Lecture 11 : Principles of Compost Production


So, I welcome you all, for the ah, lecture
number 11, Principles of Compost Production . So, earlier lectures, we have ah, discussed
about the Sustainability Agricultural Productions and the Role of Organic Farmer, farming for
Sustainable Agricultural Productions and the key indicators of Sustainable Agriculture.
So, this lecture will be going to the main topic a compost production. As one of the
inputs of organic farming ; so, we will discuss this one the principals involved in compost
production . So, ah ; so, first of all, what is compost?
The compost is a organic matter, that has been decomposed and recycled as a fertilizer
and as a used, as a soil amendment . Compost ah is a key ingredient of organic farming
and the end products of the decomposition of organic matter, that is compost .
Compost is rich in nutrients . It acts as a soil conditioner , a fertilizer , addition
of humus, as one of the most important constituents , in agricultural productions for ah, maintaining
soil for fertility and the soil health on long term basis . So, Humic acids and as a
natural pesticide for soil . In ecosystem, compost is useful for erosion
control, land reclamations , wetland constructions and as a landfill ah, cover. Compost ah, is
called the gardeners gold , because it is an invaluable partner in keeping the soil
healthy. So, ah, as you know, that humus is one of
the important constituents, that is used for maintaining and improving soil health for
lung basis. So, by using compost, it enriches the soil with humus. So, what is humus; humus
is a complex mixture of dark brown amorphous and colloidal substance, modified from the
original plant tissue or synthesized by various soil organism and resistant to microbial decomposition.
So, ah, the the humus, that is responsible for building soil physical properties. It
improves the soil physical properties. If you see, the properties of soil humus , humus
particles become one day to clay and other selected surface leading to formation of soil
humus complex and the humus stores and a releases soil nitrogen. So, being a ah, soil humus
complex, by adding organic manures or the organic matter , that increases the humus
content of the soils and that helps in increasing the , say cation exchange capacity or the
anion exchange capacity, in the soils by having higher humus content.
And humus, also processes buffering capacity; that means, the suffer soil buffering capacity,
means the soil has high buffering capacity, is soil is a robust soil; that means, a good
soil good fertile soil healthy soils has high buffering capacity. So, it resists to any
type of changes in the properties or pH changes is . It is not so easy. The soil as a high
buffering capacity; that means, soil has high and anion exchange capacity.
So, having humus or having more amount of humus, in soil that, causes , that increases
the buffering capacity of soil , and this soil having higher amount of humus, that are
judged pesticides and other agricultural chemicals; that means, a soil has higher humus , as a
humus , soil humus complex . So, the , if there is a pesticide or the agricultural chemicals
applications soil having higher amount of humus.
So, those pesticide is not allowed to the ah, below the soils and containing the groundwater;
that means, the soil having higher amount of humus content, that can protect the environments
from the contamination of the pesticides or the leaching of the nutrients to down ward
groundwater . And, then what is composting; the composting
is a natural, biological process, carried out under controlled aerobic conditions . In
this process, various microorganisms including bacteria and fungi breakdown ah, and the organic
, organic matters into into , simpler or the ah, substances by presence of the bacteria
and the fungi . Their job is to decompose or the breakdown the organic resides into
ah, simpler substances. That is a composting .
The other one, composting is a nature’s way of recycling . Composting biodegrades organic
waste that is your food waste, manure leaves, grasses wood feathers crop residue and turn
it into a valuable organic fertilizer. The effectiveness of composting process is dependent
upon the environmental conditions . That is a ah, air contents temperature and the moistures
of the composting beds and the materials the ah, composting materials organic materials
and the activity of the microbial populations or the microorganisms present during the composting
process. So, there are different type of composting.
One is called, the Aerobic Composting , Anaerobic Composting and Vermi Composting ah . Aerobic
composting, where we have the, the composting process takes place in presence of oxygens
. That Is a quick breakdown of organic waste, during the aerobic composting. So, that needs
a maintenance ah, due to the by the turning in the organic materials regularly in the
composting beds . So, that you can maintain the moisture, you
can maintain the temperatures , ah, of the ah, composting systems and and this aerobic
composting that needs to maintain the favorable moisture and temperature. That is a proper
decompositions and the early decomposition of the organic residues, and the other one
, it is a anaerobic composting . So, this compositing takes place in absence
of oxygens under reduced conditions . That, that takes long time for the breakdown of
the organic waste , and that needs less maintenance, because this is done in a close feet , and
in this composting, there is a release of many toxic compounds and release of ammonia
and Methanes during the composting process and the other one which will discuss in detail
that is vermicomposting . So, this is a most effective composting. Here,
the maintenance of oxygen moisture for a healthy compost, we do maintain in a vermicomposting
bed. So, the favorable or the requirement mount of oxygens and also this , the temperatures
and the moistures for the growth of the , the workers, who are involved in composting process
they are the earthworms . So, the earthworms are added here in vermicomposting process.
So, their job is to degrade and decompose this organic waste to minute particles and
during , during this composting process. Also they secrete, they are body parts, they are
the , they also secrete many hormones antibiotic, that helps in enriching , the value of the
compost . So, now we will discuss. So, . So, what are
the , the main principles, in vermicomposting process, when you go for composting what are
the principles. Are there , there main seven principles; one is C:N ratio of organic residue
. C N means the carbon and nitrogen ratio of the organic residues , because the quality,
this this indicates the quality of the organic residue.
The residues, having higher nitrogen content, they are suitable for early decompositions
or degradations the residue having the , sorry the sorry the residue having the yes higher
Nitron content they have the low C:N ratio. So, they are most suitable for quick decompositions
and the residue having ah, low C:N ratio ; that means, they have the high nitrogen content.
So, they are the easily degradables, quick degrade degradable and the residue having,
higher more N content . They have the ah, low C:N ratio and the residue having low n.
content , they are the higher C:N ratio those residues are less suitable for the microbial
degradations, because that residue takes longer times having the low nitrogen and high C:N
ratio. So, in those cases ah, the this depends the
quality of the organic residue suppose those, legume residues have the high n content they
have the very low c n ratio. So, they can be easily degraded by the ah, microorganisms
, but if you see the rice straws or the hood straws cereal crop residue or the saw dust,
they have very lower low N content. So, that very high C:N ratio. So, they take a long
time for the decompositions. Then, the mixing of organic materials they
depends upon the residue or type ah the C:N ratio of the residue depends C:N ratio we
can we can think which organic material should be mixed together. So, that we can be, bring
the C:N ratio the comfortable range for the better decompositions by the microbes .
Then, size of the residue , because So, now, if we can have the larger size residue it
takes longer time for the microbial decompositions . So, size has to be reduced to a comfortable
range . So, that it increases a surface area and the decomposition becomes faster.
Then, as we will discussing moisture and temperature in the compost beds , the what type what are
the content ah, quantity of moisture range of moisture and temperature should be there
in compost beds . So, that the earth worm can ah, work better than they get a better
environments for the degradation or the decomposition of the waste material.
Then pH in the compost bed and then, microorganisms and the microbial inoculants . They are ah,
applied to the compost bed. They are relay the compost beds for the better decompositions
or the quick decompositions and also the enriching the quality of the compost, and finally, the
amendment with rock minerals , this is also one type of enrich in the compost with the
natural minerals. So, depending upon the compost , type of compost,
you are making . So, in that case, if you you can you can add different rock minerals.
So, the compost can be enriched with specific elements.
So, coming to the first one C:N ratio . So, ah, usually the preferred the C:N ratio is
30:40, is to one . So, C N means the carbon the, the the micro organic requires carbon
for their growth and nitrogen for their protein synthesis. So, C N ratio of the waste materials
should be 30-40 is to one ah, that is optimal for composting.
So, if suppose in case the materials the waste materials having higher C:N ratio; that means,
the greater than 40; that means, it takes a longer time for composting. For examples-
the materials having higher C N ratio may be serial ah, straws like a rice straws or
wheat straws or the saw dust also . So, they have the very high C:N ratio and the materials
has low C N ratio supposing less than 30. In that case, the N , the N content the materials
are very high in that C:N ratio is low . So, if there is a higher N content ; that
means, N is excess or the requirement of the microbes . So, there is a loss of nitrogen
through ammonia volatilizations . So, this has been observed that about 40-50 is the
lost through ammonia, if you are the waste materials are water hyacinth animal or the
cow dung and the immature green organic materials those are having higher nitron contents and
very low C:N ratio less than 30. In that case, there is loss of nitrogen through ammonia
volatilization. If, this is the case, if C N ratio beyond
the range either less than 30 or greater than 40, then we go for the mixing of organic materials
. So, is the C N ratio is greater than 40 ; that means, the materials contents very
low or the low lower nitrogen content. In that case, these organic materials can be
mixed the materials having higher nitrogen contents.
So, those materials having higher N content are sewage sludge . Legume residues aquatic
weeds slaughterhouse wastes can be mixed with those materials having high C N ratio. So,
that C N ratio can be brought to the comfortable range for proper activity of the microbes
. The materials having very low C N ratio, suppose
less than 30 , in that case, that has a high N content. Then, for those cases, we can add
dry soil around 5 to 10 percent . So, that ; so, can observe the moisture from the materials
and they can minimize the release of a ammonia to the atmosphere. They can observe the ammonia
present in the waste materials . So, depending upon the waste materials or
the C N ratio, we can, we can decide what type of organic materials should be used or
the mixing of the organic materials. So, that the C N ratio, as the the quality of the organic
material that can be ah, maintained in a comfortable range in an optimum range .
Then, size of residue ah, the ah, most desirable particle size is around 3 to 5 centimeters
. So, if there is a ah, larger size of the residue so, it, it will go for composting
only thing that it will take more time. So, you have to reduce the time for the composting
. You have to make the compost quickly. Then we have to ah, reduce the size of the waste
materials ah, using the like shredder is shown here .
So, using this shredder tires shredder. So, that you can put the waste materials of different
sizes and we can, we can have the waste the , the final ah, size of around ah, less than
5 centimeters ah, which is very optimum size , for preparing a good compost . Compost means,
the compost can be ah, made very quickly . Then moisture and temperature ah, usually
the moisture content say ah, varies from 50-60 or it can go to for the 80 percent for the
aerobic composting and the temperature usually the temperature, when you go for the ah, loading
of the waste materials in the compost bed . So, there is a raise in temperature temperature
may go up to 55 to 70 degree Celsius . Ah, when the temperature rises above 40 degree
Celsius , the mesophilic microorganisms, they are replaced by thermophilic microorganisms
. So, ah, ; so, they do not survive , they do not survive ah, above 40 degree Celsius
. Ah, when the thermophilic condition appears that conditions within 2-7 days of the start
of composting process with thermophilic bacteria. They become very active and they do give up
the temperatures. The temperature goes maybe around 55 to 70 degree Celsius and the presence
of the thermophilic bacteria and, because of high temperature the de, decomposition
starts in a faster rate . So, this 55-70 degree Celsius or above I can
say 50-degree, 55 degree Celsius is required , during composting process, at least for
three days. What will happen, if there is a high temperature? There are some pathogens,
they are get killed temperature ah, beyond 55 degree Celsius or 60 degree Celsius , like
a shigella species . That causes dysentery and equally common in C S sewage they are
killed at 60 degree Celsius. Similarly, tape worm and hookworm, they are
killed at 55 degree Celsius; that means, most of the common pathogens. So, they are killed
at 60 degree Celsius and for that, so, maintenance of temperatures at least 50 degree and higher
50 degree is required for, at least 3 days in the composting process. So, that the compost
can be free from many pathogens and usually when you go on ah, loading the compost the
past 2-7 days. So, the thermophilic bacteria they become
active, because of raise in temperatures and they start on degradations and during that
periods many of the pathogenic organism , organism they are get killed . And next is pH , if
you see the ah, the pH usually the the earthworms or any micron.
They do a ah, live comfortably pH neutral range around 6 to each ah, 8 and most of the
macro organ they grow under the neutral pH range 6-8 and there will be a drop in pH due
to acid forming bacteria during the composting process at the same time the pH ah, may increase
due to formation of ammonia during the decomposition process .
So, there is an auto regulation in the pH in the composting process this maintained
around 6 .5 to 7.5 ah, range and then you go for the ah, microorganism and the microbial
inoculants , because when you go for ah, increasing the enhancing the quality of the compost with
some specific nutrients or ah, or to have an only decomposition process, when you go
for the inoculation of the ah, microbial ah, organisms say mesophilic bacteria, they are
involved in consuming the readily degradable carbohydrates and proteins .
The thermophilic bacteria, they attack only lipid and hemicellulose . The carbohydrates
and the proteins they degrade very fast . Lipid, it takes a a long time and this they the decompositions,
also that leads to the formation of a humus in the, the compost , that comes from the
the slow decompositions. That are those lipids and the hemicellulose
they are very hard to a a very very resistant to breakdown and after that the materials
remain that , that they do not break down or variation breakdown, that comes as a humus
and that leads to the physical property. That leads to improving the physical properties
of the soil . So, those thermophilic bacteria, so, they
are active , they are active and their , their under high temperature and the decomposition
becomes the faster rate, and during that process many of the pathogens are made killed . Then
actinomycetes are such the thermonosopracurvata and many fungi involved in cellulose decompositions.
Then preparation a sawdust compost , that comes of the the industry with inoculation
of cellulolytic fungi . That is coprinus phemerus hasten, the composting from 1-2 years 2-3
months; that means, if the materials having high cellulose contents like the saw dust
has very high C N ratio that is very, very low N content. In that case, you have to inoculate
the waste materials with cellulolytic fungus. So, that the degradation of this materials
become faster and the composting can be ready , in a short time and a coming to ah, next
one that is a ah, are the amendment with the rock minerals; that means, the application
of the natural minerals the rock phosphate at 5 percent resides improving the phosphorous
and N content also improves the micro contents in the vermicompost.
So, ah, this a rock minerals can be added, during composting process at different doses
also . That is in the 5 percent gives one of the better results and I , there are phosphate
with addition of the paddy straw along with inoculation of aspergillus Niger .
And AzotobacterChroococum accelerates the process of composting and improves the nitrogen
and phosphorus content of the compost; that means, by adding this ah, rock minerals along
with the microorganisms like the aspergillus Niger and the other AzotobacterChroococum.
So, they do accelerate the composting process, at the same time they do improve the quality
of ah, compost by enriching nitrogen and phosphorus .
That means. So, these are the sum of the principals involved in a composting process. So, we need
to ah, see the what , because you have the different type of waste materials for waste
material, what type of waste material is there , depending upon the C N ratio the waste materials
are very high in C N ratio . Then we have arced the waste materials have having the
higher N content. So, that this C N ratio can be lower.
Similarly, other cases you have the lower C N ratio. We add with the soil ah, other
material for that is the ah, nitrogen loss through ammonia volatilizations can be checked
and the size of the materials , the what size of the materials can have moisture and the
temperature should be maintained around 60 maximum ah, 80 percent moisture content should
be maintained, because the earth worm the inside the microorganism.
They leave a comfortable environment and 50-60 percent moisture content and the temperature,
because temperature is a, because initially temperature goes up ah, initial grade of composting
where the thermophilic bacteria, they become active and this is required in a composting
process as it kills many of the pathogens. So, that com , de compost can be pathogen
free and using microbes and the amendment with rock minerals they can they can enrich
the compost quality. And, if you see, the factors ah, that is controlling
composting . So, as you discussed one is your C N ratio. That means, the C N ratio, that
should be maintained 30-40 is to one the carbon and nitrogen ratio ah. So, ah, as you discussed
depending upon the the type of the materials .
So, C N ratio the , because materials vary and the locations . In the farm, waste has
many types of waste , we have these straws rice straw, wheat straw or the legume straws
. So, if they can I can mix together . We will try to see how we can we can maintain
this C N ratio around 30-40. So, that the this is required for the proper
growth of the microbes, because microbes they need nitrogen for the for their own growth
and multiplications and to have their own own growth and multiplications. We need to
maintain at least the required amount of nitrogen . So, that in a the there is a comfortable
environment for the microbe’s organism for their growth.
Then, particle size that, we discussed particle size is 3-5 centimeters, because this particle
size, if you have this small particle that increases this surface area of the particles
and. So, that the microbial activity will be faster the decomposition will become , become
the faster with the the smaller particle size .
Then moisture content . So, 50-60 percent moisture content that should be maintained
ah, during the process of composting, because ah, high moisture content there will be less
of if increase the moisture content . So, the divide of oxygens . So, microorganism
has a minerals survive in the less oxygens. The oxygen requirement around 10-18 percent
oxygens to maintain the oxygens and the moisture content should be 50-60 percent throughout
the composting process for the ah, better growth, because we need to ah, maintain the
population of microbes microbial growth. So, that they can work faster they can degrade
the the organ organic waste for the decomposition process temperature .
So, that we are discussing that should be 55-60 degrees Celsius for at least 3 days.
This is very, very important in the composting process, because and to make the the compost
free of pathogens . There should not be any sea glass species or equally species or the
tape worm hookworm. So, many pathogens they are get they get killed
the temperature above 50 or 55 degree Celsius. So, maintenance of temperature at least 55
degree Celsius and the higher for at least 3 days. It is really essential , essential
in the composting process and its very natural when you go for the ah, compost and the mixing
with the ah, cow dung phase cow dung and loaded in the beds.
So, initial period of composting the temperature increases and it may go up to 70 degree Celsius
. So, that is helpful for killing many of the pathogens pH control pH control, as we
discussing this not necessary, because this is auto regulated because pH comes down, because
permission of the the acid forming bacteria also pH goes off when, there is a release
of breakdown of the organic compounds and release of ammonia then pH goes off.
So, ah, pH is regulated auto generated in the compost ah, compost feet around 7 6.5
to 7.5 heap size heap size can be any length because length is not an issue. So, it should
be 2.5 meter wide and 1.5 meter high height, because the 2.5 meter wide we make, because
for proper uniformity in the compost making .
And we can , we can draw the compost quality with the wide of 2.5 meter and height should
be ah, not more than 1.5 meter . If you increase the height even 1 meter height also convenient,
if you increase the height of the ah, heaps then it becomes an anaerobic decompositions.
So, ah, because many of the organism and the aerobic organism they may not survive the
anaerobic conditions to have a proper variation. So, heap size should be less than 1.5 meter.
And, the activators used efficient cellulolytic fungi , because for this accelerating the
process of composting for the or enriching the compost with specific nutrients or or
ah, nutrients , we can go for the use efficient cellulolytic fungi that as we discussed earlier
that can be inoculated during composting process. So, that the compost can be made bigger .
So, ah, if you see the, quality the the properties of good quality compost. These are the ah,
the of compost depending upon the type of organic materials and depending upon the microorganisms
present and the depending upon the environments, that depend time taken for the compositing
process in general the compost is judged based on this parameter color smell pH ah, C N ratio
temperature moisture humus content and nitrogen contents .
The color, that is a good quality compost. So, brown to black and the poor quality it
may have the different colors and is a is a compost is ready and mature is pleasant
the smell is , there is no smell you can no smell or at this smell in case of the poor
quality ah, is gives a bad odor because of the poor decomposition; that means, the compost
is not the materials not decomposed, in that case, you can have the odor of the smell if
the material is fully de compost. That is a no smell or at the smell or a very pleasant
smell you can get from the the final compost. So, pH for the good quality within 6.5-8 and
for the poor quality. It may be less than 6 or may be higher than 8; that means, the
compost is not well de compost the compost not well matured in that case the pH may be
vary from less than 6 to may be higher than 8 and the C N ratio of the good quality may
be 10 to 20 :1. And, case of the poor quality C N ratio may
be less than 10 or higher than 20 the temperature of the the final compost may be 30-45 degree
Celsius and for the poor quality may be high temperature; that means, this, dis compost
is not the de compost , de compost is not well de compost the temperature maybe 45 40
or may be higher than 45 degree Celsius . Moisture content around 25-30 percent , for
the good quality compost and the humus should be more than 4 percent and the nitrogen, at
least the main nutrient as you say nitrogen that should be more than, higher than 1.5
percent . So, these are the ah, qualities, when you go for the lab analysis .
We can check, the quality of the compost and this quality can be maintained depending upon
the , the input materials. What type of materials are used on the depending up on the input
materials ; we can think of what type of materials can be mixed together. So, that we can maintain
one optimum C N ratio . You can maintain the the input to the optimum C N ratio and the
proper environment during the composting process as we discussed the moisture temperatures
and addition of the microbial inoculants as per the need of the organic waste .
So, we can get a good quality compost and that can that can feed as your requirement
and that can feed the ah, several in general for a many crop and then you can I, go on
adding enriching for specific crops ok, ah. So, these are the qualities of good compost.
So, if you prepare you are the waste materials and the conditions inside the compost bed.
We can get a quality which can meet the requirement, for this organic farming and ah, we will discuss
now the finally, . So, what is the benefits of the compost application.
If it is the benefits of compost . Compost is a store house of energy for growth and
multiplication of microbes and their activity in soil, which is vital for plant nutrient
cycling it supplies both macro and micronutrients then, it provides the growth promoting substances
which stimulates only plant growth and it act as a soil conditioner as it improves the
physical condition of soils such as soil tilth .
Soil tilth, means, it is an equal proportion of macro and the micro ports then that influence
the water holding capacity of soils of course, cation exchange capacity. So, that is there
those are regulated with having the higher the adding the compost .
The compost it is a pathogen free as all the pathogens are killed at high temperature,
then increases the biological activity of soils and produce crops ah, growth with the
less disease , because addition of compost is a pathogen free it can give a disease free
or the phase free environments. So, these are the , some of the benefits of compost
applications ah. So, while making the compost and the applying. So, we should be very careful
and the meeting the principles of the compost preparation ok.
Thank you.

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