Pits compost A Presentation By Mr.Allah Dad khan Former DG Agri Extension Khyber Pakhtunkhwa Province

2. Pits /underground/
trench Method of
Composting
By
Allah Dad Khan

4. Pit composting
• For pit composting, holes or trenches are dug to bury
your waste. After that, you sit back and forget about it,
while the organic materials gradually break down over
a period of six months to a year. This method is
effective for those who want their decomposing
organic matter to be completely out of sight. The
trench is also a good place to stick those weedy plants
you have pulled up. If buried deep enough, the weed
seeds will not see the light of day, so they won’t
resprout

5. Why is compost important?
• Compost is important because it:
1. Contains the main plant nutrients – nitrogen (N),
phosphorus (P) and potassium (K),
2. often written as NPK;
3. Improves the organic matter in the soil by
providing humus;
4. Helps the soil hold both water and air for plants;
and
5. Makes trace elements or micronutrients
available to plants.

6. What is needed to make compost?
• Plant materials, both dry and green
1.Weeds, grasses and any other plant materials cut from inside and around
fields, in clearing paths, in weeding, etc.
2. Wastes from cleaning grain, cooking and cleaning the house and
compound,making food and different drinks, particularly coffee, tea,
home-made beer, etc.
3. Crop residues: stems, leaves, straw and chaff1
of all field crops – both big and small – cereals, pulses, oil crops, horticultural
crops and spices, from threshing grounds and from fields after harvesting.
4. Garden wastes – old leaves, dead flowers, hedge trimmings, grass cuttings,
etc.
5. Dry grass, hay and straw left over from feeding and bedding animals.
Animal bedding is very useful because it has been mixed with the urine
and droppings of the animals.

7. Pit Compost
• If you live in a place where digging holes in the
ground is no big deal, you can make a
pit compost. The following info helps you add
anaerobic composting to your repertoire.
Good choices for your pit compost include
areas where you want to add a future garden
bed or between rows of existing garden beds.
Avoid marshy areas or low spots with wet soil
or poor drainage.

8. Pit Compost contd
• Stay away from existing root systems when
digging composting holes. Tree and shrub
roots easily expand to twice the diameter of
their aboveground canopy! Slicing through
roots with a shovel creates easy wounds for
pests and diseases to enter, ultimately
weakening and possibly killing your plant. If
you're unsure how far roots may have spread,
stick to digging compost trenches in garden
beds.

9. Pit Compost contd
• Depending upon what you want to achieve,
you can employ several different methods of
pit or trench composting, such as digging
random holes, filling trench rows in garden
beds, or rotating trenches over a three-year
period to improve an expanded planting area.
Use the basic anaerobic trench compost
recipe that follows for whichever method you
choose.

10. Pit Compost contd
• How deep and wide to dig depends on how
much organic matter you have to compost,
what kind of material it is (landscape waste
versus kitchen waste), how easy it is to dig,
and whether digging pests might be an issue.

12. Steps For Compost
Follow these steps to create a pit compost.
1. Dig the hole or trench, reserving the soil that you
remove.
2. Start with browns on the bottom, alternate layers of
brown and green materials, moistening as you build.
3. Spread a 1-inch (2.5-centimeter) layer of your
reserved soil between layers of browns and greens.
4. Cover with 4 to 8 inches (10 to 20 centimeters) of
soil. If you plan to retrieve the compost later, mark
the area with a stone or other reminder.

13. Steps contd
1. Dig the hole for your compost pit. Your
compost hole should be about 1 foot (30 cm)
deep. The area of the hole will be determined
by the amount of organic matter you want to
add. Keep in mind that the compost will be
finely chopped and piled to a height of 4
inches (10 cm) in the bottom of the hole when
estimating the hole's size.

14. Steps contd

15. Steps contd
2. Chop your composting materials
finely. Underground composting proceeds
more slowly than above ground setups, and
maximizing the surface area of your scraps is
key to speeding the process. Kitchen scraps
can be ripped apart by hand, chopped with a
knife, or even pulverized in a food processor.
Yard scraps can be broken down using a lawn
mower. Aim for pieces no bigger than 2 or 3
inches (5 - 8 cm) in any dimension.

16. Steps contd
3. Add the organic materials to the compost
pit. Pile your food scraps and yard waste into
the hole you dug to a depth of about 4 inches
(10 cm). Make sure your carbon-rich materials
(such as paper and dried leaves) are mixed
thoroughly with your nitrogen-rich materials
(like vegetable scraps and fresh grass
clippings), as you will not be turning the
underground pile.

17. Steps contd
4. Place a board over the hole if you plan to
add more scraps. If you want to be able to
continually add scraps to the compost pit,
cover the compost with a thin layer of soil or
carbon-rich material. Then place a wooden
board over the hole to prevent anyone from
tripping into it. Be careful not to add materials
to a depth of more than 4 inches (10 cm), as
this will make it difficult to adequately cover
the compost with soil later.

18. Steps contd
5.Cover your compost with soil. Once you
have finished adding your organic scraps to
the compost pit, you can backfill it with the
soil you removed. Add the soil on top of the
compost, filling the pit until it is again level
with the surrounding soil. Recover with sod or
seed with grass if desired.

19. Steps contd
6. Keep the compost pit wet while it is
decomposing. Underground compost
decomposes slowly, because it doesn't have
access to as much fresh oxygen as above ground
piles. To speed the process, ensure the area stays
fairly wet. During dry weather, soak the ground
above the compost pit with a garden hose.
Inadequate moisture will prohibit microbes from
breaking down your scraps. If the area is kept
sufficiently moist, underground compost should
be fully decomposed in about a year.

20. Steps contd
7. Sow plants above the compost after it has
decomposed. A major benefit of underground
composting is that you don't have to perform any extra
steps to harvest the compost and amend your soil. The
work is done for you, as the decomposed scraps will
work themselves into the soil naturally. The best way to
take advantage of this benefit is to plant your plants
directly over the area where you composted your
scraps. In fact, each season you can cycle the locations
where you grow plants and compost; this will ensure
your plants' soil is always freshly amended with organic
matter

21. Points to remember when making compost in a
pit
 1. This is good anytime of the year where moisture is limiting, and is the best way
to make compost after the rains have finished and during the dry season.
 2. Prepare and dig the pit, or better still, a series of three pits, when the land is
moist
 and easier to dig, and/or when there is a gap between other farming activities.
 3. If possible, make the compost immediately at the end of the rainy season while
there are plenty of green and moist plant materials.
 4. In the dry season, make the pit near a place where water can be added, e.g.
next
 to the home compound where waste water and urine can be thrown on the
compost materials, or near a water point, e.g. a pond, or near a stream where
animals come to drink.
 5. Mark the place of the pit with a ring of stones or a small fence so people and
animals do not fall into it accidentally

22. Selecting and preparing the site
1. It should be in a place that is easy to take the
materials,including water and urine, to the pit as well
as for watching and follow-up.
2. The site should be protected from strong sunlight and
wind. It can thus be, for example, in the shade of a
tree, or on the west or north side of a building or wall.
3. The pit should be marked or have a ring of stones or a
fence of branches around it so that people and animals
do not fall into it.
4. The site should be protected and away from where
floods can come

23. Digging the pit
1. The minimum size of a pit should be:
I. }1 metre deep (pits should NOT be deeper than 1 metre)
II. }1–2 metres wide
III. }1–2 metres long
2. If a farmer and his/her family, or urban household, can collect more compost
making materials, the pit can be made longer, but NOT either wider
or deeper.
3. If a pit is deeper than 1 metre, the material at the bottom does not get decomposed
because many of the micro-organisms cannot live so deep down as the oxygen
they need will not reach them.
4. Before any materials are put into the pit, the sides and bottom should be checked
to make sure no water is leaking into the pit.
5. The bottom and sides should be plastered with a mixture of fresh animal dung
and water, or top soil and water, to seal the surface so that the moisture in the
compost materials is kept in the pit.

24. Filling the pit
The foundation layer
1. Dry plant materials, e.g. strong straw, stalks of maize and sorghum or tall grasses,
as well as rose and hedge clippings from gardens, are used for the foundation. These
need to be crushed or chopped or broken into short lengths (about 10–15 cm). If
possible, let the domestic animals walk over them and sleep on them for one or
two nights so the materials get broken up and mixed with urine and dung.
2. Spread the materials evenly over the bottom of the pit to make a layer 15–25 cm
thick. Then sprinkle/scatter water evenly so that the materials are moist, but
not wet.
3. This is a very important layer in making compost in a pit as it makes sure that
air can circulate to the bottom.
4. Cover the foundation layer with large leaves, e.g. those of pumpkin, banana,
fig leaves etc., and/or plastic to keep the material moist

25. Putting the other layers into the pit
1. Each week, collect materials and put them in a container such as an old
jerry
can or pile them next to the compost pit. Mix the fresh moist materials with
dry ones. These materials can come from spoiled animal feed, old animal
bedding, from cleaning the house and compound, preparing vegetables for
food, clearing paths, weeding, stems and leaves after harvesting vegetables,
damaged fruits and vegetables, etc.
2. If the farmer has a biogas digester, the bioslurry can be collected also to be
mixed with the other materials. The bioslurry is an excellent compost making
aid.
3. At the end of a week, remove the large leaves or plastic covering the top of
The foundation layer so they can be used again, or leave the leaves to
become part of the compost if they are too damaged to be used again

26. Putting the other layers into the pit
contd
4. Make a mixture of compost making aids like good soil, manure and/or some
ashes as a fine powder. Mix these with the dry plant material, or with the mixture
of dry and moist plant material.
5. Add the prepared composting materials in layers. Each layer is 15–25 cm thick
at the edge and a bit thicker in the middle so that the heap becomes domeshaped
6. Cover each of the layers with a thin layer of soil and/or big leaves like those from
banana or pumpkin or fig trees so that the composting materials do not dry out.
7. Repeat this process each week, or whenever there are enough materials collected
to make one or two new layers, until the pit is full. Make the centre of the layers in the
pit higher than the sides so that the top has a dome shape.
8. Put a ventilation and/or testing stick into the middle of the pit.

27. Making the covering layer
The pit full of composting materials needs to be
protected
from drying out, and also from animals disturbing it.
1. The covering layer should be made of mud plaster, with
or without cow dung, with only the ventilation stick
coming out of the top. It is then covered with wide
leaves of pumpkin, banana, fig trees, etc. or plastic can
also be used to protect the top of the pit. The leaves or
plastic:
i. Prevent rainwater from getting inside the pit; and
ii. Help keep heat inside the pit.

28. Making the covering layer contd
2. The compost pit can be left untouched until there is mature compost inside it,
or it can be turned over and checked for the progress in decomposition. The
top of the pit will sink down as the compost materials get decomposed. However,
if the compost is turned over, it will lose moisture. So, it is best only to turn
compost over if there is enough water and/or urine to make it moist again while
it is being turned over.
3. The process for turning over the compost from the pit is the same as that
described for the Indore pit method. In a warm climate, mature compost can be made
in three to four months. In colder climates, decomposition can take six months or a
year.
4. The mature compost can be left covered and stored in the pit until it is needed
for adding to the soil.

29. Trench Composting
This is the simplest way for composting
kitchen scraps. Dig a one-foot-deep
hole. Chop and mix the food wastes into the
soil then cover with at least 8 inches of
additional soil. Depending on soil
temperature, the supply of microorganisms in
the soil and the content of the materials,
decomposition will occur in one month to one
year.

30. Trench Composting contd
Food waste burial can be done randomly in
unused areas of the garden or in an organized
system. One system is to bury scraps in holes
dug around the drip line of tress or shrubs. An
English system, know as pit or trench
composting, maintains a three season rotation
or soil incorporation and growing. Sometimes
this is also called Vertical composting. Divide
garden space into 3’ wide rows.

31. Year 1 – Dig a 1’ foot wide trench on the left hand 1/3 of the 3’
area (A). Add compostable materials in this trench and cover
with soil when half an inch full. Leave the center 1’ section
open for a path (B), and plant your crop in the remaining
1’ strip along the right side (C)

32. Year 2 – Section A is a path for year 2 allowing time for the
Materials to break down. Plant your crop in section B. Section
C, where you planted last year, becomes the compost trench.

33. Year 3 – Section A is now ready for planting. Section
B is your trench for composting. Section C is in the
second year of composting is it will be the path.