Kura clover living mulch reduces fertilizer N requirements and increases profitablility of maize

Authors: ALEXANDER, JONATHAN - University Of Minnesota; Baker, John; Venterea, Rodney - Rod; COULTER, JEFFREY - University Of Minnesota

Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2019
Publication Date: 8/6/2019
Citation: Alexander, J.R., Baker, J.M., Venterea, R.T., Coulter, J.A. 2019. Kura clover living mulch reduces fertilizer N requirements and increases profitablility of maize. Agronomy. 9(8):432. https://doi.org/10.3390/agronomy9080432.
DOI: https://doi.org/10.3390/agronomy9080432

Interpretive Summary: There is interest in the use of kura clover living mulch systems (KCLM) to obtain the environmental benefits they provide, but there is a lack of knowledge about the best way to manage them, and there are also questions about their economic return relative to conventional corn production. Two experiments were conducted in 2017 and 2018 to determine the response of corn grown in KCLM to applied nitrogen. The firs-year treatments considered corn planted into kura clover that had been managed as a forage for two or three years, while the 2nd year corn experiment considered corn after corn in a KCLM system. There were 8 levels of N application rate ranging from 0 to 250 kg ha-1, and both grain and stover harvests were compared. First year corn showed no response to N, i.e. - there was no significant difference in yields across all application rates. For 2nd year corn, the economically optimum N rate was equal to University of Minnesota fertilizer recommendations. Economic analysis compared the yields and production costs of the KCLM system to values for production of conventional corn in nearby fields. The net economic return for the KCLM system was the two years was $138 ha-1 greater than the conventional system. We conclude that this system is economically viable, and that less fertilizer N is needed, at least for first year corn in KCLM.

Technical Abstract: Kura clover living mulch (KCLM) systems have been investigated for their incorporation into upper Midwestern row crop rotations to provide ecosystem services through continuous living cover. Reductions in soil erosion and nitrate loss to surface and groundwater have been reported, but factors affecting agronomic performance and nutrient management are not well defined. To achieve realized environmental benefits, research must develop agronomic management techniques, determine economic opportunities, and provide management recommendations for row crop production in KCLM systems. Two experiments were conducted in 2017 and 2018 to determine the response to N fertilizer application for maize production in KCLM. The first-year maize experiment was maize following two or three years of forage management, and the second-year maize experiment followed maize after one or two years of forage management. Eight fertilizer N treatments ranging from 0–250 kg N ha-1 were applied to each experiment and grain and stover yields were compared to conventionally managed maize hybrid trials that were conducted nearby. First-year maize did not need fertilizer N to maximize yield and profitability in either year, and second-year maize required a fertilizer N rate near local University guidelines for maize following soybean. The net economic return from maize grain and stover in the KCLM averaged over first- and second-year maize experiments and 2017 and 2018 growing seasons was $138 ha-1 greater than the conventional comparison.