Abstract
Abstract Cover crops (CC) in corn ( Zea mays L.) and soybean [ Glycine max (L.) Merr.] rotations may prevent N loss and provide other ecosystem services but CC productivity in the western Corn Belt is limited by the short growing season. Our objective was to assess CC treatment and planting practice effects on CC biomass, spring soil nitrate concentrations, and soybean yield at two rainfed sites in eastern and one irrigated site in south‐central Nebraska over 4 yr. Cover crop treatments (cereal rye [ Secale cereale L.] [RYE] and a mix of rye, legume, and brassica species [MIX]) were planted by broadcast interseeding into corn stands in September (pre‐harvest broadcast) or drilling after corn harvest (post‐harvest drilled) and terminated 2 wk before planting soybean. Cover crop biomass and N uptake varied between years, but generally at the eastern sites, pre‐harvest broadcasting produced more biomass than post‐harvest drilling (1.64 and 0.79 Mg ha −1 , respectively) and had greater N uptake (37 and 24 kg ha −1 , respectively). At the south‐central site, post‐harvest drilling produced more than pre‐harvest broadcasting (1.44 and 1.20 Mg ha −1 , respectively). RYE had more biomass than MIX (1.41 and 1.09 Mg ha −1 , respectively), but the same N uptake. Soil nitrate reductions after CC were small. In 3 of 12 site‐years, soybean yielded less after pre‐harvest CC. Yield reductions were not correlated to CC biomass, but were likely due to greater weed pressure. High CC productivity is necessary for high N uptake, and requires site‐specific selection of planting practice and CC treatments.
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Claims 10
Claim · model-written summary
At the eastern sites, pre-harvest broadcasting produced more cover crop biomass than post-harvest drilling (1.64 versus 0.79 Mg ha-1).
- Taxon
- Cover cropt0
- Treatment
- pre‐harvest broadcastinge0
- Outcome
- biomasse0
- Direction
- moree0
- Value
- 1.64 and 0.79 Mg ha −1e0
- Comparator
- post‐harvest drillinge0
Not reportedSetting
Verbatim
t0“Cover crop”
e0“pre‐harvest broadcasting produced more biomass than post‐harvest drilling (1.64 and 0.79 Mg ha −1 , respectively)”
Claim · model-written summary
At the eastern sites, pre-harvest broadcasting gave greater cover crop N uptake than post-harvest drilling (37 versus 24 kg ha-1).
Verbatim
t0“Cover crop”
e0“pre‐harvest broadcasting produced more biomass than post‐harvest drilling”
e1“had greater N uptake (37 and 24 kg ha −1 , respectively)”
Claim · model-written summary
At the south-central site, post-harvest drilling produced more cover crop biomass than pre-harvest broadcasting (1.44 versus 1.20 Mg ha-1).
Verbatim
t0“Cover crop”
e0“At the south‐central site, post‐harvest drilling produced more than pre‐harvest broadcasting (1.44 and 1.20 Mg ha −1 , respectively)”
Claim · model-written summary
Cereal rye (RYE) had more biomass than the rye-legume-brassica mix (MIX) (1.41 versus 1.09 Mg ha-1).
Verbatim
t0“Cover crop”
e0“RYE had more biomass than MIX (1.41 and 1.09 Mg ha −1 , respectively)”
Claim · model-written summary
RYE and MIX had the same N uptake.
Verbatim
t0“Cover crop”
e0“RYE had more biomass than MIX (1.41 and 1.09 Mg ha −1 , respectively), but the same N uptake”
Claim · model-written summary
Soil nitrate reductions after cover crops were small.
Verbatim
t0“Cover crop”
e0“Soil nitrate reductions after CC were small”
Claim · model-written summary
In 3 of 12 site-years, soybean yielded less after pre-harvest cover crops.
- Taxon
- soybean
Glycine maxe3 - Treatment
- pre‐harvest CCe3
- Outcome
- yieldede3
- Direction
- lesse3
- Qualifier
- 3 of 12 site‐yearse3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“In 3 of 12 site‐years, soybean yielded less after pre‐harvest CC”
Claim · model-written summary
Soybean yield reductions were not correlated with cover crop biomass.
- Taxon
- soybeanGlycine maxe3
- Treatment
- CC biomasse4
- Outcome
- Yield reductionse4
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“soybean yielded less after pre‐harvest CC”
e4“Yield reductions were not correlated to CC biomass, but were likely due to greater weed pressure”
Claim · model-written summary
The soybean yield reductions were likely due to greater weed pressure.
- Taxon
- soybeanGlycine maxe3
- Outcome
- Yield reductionse4
- Qualifier
- greater weed pressuree4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“soybean yielded less after pre‐harvest CC”
e4“Yield reductions were not correlated to CC biomass, but were likely due to greater weed pressure”
Claim · model-written summary
High cover crop productivity is necessary for high N uptake and requires site-specific selection of planting practice and cover crop treatments.
Verbatim
t0“Cover crop”
e0“High CC productivity is necessary for high N uptake, and requires site‐specific selection of planting practice and CC treatments”
The same questions in other papers
cover crop · yield · Glycine max (soybean)Positive and negative results
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