Location: Soil and Water Management ResearchTitle: Soil carbon and nitrogen dynamics under zone tillage of varying intensities in a kura clover living mulch system
|GINAKES, PEYTON - University Of Minnesota|
|GROSSMAN, JULIE - University Of Minnesota|
|SOOKSA-NGUAN, THANWAL - University Of Minnesota|
|DOBBRATZ, M - University Of Minnesota|
Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/27/2018
Publication Date: 8/27/2018
Citation: Ginakes, P., Grossman, J., Sooksa-Nguan, T., Dobbratz, M., Baker, J.M. 2018. Soil carbon and nitrogen dynamics under zone tillage of varying intensities in a kura clover living mulch system. Soil & Tillage Research. 184(12):310-316. https://doi.org/10.1016/j.still.2018.07.017.
Interpretive Summary: The kura clover living mulch system was dsigned to reduce the environmental impact of row crops like corn and soybeans. It relies on the establishment of a perennial ground cover (kura clover), in which row crops can be planted each year by first using some form of zone tillage to establish a row in which to plant. OUr goal was to compare tillage treatments of differing intensity to see hou they affect nitrogen and carbon dynamics in the soil. The research took place at the University of Minnesota's Rosemount Research and Outreach Center in 2015 and 2016, in a previously established stand of kura clover. Four different tillage intensities were tested: NT (no-till, using herbicide to establish the row), ST (dtrip-tillage with a conventional strip-tillage unit), ZT (zone tillage, using a specially designed, rotary zone till unit), and DT (double tillage, using both the strip till and zone till units). Soils were sampled at 3 times during the growing season in each system, and were analyzed for microbial biomass, inorganic nitrogen (N), and readily oxidizable carbon. The DT system had greater soil N than the the NT treatment after tillage, and at the end of the season both DT and RZT had greater soil N than the NT treatment, indicating that incorporating the clover biomass through tillage has a favorable impact on soil N levels. DT also produced a cleaner seed row than NT. We conclude thatboth DT and RZT provide benefit for corn production in living mulch systems relative to row establishment with herbicide. This will be useful information for producers wishing to capture the environmental benefits of living mulch systems.
Technical Abstract: Zone tillage is a reduced-tillage approach that attempts to capture both the environmental advantages of year-round ground cover and the agronomic benefits of in-row tillage. This study was conducted to determine the effect of differing levels of zone tillage intensity on soil carbon and nitrogen cycling in a corn-kura clover cropping system (Zea maize-Trifolium ambiguum). Research took place in Rosemount, MN in 2015 and 2016 in an established kura clover stand. Soils and kura clover biomass were each sampled three times in crop rows per year in four treatments that varied by intensity: NT (spray-down no-till), ST (shank-till, traditional strip till unit), RZT (zone-till, PTO-driven rotary zone tiller), nd DT (double-till, ST+RZT). Samples were analyzed for microbial biomass (MB), soil inorganic nitrogen, and permanganate oxidizable carbon (POXC). Additionally, potentially mineralizable nitrogen (PMN) was measured on 2016 after spring tillage soils. Greater spring kura clover biomass in 2016 (2,449 kg ha-1) relative to 2015 (187 kgha-1) influenced overall differences in soil quality between years. The double-till (DT) treatment had greater post-till soil inorganic N than the no-till (NT) treatment in 2016, and by corn harvest, both zone-till (RZT) and double-till (DT) had higher soil inorganic N than NT, indicating that the addition of kura clover biomass contributed to in-row, plantavailable nitrogen. Double-till was also more effective in reducing kura clover encroachment into crop rows than NT. No effect of tillage intensity on PMN, MB, or POXC was observed at any sampling time, although trends of decreasing POXC paired with increasing MB over the 2016 growing season suggest that the quantity of incorporated kura clover biomass may have governed belowground nutrient cycling and soil fertility.