Agriculture Reference
In-Depth Information
age systems. Very little is directly eaten by humans, and that amount could easily be grown
by the Fukuoka method.
Nevertheless, it is unreasonable to suppose that farmers will change
en masse
to
something so radically different to what they are used to in the short-term. Fortunately,
there are methods now being developed which could be called a 'halfway house'. One such
method is the clover/sheep/cereal system being developed at the Institute of Grassland and
Environmental Research in Britain.
This consists of growing a wheat crop in a field which also has a permanent stand of
white clover. First the clover is established and, just before the grain crop is sown, it is
grazed hard by sheep so that it is not sufficiently vigorous to compete seriously with the
cereal. The cereal crop is sown with a machine known as a Rotaseeder, which cultivates a
series of narrow strips in the turf and places the seeds in these, leaving almost all the clover
undisturbed. The crop is harvested in the normal way with a slightly modified combine and
sheep are let in again to prepare for the next crop.
The total amount of machine power used is much less than for a conventional crop, as
one pass with a tractor replaces the three or four needed to plough, harrow and sow. Pest
infestation is also much lower than on conventionally grown crops. One reason for this is
believed to be the year-round cover the clover crop gives to insects which prey on the pests.
The clover provides the cereal crop with the nitrogen it needs.
Nitrate pollution arises when there is more soluble nitrate in the soil than can be used
by the plants growing there. A proportion of it drains to the ground water where plants can
no longer reach it. The ground water forms part of our drinking supply and, although ni-
trates are food to plants, to humans they are poison when taken in high doses. The excess
nitrate may come from artificial fertilisers, which are very soluble, or it may come from the
break-up of clover-rich grassland when it is ploughed up to make way for cereals in a ro-
tation. But growing clover and cereals simultaneously means that nitrate is never released
in greater quantities than can be used by the crop. By making the right connection between
clover and cereal, what was a pollutant becomes a useful input.
Again, considerable skill is required on the part of the farmer to maintain the balance
between clover and grain so that they complement each other rather than compete. Weed
control is more difficult than in a conventional system as many of the herbicides farmers
normally use would kill the clover, and weeding by cultivation is not an option when most
of the soil remains untilled. Skill is being substituted for some of the inputs of energy and
chemicals.
A completely different approach to grain growing is that pioneered by Wes Jackson and
his co-workers at the Land Institute in Kansas, USA. Horrified by the massive soil erosion
on farmland in North America and inspired by the prairie, the natural vegetation in that part
of the world, they have been working towards a 'polyculture of herbaceous perennials' for
grain production.
