Kura clover living mulch: Spring management effects on nitrogen

Authors: ALEXANDER, JONATHAN - UNIVERSITY OF MINNESOTA; Venterea, Rodney - Rod; BAKER, JOHN; COULTER, JEFFREY - UNIVERSITY OF MINNESOTA

Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2019
Publication Date: 2/9/2019
Citation: Alexander, J.R., Venterea, R.T., Baker, J.M., Coulter, J.A. 2019. Kura clover living mulch: Spring management effects on nitrogen. Agronomy. 9(2),69:1-14. https://doi.org/10.3390/agronomy9020069.
DOI: https://doi.org/10.3390/agronomy9020069

Interpretive Summary: Kura clover living mulch (KCLM) systems have the potential to provide ecosystem services in intensively managed cropping systems while supplying soil mineral nitrogen (N) to the growing cash crop. Living mulch management relies on strong spring suppression to reduce competition between vigorous kura clover and emerging row crop seedlings, but standard suppression management practices utilize widely different modes of action. The objective of this research was to gain insight into the impact of common KCLM management practices on early season N dynamics. Kura clover was mowed, and residue was either harvested or returned before rows were established via strip tillage or banded herbicide. Soil and gaseous N pools were monitored 12 wk post initial application of suppression management treatments. An enrichment factor (EF) approach was utilized to compare N pools under managed treatments relative to anunmanaged clover control. Strip tillage increased soil N by 300%, while banded herbicide row establishment increased soil N by 220% relative to the unmanaged control. Pre-plant clover harvest reduced short term soil NO3-N, but during later time intervals there was no relationship between residue management and soil N. We conclude that, for the dual goals of maintaining clover perenniality while providing greater soil N enrichment, strip tillage is superior to band herbicide for row establishment. Additionally, pre-plant clover harvest may open opportunities for dual harvests in a single growing season; increasing economic return while maintaining in-season N contributions from the living mulch. These results will be useful to farmers, regulators and scientists interested in developing increasingly sustainable agricultural practices that conserve natural resources while maintaining optimum productivity.

Technical Abstract: Kura clover living mulch (KCLM) systems have the potential to provide ecosystem services in intensively managed cropping systems while supplying soil mineral nitrogen (N) to the growing cash crop. Living mulch management relies on strong spring suppression to reduce competition between vigorous kura clover and emerging row crop seedlings, but standard suppression management practices utilize widely different modes of action. The objective of this research was to gain insight into the impact of common KCLM management practices on early season N dynamics. Kura clover was mowed, and residue was either harvested or returned before rows were established via strip tillage or banded herbicide. Soil and gaseous N pools were monitored 12 wk post initial application of suppression management treatments. An enrichment factor (EF) approach was utilized to compare N pools under managed treatments relative to anunmanaged clover control. Strip tillage increased soil N by 300%, while banded herbicide row establishment increased soil N by 220% relative to the unmanaged control. Pre-plant clover harvest reduced short term soil NO3-N, but during later time intervals there was no relationship between residue management and soil N. We conclude that, for the dual goals of maintaining clover perenniality while providing greater soil N enrichment, strip tillage is superior to band herbicide for row establishment. Additionally, pre-plant clover harvest may open opportunities for dual harvests in a single growing season; increasing economic return while maintaining in-season N contributions from the living mulch.