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Research Conducted
We evaluated chisel plow, shallow vertical till, strip till (shank), and strip till (coulter) systems in a 4-year study for:
1. Soil warming/drying
2. Crop stands and yields
3. Soil health
Four on-farm sites in corn-soybean rotations were used with full-sized equipment on soils representing >67 million acres in the region.
Why the research is important to ND soybean farmers
This on-farm research is to help farmers be more informed with their residue management so they can be more efficient and profitable while making their soils healthier and less prone to erosion.
To date, the study’s findings have been disseminated in:
1. YouTube videos (>10,000 views),
2. >70 field days, presentations, and other university events,
3. The Upper Midwest Tillage Guide
4. >60 publications, news articles, and other media sources
Final findings of the results
Crop residue cover among tillage systems ranged from 25-83%. Tillage did not affect plant populations within sites, but strip till (shanks) had lower corn yields at one farm in 2015, whereas both strip tills had higher soybean yields at one farm in 2018. Otherwise, yields did not differ among tillage practices. Strip till was estimated to have the least costs among the systems, with $10-22 less per acre than chisel plow.
Soil temperatures were highest and moisture lowest in the strip till berms and chisel plowed strips as compared to the vertical till and undisturbed areas between the strip till berms. These differences were largest in sandy soils, but rarely observed in clay soils. The vertical till tended to warm and dry approximately midway between that observed for chisel plow and areas with no-tillage.
Among 19 soil properties for soil health, only one (fungal/bacteria ratio) slightly differed among tillage systems for one farm after four years. However, soil microbial communities showed distinct biweekly and bimonthly cyclical patterns that were also not affected by tillage system.
Benefits/Recommendations to North Dakota soybean farms and industry
Our results suggest that reduced tillage does not necessarily translate to yield reductions, but are typically more economical. We recommend that economics and desired erosion control among tillage systems, rather than yield alone, be used to guide tillage preferences. This research also suggests that quantifiable changes to soil health may take >4 years to be observable in the region. Lastly, the weekly-to-monthly cycles in soil microbial communities need to be considered if used as a measure of soil health.