The Arizona sentinel., 1896-02-22

of tlic Gia and Colorado rivers have fol the most part deep sedinentary soil of brownish gray san'ly To m, resting, in most places, upon gray clay suhsoi at a depth of from Sen to twenty feet below the surface The clay subsoil forms hard pan whiah is imperyous to water. These soils have been slowly formed by the decomposition of shales sandstoncs, marls. lmestones, etc., mixed with or gznic and vegetable matter, washed down by the mighty rivers and have been gradually deposited during the course of centuries. The fertilzing brownish mud held in the wat tlof the Colorado and Gila rivers resembles that from the Nile, and its quantity varies from O.1 to O5 per cent, though the water when even considerably discolor- ed by mud is good to drink, resembling in this pect the Missouri river water. A chemical analysis of the sediments of the Colorado and of the Nile exhibits wonderful similarity in the constituent parts of each. That of the Colorado exhibiting a trile less potassa, most phosphoric acid and car bonade of limestone beds through which the Colo rado pessTs. In other respects the sediment of the Colorado is almost identical with tbat of the Nile It will be noticed therefore, that when this water is used for irrigation it is superior to aresan waters since it is constantly supplying the land with the richestferilizng elements. The soil of the valleys
 
 and uncombined carbon, readily absorbing the aerial gases such especially, oxygen, which en- ering the soil, dccomposes the organic matters so that they can be taken up and nouriSh the plants which may De considered leading featur, in it's fertility. It also readily takes up and retains moisture, while the rmness of its particles affords every facility for percoation and the activity of capillary action. In its mechanical composition it's particles are in a state of very fine division, which renders it more productive than coarser soils It acquires heat adiy in the daytime, and the loss of the heat at n.,. is very gradual so that it re- mains always warln and is not subject to sudden changes of heat and cold. Besides its essential stituents of water, organic vegetable matter, sand and clay, chemical analysis shows that lime, soda, magnesia iron, ammonia and available forms of nitrogen, phosphoric acid and potash enter into composition in tn proportions best adapted to add to it's fertility, though, of course, is alway the in soil analysis, it's composition varies in different localities and is not always constant.
 The soil of the uplandS, or mesas, lighter and more gravelly and in some places of free, loarny, calcareous character. The mesa lands are warm and generous They seem especially adapted for the grape, olive and citrus fruits generally. Their soil contains more magnesia, lime or chalk than the bottom lands. It never cracks and retains moisture admirably in summer It is of that character which will produce wine that will keep good for fifty a hundred years, and improve annually, not being liable to sour, on exposure to the air after year old, to become turbid and change color fl tic bottle or glass.
 We safely say that the soil of Yuma County ba ;+ j oil the essential elements of richness and fertility.