Ithaka Institute - Agriculture

Georgette - 2nd Vineyard Field Trial

In 2011 we set-up a new extended biochar field trial on a 1000 m2 Pinot Noir vineyard with five replications. The amendments of biochar alone (8 t ha^-1, produced from wood at 500 °C), aerobic compost (55 t ha^-1) and biochar-compost (8 t ha^-1+ 55 t ha^-1, mixed before the composting process) were compared to a control soil which did not receive amendments. During the years 2011, 2012 and 2013 various vine and green cover growth, vine health and grape quality parameters were monitored.

Contrary to our initial impressions from our first biochar field trial in a vineyard, the new biochar trial and biochar-compost treatments induced only small, economically irrelevant and mostly non-significant effects over a three year period. We concluded that topsoil application of higher amounts of biochar has no immediate economic value for vine growing in poor fertility, alkaline, temperate soil. However, the biochar application had no negative effects. Therefore, the application of biochar might become a suitable tool to improve ecosystem services and to decrease the environmental impact of pesticides, heavy metals (especially the widely used copper, in particular in organic viticulture), herbicides, and chemical fertilizers. Results of the first year can be found in the Ithaka Journal: Biochar in European Viticulture. The complete results are accepted and will be published in the Journal for Agriculture, Ecosystem and Environment.

We are still not sure and rather puzzled why none of the treatments showed any significant longer term effects. The compost and biochar-compost that both proved highly fertile in a wide variety of pod trials should have induced at least some effects on the vines and the green cover between the vines. It should be noted that the vineyard where the trial took place had been cultivated using conventional agriculture techniques until the start of the experiment when it was changed to organic cultivation methods which later included the installation of a permanent green cover. Previously the soil was uncovered, treated with herbicides and high doses of chemical pesticides and mineral fertilizers. We hypothesize that the effect of the newly installed green cover resulted in a biological activation of the soil (microbial growth, mobilisation of soil organic mater and minerals) that might overlay all effects of the biochar and compost substrates. Further soil measurements and analysis of the on-going field experiment (especially C and nutrient dynamics and metagenomics) might help to understand the reason behind the missing effects of biochar and compost in this trial.

We further hypothesize that it could be advantageous to incorporate (nutritionally enhanced) biochar or biochar-substrates in trenches of 30 to 50 cm on one or both sides of the vines instead of applying the substrates homogenously over the entire surface of the plots. Higher concentrations of biochar or biochar containing substrate closer to the main roots of the vines could increase their effect on the vines, creating spots with higher water retention and nutrient concentration. Several new trials with varied application techniques closer to the vine root system were set-up in new-planted vines and also older vineyards since 2012.

Biochar experimental site at the Ithaka Institute in Valais (June 2011). After dispersing the substrates, seeds of low-growth vegetation were sown.