Collapsed - Chapter 1 (Pt. 3)

the Bitterroot Valley's boom in commercial apple orchards, which were initially very profitable, collapsed, due in part to apple trees exhausting the soil's nitrogen. A more widespread soil problem is erosion, resulting from any of several changes that remove the plant cover normally protecting the soil: overgrazing, noxious weed infestation, logging, or excessively hot forest fires that sterilize the topsoil. Long-timer ranching families know better than to overgraze their pastures: as **** and Jack Hirschy expressed it to me, "We must take good care of our land, or we will be ruined."

Other neighbors made the mistake of renting grazing rights on their land to tenants, who overgrazed for a quick profit during their three-year lease and didn't care about the resulting longterm damage.

The net result of these various causes of soil erosion is that about one-third of the Bitterroot's watersheds are considered to be in good shape and not eroded, one-third are at risk of erosion, and one-third are already eroded and in need of restoration.

Remaining soil issue in Montana is salinization, a process involving salt accumulation in soil and groundwater. More recent concern is the ruining of large areas of farmland by salinization resulting from some human agricultural practices; in parts of Montana, salt concentrations in soil water have reached levels double those of seawater.

Besides certain salts having specific toxic effects on crops, high salt concentrations exert a general harmful effect on crops similar to the effect of a drought, by raising the osmotic pressure of soil water and thereby making it harder for roots to absorb water by osmosis. The salty groundwater may also end up in wells and streams and may evaporate on the surface to leave a caked layer of salt.

Salinization is a problem today in many parts of the world besides the U.S., including India, Turkey, and especially Australia (see Chapter 13). In the past it contributed to the decline of the world's oldest civilizations, those of Mesopotamia: salinization provides a large part of the explanation for why applying the term "Fertile Crescent" today to Iraq and Syria, formerly the leading center of world agriculture, would be a cruel joke.

Montana's main form of salinization is one that has ruined several million acres of cropland in the northern Great Plains as a whole, including several hundred thousand acres in northern, eastern, and central Montana. The form is called "saline seep," because salty water building up in the ground in an uphill area percolates through the soil to emerge as a seep in a downhill area up to half a mile or farther distant.

Saline seeps frequently become bad for neighborly friendship when the agricultural practices of one farmer uphill cause a saline seep on a downhill neighbor's property. Here is how a saline seep arises. Eastern Montana has lots of watersoluble salts (especially sodium, calcium, and magnesium sulfates) present as components of the rocks and soils themselves, and also trapped in marine deposits (because much of the region used to be ocean).

Here is how a saline seep arises. Eastern Montana has lots of watersoluble salts (especially sodium, calcium, and magnesium sulfates) present as components of the rocks and soils themselves, and also trapped in marine deposits (because much of…