Arizona republican., 1898-06-29

various parts of the cultivated portions of Salt River valley adjacent to Glen dale, Phoenix, Tempe and Mesa. The bulletin contains a map with locations of soil samples marked so that those with the valley will be able to connect their own experience with the discussion of the laboratory results contained in the bulletin.
 The points especially considered in the bulletin are:
 1. The amount of the various es- sential elements of fertility, including lime, potash, phosphoric acid and ni- trogen, together with other constitu- cnts of more or less direct value in sustaining plant life.
 2. Because of the importance of the behavior of soils with water in an ir- rigated country much attention has been paid in these examinations to tue power of these soils to hold water, to supply it to crops. and the comparative rapidity with which it is taken up dur ing irrigation and lost by drainage. In this connection the various types of soils adapted to different crops, such as grains, trees, and alfalfa are In- dicated and the bulletin may be of practical value in the selection of land for these various purposes.
 3 In all the samples the amount and nature Of the alkali is determined and its probable effect, injurious or otherwise, discussed in each case
 In summing up the results of the bulletin it is stated that the soils of Salt River valley are rich in the ele- ments of fertility commonly supplied ill fertilizers, with the possible excep- ton of n;trogenous compounds, such as are supplied by means of nitrates and to some extent in barnyard ma nure and other common fertilizers. The presence in the soil of large amounts of zeolites, containing large stores Of plant food, which are slowly given up as required, points to excellent wear ing power in the soils of this regicn.
 With few exceptions alkali Is not present in injurious amounts for most crops. In a few localities it is suffi- ciently abundant to prevent cultivation of the soil until special means for its removal 3ave been taker but on the whole the alkali is much less of a problem in Salt River valley than in many other agricultural regions of the southwest. The alkali, as should be noted, also is very white in char acter, white alkali consisting chiefly of common and Glauber's salts and much less injurious than ''black" all kali, which is simply another name for salsoda.
 The opinion is advanced that the chief trouble with the soils of this re- zion lies less in any deficiency of the elements of fertiliey than in the dens } competed condition of these arid soils. This is due TO various causes. such as burning up of vegetable mould, or humus. by the heat and drouth Of our long, hot summers, presence of al kali, the packing action of heavy rains, etc.
 The cheapest and most practical
 method of relieving the dense condi- ton of the virgin soils of the valley in connection, of course, with the rough tillage, is the addition of humus to these soils. Since humu5 contains large amounts of nitrogen Its addition to the soil would result in making good the deficiency of this el- ement of fertility in most of the soils of the valley. The principal means by which this addition of humus and nitrogen is made is the growth of all falfa and other leguminous crops upon the land. The strong roots of alfalfa in particular loosen the soil to great depths, making it impervious to air and water, while the decay of old roots and stubble contributes
 humus to the soil. More than this, alfalfa has the remarkable power of
 taking nitrogen from the air and transferring it to the soil in forms which make it available to subsequent crops. Alfalfa is simply one of a great class of plants known as le- gumes which have this particular pow CT and one of the most important questions for investigation at the pres ent time is that of finding out the most useful leguminous plants for the purpose of green-manuring in this re- zion.
 In few words the chief conclusions arrived at in the bulletin are:
 l. That the chief deficiencies of the soils of the valley, in general, are the lack of vegetable mould, or humus, and of nitrogen, which is usually as sociated with humus.
 ,. That these deficiencies, in any reasonable scheme of agriculture in this region. must be made good by some process of fgreen-manuring, which simply means that various leguminous crops such as alfalfa, clover, vetches CT others must be grown upon the land for at least part of the time.
 Copies Of this bulletin may be had free of charge by addressing the ex- pertinent station, Tucson, Arizona. CROPS AND CLIMATE.