Club of bologna proceedings

Soil tillage: methods and
 
technologies to mee
t
 
agronomic
 
requirements 
by 
Luigi Cavazza
ITALY 
1. Introduction 
Theophrastus wrote that season, not soil is
responsible for yield ("
a
nnus fructificat
, 
n
on 
tellus
"). We shall not enter into a discussion on 
this point; it is a fact, however, that since th
e
dawn of neolithic agriculture soil has been the 
plant environment subsystem on which the farmer 
can intervene more eff iciently to affect yields at 
field level. 
Soil tillage was considered one of the most
important practices by most ancient writers on
agriculture (Esiodus, Virgil, Columella) and also 
through the following centuries. In the 1800's it 
gained increasing scientific 
in
terest, initially
centred on aspects of
m 
echanical power and
machinery and some i
n
novations in soil loosening 
techniques (e.g. iron cast mouldboard ploughing). 
A brief but accurate summary of the main steps 
of the proposals and evolution in this field up to 
the present day was given [1]. 
Until the first half of the 20th century atte
n
tion 
was essentially paid to the agronomic, mecha
n
ical 
and economic performance of tillage under the 
farmer's point of view. In succeeding decades the 
attention of researc
he
rs moved from energy
consumption prolems [2; 3] to the wider
aspects of enviromental protection and soil
fertility conservtion wi thin the framework of
sustainable land use [4; 5; 6; 7; 8].
Little by little the traditional dogmatic pre
f
erence 
for soil inversion ploughing wavered, and the
pro's and con's of this and its alte
r
natives were 
brought into discussion.
A
dvantages and
drawbacks of burying crop residues or their use 
for mulching were d ebated and problems of soil 
compaction not only as ploughpan but even more 
so coming from wheeled traffic were tackled,
trying to find new solutions [9; 10].
In a number of valuable review papers 
c
oncern is 
evident for adaptation of the many proposed and 
tested techniques to different climates, soil types, 
crops and crop systems [6; 8; 11]. This effort, as 
well as the still open debate on the subject [12] 
demonstrates the extreme complexity of the
argument. The real clue to the problem is that 
while the 
i
nvention of valuable implements for 
tilling the soil can rely on a well
-
prepared and 
qualified rank of engineers, the multifaceted
agronomic objective is rather fuzzy, changing in 
space and time, ex
p
osed to uncertain climatic 
variations and merging with a number of other 
factors in farmer's decisions. 
The number of experiments on soil tillage
increased exponentially during the past ce
n
tury 
although they are still fewer than those involved in 
other agronomic problems, like soil fertilization. 
This is mainly due to the cost and complexity of 
both the implement ation of this kind of trial and 
the evaluation and interpretation of the results
based on a number of processes and parameters 
of the system. 
In any case, up to now a wide pool of
knowledge has been accumulated on the
response of the agronomic system to the many 
alternatives proposed to traditional ploughing in 
different environmental conditions. The debate
doesn't seem to be concluded and the ques
ti
on
is: 
where are we now, then? At this point let us 
return to the very start of the whole conceptual 
problem.