As a companion piece to my earlier article about mycorrhizal fungi, tomatoes and salty beach sand, an agricultural advisor who lives near Yuma, Arizona, told me an interesting story about creating cropland from desert sand.
A farmer in his area set out to create a large field of alfalfa to be watered by circle irrigation - a long motorized pivoting pipe. The area to be converted was basically pure sand with a few widely scattered greasewood bushes.
Growing conditions were not the best that first season - there were some water supply problems, the seeding was not done quite early enough, etc., so the alfalfa didn't perform well...except in a few spots where the difference was obvious from a quarter-mile away. In those spots, the plants were tall and beautiful compared to the rest of the new field.
This was puzzling until my friend, who had been involved with conversion of desert into cropland during Egypt's "Green Revolution", pointed out that the good-growth spots were where the greasewood bushes had been located.
His analysis, which I agree with, was that there had been mycorrhizal fungi and beneficial bacteria colonizing the greasewood roots and that dormant spores in those spots were activated by the exudates from the alfalfa roots.
The alfalfa plants that had been lucky enough to gain the symbiotic assist of these powerful biological agents thrived under the extremely difficult growing conditions, while those that lacked the nutrient-uptaking fungi had trouble even surviving.
Using this observation, it seems to me that any desert conversion project might benefit from dusting mycorrhizal spores on the roots of transplants, or by simply adding spores to seed coatings.
Of course, the ideal approach would be to use the fungi types that are best adapted to the local plant/soil/climate conditions. (There is often more than one type colonizing a plant's root system, perhaps performing differing functions for their host plants?). I would wager that excellent candidates for controlled propagation could be easily found by digging up roots of the nearest greasewood, cactus, or acacia tree.
Two related ideas: The mycorrhizal fungi are not as plant-specific as many people seem to think - they seem to attach quite happily to nearly any new roots that come nearby - and the mature fungi spores are extremely durable. One microbioogist told me he thought some spores from inside the pyramids would probably still activate with exposure to root exudates.
These are some very determined (and useful) survivalist organisms, folks!
Good growing to you, my friends,
President, BioOrganics, Inc.