The allopathic effect of brassicas and actually rye don't seem severe. I am not 100% on this but from what I've seen it is the residue on top of the soil that has the allopathic qualities. The picture taken today below you'll see beans in the food plot and oats in the kill plot. Last Aug I planted radish and kale in the kill plot and in April I planted oats. The oats did really well. I cut the oats down yesterday and nuked it today (completely wrong order!). I will plant forage radishes and forage kale again after I disc the kill plot. I also plan on planting rape seed on the other side of the beans this fall. I'm hoping the deer don't demolish the beans. Once a bean patch is left to go to seed and dug under it grows the following hear much more dense.lituani wrote: ↑Sat Jul 24, 2021 8:09 amHave you ever planted anything else into the plots where you previously planted brassicas? Curious whether that biotoxin/herbicide-like effect dissipates after a winter and lotsa precipitation, or whether it attaches itself to soil and hangs around doing its thing for one or two seasons hence.Boo wrote: ↑Fri Jul 16, 2021 10:52 amI am certainly no expert but, I think the only problem with that if you're planting brassicas, they will crowd out others because they grow so fast and produce a bio toxin that acts like a herbicide that inhibits growth of other plants. That bio toxin is not as powerful as a herbicide though. I no longer mix other than mixing different brassicas together like radishes and kale.
Below is quoted from https://www.nrcs.usda.gov/Internet/FSE_PLANTMATERIALS/publications/mopmstn2825.pdf
How long do these allelochemicals persist for weed suppression?
Weed suppression of small-seeded annual weeds can persist for a few weeks after the cover
crop is terminated. If cover crop residue is left on the soil surface the residue can last for
several weeks depending on weather conditions. In a no-till cropping situation the allelopathic
effects are at the soil surface (Schonbeck 2015).
Are these allelochemicals harmful to the cash crop?
Cereal rye residue on the surface is responsible for suppression of weeds due to factors such
as shading out sunlight for weed seeds and biomass accumulation on soil surface.
Susceptibility to allelochemicals is indirectly related to seed size based on research. Smaller
seeds are more susceptible to the allelopathic chemicals of the plant. The large seed of corn
and its deep planting depth should minimize the impact of allelochemicals released by the
cover crop (Hartzler 2014).