[permaculture] Here's how to grow more mycorrhizal fungi

Lawrence London lfljvenaura at gmail.com
Sat Jan 5 01:28:11 EST 2019

Here's how to grow more mycorrhizal fungi

[image: AMF hyphae] USDA-NRCS
The hyphae from arbuscular mycorrhizal fungi act like a force multiplier
for plant roots, but they are fragile and can be easily destroyed by
Here's how to grow more mycorrhizal fungi
If you want lower costs and higher productivity, you need to get the goods
from growing more mycorrhizal fungi.

Alan Newport <https://www.farmprogress.com/author/Alan-Newport> | May 17,

Advice about boosting the health of arbuscular mycorrhizal fungi is
probably best started with the list of three "do-not" commandments.

1. Do not till. Tillage breaks up the myriad of hyphae/mycellium, most of
which can never reconnect. Once broken, they must start all over, says
Wendy Taheri, an expert on arbuscular mycorrhizal fungi. Dramatically
shorter mycellium equals dramatically reduced plant food for your crops or
forages. One source says it is not uncommon to have 20 meters of fungal
root in one cubic centimeter of soil. Calculate that out to just the top
inch of soil in an acre and you get a length that would stretch about 80%
of the way to the moon; roughly 195,000 miles of food collectors per acre,
all interconnected, all sharing stuff.

2. Do not provide much phosphorus. Taheri says too much phosphorus
fertility in the soil, especially with crops and farm ground, can be almost
as damaging as tillage. The plants latch onto the inorganic phosphorus
source when young and never develop much of a trading relationship with the
AMF. Remember that phosphorus is so necessary to plant life and so
generally unavailable in a natural setting, that plants are programmed to
make most of the trade deals with AMF based first on the need for
phosphorus. You want the plants to be a bit hungry for phosphorus, Taheri
says. For example, 200 ppm of phosphorus in a soil test is usually
considered adequate for crop growth. If you want AMF to successfully
colonize and trade with your plants, 50-100 ppm is a more AMF-encouraging
range for phosphorus fertility.

3. Avoid pesticides as much as possible. Although AMF have a lot of
resistance to even such compounds as fungicides, Taheri says most
pesticides can be hard on AMF. The more you put on and the more frequently
and the more you rotate pesticides, the more you will damage your AMF.

*4 good things to do*

1. Diversity is key. Manage for diversity above ground to build mycorrhizal
and microbial diversity below ground. Although varied species of AMF tend
to favor certain species or types of plants, their interactions directly
and/or through microbial relationships, will add benefits at a compounding

Plant roots become colonized by many species of AMF. Some are better at
taking up water,  others may be good defenders against certain pathogens,
some relieve other environmental stresses such as soil compaction or
excessive salinity. More is better.

Virtually every other trace mineral plants need for good health is provided
by AMF, and those nutrients pass up through the food chain. Research has
shown that plants associating with AMF have a higher nutrient density than
the same plants without AMF.

2. Graze right. Use multi-paddock, adaptive grazing to alternate the
natural pulse of grazing and defoliation with fairly lengthy recovery
periods. This was a common behavior in the drier environments where large
herds of ruminants grazed for hundreds of thousands of years. If done well,
such forages can develop deeper, more highly functioning root systems. Also
remember that cattle speed up the nutrient cycling by turning forage into
urine and manure, which are more available forms of nutrients. Early
scientific examination of these practices suggests this kind of controlled
grazing will build soil fungal populations and overall productivity.
Further, a study in North Dakota showed recovery time between grazing
periods increased AMF.
Texas Agri-Life Extension

A study of three ranches with similar habitat and soils, but different
management, showed that multi-paddock adaptive grazing produced the most
soil life, and especially the highest fungal-to-microbial ratio.

3. Keep the soil covered. Leaving ample plant material on the soil surface
at all times keeps it cooler and captures more rainfall. This is good for
all soil life, which needs moderate temperature and moisture to function.

4. Develop a long growing season. The longer you can keep things growing in
the soil, the more opportunity to feed the microorganisms. Diversity helps
a lot in pastureland, and multi-species cover crops do that in crop ground.

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