of depth." (52 to 104 inches per year). Applied at this same rate year long to a 1,000 square foot garden would require a reliable supply of 33,800 to 67,600 gallons. At 12" annual rainfall and 100% collection rate, the collection area per person needs to be 4,300 to 8,600 square feet. As long as your home waste water does not contain toxic materials, and is sterlized if containing disease organisms, your garden water supply can include the runoff from your home gray water. Examine the commercial product "Infiltrators". Consider in reverse something like home drain gutters, filled with rock or sand, and buried to route water to the garden areas.
"SOLID" NUTRIENTS Edit
Compared to the demand for CO2 and H2O, the need for other factors is "small", but nevertheless essential. Plants don't have teeth. Plant roots do not crush substances and eat them. 98% of the nutrients plants absorb with their roots must first be dissolved in the soil water. For nutrients "locked up" in dead plant or animal matter, the cell walls must somehow be ruptured, so the inner nutrients can be reached by the roots. In commercial processing of the algae Chlorella, flash heating is used. In making leaf concentrate, it's a simple blender or grinder. (Blended food scraps anyone?) Rock dust, or cement kiln dust (before burning) can be applied as a valuable multi-nutrient fertilizer. Logic seems to say that all of the atoms taken from the soil to build the plant end up as either part of my body, or excreted. We're bound to lose some other atoms in our... body gas... perhaps sulfur, but I don't believe it's a lot... Average pounds produced per person per year. Source: Future Fertility
Nitrogen Phosphorus Potassium Calcium
Urine 7.5 1.6 1.6 2.3 Manure 2.8 1.9 0.8 2.0 Total 10.3 3.5 2.4 4.3
Range required per 100 ft. sq. of garden
Nitrogen Phosphorus Potassium Calcium
0.1 - 0.5 0.2 - 0.6 0.15 - 0.50 0.2 - 0.8
Range one human's effluent can fertilize each year in ft. sq.
Nitrogen Phosphorus Potassium Calcium
Urine 1500 - 7500 266 - 800 320 - 1067 287 - 1150
Manure 560 - 2800 316 - 950 160 - 533 250 - 1000
Total 2060 - 10300 582 - 1750 480 - 1600 537 - 2150
Expect each person to produce around 1 gallon of manure per month, which should be applied to no less than 50 ft. sq. monthly, otherwise you're adding too much nitrogen to the growing medium. Layer manure, then 2" soil, seeds, and sprinkle soil. Move on to next 50 ft. sq., cycle back annually for 3 years, then shift to another set of beds.
Urine must be diluted with water from 5 to 10 to 1.
The "big three" plants need in their soil are nitrogen (N) phosphorus (P) and potassium (K). NPK are the three numbers you will typically find prominent on fertilizer packages, which refer to the percentage by weight of each. In a 20 pound bag of 21-7-14 it therefore means the bag contains 4.2 pounds nitrogen, 1.4 pounds phosphorus, and 2.8 pounds potassium. Also needed in the soil in relatively large amounts by plants are sulfur, magnesium, and calcium. Green manures add back nitrogen and carbon to the growing medium, but unless you grow them elsewhere and add them to the medium, they can't add any other non-gas element that is not already in the medium, or in the water or fertilizer applied. The remaining macronutrients, carbon, hydrogen and oxygen plants get from air and water.
Nitrogen is a major component of proteins, hormones, chlorophyll, vitamins and enzymes essential for plant life. Nitrogen metabolism is a major factor in stem and leaf growth (vegetative growth). Too much can delay flowering and fruiting. Deficiencies can reduce yields, cause yellowing of the leaves and stunt growth.
Phosphorus is necessary for seed germination, photosynthesis, protein formation and almost all aspects of growth and metabolism in plants. It is essential for flower and fruit formation. Low pH (<4) results in phosphate being chemically locked up in organic soils. Deficiency symptoms are purple stems and leaves; maturity and growth are retarded. Yields of fruit and flowers are poor. Premature drop of fruits and flowers may often occur. Phosphorus must be applied close to the plant's roots in order for the plant to utilize it. Large applications of phosphorus without adequate levels of zinc can cause a zinc deficiency.
Potassium is necessary for formation of sugars, starches, carbohydrates, protein synthesis and cell division in roots and other parts of the plant. It helps to adjust water balance, improves stem rigidity and cold hardiness, enhances flavor and color on fruit and vegetable crops, increases the oil content of fruits and is important for leafy crops. Deficiencies result in low yields, mottled, spotted or curled leaves, scorched or burned look to leaves.
Sulfur is a structural component of amino acids, proteins, vitamins and enzymes and is essential to produce chlorophyll. It imparts flavor to many vegetables. Deficiencies show as light green leaves. Sulfur is readily lost by leaching from soils and should be applied with a nutrient formula. Some water supplies may contain Sulfur.
Magnesium is a critical structural component of the chlorophyll molecule and is necessary for functioning of plant enzymes to produce carbohydrates, sugars and fats. It is used for fruit and nut formation and essential for germination of seeds. Deficient plants appear chlorotic, show yellowing between veins of older leaves; leaves may droop. Magnesium is leached by watering and must be supplied when feeding. It can be applied as a foliar spray to correct deficiencies.
Calcium activates enzymes, is a structural component of cell walls, influences water movement in cells and is necessary for cell growth and division. Some plants must have calcium to take up nitrogen and other minerals. Calcium is easily leached. Calcium, once deposited in plant tissue, is immobile (non-translocatable) so there must be a constant supply for growth. Deficiency causes stunting of new growth in stems, flowers and roots. Symptoms range from distorted new growth to black spots on leaves and fruit. Yellow leaf margins may also appear.
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