The
Paradigm of Tillage
Is soil tillage necessary to grow a
crop?
Regarding the overall
fertility including soil structure Virgin soils are usually more fertile than the soils
after decades of cultivation.
Nature shows that plant
growth is possible without any soil tillage; otherwise all virgin lands would be deserts.
There is scientific evidence
that water infiltration is highest on not disturbed soils (not tilled soils).
Explanation:
In a long term scenario of an
undisturbed soil the accumulation of a ground mulch cover protects and feeds intensive
soil life which then provides a stable and favourable soil structure and sufficient
continuous deep reaching macro-pores for improved water infiltration. This process can be
called biological tillage. It is building up as mechanical tillage is reduced and it is
decreasing with increasing mechanical tillage.
Why did mankind till in the first
place?
First agricultural
intervention was a kind of no-till within a slash and burn agriculture using a planting
stick to make a hole for the seed.
As agriculture became more
intensive the technologies available allowed only a clean tillage approach to large scale
farming.
In moderate climatic zones
the detrimental effects of tillage were not as pronounced as in the tropics.
Tillage produced an aeration
and thus a mineralization of the virgin soils, rich in organic matter. Due to this the
yield was proportional to the intensity of tillage. From that time origins the misbelieve
that tillage increases soil fertility.
Intensive tillage is mining
soil organic matter. While the fertilizer function of soil organic matter was taken over
by mineral fertilizer, the soil structuring function had to be taken over by more
intensive tillage. This mechanical soil structuring does not last very long and calls for
ever increasing tillage efforts which over the years decreases the amount of soil organic
matter and aggravates the problem. Tractor power required for tillage operation in
conventional tillage has been steadily rising.
Consequence:
On most agricultural soils it
is impossible to grow a crop without tillage because of a general soil degradation process
Farmers and the general
public cannot imagine to grow a crop without tillage
Soil tillage is understood as
a purely mechanical problem.
|