الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 139 |  |  |
| | | from | 139 | | |
Abstract
Bark is currently of the most puzzling residues problems facing
the wood conversion industries. A continuous removal of such
wastes from the production sites has therefore become necessary.
The possibility of composting fresh hard wood bark either alone
or after mixing with other organic wastes (such as town refuse,
plant residues, manures, sewage sludge .. etc) to produce
substrates - with suitable characteristics - for plant growth is
the aim of the present work.
I. Composting hard wood bark to produce substrates for growing
plants:
The aerobic composting of fresh hard wood bark has been
carried out under the following circumstances:
1. Added mineral fertilizers were ::: 1.0% N (in the forms of
NH4.N03 33.5% N, (NH4hS04 20.5% N or urea 46-48% N),
:: 0.75% P20S in the form of calcium super phosphate 15.5%
P20S and 0.5% K20 in the form K2S04 48-52% K20. Nonfertilized
treatment was also examined.
2. Moisture content during composting was adjusted twice a
week at 60% of total water holding capacity.
3. Aeration was also provided twice a week by turning over the
compost samples.
Obtained results refer to the following:
1- Fresh bark has a very low nitrogen content (:: 0.4%), a high
initial C/N ratio (120 to 130: 1) and a low content of other
components needed for plant growth besides its phytotoxic
effect. Composting process is needed to decrease the carbon
nitrogen ratio and to degrade the phytotoxic components
present in fresh bark.
2- Each kg of bark needs monthly about its weight of water
during the I st two months of compostation. Added water
-------------- --- ----
110
during the 3rd month of compostation was minimized to be
only about 100-260 g/kg bark depending on the treatment.
3- The increase in temperature ranged between 14 and 27°C
during the 1st two months of the compo sting process. After
this period and until the end of the 3rd month, temperature in
the composted bark was more or less the same as air
temperature indicating that the compostation is complete.
4- Composting process decreases the growth inhibition
characteristics of fresh bark to its minimum that can’t
adversely affect plant growth.
5- Under the conditions of conducted experiments, i.e. during
hot summer months (August and September), two months are
enough for compostation of bark.
6- Ammonium nitrate 33.5% N used as a source of nitrogen
during composting process seems to be the suitable source.
Composting fresh hard wood bark realizes the following
characteristics for the obtained media (Substrates).
1. the increase of finer particles in composted bark using
NH4N03 as a nitrogen source is obvious. Composting
treatments could be arranged according to their effect on
particle size distribution of composted bark.