Club of bologna proceedings

Figure 9
demonstrates, how the result
s
are
effected by the physi cal structure of the straw
and by soils, which are completely di fferent. The 
straw was either chopped or ground; in addition 
to pure sand a standard garden soil was used. 
The standard garden soil is a mixture of 30% clay 
and 70 % peat. It is a very fertile soil and used 
extensively by gardeners and in glass houses. 

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50
In the pure sand chopped as well as ground
straw again gave the highest emergences when it 
was incorporated or mixed with the soil. Straw 
on top was the worst alternat
i
ve with chop ped 
straw and the second best choice with ground 
straw. As far as the
s
e
quence is concerned, this 
is in line with the data in 
Figure 8
. 
The standard garden soil always had a higher 
emergence than the pure sand under the same 
conditions. Howev
e
r, whereas incorpo rating the 
straw with pure sand was the best choice, for 
standard garden soil it was the worst a
l
ternative 
with chopped straw. This is an i
m
portant result. 
The pure sand without any o
r
ganic matter needs 
incorporating the straw into the
soil, since this 
improves the soil structure for an adaequate air to 
water supply. On the other hand, the standard 
garden soil already is high in organic matter;
incorporating the crop residues makes it too fluffy 
or downy in case the straw is only choppe d. This 
is quite in line with the experi
e
nce often
expressed by farmers. 
Grinding the straw in all cases resulted in
distinctly 
higher emergence than chopping it. This applies 
to the pure sand as well as to the
standard garden 
soil. For the combination of
ground straw and 
standard garden soil e xtremely good results 
were recorded almost independently 
of the
placement (
Fig. 9
). 
The pure sand as well as the standard garden soil 
represent ex
t
remes; they do not show the
conditions in practical farming. Therefo
r
e, the
same experiments were carried out with two
natural soils, a loamy sand and a clay loam soil 
(
Fig. 10
). Whereas results obtained with the two 
artificial soils were partly quite surprising, the
results recorded for these two natural soils were 
about in line with expect
a
tions. The order of
increasing emergence - with one exception - was 
straw incorporated, straw on the top, no straw. 
The exception occured with the loamy sand soil 
and ground straw; for this combination the
alternative in straw placemen
t
hardly did matter. 
In all cases grinding the straw instead of chopping 
it clearly improved the emergence, as it did with 
the artificial soils. 
Similar results as with rape were obtained for 
small grains with the exception, that the
differences between th
e
treatments were
somewhat smaller.
Improvements in the straw distribution over the 
area by the combines too are important. Most 
combines still distribute the chopped straw very 
unevenly over the area. The straw topic is
especially relevant for cultivatio
n
and sowing
without plowing within a short p
e
riod after late 
harvested cereals. It probably will become even 
more important, since high yielding cereals need 
a 
long growing period, which means either early
sowing or late ha rvesting, perhaps even both. It 
is 
difficult to predict at the present time, whether 
placing the straw on the top of the seedbed or 
breaking it up more during combining is a better 
alternative. So there is still need for research.