Agriculture Reference
In-Depth Information
for the home and export markets. Perhaps inevitably for plants such as these legume
teas, which can grow naturally on very poor soils, there is a niche market for organic
production. Since this market tends to be relatively small volume, it is well suited to
community-based production and can be important for sustaining local developments
(Nel et al., 2007).
There are serious concerns about farming carnivorous fish such as salmon on feed
that consists largely of wild fish such as anchoveta, because of its unsustainablility.
Various grain legumes, including soybeans, peas and lupins are being considered in
Europe and elsewhere, with lupins generally being preferred. The Australian Gov-
ernment has a programme looking at lupins for all types of aquaculture, both fin
fish and shellfish, details of which can be found on http://www.fish.wa.gov.au/docs/
op/op031/fop/031.pdf. Different fish species may vary in the acceptability of different
grain legumes (Glencross et al., 2004). In warmer waters, herbivorous freshwater fish
such as Tilapia can be farmed and these can use legumes such as prunings of
Calliandra
from agroforestry as a part of their diet (J. Wilson, personal communication).
Natural dyes have been in use for millenia, but renewed interested in them for
providing local income is being shown. In Madagascar, Natal indigo, made from the
leafy shoots of
Indigofera arracta
, is being developed and is proving to be a high-quality
product, with good colour fastness in light, unusual for a blue dye (Borus, 2008).
Production of bioethanol and biodiesel for use in road and other forms of transport
is currently very newsworthy, largely because of diverting agricultural land away
from growing food crops. However,
Millettia pinnata
(pongamia) is a small tree from
India that grows profusely on land, including mangrove swamps, that is unsuitable for
crops. It fruits profusely and its seeds have a high content of oil that needs very little
processing to produce an excellent type of diesel. It nodulates well with bacteria that
can grow in pure seawater and is currently under extensive evaluation in Australia
and elswhere (Scott et al., 2008; P.M. Gresshoff, personal communication).
As well as using legumes as a source of various products, those adapted for harsh
environments could provide genetic material to be introduced into other crops, either
by conventional breeding or by genetic engineering. For example, one of the uses
suggested for
Canavalia maritima
(see Section 6.1.2) was as a source of genetic material
to confer salt resistance (Sridhar & Bhaghy, 2007). Many people in developing countries
cannot understand why Europe is so averse to using genetically modified plants.
Neither can I.
Finally, on a global scale, legumes can have a major role to play in providing ecosys-
tems services, particularly inmaintaining a sufficient supply of reduced nitrogen under
increasing atmospheric carbon dioxide (Jackson et al., 2008). As Sisti et al. (2004) point
out, if soil is to be used as a carbon store, there may be an important role for managing
legumes to optimise carbon sequestration.
