@article{vann_reberg-horton_brinton_2016, title={Row spacing and seeding rate effects on canola population, weed competition and yield in winter organic canola production}, volume={108}, ISSN={["1435-0645"]}, DOI={10.2134/agronj2016.02.0097}, abstractNote={Increasing seeding rate and widening row spacing to allow for between row cultivation may reduce weed competition in organic canola (Brassica napus L.) production. Research was conducted to evaluate the effects of row spacing and seeding rate on canola population, weed competition, and yield in organic canola production. Canola variety Hornet was planted at five seeding rates (3.4, 6.7, 10.1, 13.4, and 16.8 kg ha−1) at three row spacings (17, 34, 68 cm) in Goldsboro, Kinston, and Salisbury, NC, in 2011 and 2012. Between row cultivation was performed in the 68‐cm row spacing as weather permitted. Canola population increased with increasing seeding rate across all row spacings, and canola populations were highest with the 17‐cm row spacing, followed by the 34‐ then 68‐cm row spacings. Yield was similar across row spacings at the lower seeding rates in five of the six environments. At these environments, yield tended to increase in the 17‐cm row spacing as seeding rate increased but declined in the 68‐cm row spacing with increasing seeding rate. In one environment with a unique weed community, weed suppression and yield were higher with the 68‐cm row spacing. It was concluded that the yield plasticity of canola will provide producers flexibility in selecting row spacing, and seeding rate selections should be based on desired row spacing.Core Ideas

Increasing canola seeding rate and widening row spacing to allow for between row cultivation may serve as mechanisms to reduce weed competition in canola production, but have rarely been evaluated in organic production. This study was conducted to evaluate seeding rate and row spacing effects on weed competition and yield in organic canola production.
Despite different canola populations across canola row spacings, yield tended to be similar at low seeding rates across the row spacings indicating canola has the ability to compensate for low population.
Depending on the weed species at your environment, widening row spacing to allow for between row cultivation may prove critical for reducing weed competition and increasing canola yield.
Yield tended to increase with increases in seeding rate at the 17‐cm row spacing, however yield declines were observed with higher seeding rates in the 68‐cm row spacing, which is likely attributed to intraspecific competition.
Organic canola producers have flexibility when selecting row spacing and seeding rates due to the great plasticity of canola.
}, number={6}, journal={Agronomy Journal}, publisher={American Society of Agronomy}, author={Vann, R.A. and Reberg-Horton, S.C. and Brinton, C.M.}, year={2016}, pages={2425–2432} }
 @article{wells_brinton_reberg-horton_2016, title={Weed suppression and soybean yield in a no-till cover-crop mulched system as influenced by six rye cultivars}, volume={31}, ISSN={["1742-1713"]}, DOI={10.1017/s1742170515000344}, abstractNote={AbstractCover crop mulches have been successful in reducing weed severity in organic soybeans. This study examined six rye cultivars (SRCs) used as cover crops to determine which were most adapted for use with a roller–crimper in the southeastern U.S. To be an effective mulch, a rye cultivar must produce high biomass and reach reproductive growth stage to facilitate mechanical termination via the roller–crimper prior to soybean planting. Rye cultivars were planted at three locations in North Carolina over the 2009 and 2010 growing seasons. Each rye cultivar was mechanically terminated via a roller–crimper implement. Rye cover crops were terminated on two dates and soybeans were immediately no-till planted into the mulch. In 2009, all rye cultivars produced greater than 9000 kg ha−1 rye biomass dry matter (DM) with the exception of Rymin at Plymouth (2009), but in 2010 only the early flowering cultivars produced in excess of 9000 kg ha−1 DM. There were no detectable soybean yield differences between the SRCs and the weed-free checks, and weed control was excellent across all SRCs at both Plymouth and Salisbury (2009). After an unseasonably cold and wet winter in 2010, the late flowering rye cultivars were not fully controlled by the early termination date due to delayed maturation (less than 65% control at 2 WAP) whereas the early flowering cultivars were fully controlled (100% control at 2 WAP). Rye biomass production was below 9000 kg ha−1 DM for the late flowering and dough development rye cultivars. The early-terminated rye plots had greater weed coverage across all SRCs than those from the late termination date (P < 0.01). However, weeds did not impact soybean yield for either of the termination dates. Soybean yield in 2010 was modeled with rye biomass and soybean population used as covariates, and for both termination dates, soybean yield was proportional to rye biomass production. Early flowering rye cultivars offer producers the widest range of termination opportunities that best coincide with their cash crop planting dates.}, number={5}, journal={RENEWABLE AGRICULTURE AND FOOD SYSTEMS}, author={Wells, M. Scott and Brinton, Carrie M. and Reberg-Horton, S. Chris}, year={2016}, month={Oct}, pages={429–440} }
 @article{parr_grossman_reberg-horton_brinton_crozier_2014, title={Roller-Crimper Termination for Legume Cover Crops in North Carolina: Impacts on Nutrient Availability to a Succeeding Corn Crop}, volume={45}, ISSN={["1532-2416"]}, DOI={10.1080/00103624.2013.867061}, abstractNote={Nitrogen (N) release from roll-killed legume cover crops was determined for hairy vetch (Vicia villosa Roth), crimson clover (Trifolium incarnatum L.), and a hairy vetch + rye (Secale cereale L.) biculture in an organic corn production system in North Carolina, USA. Cover crops were planted at two locations in fall 2008 and 2009, roll-killed in May, and no-till planted with corn (Zea mays L.). Inorganic soil N and mineral N flux were determined using potassium chloride (KCl) extractions and ion-exchange resin (Plant Root Simulator, PRS) probes at 2-week intervals for 12 weeks and compared to fertilized controls of 0 and 168 kg N ha−1. In 2009, greater plant available N under hairy vetch than under either 0 N control or crimson clover was found, with peak soil N occurring between 4 and 6 weeks after roll kill. Available soil N under crimson clover mulches was less than or equal to 0 N, suggesting net immobilization.}, number={8}, journal={COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS}, publisher={Informa UK Limited}, author={Parr, Mary and Grossman, Julie M. and Reberg-Horton, S. Chris and Brinton, Carrie and Crozier, Carl}, year={2014}, month={Apr}, pages={1106–1119} }
 @article{parr_grossman_reberg-horton_brinton_crozier_2011, title={Nitrogen Delivery from Legume Cover Crops in No-Till Organic Corn Production}, volume={103}, ISSN={["0002-1962"]}, DOI={10.2134/agronj2011.0007}, abstractNote={Sixteen winter annual cover crop cultivars were grown in North Carolina to determine total N accumulation, biological N fixation (BNF) potential, and compatibility with a roller‐crimper‐terminated organic corn (Zea maysL.) production system. Cover crops and termination dates were tested in a stripped block design. Treatments included hairy vetch (Vicia villosaRoth), common vetch (Vicia sativaL.), crimson clover (Trifolium incarnatumL.), Austrian winter pea (Pisum sativumL.), berseem clover (Trifolium alexandrinumL.), subterranean clover (Trifolium subterraneumL.), narrow leaf lupin (Lupinus angustifoliusL.), and Balansa clover (Trifolium michelianumSavi.), as well as bicultures of rye (Secale cerealeL.), hairy vetch, and Austrian winter pea. Roller‐crimper termination occurred in mid‐April, early May, and mid‐May. Total biomass, N concentration, and C/N ratios were determined for cover crops at all roll times and natural15N abundance at the optimal kill date. Hairy vetch and crimson clover monocultures had the greatest overall biomass in 2009, and bicultures the greatest biomass in 2010. Crimson clover successfully terminated in late April, hairy vetch and Austrian winter pea in mid‐May, and berseem clover and common vetch in late May. All cover crops except lupin and subterranean clover derived between 70 and 100% of their N from the atmosphere. Corn response to cover crop mulches was significantly affected by the time of rolling, with poor stands resulting from competition with insufficiently terminated mulches. Crimson, Balansa, and subterranean clover mulches resulted in poor corn yields despite relatively high levels of total N. The highest corn yields were achieved in hairy vetch and rye plus hairy vetch bicultures.}, number={6}, journal={AGRONOMY JOURNAL}, publisher={American Society of Agronomy}, author={Parr, M. and Grossman, J. M. and Reberg-Horton, S. C. and Brinton, C. and Crozier, C.}, year={2011}, pages={1578–1590} }