Club of bologna proceedings

 

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72
Tullberg’s measurements [6] similarly suggested 
that for a single loosening oper
a
tion, only two 
thirds of the power of the tractor would be
needed to do the same job if wheel compaction 
were avoided. 
Yield loss and structural degradation as a r
e
sult 
of compaction are illustrated in 
Ta
bles 5 and 6
.
Table 5
shows that in the sub
-
tropics, the highly 
variable nature and intesity of rainfall make
maintenance of soil structure of considerable
importance. Cro
p
ping without traffic reduced
run-off by around 30% and increased yields by 
around 18%. 
In the UK, no
n-
trafficked soil was found to drain 
more freely and to contain more ma cropores than 
where it had 
b 
een compacted by conventional 
practice [7]. Improved drainage was almost
certainly the reason for the 
i 
ncreased yields
shown in
Table
 6 
 
. Over four harvests, the
average cereal crop yields on non
-
trafficked soil 
were increased by 15% compared with random 
traffic. 
Evidence of environmental damage due to over
-
compaction has been widely reported [1; 7; 8; 9; 
10; 11]. Increasing tillage energy increased the 
destabilisation of soil, but that soil organic matter 
gave some protection against this process [12]. It 
is therefore vital that we minimise losses of
organic matter in particular, and that we design 
our soil ma nagement and cultivation operations 
appropriately and efficiently and with due regard 
to the negative effects of soil compaction.
 
4.2. Cultivation and crop establishment