increase water infiltration and cut down on soil erosion
and runoff. Conservation tillage is an intermediate form
of CA since it keeps some soil cover as residue from the
previous crop. But some tillage is usually done. It developed as a management system after the “Dust Bowl” of
the 1930’s in the Mid-West areas of the USA. It was
found to reduce erosion by protecting the soil surface
from wind and rain.
Direct planting, direct drilling, plantio direto and
siembra directa
These are terms used for ZT in other countries like Australia and South America. They use special equipment
(e.g. NT drill) to plant seeds directly into crop residues
left on the soil surface without preparing a seedbed
beforehand.
Direct seeding This term is usually associated with
growing a rice crop like any other cereal crop without
producing seedlings that are then transplanted into the
main field. However, it can also be called NT or ZT if the
seed are drilled without tillage.
Organic farming
Organic agriculture does not permit the use of synthetic
chemicals to produce plant and animal products, relying instead on the management of soil organic matter
(SOM) and biological processes. In some parts of the
world, farms must be inspected and certified before
their food products can be sold as organic, indicating
that no synthetic chemicals were used in producing
them. But organic farming uses the principles of CA to
some extent and one objective similar to CA is to maintain and improve soil health. Unlike organic farming, CA
does allow farmers to apply synthetic chemical fertilizers, fungicides, pesticides and herbicides. Many farmers
rely on using these to control weed and pest problems,
particularly during the early transition years. As soil
physical, chemical and biological health improves over
time; the use of agrichemicals can be significantly reduced or, in some cases, phased out entirely.
CA is often used synonymously with ZT that is also believed to require heavy implements and large tractors.
However, CA can be used by farmers with large or small
holdings as follows:
Manual systems can include practices that build hills
(eg. The traditional Iroquois Indian “Three Sisters”
system) or basins (W.African Zai system) or use hand
held planters (jabbar planters or matracas) or planting sticks to get seed into the ground without tilling
the soil.
Animal traction systems can be as simple as making
a furrow for placement of seed and micro-placement
of nutrients to planters that can place seed and fertilizer even when residues are present.
Tractor power systems range from low horsepower,
two wheel tractor systems to large, high horsepower 4wheel or more models. They can be low co