Must go now and spray some noxious Pommie import.....gorse, the bane of my existence. ![Angry >:(](https://www.eevblog.com/forum/Smileys/default/xangry.gif.pagespeed.ic.0w4zhwjvDw.png)
Totally OT:
If you want a completely natural, harmless (but deadly?) way to kill off gorse, you should take a look at stearic acid from coconut oil. It's also known as P-20, polysorbate-20 and Tween-20 (
![Clapping :clap:](https://www.eevblog.com/forum/Smileys/default/clap.gif.pagespeed.ce.LImJbaO0yv.gif)
), but it's a 100% organic non-ionic surfactant that has amazing effects on plant growth. It's widely used in agriculture s a soil wetting agent, but if you add more than a certain percentage (about 2-3% by volume) you will make the roots of any plant watered with it absorb far too much moisture and causing the roots to rot.
If you use it in the usual agri- quantities (around 0.5-1%) it will stop water from sitting on the top soil and will help the plants take up water and nutrients a little better, but you won't see much of a yield increase (or bigger flowers, healthier growth) from it. If, however you get the concentration in a very narrow window around 100 ppm, or 0.1g per liter (the drop-off in the effects occur 10-15 ppm either side of 100 ppm) there is a change that occurs in the cell membrane of the plant's cells. The ionic transfer of nutrients across the cell membrane is dramatically enhanced along with both the absorbtion and retention of water. Yield, both dry-weight and wet, are increased 30-40% with some species (lillies did particularly well in this one study I found) and cuts water-cycling through transpiration by up to 400%. Given that a plant will generally only use 5-6% of the moisture it takes up through its roots, expelling the rest from stomatophores in the leaves through transpiration (the botanical version of respiration) this results in a huge reduction in the water required to go from seed to mature plant, in the order of 50% once all other factors are accounted for. Half the water for a 30% increase in weight from a 'chemical' that costs £7 a liter from natural cosmetics companies! (They use it as an emuslifier in all sorts of bath-oils and facial washes).
It also kills fungal spores, viruses, spider-mite and aphid eggs in the 100 ppm concentration by the same mechanism as that which benefits the plants so much: increasing the permeability of the cell membrane throughout the organism.
I can't link to anything much except scholarly stuff, the original study that found the 100 ppm effects (
https://etd.auburn.edu/bitstream/handle/10415/1203/Yang_Xiaomei_2.pdf?sequence=1) is from 2008 and seems to have got missed for many years, although the research is starting to be replicated by academics, rather than just weird old cripples with esoteric interests (me).
Here's a paper on using at as a weedkiller:
https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=4904&context=rtdOh, and if any metrologist here fancies working out an easy circuit/device to automate the precise mixing of 100 ppm of a gloopy liquid with exactly one liter of water they would be benefitting the whole world! I've been evangelising about the stuff whenever I can, and even when I shouldn't (sorry, I tried to bring it back on topic, but I feel like that failed
![Undecided :-\](https://www.eevblog.com/forum/Smileys/default/undecided.gif.pagespeed.ce.cCZ6w-jWpR.gif)
)