Effects of biodynamic treatment 500 and 501 in managed vineyards in Switzerland: influences on soil, plants and grape quality
Matthias Graeme Lorimer
Abstract
In the past few years, wines produced applying the biodynamic system have received increasing attention. This system, like organic farming, eliminates the use of synthetic chemical fertilizers and pesticides, and replaces these traditional treatments with soil and plant amendments called preparations (500 applied on soil and 501 atomized on plants).
In this thesis we shall analyze whether biodynamic preparations 500 and 501 actually augment the health of soil and plants and the quanta-quality of grapes and wine. Presently, the effects of biodynamic treatments in general and on wine making are still unclear. In 2006, FIBL (Forschungsinstitut für biologischen Land- bau) with other partners carried out a 6-year study in four biodynamic farms located in two different regions of Switzerland (three grown with cv. Chasselas and one grown with cv. Riesling & Silvaner).
The experimental design provided for: 1 plot treated with a 500 preparation, 1 plot treated with a 501 preparation, 1 plot treated with a combination of 500 and 501 (Combi), 1 plot, the control plot, no treatment and exclusively organically farmed.
The object of monitoring was the chemical analysis of the soil, the analysis of the structure of aggregates in the soil, and the microbial activity. For the plant part the nutrients in leaf tissue, chlorophyll-index, phyto-alexine, disease pressure, and the weight and length of the shoots.
No differences were noticed in the chemical composition, but over the six-year period the humus percentage was reduced in the biodynamic plots (contrarily to literature), however to this respect there is thesis arguing that this fact may be due to an insufficient supply of manure. In fact in Elfingen the elements K, P increased and presented a higher increase in humus compared to the other sites. Statistical differences were noticed in higher structure of the aggregates in the Combi soil than Control, Elfingen evidenced the highest improvement. This date is relative to the measurements carried out in 2009, but was not confirmed in 2011.
As for the microbial activity, the microbial analysis show differences only in depth and position in the row, only in Elfingen there was an improvement in mi- crobial activity. In order to gather a better view and avoid environmental inter- ferences, each site was individually studied.
Significant results were obtained in the SPAD values and wood weight for the plants treated with 501, in order to gather a better view each site was individu- ally studied and the univariate ANOVA test evidenced an interaction 500x501. No differences were observed in the nutrient analyses carried out on the leaves, except for Mn, Mg and K.
Disease incidents and severity show no statistical differences except for an statis- tically interesting high presence of phyto-alexine in the leaves of plants treated with 501. Remarkable but not statistically significant the treatment with 500; the combination of the two treatments yields a higher effect in the plant’s immune system.
No statistical differences were observed in the grape harvest yield, in the quality of the must.
Wines for the period 2008-2010 were subjected to standard analysis evidenced no differences except for nearly significant lactic acid, which was higher in Combi plot wines, while malic acid was lower in Combi wines.
Wine sensorial analysis were done with a triangle test and show no differences except for Chasselas 2009.
The organoleptic sensorial blind tests evidence results only in the criteria minerality nose.