A unique research project: comparison of three agricultural systems

For the past 40 years the DOK field trial, unique in the world, has been underway at Therwil in the Basel region, comparing biodynamic, organic and conventional agricultural practices. These trials are not conducted in laboratories but in the open, under real conditions.

Pure and natural. Horn silica preparation is applied.

In one small pile of earth there are as many living entities as human beings on the planet: they teem, nibble, devour and digest, and as they do so release nutrients for plants, form tilth, keep the soil fertile, and protect it from erosion by water and wind. Their presence and their activities are vital in order for the soil to provide a sound basis for healthy plants that nourish both animals and people.

Humans intervene in the natural ecosystem

Humus, created over millennia through the breakdown of plant matter, is a thin, dark stratum, like a skin, that envelops our earth. On this skin depends the growth of soil biota but also the plants in our pastures and fields.

Since ceasing to be nomadic, around 8000 years ago, and beginning to farm the land, human beings have intervened in this natural weft. Modern intensive farming, with chemical fertilizers and pesticides, and heavy machinery, has a destructive impact on our soils. Across the globe, around 35% of farmland fertility has already been lost. In Switzerland, thanks to well-trained farmers and a sophisticated subsidy system, the soil is less intensively exploited. Nevertheless, organic, and especially biodynamic fields have a higher humus content, more vitality, are home to more species and release fewer greenhouse gases into the atmosphere. In addition, they make more efficient use of energy and nutrients.

Globally unique long-term study 

The major findings of the 40-year study in Therwil, near Basel, run by the Research Institute for Organic Agriculture (FiBL) together with the government research institute Agroscope, have attracted great attention worldwide. The Therwil trial, known as DOK (biodynamic = D, organic = O, conventional = K) has subjected organic, biodynamic and conventional forms of agriculture to scientifically controlled comparison. 

“100% less toxic substances.”

The crops cultivated are maize, winter wheat, potatoes, grass-clover leys and soya. In the biodynamic model, soils are treated with composted manure and biodynamic preparations, in the organic method fresher manure is applied, and in the conventional system chemical fertilizers are used, sometimes in combination with manure. No pesticides whatever are used in the biodynamic model, whereas in the organic model potatoes are sprayed with copper to protect against disease. Colorado beetle is combated by organic means in both organic models. Over the years, therefore, 100% fewer toxic substances were sprayed in the biodynamic than the conventional system, and 95% fewer in the organic system. This not only affects the insect world but is relevant to production of pesticide-free food and the maintaining of clean drinking water.

Better soil structure, more humus and more active soil life in organic agriculture

Especially after heavy rain, visitors to the field trials are struck by the visibly better soil structure of organic plots treated with manure and slurry but no chemical pesticides.

Numerous worm holes in the organic plots conduct rain water into the soil, making it much less muddy. Bacteria, fungi and unicellular organisms likewise fare better in the organic plots, and greater diversity of microbial life ensures that nutrient cycles are well sustained even during periods of drought stress.

Not just more soil life but more plant species

The diversity of root-symbiotic fungi as well as beneficial ground beetles is enhanced in the organic model. But it is interesting that the diversity of beneficial weeds is also raised, alongside that of soil biota. 30% and 60% more soil biota are found, respectively, on the organically and biodynamically managed plots than on the conventionally cultivated plots.

In two large-scale literature reviews, FiBL evaluated all available studies worldwide on humus content and bio-activity: organic soils contain 3.2 tonnes more humus per hectare and have up to 84% more bio-activity (published in PNAS and PlosOne). This shows that the findings of the DOK trial have been very well replicated elsewhere.

Complete avoidance of chemical pesticides

On our tour of the field trial we also note that the conventionally cultivated potato plants are much more abundant than the organically grown ones. There is good reason for this. The conventional potatoes receive on average twice as much fertilizer, and are sprayed 12 times against weeds, fungi and insects. This also results in a markedly higher yield. The organic wheat stands very well and is somewhat longer because it has not been intensively sprayed with chemicals (growth regulators, chlorocholine chloride - CCC). 

Better nutrient and energy efficiency in the organic model

In terms of yield, therefore, the conventional system comes out on top. But the organic methods still produce around 80% of conventional yields with around 50% less application of fertilizer and energy. In other words, organic systems are a more efficient method, and at the same time environmentally-friendly. Potato yields under organic cultivation, with copper spraying, are around 15% higher than in the biodynamic system (which prohibits copper use), but biodynamic wheat yields have been around one tonne per hectare higher (+20%) than organic over the last 14 years. This increased yield can no doubt be explained by the better soil structure and greater bio-activity in the biodynamic system, as well as by the use of adapted breeds of wheat developed by the Peter Kunz association.

“Biodiversity markedly higher also in beneficial weeds”

Organic agriculture produces fewer greenhouse gases 

Our long-term field readings have shown that the organic and the biodynamic plots produce, respectively, 30% and 60% less of the harmful greenhouse gas nitrous oxide (N2O). This is due partly to the reduced use of nitrogen in biosystems, but also to the better soil structure, and to the microbial communities that can convert nitrous oxide into a harmless, elementary form of nitrogen. Together with raised humus contents, the biodynamic system is shown in these studies to be the most climate-friendly form of agriculture.

The DOK trial as a national and international research platform

Where do we go from here? The DOK trial initiated by pioneers of biodynamic and organic agriculture is today one of the most important national and international agricultural and environmental research platforms. Its basic funding is provided by the Swiss Ministry of Agriculture. The department for Education, Research and Innovation recently included the DOK trial in its list of important national research infrastructures. For the past forty years, farmers and scientists have been collaborating within DOK, together formulating important principles for political and social decision makers.

So far, over 120 scientific publications have appeared arising from projects supported by the Swiss Nationalfond, the European Union and other national and international funders. The DOK trial also serves as a model for numerous systems-comparison studies in European countries and in southern countries outside Europe. It is continually adapted in line with the latest developments, and the most topical research issues are studied by highly regarded institutes both here and abroad.

Paul Mäder
PhD, agrobiologist, ETH, FiBl

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