Does organic farming improve soil structure?
Organic soil management improves soil structure by increasing soil activity, thus reducing the risk of erosion.
The build up of soil fertility is an important goal of sustainable land use. The Swiss «Ordinance relating to Impacts on the Soil» (OIS) defines a soil as fertile, if it provides a species-rich, biologically active, biotic community typical for the site, and if it has a typical soil structure and allows for undisturbed decomposition.
In early spring, distinct differences in disaggregation of soil particles and structure are visible at the soil surface. Most obvious is the difference between the bio-dynamic (left) and the conventional (mineral) (right) field trial plots.
(Photographs: Thomas Alfoeldi, FiBL)
Organic matter has a positive effect on the development and stability of soil structure. Silty and loamy soils profit from organic matter by an enhanced aggregate structure. Organic matter is adsorbed to the charged surfaces of clay minerals. The negative charge decreases with increasing particle size. Silt is very susceptible to erosion since it is not charged, but organic matter layers on the silt surface may favour aggregates with silt too.
The results of the DOK-trial show that not only prudent use of heavy machinery that may lead to soil compaction is required to maintain soil structure. Fertilization and plant protection strategies must also be designed in such a way that soil biological processes leading to a better soil structure are supported. |
