Agriculture Reference
In-Depth Information
After nine to ten days the decomposing organic
matter is made into the hot bed at the site where
plants are to be grown. The material in the heap is
forked into a layer about 10 cm deep and tamped
down. This is repeated with further layers to a depth
of 20 cm or more. This can all be done within a brick
construction on which 'lights' can be placed like a 'cold
frame'. Alternatively, a free-standing frame can be put
on top of the block created. The size of the frame is
usually made to be a multiple of the 'lights' being used
(see Figure 11.6). Traditionally heat was retained by
earthing up the sides, but modern materials such as
polystyrene can be used to line the frame. The 'lights'
are put on but kept open for ventilation.
In less than a day the material starts to heat up
significantly. This can be tested with a thermometer
or, more crudely, with a cane pushed into the centre
of the block and tested by hand. Temperature
should be monitored over the next three days when
the maximum is usually achieved. As soon as the
temperature begins to drop, a 15 cm layer of moist
soil is put on top and is ready to use. Once seeds or
plants are in place, the temperature is controlled by
opening and closing the 'lights' in the same way as
growing in cold frames. The heat provided from the
decomposition process will last until the days warm
up in the spring and growing in the frame can continue
until the autumn when the well-rotted manure can be
used as a mulch or dug in to the soil.
X
Use gloves to protect against the irritants produced
by the leaves of both these plants.
X
Chop up leaves.
X
Pack tightly into a container with a lid (this is
to contain the smell which develops as leaves
decompose).
X
Keep warm (e.g. in the sun; a black container
absorbs heat well).
X
Mix daily (i.e. aerate), foaming indicates leaves are
decomposing.
X
When foaming stops (after about a fortnight) draw
off liquid (stock).
X
Dilute the stock liquid 1:10 for use as a potassium
rich liquid feed (see p. 167).
13
Bulky organic matter
Bulky organic matter is an important means of
maintaining organic matter and humus levels in the
soil and includes:
X
farmyard manure
X
garden compost
X
composted municipal waste
X
spent mushroom compost
X
leaf mould
X
chipped bark
X
green manures.
These materials also 'open up' the soil, that is,
improve aeration (see soil structure p. 000). The main
problem is obtaining cheap enough sources because
their bulk makes transport and handling a major part
of the cost. They can be evaluated on the basis of
their effect on the physical properties of soil and their
(small) nutrient content.
Organic fertilizers and compost teas
Most organic fertilizers are of animal origin - for
example, blood meal, hoof and horn, bone meal.
However, concentrated sources of nutrients can be
produced from plant material. They are particularly
useful as a liquid feed (see p. 171) and can be made
from a wide range of plants including compost,
comfrey, nettles, borage, clover and bracken. More
biologically active 'teas' can be made from these by
steeping in oxygenated water. Further details can be
found on the companion website: www.routledge.
com/cw/adams.
Using comfrey is particularly attractive to organic
growers as it is deep rooted and able to extract
nutrients below that of most plants. These deep roots
also make it difficult to get rid of so choosing it to put
in a garden needs to be thought through. The leaves
are harvested to produce a nutrient-rich plant food.
There are many different methods of making the
liquid feed from comfrey and other plants, all of which
should be diluted before use. Both comfrey and nettle
leaves can be used to in the following way:
Farmyard manure
This is the traditional material used to maintain and
improve soil fertility. It consists of straw, or other
bedding, mixed with animal faeces and urine that
provides the nitrogen that offsets the problem of using
straw alone. The exact value of this material in nutrient
terms depends on the proportions of the ingredients,
the degree of decomposition and the method of
storage. Samples vary considerably. Much of the
manure is rotted down in the first growing season but
almost half survives for another year, and half of that
goes on to a third season, and so on. A full range of
nutrients is released into the soil and the addition of the
major nutrients should be allowed for when calculating
fertilizer requirements. The continued release of large
quantities of nitrogen can be a problem, especially on
unplanted ground in the autumn, when the nitrates
