Browsing by Subject "Kura clover"
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Item Early Season Corn Development in a Kura Clover (Trifolium ambiguum Bieb.) Living Mulch(2017-04) Dobbratz, MichelleKura clover (Trifolium ambiguum Bieb.) perennial living mulch has many agronomic and ecological benefits, but corn produced in this system is often lower yielding than monocrop corn, and this yield loss is often preceded by delayed emergence and development. To prepare rows for corn production, kura clover is selectively killed in strips using mechanical or chemical means. We monitored kura clover health, soil moisture & temperature, corn emergence, corn development, and corn yield in four row preparation strategies: herbicide band kill (BK), shank tillage (ST), novel rotary zone tillage (RZT), and dual tillage (DT) which consisted of shank tillage followed by rotary zone tillage. Our primary objective was to compare novel RZT with the traditional strip tillage unit (ST). In 2015, corn grown in RZT plots emerged and developed faster than corn grown in ST plots, but this did not lead to a difference in grain or stover yield. In 2016, corn grown in RZT and DT plots emerged and developed faster than corn grown in ST and BK plots, and grain yield in 2016 was higher (P=0.05) in the RZT and DT (10.9 Mg ha-1 and 11.6 Mg ha-1) than in the ST and BK treatments (6.9 Mg ha-1 for both treatments). Kura clover biomass was not affected by treatment in either year. Based on these results, rotary zone tillage is a promising row preparation strategy in kura clover living mulch for corn production with minimal herbicide use.Item Nitrate Leaching Mitigation with Kura Clover and Rye Covers for Corn and Soybean in Irrigated Sands(2021-10) Wayment, JessicaIn addition to best nitrogen (N) management practices, integration of cover crops, such as winter rye (Secale cerale L.) and kura clover (Trifolium ambiguum), into annual row crops may be an effective mitigation strategy to reduce nitrate (NO3-- N) leaching from irrigated sandy soils. This study was conducted in the Central Sands region of Minnesota from 2016-2020. The objectives were to evaluate, at variable N rates, rye and kura’s ability to reduce NO3-- N leaching and determine the impacts of the covers on soil N availability, corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] N uptake, and grain yield in continuous corn (CC), corn-soybean (CSb) and soybean-corn (SbC) cropping systems. From 2017-2020, kura reduced NO3-- N leaching by 69% (42 kg NO3-- N ha-1) compared to no cover crop but inter-crop competition resulted in reduction of 26% (2.3 Mg ha-1) in corn and 21% (0.8 Mg ha-1) in soybean grain yield. While inter-crop competition was successfully reduced with chemical suppression of kura, this also reduced the NO3-- N leaching benefit of kura. Inconsistent establishment and growth of rye resulted in variable results across years. Overall, however, rye had little effect on corn yield and reduced NO3-- N leaching compared to no cover by 11% (7 kg NO3-- N ha-1) in CC and 26% (19 kg NO3-- N ha-1) in CSb. In SbC, rye reduced yields 5% (0.2 Mg ha-1) and increased leaching by 25% (15 kg NO3-- N ha-1). Regardless of cropping system or cover crop variables, applying N above optimum rates provides no agronomic benefit and increases risk of NO3-- N leaching. Restricting N applications below optimum rates provides little or no NO3-- N leaching benefits and reduced grain yield. While best N management practices combined with cover crops can meet the need for grain production and minimize NO3-- N leaching in certain situations, minimizing inter-crop competition, and ensuring adequate annual rye establishment and N availability will prove essential to wide adoption of these alternative management systems.Item Nitrogen Dynamics and Management for Maize Production in Kura Clover Living Mulch(2019-06) Alexander, JonathanKura clover living mulch (KCLM) systems have been investigated for incorporation into upper-Midwestern row-crop rotations to provide living groundcover during vulnerable spring and fall fallow periods. The extended growing season of the cool season legume crop takes advantage of sunlight energy that is not utilized for photosynthesis in monocrop systems; increasing carbon capture, supplies of root exudates to the soil microbiome, and tightening nutrient cycles through active root growth. These conceptual advantages, as well as observed improvements in water infiltration and reductions of soil erosion and nitrate leaching, may help to mitigate regionally important environmental impacts from agricultural production. Designing KCLM systems for upper-Midwestern row-crop production requires consideration of the current production needs and management strategies, and the full quantification of environmental benefits cannot be determined in the absence of robust nitrogen (N) management guidelines for maize production in KCLM systems. The objectives of this study were to (i) determine spring agronomic management strategies that improve N contributions from the KCLM system, and (ii) determine factors influencing N management guidelines for continuous maize grain and stover production in KCLM. These questions were addressed with two field experiments, both conducted at the Rosemount Research and Outreach Center in Rosemount, MN. To determine the effect of agronomic management techniques on in-season N contributions from the KCLM, soil and gaseous N pools were measured over 12 weeks in 2018 following treatment applications of clover residue removal or return and banded herbicide or rotary zone tillage. Clover residue removal did not influence N pool concentrations, while banded herbicide and rotary zone tillage enriched the soil with inorganic N relative to an unmanaged control, where rotary zone tillage was superior to banded herbicide. This experiment concludes that a producer may harvest clover prior to seeding row-crops without altering N management and rotary zone tillage increases in-season N contributions from the living mulch through greater disturbance and incorporation of above and below-ground N-rich clover biomass pools. To determine factors influencing N requirements for continuous maize production in KCLM, a two-year nitrogen rate trial was conducted in 2017 and 2018 on first-year maize and second-year maize after maize following forage management in a KCLM system. This study determined that first-year maize production after at least one year of forage management is self-sufficient in N, while N contributions for second-year maize production is reliant on the number of years in forage management prior to first-year maize seeding. While spring management of the KCLM enriches the soil with inorganic N, this contribution does not provide the total N requirements for high-yielding maize. Continuous maize production in KCLM depletes labile and biomass N pools that accumulate during forage management and subsequent years of crop production require fertilizer N at similar rates to conventional production systems.