Abstract
Broadcast interseeding cover crops into corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) instead of drill-planting after harvest extends the cover crop season and improves productivity, but establishment can be insufficient. Our objectives were to find broadcast seeding rates that result in maximum spring biomass and N uptake. We tested cereal rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth) in south-central and eastern Nebraska in 2016–2017 and 2017–2018. Seeding rates for rye were 341, 512, and 682 seeds∙m−2, and 119, 178, and 238 seeds∙m−2 for vetch. We broadcast in late September and terminated by early May. Fall emergence was between 3 and 54% of broadcast seeds, and greater for vetch. When broadcast into corn, rye spring biomass was 1472 kg∙ha−1 with N uptake of 38 kg∙ha−1. Vetch biomass was 361 kg∙ha−1 with 13 kg∙ha−1 N uptake. In soybean, rye produced 2318 kg∙ha−1 with 59 kg N∙ha−1 and vetch produced 535 kg∙ha−1 with 21 kg N∙ha−1. Higher seeding rates increased biomass and N uptake only for rye broadcast into corn. Year and site effects and possibly differences in main crops influenced cover crop productivity.
Highlights
For cover crops to improve soil health and fulfill species-specific functions, high productivity is essential and is commonly measured as the amount of biomass produced by the cover crop at its termination time
In legume cover crops, such as hairy vetch (Vicia villosa Roth), high biomass production is associated with their ability to provide N to a subsequent crop [1,3]
Long-term average growing degree days (GDD) accumulation between 21 September and 8 May is similar at both sites: 1113 for rye and 626 for vetch at Clay Center, and 1162 for rye and 672 for vetch at Mead
Summary
For cover crops to improve soil health and fulfill species-specific functions, high productivity is essential and is commonly measured as the amount of biomass produced by the cover crop at its termination time. Biomass production is tied to the prevention of soil nitrate leaching, an important function of grass cover crops such as cereal rye (Secale cereale L.) (from here on rye). Cover crops with greater biomass are more effective at suppressing weeds, preventing erosion, and adding organic carbon to the soil [1,2]. Cover crop biomass characteristics, such as its biomass N concentration and carbon-to-nitrogen ratio, influence biomass decomposition [4] and can help stabilize soil N [5]. In legume cover crops, such as hairy vetch (Vicia villosa Roth) (from here on vetch), high biomass production is associated with their ability to provide N to a subsequent crop [1,3].
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