Special Reports/Organic Farming
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Organic
farming - composting & its mechanism
By: Rana Mujahid
Ali Khan, Tanveer Hussain Khan
Organic Farming is a modern, sustaining & close to nature
farming system, which maintains the long-term fertility of
the soil and uses less of the Earth’s finite resources to
produce high quality nutritious food
grains/vegetables/fruits. Organic techniques have been
developed from an understanding of and research into soil
science, crop breeding, animal husbandry and ecology. The
maintenance of soil fertility relies principally on the use
of legumes, crop rotation, the application of composted
animal manures and ground rock minerals. Weeds are
controlled by mechanically methods, while pests & diseases
tend not to be a problem due to the inherent bio-diversity
in the system. Artificial fertilizers, pesticides, growth
regulators and livestock feed additives are
restricted/prohibited. Organic Farming implies that the
farmers should use organically produced seed, which shows
more strength & yield due to bio-diversity.
Whilst
the sector is still in negligible ratio in Pakistan;
however, it would expand dramatically and set to be the most
exciting sector within agriculture industry.
No doubt, organic farming has to be understood as part of a
sustainable farming system and a viable alternative to the
more traditional approaches to agriculture. Thousands of
farmers have been converted to this system, as a result of
increased consumer awareness of, and demand for, organically
grown products. Sustainable development in Organic Farming
would encompass food production alongside conservation of
finite resources and protection of the natural environment,
so that the needs of people living today can be met without
compromising the ability of future generations to meet their
own needs. This objective requires farmers to consider the
effect that their activities should have on the future of
agriculture and how the systems, they employ shape the
environment. As a consequence, farmers, consumers and policy
makers are showing a renewed interest in organic farming.
a) Understanding how nature works instead of relying on
chemicals A common misconception about organic farming is
that it lacks sophistication, or “Science”. Some people
think that organic farmers just put seeds in the ground and
“let nature take its course”. Nothing could be farther from
the truth.
Organic farmers rely heavily on a complex understanding of
ecology and soil science. Modern organic farming techniques
are used in concert with traditional methods of crop
rotations to ensure fertility and weed/pest control. We know
that when we farm, we interact intimately with many
creatures and ecological micro-system _ from tiny bacteria
and fungi in healthy soil, to larger soil organisms,
beneficial insects, and other animals with whom we share the
planet.
The methods, we use to farm organically tend to be more
labour intensive and costly in the short run, but cost
effective in long run. It is notable that groundwater
pollution, soil erosion, loss of biodiversity, and human
health problems caused by chemical residues are seriously
effects of conventional agriculture.
Although organic produce may cost a bit more in the grocery
store, because long term costs associated with these
problems are factored in, the organic choice is the
healthiest and, ultimately least costly option
b) Developing healthy, fertile soil - the natural way
Organic matter means the part of the soil that is comprised
of anything that once lived, including plants and soil
organism. Field high in organic matter have less soil
erosion, retain water better, and release nutrients more
slowly into soil for natural, healthy plant growth.
Every time crops are harvested or weeds pulled, nutrients
and organic matter are withdrawn from the soil. If they are
not replaced, the soil is eventually depleted of the
resources that plants need to flourish. Healthy soil, rich
in organic matter, is “alive” with microorganisms. These
vital organisms break down nutrients to make them available
to plants and they not only make the soil more fertile but
also kill plant pathogens in the soil. The natural way outs
to meet the challenges are appended:
c) Introduction of Compost:
A quality compost recycle and some time animal waste
materials, and turns them into nature’s best plant food,
containing high quality organic matter and beneficial
microorganisms. Microorganisms {Bacteria, fungi, nematodes,
protozoa, earthworm} break down {Digest}, the raw components
of compost.
This metabolic activity generates heat. Before compost
applying to the field, it reaches & maintains an internal
temperature of 120 to 130F for at least five days to kill
any disease-causing bacteria and weed seeds.
Litter/Palletized chicken manure is also used for heat-steam
process to kill unwanted bacteria. Mature compost is also
containing minimal amounts of undigested carbonaceous {i.e.
Woody/Saw dust} materials because these tend to immobilize
nitrogen supplies in the soil and thereby starve plants of
this critical nutrient.
The most immediate and dramatic effect of the regular
additions of compost is an increase in the water holding
capacity of sandy soil, increased oxygen content and
drainage in clay soils, and significantly healthier and more
production of crops. Less obvious, however, are the
environmental and human health benefits of using compost
such as recycling, otherwise unused “Waste” products (e.g.
surplus farm manure, food waste, leaves, grass clippings
etc.) and avoiding & minimizing the use of harmful synthetic
fertilizers and pesticides.
While compost is being used as a “ nutritive-mulch”
throughout the growing season, incorporating compost into
the soil prior to planting is the quickest and most
efficient way to improve soil fertility. Specific compost
application rates are determined by an evaluation of exiting
organic matter and nutrient levels. A good rule of thumb is
to apply at least one inch but not more than four inches per
year.
d) Horse Manure and its Composting:
Horse Manure Composting is a microbial process that has long
been used to manage a wide variety (i.e. Carbon-Containing)
waste. Horse owners are increasingly taking advantage of
many environmental and economic benefits of this practice.
The horse manure contains nutrients and pathogens that can
pollute surface and ground water, if managed properly. For
example, phosphorus rich runoff from stock piled manure can
cause uncontrolled growth of aquatic plants in streams,
ponds, and lakes. These algae “blooms” kill fish and other
aquatic organisms by using up the dis-solved oxygen supplies
in water. Runoff and leachate from manure piles also contain
nitrates and bacteria, which can make surface and
groundwater un-safe for drinking and recreational use.
Through a combination of composting and proper environmental
controls, pathogens can be destroyed and local water
resources protected.
Horse manure commonly contains the larvae or eggs of equine
parasites. While spreading untreated manure on pasture
increases the risk of exposure to horses that graze there,
the heat generated in properly managed compost pile (120 to
155 F) has shown to effectively kill these harmful pests.
BENEFITS OF COMPOSTING / WHY MAKE COMPOST:
Compost has several advantages over using un-composted
organic matter and synthetic fertilizers. To begin with,
composting makes plant nutrients available over a longer
period of time. Most agronomic and soil fertility research
has focused on nitrogen, phosphorus and potash (NPK) as
plant nutrients. Studies have shown that only a small
percentage of these nutrients will ever be taken up by
plants, when readily available form, and the remaining N, P,
or K will either leach, volatilize or become immobilized.
The advantage of compost is most apparent with nitrogen.
Composting mineralizes complex nitrogen, slowly putting it
into a form that is available to higher plants. Mineralized
nitrogen is released as nitrate more slowly compared to
soluble and volatile forms. Soluble nitrate, whether
contained in nitrate-salt fertilizers or raw manure, is more
likely to leach to the ground water. A significant portion
of ammonia is lost to the atmosphere, when it is applied as
raw manure or ammonia-based fertilizers, such as urea or
anhydrous. Other nutrients, such as phosphorus, potassium
and calcium, are usually present in sufficient quantities,
but in a form un-available to plants. Research has shown
that compost can activate minerals that are ordinarily
un-available - such as rock phosphorus - can be activated by
composting. This may be accomplished by the microbial action
of a compost pile, or by acidification by humic acid. Humus
consists mostly of organic carbon groups that form exchange
sites for available essential plant nutrients. The
importance of humus and organic matter is a matter of debate
in soil science. The role in plant nutrient cycling played
by organic matter decomposition into humus and humic acid is
not well understood.
Compost also conditions the soil and builds soil structure.
Organic matter in compost lightens and aerates heavy clay
soils, while it improves soil moisture holding capacity in
sandy soils. In irrigate systems, compost serves to improve
water penetration, stores & releases water, and , with humic
acid, neutralizes alkalinity of saline water.
More over, the composting process can decompose many
contaminants found in agriculture wastes. For example, the
heat of composting process kills most plants and human
pathogens. Plant pathogens seldom survive temperature above
50 C degree (122F). In addition composting also decomposes
many pesticides. For this reason, cotton gin trash,
cottonseed meal, sugar beet, lime and mushroom compost must
either be composted or prove by testing that they have no
detected pesticide residues.
MECHANICS OF COMPOSTING:
For most growers, aerobic composting is the easiest and most
reliable method. Aerobic methods rely on organisms that
require oxygen to digest organic matter. The following steps
are recommended for compost making:
a) Collection and Preparation of Feedstock:
Raw organic matter that is being turned into compost is
called the feedstock. It is important to use a variety of
materials, since nutrient content of compost made from a
single material is unlikely to be balanced or have a carbon
to nitrogen (C: N) ratio favourable to decomposing
organisms.
The single most important ingredient in composts is animal
manure. The nutrient contents of different animal manures
vary from species to species, and analysis can vary widely
within animal type depending on diet and handling. Proper
handing of manure ensures that the most unstable major
nutrient, nitrogen, does not volatilize or leach.
Collection, handling and disposal of manure has been further
complicated by the increased concentration of the livestock
industry.
Ingredients such as straw, cotton gin trash, sawdust and
even wood chips provide a substrate for cellulolytic
(cellulose eating) micro-organisms to function. It is
important to decrease particle size, so that the surface
area for microorganisms to consume and accelerate
decomposition is increased. However, particle size should
not be so fine that it makes the material more prone to go
anaerobic. Cellulolytic and non-cellulolytic microorganisms
appear to have a symbiotic relationship with one another,
given that mixed communities of microorganisms in the lab
decompose faster than single organism communities. Finally,
minerals can be added to the pile to balance essential plant
nutrients in the compost and make relatively immobile
nutrients available.
NUTRIENT COMPOSITION OF COPOSTABLE MATERIALS IN %
Feed Stock
Nitrogen Phosphate
Potash
Blood Meal
15.00 1.30
0.70
Bone Meal
4.00
21.00
0.20
Brewer’s Grain (Wet) 0.90
0.50
0.05
Cotton Seed Meal 7.00
2.50
1.50
Cotton Gin Trash 1.32
0.45
0.36
Egg Shells
1.19 0.38
0.14
Fish Waste
6.50 3.75
--
Leaves (Apple)
1.00 0.15
0.35
Leaves (Grape)
0.45 0.10
0.35
Leaves (Oak)
0.65 0.13
0.52
Lemon Culls
0.15 0.06
0.26
Manure (Cattle) 0.29
0.17
0.10
Manure (Horse) 0.44
0.17
0.35
Manure (Poultry) 1.63
1.54
0.85
Manure (Sheep) 0.55
0.31
0.15
Milk
0.50
0.30
0.18
Orange Culls
0.20
0.13
0.21
Phosphate Rock --
28.00
--
Sugar Beet Residue 2.56
0.24
0.45
Straw (Corn)
1.11 0.18
1.33
Straw (Oat)
0.63 0.16
1.65
Straw (Rice)
0.60 0.09
1.16
Straw (Wheat) 0.67
0.07
0.97
Wood Ash
--
1.50
7.00
b) Forming Piles:
Aerobic Composting Methods require that the feedstock
receive adequate air and moisture, be able to absorb
adequate moisture, and shed excessive moisture. Different
feedstocks are layered to alternate dry and moist materials.
Dry materials should be on bottom, top and outer parts of
pile.
As the pile is turned, the compost becomes more homogeneous
and the different layers less distinct. Most commonly used
by commercial scale operations is the windrow, which is a
long, trapezoidal or semi-circular pile of between four and
six feet height and six to ten feet across. Height is
important, since a too shallow windrow will rapidly lose
heat, while one that higher will become compressed by its
own weight and create anaerobic conditions.
c) Compost Site Selection:
Any pile of organic matter will eventually rot, but a
well-chosen site can speed up the process. Look for a level,
well-drained area. If you plan to add kitchen scraps, keep
it accessible to the back door. Don't put it so far away
you'll neglect the pile. In cooler latitudes, keep the pile
in a sunny spot to trap solar heat. Look for some shelter to
protect the pile from freezing cold winds which could slow
down the decaying process. In warm, dry latitudes, shelter
the pile in a shadier spot so it doesn't dry out too
quickly.
Build the pile over soil or lawn rather than concrete or
asphalt, to take advantage of the earthworms, beneficial
microbes, and other decomposers, which will migrate up and
down as the seasons change. Uncovered soil also allows for
drainage. If tree roots are extending their roots into the
pile, turn it frequently so they can't make headway.
Look for a spot that allows you to compost discretely,
especially if you have neighboring yards in close proximity.
Aim for distance and visual barriers between the pile and
the neighbors.
d) Maintain Optimum Conditions:
The conditions most critical to compost are air, moisture
and temperature. Aerobic methods require that the pile be
turned regularly to improve air circulation. Microorganisms
require moisture in order to thrive and reproduce rapidly.
Most feedstocks contain some decomposition organism.
Introducing microorganisms can accelerate decomposition
process. Adding soil can introduce most organisms necessary
to initiate the compost process, but can reduce both carbon
and nitrogen. Cultured microorganisms are also commercially
available. The compost must be moist, but not waterlogged.
During rainy season, compost piles may need to be covered to
keep them from becoming waterlogged. Some composters also
cover their piles during the dry season to maintain
moisture. The more often a pile is turned, the faster will
be decomposition. Some methods turn the compost in14 to 21
days.
Turning every week to ten days will usually produce finished
compost in four to six weeks, depending on temperature.
e) Finished Compost:
Finished compost should cool back down to ambient air
temperatures. It should be dark and moist, with rich, earthy
smell. The texture should be fairly loose and homogeneous,
with the ingredients thoroughly decomposed.
After the pile has “Cooked” or “Roasted”, the compost can be
spread in the cropping area. Loading rates depend on
existing soil nutrient levels, soil structure being grown,
and previous crop grown. Unlike with synthetic fertilizers
or raw manure, there is little chance that compost will burn
crops.
Compost is indispensable to most organic soil building
programs, offering growers a source of balanced nutrients,
organic matter and soil conditioner.
Organic growers, who do not now use this nature soil
amendment should examine the benefits of compost and
consider introducing it to their program. It is possible to
tell, if compost is finished without any more any
complicated equipment than one’s senses.
SENSE COMPOST NOT COMPOST
Look Dark, Uniformly, Decomposed Light, un-even, with
un-decomposed pieces. Smell Earthy Ammonia (un-finished),
Putrid and rotten (Anaerobic un-finished) Feel Cool, Moist
Warm (still decomposing), Dry (un-finished, or past its
prime) or wet (anaerobic) Vermi-Composting / Composting with
Worms: Vermi-composting, or worm composting, is different
than traditional composting.
Worm composting is a process that uses red earthworms, also
commonly called red worms, to consume organic waste,
producing castings (an odor-free compost product for use as
mulch), soil conditioner, and topsoil additive. Naturally
occurring organisms, such as bacteria and millipedes, also
assist in the aerobic degradation of the organic material.
Using Compost:
Finished compost is dark brown, crumbly, and earthy-smells.
Small pieces of leaves or other ingredients may be visible.
If the compost contains many materials, which are not broken
down, it is only partly decomposed.
This product can be used as mulch, but adding partly
decomposed compost to the soil can reduce the amount of
nitrogen available to the plants. The microorganisms will
continue to do the work of decomposing, but will use soil
nitrogen for their own growth, restricting the nitrogen's
availability to plants growing nearby.
Allow partly decomposed compost particles to break down
further or separate them out before using compost on growing
plants. Or add extra nitrogen such as manure, to ensure that
growing plants will not suffer from a nitrogen deficiency.
Compost serves primarily as a soil conditioner, whether it's
spread in a layer on the soil surface or is dug in. A garden
soil regularly amended with compost is better able to hold
air and water, drains more efficiently, and contains a
nutrient reserve that plants can draw on. The amended soil
also tends to produce plants with fewer insect and disease
problems. The compost encourages a larger population of
beneficial soil microorganisms, which control harmful
microorganisms. It also fosters healthy plant growth, and
healthy plants are better able to resist pests. One inch
thick is enough to spread on farm beds. Compost continues to
decompose, so eventually the percentage of organic matter in
the soil begins to decline.
To bolster poor soil with little organic matter, spread 2 to
3 inches of compost over a newly dug surface. Then work the
compost into the top 6 inches of earth. A farm soil that has
been well mulched and amended periodically requires only
about a ½ inch layer of compost yearly to maintain its
quality.
Some people recommend late fall as a good time to spread
compost over a garden bed, and cover it with winter mulch,
such as chopped leaves. By spring, soil organisms will have
worked the compost into the soil. Others recommend spreading
compost two weeks before planting time in the spring. There
is really no wrong time to spread it. The benefits remain
the same.
If your supply of compost is really limited, consider side
dressing, a way to use compost sparingly by strategically
placing it around certain plants or along certain rows. This
is best done in late spring and early summer so that the
rapidly growing plants can derive the maximum benefit from
the compost.
To side-dress a plant, work the compost into the soil around
the plant, starting about an inch from the stem, out to the
drip line, taking care not to disturb the roots. For shallow
rooted plants, leave the compost on the soil surface.
Compost mulch can benefit trees and shrubs just as it does
other plants. Spread a ½" to 1" layer of compost on the bare
soil under the tree as far as the drip line. Then cover with
a 2-3" layer of some other kind of organic mulch, such as
chopped leaves or pine needles. The mulch will hold the
compost in place and keep it from drying out.
Adding compost to the planting hole of small perennial
plants is valuable, particularly perennial food plants.
Annuals will also benefit from a dose of compost at planting
time.
Compost is the ultimate farm fertilizer. It contains
virtually all the nutrients a living plant needs and
delivers them in a slow-release manner over a period of
years. Compost made with a wide variety of ingredients will
provide an even more nutritious meal to your growing plants.
Compost is the best material available to enliven your soil
no matter where you live.
Farmers around the world will testify that healthier soil
grows healthier plants that naturally resist disease,
insects, and other environmental pressures. Adding compost
to your farm is a long-term investment - it becomes a
permanent part of the soil structure, helping to feed future
plantings in years to come.
Warm Castings and Worm Juice:
Compost Worms produce a safe, organic alternative to
expensive chemical fertilizers. These will not burn the most
sensitive plants and being full of richness only needs to be
sparingly.
Worm Castings contain approximately:
• Five times more available…………………………………… Nitrogen
• Seven time more available………………………………….. Phosphorous
• Three times more available…………………………………. Potassium
• One & Half time more available……………………………. Calcium
.......………………………………………………….than ordinary top soil.
Worm Casting also……………. Promotes…………….. Strong root
growth…………….. Better water penetration…………..Improved soil
stability
Recommended Feeding To Plant:
a. Sprinkle 1-2 teaspoons around plants every two weeks and
water well. For larger area apply 250-litres per hectare.
b. 5 liters Worm Juice Concentrate, a rich liquid fertilizer
may be used per hectare.
Worm Juice Contains:
•
Nitrate-Phosphorous-Potassium-Magnesium-Calcium-Manganese-Zinc-Boron-Copper-Sulpher-Sodium.
COMPOST TEA:
Compost Tea describes many different preparations made using
compost as a starting material and producing a liquid
extract or in some cases a “liquid Version” of the original
compost. There are probably many recipes for compost tea and
a focus on its use for more specific applications. For
instance, when making compost tea to combat plant pathogens,
the trend is to have as much microbial diversity as
possible. When making a tea to supplement plant nutrients,
many producers are fortifying the tea with supplements
either during production or as a post-production addition.
Optimism about compost tea is high, but understanding its
limitations and having realistic expectations are necessary.
With all of the variations in compost tea production, there
are some applicable basic guidelines independent of recipe
or equipment differences.
I) Quality - From Maturity to Microorganism Content:
Compost tea is a readily available form of compost that will
impact the plant more quickly than compost mixed into the
soil. Compost quality issues, including maturity and
microorganism content, become very important for making
effective compost tea. The transformation of compost into
compost tea cannot improve on the original quality of the
compost.
Good compost has the potential to make good compost tea, if
made properly; poor compost will always make poor compost
tea. Many imperfections in the starting compost, such as
high salt concentrations, high levels of anaerobic
microorganisms and the presence of pathogens may actually be
amplified in the final compost tea. It is critical,
therefore, to use only the highest quality compost
available. It is recommended that save the lesser quality
compost for soil applications and use only the best for
compost tea production.
II) Microbial Numbers & Diversity:
Compost that is rich in microbial numbers and diversity can
result in compost tea with these same qualities. Even so,
the typical representation of microorganisms in compost tea
differs from the original compost. Some types of
microorganisms like to live attached to particulate matter
and a compost tea made using a fine mesh strainer popular
for tea destined for drip irrigation, does not let a
sufficient amount of particulate matter through to support
these microorganisms. The beneficial fungi and antinomycetes
prominent in good compost may be poorly represented in the
compost tea simply due to the necessity of straining out the
material to which they would attach due to the demands of
the irrigation system equipment. It is imperative to note
that compost tea microbiology is most impacted by oxygen
availability, nutrient availability and initial microbiology
of the compost used to make the tea.
Compost tea is analyzed for the same microbiological
parameters as compost. This includes beneficial
microorganisms including aerobic and anaerobic bacteria,
fungi, actinomycetes, pseudomonads and nitrogen fixing
bacteria, as well as pathogens such E. coli and Samonella.
There is no gain to saying that compost tea microbiology is
most influenced by oxygen availability, nutrient
availability, and the initial microbiology of the compost
used to make the tea.
III) Storage and Application Methods:
Compost Tea does not typically improve with time. For best
results, it should be used as soon as possible and should
store in shaded area with agitation and ventilation to the
tank. Long storage times will negatively impact the
diversity of microorganisms as well as the nutrients carried
by the tea for plant use.
Compost Teas are applied either to the soil or to the plant
foliage. Those applied to the soil will move into the root
zone and affect the rhizosphere of the plant. The plant as
well as the microorganisms in the soil will use nutrients
carried in the tea area. The microbes in the compost tea may
have a lot of competition with other soil microorganisms,
but have the opportunity to become a part of the soil and
rhizosphere microbial ecology.
Alternatively, compost tea applied to the plant foliage will
immediately impact the plant and there is very little room
for forgiveness from the plant, if a tea with toxic
qualities is used. A good quality compost will provided
beneficial microorganisms and nutrients to the surface of
the plant to assist the plant in disease suppression and
nutrient availability. Poor quality compost may be supplying
the plant surface with unwanted component, such as salts and
problem microorganisms. Compost tea destined for foliar
applications in particular should only be made with the
highest quality of pathogens in critical areas of the plant.
References:
1. Canadian Council of Ministers of the Environment, 1996,
Guidelines for Compost Quality.
2. B.C. Ministry of Agriculture, Fisheries and Food, 1996,
B.C. Agriculture Composting Handbook.
3. Northeast Regional Agricultural Engineering Service,
1992, On-Farm Composting Handbook.
4. H.A. Hoitink, D.Y. Yan, A.G. Stone, M.S. Krause, W.
Zhang, W.A. Dick, Natural Suppression American Nurseryman,
October 1997.
5. Chany, David E., Laurie E. Drinkwater and G. stuart
Pettygrove {Organic Soil Amendments and Fertilizers, Okland:
University of California, USA.
6. Gasser, J.K.R. Composting & other Wastes. New York,
Elsevier Applied Science Publishers, 1985
7. Vicki H. Bess, BBC Laboratories, Inc. Tempe, Arizona.
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