To investigate the possibilities for effective soil tillage, that could imply lower costs,
lower negative environmental impact and in addition a meaningful occupation for foraging pigs, a field experiment was carried out in Gränna, Småland, during growing season 2006.
The experiment contained two treatments that were repeated three times and were carried
out on a couch grass-infected fallow on a light soil close to Sweden’s second largest lake, Vättern. Ploughing was one treatment and pig rooting followed by ploughing, was the
other. The experiment was conducted according to the guidelines of organic growing and
seedbed preparation was done the same way in the two treatments. The pigs, three groups
of five half-year old Linderödssvin (an old Swedish breed), was encouraged to perform
an even tillage by strip-grazing, i.e. they were allowed the land area piece by piece, in
this case the plot was divided up into five small plots.
The judgment of the results was based on three parameters: the amount of weed before
and after tillage, the quality of seedbed, and yield of succeeding crop. Except the
comparison of the two treatments, the five small plots in the pig tilled area was judged by above mentioned parameters in relation to the duration of the pig tillage and also the soil moisture content at the time the pigs were allotted each small plot.
Results showed that pig treatment was significantly better for reducing couch grass than
the ploughed treatment, but on the other hand the seed weed increased more after pig
tillage. Results also showed that the seedbed contained a larger part large soil aggregates and had a dryer seedbed bottom than was the case in ploughed treatment. Other results showed that pig tilled treatment had a significantly more numerous plant population and better yield than ploughed treatment. There weren’t any significant results from the comparison of the pig-tilled small plots. No connection between soil moist content and pig rooting were found in the data.
The pigs proved to be effective for couch grass fighting, but exposed the soil to
compaction, which could be a consequence of leaving them too long at the plot. The
compacted soil dried out quicker than the soil in ploughed treatment, which had looser
topsoil to prevent evaporation, also the compacted soil after ploughing gave arise to big
soil aggregates. The seedbed quality was therefore worse in pig-tilled treatment than in
ploughed. Yield wasn’t good in either treatment, which is important to consider while
studying the results, but in this case it seemed like the couch grass reduction was more
important to the yield than the differences in s...
