Chemistry Reference
In-Depth Information
Table 2
Place and time of production of organic matter (fallow species)
relative to crop growth and the respective advantages/disadvantages
of the mentioned organic matter production systems with respect to
soil fertility management and crop growth. 'Same place' and 'same
time' mean 'in the same place as the crop' and 'during crop growth'.
d
n
1
r
2
n
g
|
5
Place and time of
organic matter
production - example of
farming system
Advantages
Disadvantages
Same place, same time
- 'Safety-net' hypothesis
(complementary
rooting depths)
- Potential competition between
crop and fallow species
- Alley cropping
- Possible direct transfer
from N
2
fixed by
legume species
- Reduction of available crop
land
Same place, different
time
- 'Rotation' effects (N
transfer, improvement
of soil P status, etc.)
- Land out of crop production
for a certain period
- Crop residues
- In situ recycling of less
mobile nutrients
- Decomposition of organic
matter may start before crop
growth (potential losses of
mobile nutrients, e.g. N, K)
- Legume-cereal
rotation
- No competition
between fallow species
and crops
- Extra labour needed to move
organic matter (manure)
- Manure, derived
from livestock fed
from residues
collected from same
field
Different place
- Utilisation of land/
nutrients otherwise not
used
- Extra labour needed to move
organic matter
- Cut-and-carry
systems
- No competition
between fallow species
and crops
- No recycling of nutrients on
crop land
- Household waste
- Need for access to extra land
- Animal manure, not
originating from
same field
- Manure and household waste
often have low quality
legumes, such as Mucuna pruriens (L.) var utilis (Wright) Burck, were observed
to produce a similar range of biomass values (1800-8700 kg dry matter ha
21
season
21
) under similar agro-ecological conditions.
17
Major observations
related to such systems are: (i) herbaceous fallow cover cropping systems are a
technically sound system under most agro-ecological conditions, provided the
soil fertility status is not degraded below specific thresholds; (ii) as with
agroforestry systems, herbaceous legumes require immediate investments in
