The St. Johns herald., 1900-03-10
TIMELY HINTS FOR FARMERS. NO. II.
BLACK ALKALI.
BY THE CHEMIST.

6H HE C6h4AOAs Black Alkali, though a white. sub stance, is so named because, in contact with the vegetable matter of vet soil, it produces the dark appearance 30 wen and unfavorably known to the irrigation farmer. 1t is the same in composition US common washing Soda. which rssen- bles ;he csustic principle of wood ashes extracted in common lye. It is chiefly formed by the decomposition of granite rocks, and when the natural rainfall and drainage are not sufficient to carry ik away it remains in the soil.
 Southern Arizona, being semi-srid and traversed by many granite mount ain ranges, contains some black alkak in the agricultural soils, though the g. mounts are not excessive excepting where irrigation has caused concentra- ton of the alkaline salts.
 This fortunate deficiency is probably due in part to those occasional down pours of rain characteristic of the south west, which suddenly food the surfass oi the country and which probably zk such times sweep away large anounta of soluble alkaline salts This, indeed, has been observed to be true, as shown by the changed character of the salts in solution in Salt River iR time of food
 The limit for black alkai in a soil va ries with the kind of crop and tie natuie of the soil. Sugar beets, for instance. are more hardy than grains, and plants from arid countries usually endure moro aIkai than those from humid regions Clay soils, more than sandy ones, are injured in tilth by black alkali. In gen. eral, I per cent of black alkali in the two top feet soil will prove destructive to most crops.
 The injuries effects of black alkali arc brought about in various ways; it de- stroys the tilth of heavy soils. causing thrm to become cloddy and difficult to cultivate. Also, in presence of water, is dissolves the humus or vegetable mould fin the soil and thus allows of it's removal. But its worst effect is its corrOsiveaetiOn directly upon the plant at or near tho ground where, especially in hot, dry weather after an irrigation, the alkali, as an effect of evaporation, collects in the form of a crust.
 In Salt River valley the average of % analyses shows only .044 per cent of black alkali, but at some of the lower lew els where the ground IS subirrigated by water from the canals, black alkali ex- ists in destructive amounts having been concentrated through the action of irri- gating water.
 The seepage from such localities car ries black aikali in solution, as the case is in Jenkins seepage ditch near Double Buttes, southwest of Tempe. On the Oth- CT hand, Salt River hasbeen observed to contain lime in the form of gypsum which is an antidote for black aIkali. In time of high water this uper river water may modify or overcome the alkaline charse- ter ot seepage water. It is therefore probable that lands lying under seepage canals are at some times benefited. a. part frorl the addition of silt, by the sp- plication of upper river water.
 The best remedy for alkaline salts of any sort, where drainage is possibls, is to flood the ground for sufficient times many days if necessary, to carry the salts down and entirely away into the country drainage. This is praetised in Utah and is stated to have been done near Buckeye.
 In small areas of valuable lands. gyp- sum, in we'll drained soIl. can some- times be used with economy to overcome black alksli. One ton per acre of gyp- sum would overcome about .U36 per cent of black alkali in the surface tOot of soil. Gypsum exists near ysil's Sta ticn, twenty miles east of Tucson, and the chief cost would be that of transpoT- tation.
 Much land IS being cleared at this tiue-sf year in preparation for planting DIhe brush often being collected in graak piles and burned. Since ashes contain black alkali in considerable amount, the site of an old brush fire may easily be marked by an alkaline spot in years to come. It would be better to drag the brush to the roadside where possible, or burn it in very small piles so as to dis tribute the alkaline ashes.
 Ashes, also, are sometimes used here as fertilizer. Tn eastern states, where
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