by Did67 » 17/07/18, 10:17
MSV Videos of the Sélosse Conference - a small additional opinion
I was at the end of the videos.
And my initial enthusiasm faded like leaves in the fall ...
I found that he laid the fundamentals: enthusiasm. No discussion. It's mastered.
And then he did not take off his posture of "lab" scientist, with his little frills, threading the pearls, such a curious botanical case then such a forest eccentricity: it always went in the same. But we don't need 6 hours to admit (or not) that mycorrhizae exist.
No one doubts that mycorrhizae exist and that they are effective.
And after that ???? Nothing. Redundancies. Improvements. Questions without answers. Broken promises (perhaps not filmed): "we have to talk about organic again" ... I didn't see anything. I doubt what he was going to say.
His schema on the fact that such plant can "lose" in mycorrhizal exchanges with such specific mushroom is interesting. And must urge us to be careful. A symbiosis is not necessarily beneficial to one of the parties. The other can take the chestnuts out of the fire. There are unbalanced marriages. But that doesn't mean anything in practice: Selossus himself indicates that plants collaborate with dozens, hundreds of species of fungi. Therefore, who says that the plant will, in the joyous mess of the living, engage with this mushroom there? Who says there won't be a divorce ??? What does this "forced marriage" tell us ??? No doubt that for this species of plants, it is not the right partner ...
[But actually, at the top, when I do not remember who mentioned it, I said "beside" !!! I did not know there was a specific mycorrhizal fungi and I am talking about "mycorrhizae" in general, in symbiosis with a plant in the happy living mess ... I cannot demonstrate it scientifically, but I have the intuition that the plant finds its way there - not necessarily in terms of "produced biomass", which was the only criterion retained; there are other aspects: phytosanitary protection, communications between subjects of the same species, or, in orchids, triggering of seed germination ... When evolution leads to a system where, according to human criteria, it is not reasonable, it is the criteria of the man which are not good. No one at Airbus would have invented a flying thing as crass as the drone! And it is this vibrating awkwardness that causes pollen to fall in some plants and fertilizes much better than bees - eg in tomatoes !!]
I was amazed that he could not indicate thresholds for phosphates. He seems to ignore or prefer to ignore (competition of researchers ??? snobbery of "pure" researchers against "field agronomists" ???) Fortin's work in practical conditions. Page 91 of their book (which suddenly I recommend, without advertising!) There is a table which gives for 9 market garden or agricultural species, the "mycorrhizal dependence of plants" = the part of P supplied to them by the mycorrhizae for a content of 100 ppm of P in the soil. We see that in wheat, at this content, it is "independent". But at 50 ppm, it receives 30% of its P from mycorrhizae. Leek, at 100 ppm P, receives 95,7% of mycorrhizae. At 50 ppm, it is 97%. But at 150 ppm, that dropped to 50. Several vegetables are in similar orders of magnitude: carrots, peas, beans, beans, sweet corn. Tomato and potato are less dependent [40 to 60% at 100 ppm; slightly more at 50 ppm - 60/65%] and become "independent" at 150 ppm [0% P of mycorrhizal origin].
The commentary says this was obtained "from a field experiment".
That was the answer to the young man who questioned him. And not "we don't know precisely"! And shut up. There is clearly, for vegetables, a threshold, between 100 and 150 ppm P in the soil, at which the benefit of mycorrhizae decreases or collapses. On this basis, I recommend not to fertilize, at the risk of making the plant "independent" - since it easily finds what it needs - mycorrhizal fungi. The mycorrhizal fungus then becomes a parasite, from the point of view of the vegetable - "which has everything it needs". Why would he feed him ??? Because this mushroom costs him (I did not note the figures of Selossus: up to 40% of the products of his photosynthesis; I often say 20/25% - I do not know if I am wrong). It is then the gardener who becomes dependent, because he took charge, at his expense, what the living system was doing [for the same reason, I advise against watering as long as the soil is stable and as long as the vegetables do not show obvious signs of wilting. And especially not at the plantation. But I do Neanderthal agronomy! No "research" publishable in "Nature" or "Science" - I'm talking about prestigious journals]
It is clear that an agronomist advances even on fragile knowledge. Or sometimes without, from what he imagines to understand of the living system! At risk of crashing. But if the Neanderthals had expected to understand everything before inventing a very very rough agriculture, we would not be here! I am a Neanderthal !!!
Of course, this is only an opinion. Mine.
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