Location: Soil and Water Management ResearchTitle: Tillage intensity influences nitrogen cycling in organic kura clover living mulch
|GINAKES, PEYTON - University Of Maine|
|GROSSMAN, JULIE - University Of Minnesota|
|SOOKSA-NGUAN, THANWALEE - University Of Minnesota|
Submitted to: Nutrient Cycling in Agroecosystems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2019
Publication Date: 10/29/2019
Citation: Ginakes, P., Grossman, J., Baker, J.M., Sooksa-nguan, T. 2019. Tillage intensity influences nitrogen cycling in organic kura clover living mulch. Nutrient Cycling in Agroecosystems. 116:71-82. https://doi.org/10.1007/s10705-019-10025-0.
Interpretive Summary: There is great interest in the use of perennial living mulch systems for row crop production, particularly from organic producers, primarily because it is believed that they will improve soil quality. However, their impact, particularly on nitrogen (N) availability, is not well understood. We examined the ability of a perennial legume, kura clover, to provide N in an organic corn production system, both within and between rows, under differeing tillage intensities. This included no-till (NT), conventional strip till (ST), rotary zone tillage (ZT), and a combination of strip till plus rotary zone till (DT). The experiment was conducted in Rosemount, MN. Measurements in each treatment included kura clover biomass and N content, and soil carbon (SOC), total N, and inorganic N. Each was measured three times over two growing seasons. Corn yield was positively correlated with tillage intensity, but this was not due to greater N availability. Rather, results suggest that it was due to reduced kura clover encroachment on the row during corn emergence.
Technical Abstract: Perennial cover crops, also known as living mulches, have the ability to improve soil quality, yet their effects on nitrogen (N) cycling and provisioning in organic systems is unknown. We evaluated soil N contributions of kura clover (Trifolium ambiguum) between and within crop row locations for four zone tillage approaches of varying intensity for corn (Zea mays). In 2015 and 2016, an established kura clover field was subjected to four tillage treatments including no-till (NT), traditional shank till (ST), novel, PTO-driven rotary zone till (ZT), and combined ST and ZT (DT; double till) in Rosemount, MN, followed by corn. Kura clover biomass and percent N, and soil C, N, and inorganic N were measured at three time points over two growing seasons. Potentially mineralizable N (PMN) was measured post-tillage in 2016. Kura clover biomass varied between years (518 to 3,035 kg ha-1) and averaged 3.7% N. This difference in kura clover biomass contributions between years appeared to govern N cycling indicators. For instance, IN soil inorganic N differed by tillage treatments only in 2016 at harvest, when DT had greater in-row soil inorganic N than ST. In-row inorganic N was greater than between rows for both the ST and DT treatments after tillage in 2016. Respective grain yields in 2016 for NT and DT were 0.2 and 3.8 Mg dry matter (DM) ha-1; stover yields were 0.3 and 2.6 kg DM ha-1. Overall, in-row inorganic N was positively correlated with grain yield.