Stephen Okula, CGCS said: Andy Jorgensen said: Keith Fellenstein said: I won't be doing new greens anytime soon, but have been intrigued with the use / substitution of biochar for peat and poultry manure to assist with grow in. As for fairy ring, both courses here were re-done with traditional 80/20 and 90/10 with sand/peat, and we have been battling fairy ring from almost the beginning.
I would think the pathogen that causes fairy ring would dine on organic matter regardless of the source. I have seen it the worst on greens built with peat the first few years after construction. At least with Comand you have the microbes to break the organic down faster than it can accumulate. You're basically jump starting a sterile sand environment with beneficial bugs that have several benefits. Something that a typical biochar and peat can't provide. However, using a mix of compost and biochar would provides benefits of both products.
Sand is not sterile and there is ample scientific evidence to prove it. A quick Google search turned up this one by Dr. David Zuberer from Texas A&M University and published by the USGA in 2012;
"In the soccer field study above, we found 100,000 bacteria per gram in the sand used to construct the rootzone."
http://gsrpdf.lib.msu.edu/ticpdf.py?fil ... -20-12.pdf
Also an excellent article by Dr. Alan Gange of the University of London and published by the Royal and Ancient in 2014. He states that we might manipulate perhaps 1% of soil microbes.
https://golfcoursemanagement.randa.org/ ... Gange.aspx
I think our ability to manage soil bacteria is too frequently overstated.
I have have to argue the first article did not state the source of the material used to construct the soccer fields, but did mention that aerobic conditions must be present for microbial activity to occur. I'm not sure how much aerobic bacteria are present when my sand source for greens construction and topdressing comes from dredging operations to mine the sand from lakes in central Florida.
I would also add the second article plainly states in the last paragraph:
"So does turf need more microbes? I strongly suspect the answer is ‘yes', but only of the right type. Currently we do not know if the microbial community present lacks critical elements that might enable turf to resist drought or disease better. Should you use a microbial inoculant? It would probably do no harm and in many instances will be good, though it's not necessarily grass growth you need to enhance, otherwise you will be mowing it more often!"
The second article also briefly touches on the applications of pesticides to the soil, and it's affect on soil microbial populations. It is highly recommended to get fungicides into the soil during application. So I question what affect these applications might have on the soil microbial population, especially with the use of Strobilurin and DMI fungicides.
Although the first article addressed soil fumigation, it recommended adding back in native soil from the surrounding area. I would not suggest that for a number of reasons, but it least it stated "pathogen free". This article also did not touch on Curfew, a soil fumigant utilized for the control of plant parasitic nematodes, and the recommendation to only use quick release fertilizer after treatment due to the lack of Nitrogen fixing bacteria present.
However, I do understand what each author was alluding to. And I agree that in an existing soil present on the golf course, yes, the soil microbial populations are probably pretty abundant. But I would also argue that the ancillary benefits received from compost applications are welcomed for the relatively low-cost