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What is the best way of providing soil for soil based agriculture on Mars?
I am of the view that a dedicated soil factory probably makes sense. Here you could produce various grades of soil: grind down rocks, and then mix in Mars sand and clay, water, imported compost and nutrient solutions from Earth, human faeces from Mars colonists, waste food, and waste plant material to create perfect soils for plant growth. These factory soils could then be put into raised beds or dug outs in the farm habs. Worms and other organisms could be introduced, to begin the process of creating healthy productive soils.
Another approach might be to begin with poor soils, basically just Mars regolith, and then gradually condition and improve it. But that seems like a v. slow process to me. The factory process could probably create viable soils within a matter of weeks or months.
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Earth soils generally involve a lot of assorted organisms, bacteria, fungi, slime molds, nematodes, insects and arthropods. Not just earth worms. These break down waste and render it suitable for uptake by plants- some with assistance by symbiotic organisms.
For decent soil you will at least need mineral dust, faeces and compost and soil organisms. A warm compost heap takes several weeks to work its magic but you have to avoid overheating it.
I would be concerned that you might bring a species from earth, without also bringing its competitors and predators. That hasn't gone well in isolated parts of this planet. So a prolonged isolated testing program must be used before risking your hab being overrun by such a species.
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I think the issue of soil ecology is very important and what organisms are required and which ones can safely be deployed. This is why we do really need a Mars analogue facility on Earth where this could be tested.
Earth soils generally involve a lot of assorted organisms, bacteria, fungi, slime molds, nematodes, insects and arthropods. Not just earth worms. These break down waste and render it suitable for uptake by plants- some with assistance by symbiotic organisms.
For decent soil you will at least need mineral dust, faeces and compost and soil organisms. A warm compost heap takes several weeks to work its magic but you have to avoid overheating it.
I would be concerned that you might bring a species from earth, without also bringing its competitors and predators. That hasn't gone well in isolated parts of this planet. So a prolonged isolated testing program must be used before risking your hab being overrun by such a species.
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We have a facility: MDRS has a greenhouse. And MDRS has other donations: a small observatory with telescope, and a dome. The dome was intended to be the new greenhouse, but those running GreenHab want a transparent greenhouse, they can't use an opaque dome. So it's now the "Science Dome".
The Science Dome is a 7-meter in diameter geodesic dome that contains our solar system’s control center and is a functional microbiological and geological laboratory.
I am concerned. MDRS is supposed to simulate a Mars Direct mission. The more we add, the less it is Mars Direct. Before MDRS was built, I expressed concern that it isn't "Mars Direct". You realize a real Mars Direct habitat has only the upper deck. The lower deck is rocket engines used to land on Mars, propellant tanks (fuel & oxidizer) to feed the landing engines, RCS thrusters used to manoeuvre in space during transit from Earth to Mars, propellant tanks for RCS thrusters, life support equipment to recycle air & water and large batteries to store power from solar panels, the airlock and stairway to the upper deck, storage compartment for a rover capable of carrying all 4 crew up to 1,000km, that same storage compartment also houses surface science equipment and the greenhouse deflated, folded and stored. The storage compartment will be the size of a single car garage, pack full of stuff during transit so that space cannot be used until on Mars. However, once on Mars all that stuff will be unpacked, so the storage compartment can be used a workshop or laboratory. If you're very lucky, there will be room for a small EVA prep room. That's all. Remember, life support equipment on the US size of ISS was designed to support 3 crew, Mars Direct will have 4. And ISS life support equipment filled 3 full-size science racks, not including the CO2 sorbent or batteries. Including all that, that means 5 full size-science racks. You could build life support equipment into one wall of the lower deck storage compartment, but also remember that compartment will be depressurized when the rover and other stuff are unpacked on Mars. That means you need a pressurized enclosure around the life support racks. All this means the EVA prep room will have to double as the landing at the foot of the stairs, and at most half the size of the one in MDRS. And there won't be a "Battery Charging & Work Table" outside the EVA prep room, but on Mars there won't be any "outside". The lower deck will be nothing but airlock, storage compartment, and landing at the foot of the stairs. That's it, nothing more.
I post this here because the "Science Dome" has "a functional microbiological and geological laboratory". A real Mars Direct hab has only 2 options: contain it all in the upper deck, or store laboratory equipment in the upper deck to be deployed in the lower deck storage compartment. And again, that storage compartment will only be the size of a single car garage.
So where do you compost soil? In early days of GreenHab, they talked about recycling waste from the toilet for use in the greenhouse. That wasn't done. Another issue is soil ecology, as elderflower said (in other words). If crew have E. coli (Escherichia coli) in their gut, it will be in feces. Actually, everyone has it. It colonizes babies within 40 hours after birth. It's the primary "probiotic". But you don't want it in food. The city sewage waste treatment plants in my city use settling tanks to remove feces, which are then taken to "digester" tanks to be broken down. After a series of steps to decompose it, this can be used as manure to fertilize crops; it's called "night soil". However, "night soil" can only be used for crops fed to livestock, not food for humans. Manure from livestock is used to fertilize food crops for people. On Mars you won't have that luxury. So feces has to be carefully decomposed before using it as compost. But one critical step is to ensure Mars crew don't have diseases to start with.
MDRS changes crew every 2 weeks. It can't isolate crew. And crew on Mars will exchange each other's diseases very quickly. So this work can't be done at MDRS. At least not sewage recycling. They could do soil analysis.
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We have talked lots about how to make mars soils better in a number of topics and once it came down to a shouting match in on topic with regards to just use the clean sand and do a hybrid hydroponic feeding system to nourish the plants.
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Night soil (sewage sludge) can be conditioned in a compost heap so long as the heap is large enough to attain 70 degrees C at least. It can then be safely dug into the soil of a vegetable plot. It becomes a valuable fertilizer.
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bump
I can see a theme
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The ecoli problem can be substantially mitigated by using thermophilic bacteria in the anaerobic digestion tank that receives the human waste. These operate at temperatures of around 70°C, which will kill most toxic bacteria.
Perchlorate compounds are highly soluble and may be washed out of filtered regolith, along with much of the heavy salt content. Sludge from the digester can then be added to the regolith to produce a clay like soil. Solid wood like biomass can be disposed of by pyrolysis, which will yield liquid fuels and a solid residue of charcoal and ash. The finely ground residue can be added to the soil to improve its fertility.
Last edited by Calliban (2021-11-21 12:41:46)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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Thanks for that - interesting.
As regards "washing out" perchlorates, given water will be quite a precious resource on Mars, I guess the issue of how many tonnes of water are required to clean up one tonne of regolith is an important one (although I supposed with water recycling, it might not be such a big issue). The other thing about perchlorate that I have read is that they are more a surface phenomenon, so it is quite possible I would think that if we dig out regolith from several feet beneath the surface, we won't find that concentratino of perchlorates. If so, then that would probably be an easier solution: dig down and dig out (DDDO) rather than dig up and wash out (DUWO).
The ecoli problem can be substantially mitigated by using thermophilic bacteria in the anaerobic digestion tank that receives the human waste. These operate at temperatures of around 70°C, which will kill most toxic bacteria.
Perchlorate compounds are highly soluble and may be washed out of filtered regolith, along with much of the heavy salt content. Sludge from the digester can then be added to the regolith to produce a clay like soil. Solid wood like biomass can be disposed of by pyrolysis, which will yield liquid fuels and a solid residue of charcoal and ash. The finely ground residue can be added to the soil to improve its fertility.
Let's Go to Mars...Google on: Fast Track to Mars blogspot.com
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I don't have any information on depth distribution of perchlorate compounds. If we can dig beneath contamination, maybe it will make the job easier. But there is more in Martian soil that could prove problematic to plant growth. Take a look at the measured abundance of chemical compounds in Martian regolith in the link below.
https://en.m.wikipedia.org/wiki/File:PI … 121203.jpg
What do you think is likely to cause problems and why?
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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The first issue is identifying which perchlorate compounds is present
https://en.wikipedia.org/wiki/Perchlorate
The digger for water from soil once heated to 500'c will break down some of these.
Ammonium perchlorate ("AP") is an inorganic compound with the formula NH4ClO4. ... Upon heating to 300 °C, the AP degrades
Heating Perchloric_acid produces toxic fumes of chlorine compounds.
heating, potassium perchlorate decomposes to potassium chloride
When heated to decomposition it emits toxic fumes of /hydrogen chloride/ and Na2O.
This leaves the water processing units output less dangerous for use in planting when mixed with other minerals.
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Martian soil is highly basic. From the composition chart that I linked above, about 15% of the soil is things like magnesium oxide, sodium oxide, sodium and magnesium sulphate. The soil is probably about as basic as gypsum. That is good if you want to make bricks out of it. Not so good if you want to grow anything. We could neutralise the basic compounds with an acid, such as HCl or H2SO4. But that would load the soil with salts. A better solution is to wash the basic compounds out of the soil. The alkali solution can then be subject to boiling at reduced pressure, using solar heat. This would produce pure water and a mix of solid sulphate and solid hydroxide and magnesium hydroxide. The condensed water can be used again.
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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Here's a link to soil composition:
https://www.ctahr.hawaii.edu/mauisoil/a_comp.aspx
Organic matter is some 5% of the total, so in 1 tonne of soil, 50 kgs will be organic material. A community of 1000 people might make 1000 Kgs of faecal matter a day/sol and you can add in food waste and crop waste - so maybe overall something like 1500 kgs - enough to make 30 tonnes of soil, or over an earth year, something like 10,500 tonnes. That might feed 200 people possibly.
Basically a lot of your organic matter is going to be imported as food that is then consumed by the Mars residents and turned into waste. I think the process could be speeded up by importing highly concentrated nutritional feeds.
The air for the soil will have to be manufactured but that should not be a major issue, I think since the whole colony will be geared up for that. Likewise water will not be a big issue and nearly all of it can be recycled after transpiration from plants.
Minerals are the problem area. I think it makes more sense to source fairly pure raw materials e.g. iron ore, silica and so on and mechanically grind them down to required particulate size, then mix according to required formulae for different crops. The vast majority of minerals can be sourced from Mars but there may be a requirement to import some of the rarer ones.
I think a soil factory will be less energy intensive overall than a system of soil cleansing and rebalancing (you are going to have to mix in minerals in any case).
A soil factory could be largely automated.
We'd probably want to be aiming to double production every Earth year, to keep pace with a growing population.
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How often would a crew member not finish every morsel of food on a plate and what about food that is expired in spoiled; these both can be added into that waste stream that makes soil possible.
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Yes, I said "you can add in food waste" e.g. plate waste, potato and other vegetable peelings and unused stalks from things like cabbages. And I also mentioned crop waste which is very substantial. Yes, expired food will be available as well.
How often would a crew member not finish every morsel of food on a plate and what about food that is expired in spoiled; these both can be added into that waste stream that makes soil possible.
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Interesting. Changes in gut bacteria are making it more difficult for human beings to digest fibre. These changes are associated with high rates of degenerative disease. Worse still, as western diets become multi-generational, healthy bacteria are not easy to restore, many are actually at risk of going extinct. Even if we adopt healthy diets, there is a point of no return with this problem.
http://m.nautil.us/issue/30/identity/ho … -evolution
Mars is a new beginning in so many ways. On the one hand, we have the opportunity to change our diet to be more compatible with this new and challenging environment. Maybe there will be health benefits along the way. Unfortunately, Mars is also a sterile and lifeless environment. There are no bacteria there that we do not bring with us. This raises the risk of poor gut health and degenerative disease. More research is clearly needed.
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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Moon and Mars superoxides for oxygen farming
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"Mars is also a sterile and lifeless environment" - think that needs a "possibly" somewhere.
Interesting. Changes in gut bacteria are making it more difficult for human beings to digest fibre. These changes are associated with high rates of degenerative disease. Worse still, as western diets become multi-generational, healthy bacteria are not easy to restore, many are actually at risk of going extinct. Even if we adopt healthy diets, there is a point of no return with this problem.
http://m.nautil.us/issue/30/identity/ho … -evolutionMars is a new beginning in so many ways. On the one hand, we have the opportunity to change our diet to be more compatible with this new and challenging environment. Maybe there will be health benefits along the way. Unfortunately, Mars is also a sterile and lifeless environment. There are no bacteria there that we do not bring with us. This raises the risk of poor gut health and degenerative disease. More research is clearly needed.
Let's Go to Mars...Google on: Fast Track to Mars blogspot.com
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Mars maybe but humans are not and after a 6 to 8 month journey we will have plenty of bacterium to spread to mars.
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Mars maybe but humans are not and after a 6 to 8 month journey we will have plenty of bacterium to spread to mars.
Anaerobic digesters perhaps? These convert excrement, food waste and plant waste into methane and CO2. The sludge remaining would be excellent compost for soil generation.
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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Very true.
We have to accept that the putting humanity on Mars is a venture into the unknown.
As you observe, we are home to billions of bacteria, will these take up residence in the general environment of Mars?
How will our immune systems respond? Do we need to stimulate them artificially by ensuring Mars residents are exposed to low pathogen loads. If we don't do something like that might the Mars community become highly vulnerable to diseases brought from Earth?
How far are bacteria important to soil on Mars?
There are lots of questions and I don't think we have the answers yet.
Mars maybe but humans are not and after a 6 to 8 month journey we will have plenty of bacterium to spread to mars.
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Using bacteria to build settlements on Mars
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Yes they can be harnessed but we must build the means not only for the protection of them but also the system so that we can make use of them as well.
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Removal of heavy metals from industrial wastewater using microbial fuel cell.
https://europepmc.org/article/MED/35936070
Nitrogen use efficiency in cotton: Challenges and opportunities against environmental constraints
https://www.frontiersin.org/articles/10 … 70339/full
Fertilizers That Are Needed to Grow Tomatoes in a Greenhouse
https://homeguides.sfgate.com/fertilize … 49203.html
Nitrogen
Nitrogen is important for the growth of the leaves and stems of the tomato plant. On fertilizer labels, the nitrogen content is indicated by the first number in the N-P-K ratio. Fertilizers including the word "nitrate," such as ammonium nitrate, are good sources of nitrogen. A nitrogen deficiency is indicated by light green or yellowish leaves and pale flowers. However, too much nitrogen in the soil will result in large stems and lush leaf growth, but few fruit.
Phosphorus
Phosphorus content is the second number listed in the N-P-K ratio on the fertilizer label. Sources of phosphorus will often have "phosphate" in the name, such as monopotassium phosphate. Phosphorus is important for the growth of plant roots and aids in the formation of blooms and fruit set. Insufficient phosphorus is indicated by a purplish hue in stems and thin growth. It is not usually found in toxic amounts in the soil.
Potassium, Calcium and Magnesium
Potassium is the third number in the N-P-K ratio. Potassium helps the fruit form correctly and ripen well. If there is not enough potassium, the fruit can develop poorly. Magnesium deficiency is common in greenhouse tomatoes and is indicated by yellow leaf veins. Calcium deficiency can result in blossom end rot. Calcium, magnesium and potassium should be applied in equal amounts so they do not block the absorption of the other minerals if there is too much of one in the soil.
Peat composts to be banned from sale in garden centres - how will it affect your garden?
https://www.express.co.uk/life-style/ga … ening-news
An efficient anoxic/aerobic/aerobic/anoxic process for domestic sewage treatment: From feasibility to application
https://www.frontiersin.org/articles/10 … 70548/full
Manufacturer/Recycler Revolution Gives Agriculture Waste a Second Life
https://www.waste360.com/plastics/manuf … econd-life
Water companies are considering system to turn sewage into drinking water to avert shortages
https://www.independent.co.uk/news/uk/h … 54421.html
Biology of the Arctic
The Pan-Arctic Continental Slope: Sharp Gradients of Physical Processes Affect Pelagic and Benthic Ecosystems
https://www.frontiersin.org/articles/10 … 44386/full
some other previous newmars discussion
Crops, Unconventional
https://newmars.com/forums/viewtopic.php?id=7568
Martian industry
https://newmars.com/forums/viewtopic.php?id=5920
Cities in the Arctic
https://newmars.com/forums/viewtopic.php?id=7897
Building soil
https://newmars.com/forums/viewtopic.php?id=5466
Chemicals centre on Mars
https://newmars.com/forums/viewtopic.php?id=6107
Last edited by Mars_B4_Moon (2022-09-01 11:42:33)
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