Conservation tillage has mixed results for soil health in organic systems

Photo credit: United Soybean Board

Organic farmers rely on tillage to combat weeds in place of herbicides, incorporate organic matter into the soil and reduce soil compaction. However, there is growing interest in ways to reduce tillage intensity and depth in organic production. A recent paper published in the journal Soil and Tillage Research aimed to determine how different tillage treatments in organic farming affected soil fertility in an 11-year experiment. Tillage treatments at depths of 30 cm (traditional moldboard plowing), 18 cm (shallow moldboard plowing), 15 cm (superficial plowing with chisel), and 5-7 cm (very superficial plowing with chisel) were compared to determine the effects on physical, chemical and biological soil properties. They found that superficial and very superficial plowing treatments increased organic carbon, total nitrogen and available phosphorus in the top 15 cm of soil. However, soil compaction also increased significantly. Earthworm biomass and abundance were also higher in the deep tillage treatments than the superficial treatments. No difference in wheat yield was found among treatments. In conclusion, the study found that conservation tillage treatments had positive effects on soil chemical components in the upper soil layer, but no significant effect on the physical and biotic soil properties.