Organic farming can provide a natural barrier against flooding.
That's according to Professor Ewald Schnug and Dr Gerold Rahmann, of the Institute of Plant Nutrition and Soil Science and the Institute of Organic Farming at the Federal Agricultural Research Centre in Germany.
They point out that �organically managed soils show approximately seven times more earthworms and twice as high infiltration rates as soils on conventional farms. Employing crop rotations with forage crops (for example clover or grass) and catch crops, as well as an optimal supply of organic materials results in a higher humus content in organically managed soils.�
(picture: flooding around ennis)
These results on soil structure and infiltration rates are visible within three years, they claim.
Indeed the researchers go so far as to suggest �that substantial support of organic farms is justified to pay for a service provided by the farms to the community�, and that �support for organic farming could be an efficient measure to counteract anthropogenic soil consumption which contributes to flooding dangers�.
In the absence of synthetic fertilizers to make the plants on the surface grow faster and stronger, organic farming relies on soil building techniques such as clover stitching and composting. This, it turns out, makes the soil more able to deal with extreme weather conditions. Basically, the soil retains its elasticity.
On the other hand, with modern intensive agricultural practices, soils get compacted and loose their ability to allow water to flow, or infiltrate down deeper into the ground.
Soils are sealed or compacted when water's infiltration capacity is reduced. The main causes of this are �decreasing organic matter contents, decreasing biological activity and increasing compaction caused by high mechanic stress of soil structures� according to Schnug and Rahmann.
�Conversely, high infiltration rates of healthy soils can reduce the intensity of flood incidents�.
While conservation tillage (i.e. no plough techniques) in conventional farming helps, according to the researchers, �on organic farms a much larger number of positive factors for the development of "bio-pores" in the soil exist. Such bio-pores are the key to improved infiltration and are mainly created by earthworms.�
There is an increasing body of research into organic farming and soil structure. Hole et al 2005 conducted a literature review of 76 studies on the effect of organic farming on individual taxon, from 1981 to 2004.
In all cases organic scored better than conventional, including for all the underground taxon, such as earthworms, beetles, other arthropods and soil microbes. Plant life was also effectively positively by organic farming in 13 of the cases, with mixed results or no difference in just 2 cases. A variety of plants increases the range of depths of rooting for plants, which again aids soil structure.
Other research again (e.g. Kasperczyk and Knickel 2005) found that organic farming increases both infiltration and soil (as opposed to surface) water retention capacity.
Two long running field trials, the DOK trials in Switzerland and the Rhodale trails in the US, found similar results, in terms of organic faming preventing soil erosion and soil compaction, and coping with extreme weather conditions.
According to a 2003 peer reviewed publication on the Rhodale research, �Soils in the organic plots captured more water and retained more of it in the crop root zone than in the CNV [conventional] treatment. Water capture in the organic plots was approximately 100% higher than in CNV plots during September�s torrential rains�.
These torrential rains came after a earlier drought, where again the organic trial area coped better than the conventional one.
With the DOK trials, the organic plots not only exhibited higher soil-organism activity, but also a greater numbers and diversity of microorganism, earthworms and ground beetle species.
It appears then, that nourishing the soil rather than just the plant is the key. Synthetic fertilizers have given humanity the ability to make the grasses on the surface grow rapidly.
But what about the soil? Through a variety of techniques, organic farming not only improves soil quality, it works against the extreme weather conditions we are increasingly likely to face this century.
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