Agriculture Reference
In-Depth Information
7.2.1.3
Organic Matter
Organic matter in a soil generally counteracts any compaction. Therefore, soils that
are low in organic matter content need more cultivation. The primary cultivation
tools must go deeper. The problem is that with the intensity of cultivation the
decomposition of the organic matter too increases. Hence farmers might get into a
vicious circle: a low organic matter content induces to cultivate deeper, but this in
turn and in the long run might reduce the organic matter content even more.
The way out of this dilemma is not necessarily less cultivation, if this means
lower yields. Because lower yields might in turn mean less incorporation of organic
residues. The best solution probably is precise adaptation of cultivation needs to the
respective situation, thus preventing any superfl uous cultivation without any sacri-
fi ce in yield combined with care for organic matter in the soil by suitable residue
management. In essence, this means precise soil and crop management. Since many
fi elds do not have a uniform organic matter content and sensing the respective
organic matter situation is possible, the control of the depth of primary cultivation
via this soil property seems reasonable.
7.2.1.4
Slope
On slopes, the runoff of water deserves attention. The result of this runoff and its
effect on soil erosion is accumulation of fi nely textured soil with much organic mat-
ter in depressions to the disadvantage of hills. Hence from the outset, sloped fi elds
do not have uniform soils and need site-specifi c attention.
Site specifi c cultivation can
• either provide for improved adaptation to results of erosion that occurred in the
past or
be targeted at reducing erosion in the future.
The improved adaptation to erosion from the past is possible by controlling the
depth of cultivation according to the respective texture and organic matter content
on hills, slopes and in depressions of the fi elds.
And reducing erosion in the future can be obtained by improving the infi ltration
of water and thus decreasing the runoff. Several practices can contribute to this such
as keeping the soil surface vegetated as much as possible, leaving crop-residues at
the soil surface and fi nally - if bare soil cannot be avoided - increasing the depth of
cultivation. So whenever feasible, vegetation or its residues should be used to
improve infi ltration and to prevent erosion. Deep cultivation of bare soil as a means
for this should be regarded as an exceptional matter.
There are cases where improving the infi ltration still cannot prevent that a sub-
stantial portion of the precipitation runs off. This inevitable runoff should occur
without much soil erosion. For this, the water should be slowly channelled down-
wards via broad, saucer shaped, grassed waterways into ditches. These grassed
waterways can act as perennial runoff strips.
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