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| Am told that Darwin and Franklin both wrote about the benefits of earthworms. I know of no data which suggests that cover crops per se reduce “preferential flow”. Manure injection can clearly be beneficial but that can be required under any cropping practice. Cover crops with deep tap roots are known to significantly enhance preferential flow. Agreed, not all cropland is tiled. But there are ~ 120 million acres which are and most of this is in intensive crop production. HOWEVER, the impact of preferential flow is not just about tile lines. Any time that one has preferential flow from the surface to an area below the rooted area of crop, one has the potential for problems. The problem with preferential flow is that the process totally bypasses the natural soil filtering process. Earthworms have their place – but so does plowing. The earthworm bias appears to have shifted at the academic level. Have not read about any ag extension demonstrations counting earthworms (pound a ring into the ground and saturate the soil with water) for several years now. Nor have I seen articles in the popular farm magazines. | |
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Nitrogen from decaying cornstalks
