A few friends and I were talking organics on an other thread and talking about cooking soil in the winter. Does anyone know what temp microbes in the soil become inactive? Will a soil cook with daytime temps in the 40-50's? What about daytime temps of the 30's? I assume it will take longer to nutrient cycle in the low temps, I just thought you guys might have more detailed info on the subject. Any input would be appreciated.
i am sure it depends on ambient temp's. (caution cheesy joke coming) I hear experts are recommending cast iron I would guess you can also do better by piling it up in larger pile, to allow the microbes to fully 'connect' with the power in numbers
I've been wondering the same thing. I'm fortunate enough to have indoor space where I can cook my soil mixes in big trash cans, but the ambient air temperature averages about 59 F. I figure counting on extra cooking time at this temp'. Hope MM chimes in on this one.
Thanks... I'll save that as my last resort lmao! I make a mean Sunday breakfast but I've never tried cooking dirt.
If I want to cook my soil indoors it has to be in our 3rd story attic. So I'll be lugging it up the stairs AND up a latter if I have to cook indoors. My house is oldschool. I'm hoping I can make it work outside though, even if it takes longer. Maybe next time I can prep a large batch at the end of the summer for using all winter as needed. I'm pretty sure it would store just fine in the cool temps of winter if I prepped it ahead of time. Correct me if I'm wrong about that.
Optimum conditions for composting Oxygen / aeration If there is insufficient oxygen, a different set of anaerobic microorganism dominates the degradation process and produce odorous intermediate products such as methane, organic acids and hydrogen sulphide. A constant supply of oxygen will give the aerobic microorganisms an advantage over the anaerobic micro-organisms. Approximately a 5% minimum concentration of oxygen is required within the pore spaces in the media. Aeration is the process of providing oxygen into the composting material. This will also provide a platform to remove water vapour, gases and excess heat trapped within the material. Aeration is common practice with high rate large scale composting facilities. Moisture content Moisture supports the metabolic processes of the micro-organisms. Water is the medium for chemical reactions. Biological activity ceases below 15% moisture content and in theory activity is optimal when materials are saturated. Generally moisture content of between 40% and 65% should be maintained. At moisture content of below 40%, micro-organism activity will continue but at a slower rate and above 65% water will displace much of the air in the pore spaces of the composting material. This will limit the movement of air and lead to anaerobic conditions. Temperature Composting takes place within two temperature ranges known as mesophilic (100–400 C)(212-752 F) and thermophilic (over 420C). It is generally accepted that maintaining temperatures between 430C and 650C allows for effective composting. The thermophilic temperatures are favoured in the composting materials, because they destroy more pathogens, weed seeds and fly larvae. In some composting processes, Temperatures can continue to rise above 700C due to insulation effects and on-going microbial activity. At these temperatures many micro-organisms die or become dormant and the process effectively stops until the micro-organisms can recover. It is best that the compost bin etc, is placed in a sunny area to enable better composting in high temperatures ie,Thermophlic composting=130-160*F Nutrients and the Carbon Nitrogen (C:N) ratio The microbes involved in composting use carbon for energy and nitrogen for proteinsynthesis. The proportion of these two elements required by the microbes averages about 30 parts carbon to 1 part nitrogen. Accordingly, the ideal ratio of Carbon to Nitrogen (C: N) is 30 to 1 (measured on a dry weight basis). This ratio governs the speed at which the microbes decompose organic waste. Most organic materials do not have this ratio and, to accelerate the composting process, it may be necessary to balance the numbers by mixing different substrates. (eg.. kitchen waste is rich in nitrogen while garden waste is in poor) Particle size, porosity, structure and texture The ideal particle size is around 2 to 3 inches. In some cases, such as in the composting of kitchen waste, the raw material may be too dense to permit adequate air flow or may be too moist. A common solution to this problem is to add a bulking agent (straw, dry leaves) to allow for proper air flow. Mixing materials of different sizes and textures also helps aeration the compost pile.
That just doesn't sound right. 752 degrees for composting???? LOL I'm not sure where you got that info. I can easily look up ideal temps for composting, but it's harder to find the low temp point where things will stop nutrient cycling. Thanks for the response though. My research has led me to believe that most micros become dormant around 40 degrees but some will continue to break down organic matter at temps below freezing. So that's why it takes longer to cook soil in the winter. But it will work slowly.
You're right mjmama, There are microbes involved in composting called psychrophiles which thrive in temperatures from 0-55 degrees F. The mesophiles live in temperatures ranging from 40-115 degrees F. Optimal range for many mesophiles is 90-115 degrees F. Actinomycetes and most fungi are mesophiles. Thermophiles are microorganisms adapted to temperatures ranging from 110-160 degrees F. Temperatures above 160 degrees F kill even the thermophiles effectively sterilizing the compost pile. Back to your original post.......the decomposition rates dramatically decrease as temps drop but there is still microbial activity. Piling hay over your soil pile can keep heat in. Keeping a tent over the pile to keep it from getting saturated also helps. You want moisture, but once saturated, you cut off the oxygen. As you know, oxygen is most important to effective composting. I know we're talking about soil cooking but the science is the same. Use Google / Wiki and query psychrophile, mesophile and thermophile to learn about these microorganisms. It's interesting to learn about the harsh environments these microbes can adapt to. Chunk
Thanks Chunk. I'll have my other friends read this thread. I know talking it through here has given me a better understanding of the process. Sometimes it's the wrong answers that make me think of sometime to google that leads me to the right answer, lol. And your info is golden. Much appreciated.
mjmama, If you haven't already seen this link, it's a real keeper. Controlled Microbial Composting and Humus Management: (Luebke Compost)
LOL...My bad for not knowing the metric system that well... Those temp would just about kill every organism in sight... To set the record straight 130-160*F is optimal thermal composting. After the thermal phase the temp drops and decomposition is taken over by mesophilic microbes and is the process of curing and maturation that make compost more stable for plant use... Like you say, their is little info available to composting in cold temperatures but, can be done. I would say it would just take longer to process and less turning of the soil that releases heat....By far putting material in a heated area would be the faster way....
Ya sure ain't cookin' much of anything here - is several degrees below Zero without the damn wind chill... J
Just to put it out their. I started mixing my soil for my 2012 grow outdoors in eastern Washington in January. Wgg
I don't want to start a new thread but... on the subject of composting-cooking, does anyone feed their piles with molasses or the like? assume C:N ratios are within tolerances. My heap is outside and has been cooking all winter with a mean temp circa 50F. black gold. Also can someone define "Cooking"?
from what I've read, molasses is added to compost teas in order to feed the microbes in a liquid compost solution, yet it is unclear whether pouring molasses directly on dirt will be effective. Cooking would be the soil's status after it is mixed and amendment particles begin to break down.
Also, can someone define "cooking"? "Cooking" is slang for Nutrient cycling. This is the stage in which the soil bacteria/microbes begin to break down the organic matter in your soil mix into usable plant food. This is really a constant process but more often refers to the initial stage before you use your soil - usually a month - or more. Nutrient cycling Inorganic nutrients occur in limited quantities and their loss to an ecosystem or retention and re-use is of great importance. The cycles of chemical elements in an ecosystem are known as nutrient cycles. If there is no loss to the ecosystem the cycle is said to be a 'perfect cycle' and if loss does occur the cycle is said to be 'imperfect'. The decomposers play an important role in these cycles because they break down dead organisms and make the nutrient components available once more to other organisms. The carbon and nitrogen cycle are two such cycles. The Carbon Cycle All organic compounds contain carbon and the most important sources of all inorganic carbon is carbon dioxide in the atmosphere. carbon dioxide is taken up by autotrophic organisms during photosynthesis and the carbon is incorporated into carbohydrates and other compounds , such as proteins and fats; consumers (heterotrophic organisms) feed on plants, and their bodies assimilate carbon compounds derived from the plants; all organisms, including plants, release carbon dioxide during respiration as a by product. (Fermentation releases of carbon dioxide); when autotrophic and heterotrophic organisms die or lose body parts such as leaves, carbon dioxide is released as a result of decomposition; combustion of dead animal and plant material also releases carbon dioxide; under high pressures, dead plants and animals are carbonized, forming fossil-fuels, such as coal and crude-oil. These release carbon dioxide during combustion. A Diagrammatic representation of the Carbon Cycle The Nitrogen cycle Nitrogen is an element essential in all organisms, occurring in proteins and other nitrogenous compounds, e.g. nucleic acids. Although organisms live in nitrogen-rich environments (78% of the atmosphere is nitrogen) the gaseous forms of nitrogen can only be used by certain organisms. Free nitrogen must first be fixed into a useable form. free nitrogen in the atmosphere is mainly fixed by two groups of bacteria, nl. Azotobacter and Clostridium. The nitrogen is then used to manufacture proteins in their bodies, when they die, their proteins are broken down by decomposers (mainly bacteria and other micro-organisms), and converted into ammonia (blue-green algae, cyanobacteria, can also be use free nitrogen from the atmosphere); during electrical changes in the atmosphere(e.g. lightning), free nitrogen is fixed (combined) finally forming nitrate; nitrates are taken up by plants which use them to manufacture proteins; animals (herbivores) eat plants and convert plant proteins to animal proteins, while carnivores obtain their plant proteins by indirect means (by eating herbivores); when plants and animals die, the proteins in their bodies are broken down into ammonia by decomposers. The process is known as ammonification; ammonia is converted to nitrites by nitrite bacteria (Nitrosomonas and Nitrosococcus). Nitrites are again converted to nitrates by nitrate bacteria (Nitrobacter )This process is known as nitrification; different types of bacteria are also able to break down nitrates, nitrites and ammonia which results in the release of nitrogen. This process is known as denitrification. A Diagrammatic Representation of the Nitrogen Cycle. These two cycles emphasizes the mutual interdependence of producers, consumers and decomposers in an ecosystem.