Secret soil

The weather is cold and wet again and altogether too crappy to go out and take pictures.  I did want, though, to delve a little deeper into the the nature of soil.  We have always believed that good gardeners feed their soil and that soil takes care of the plants in them.  I'm interested in the nature of the soil ecosystem and the way that fungi and green (vascular) plants work in a mutually beneficial or synergistic fashion.

A mycorrhiza is the mutually beneficial (symbiotic) association between a green plant and a fungus. The sun's energy is captured by the plant's chlorophyll and converted to sugars.  Those sugars are transported to the fungus via the roots.  In turn, the fungus supplies water and soil nutrients to the plant. The union occurs in the plant roots and most plant species are capable of entering into this type of relationship.  Occasionally, mycorrhizal fungi do not simply collect soil nutrients, but connect individual plants together through an underground hyphal network that transports water, carbon, and mineral nutrients between plants.

Other benefits accrue to plants which form mycorrhizae:

• Disease, drought and salinity tolerance

• Insect resistence - plants connected by mycorrihzal fungi can use their underground connections to share warning signals.  When a plant is attacked by an insect, the plant signals to other plants via its mycorrhizae. The attacked plant also releases substances into the air that attract the insect's predators. The plants connected by mycorrhiza also produce their own substances which act prophylactically to protect the uninfected plants.

• Resistence to toxicity - things like heavy metals, for example