State Agricultural Society. 421 



are in general heavy and compact, are modified by the intermixture of 

 gravels, of sand, and occasionally of alkalies, into lighter sorts. But the 

 great bulk of adobe soil is compact, nearly free from grit of any kind, 

 forming with water a highly tenacious mud, and contracting, as the 

 water is expelled by heat, with the development of cracks on its surface 

 and in its substance, while the bulk of the mass bakes into true brick — 

 its degree of induration depending on the degree of heat applied. The 

 effect of these peculiarities as a soil, is that the adobe, after absorbing 

 water, forms, when exposed to the sun, a crust on top that, for a time, 

 prevents loss of moisture b}^ evaporation. Its compactness also pre- 

 vents the escape of water by percolation, and equally resists its absorp- 

 tion of water by infiltration. Thus, after having become wet, it retains 

 moisture for a season with singular tenacity. Later, when the forma- 

 tion of cracks has begun, it parts, through them, with the last particles 

 of its moisture, and becomes indurated to a greater depth than any other 

 quality of soil. In color, adobe may vary from black, through anj r shade 

 of brown or red, to a £ray — the tint depending on the presence of min- 

 eral or vegetable coloring matter. The loams, as distinguished from the 

 adobes, are light and friable, and pass by insensible degrees from the 

 more clayey heavier sorts by the infusion of increasing proportions of 

 sand, through the lighter and sandy loams, to a pure sand. They are 

 never free from grit; refuse to become fused by water into a smooth 

 homogeneous mud; and, as the water is expelled by heat, are left with 

 the particles imperfectly compacted, readily falling to pieces at a blow. 

 The effect of these peculiarities as a soil, is that the loams, after absorb- 

 ing water, part with it readily from the surface when exposed to the 

 sun, but after the upper portion has become dried the moisture from 

 deep portions is evaporated with slowness and difficulty. Their com- 

 paratively loose texture, however, permits the escape of water by per- 

 colation, and operates with equal favor to promote the absorption of 

 water by infiltration. Thus a tract of loam adjacent to running water 

 will absorb constantly from the stream and remain moist almost to the 

 surface during the hottest season and without receiving any water from 

 above. Adobe under like circumstances would bake to a brick, and in 

 effect really repel infiltration from the runuing stream. Under the in- 

 fluence of rainfall loam will absorb the water until wetted through be- 

 fore it will shed it freely from its surface. Adobe absorbs with difficulty 

 and will shed many cubic feet from its surface while slowly absorbing 

 a few into its substance. And, supposing the two classes of soil to be 

 irrigated, loam will absorb freely and allow the water to percolate as 

 freely away; adobe will absorb slowly and retain what it gets, so long 

 as cracks under the drying process do not penetrate its substance. After 

 the surface is protected from the direct rays of the sun by vegetation 

 these cracks are slow to form. The surface crust, which sometimes 

 bakes to a degree that checks the growth of vegetation, need not be 

 allowed to do so under carefully applied irrigation. It will be readily 

 seen, from these hints, that the detail of the application of irrigation 

 will vary, according as the soils treated are adobe or loam; that, in 

 attaining the best results, the amount of water applied, the frequency 

 of its application, and the copiousness of supply at different parts of the 

 season, and at different stages of crop-growth, will vary between con- 

 siderable limits for adobe soils, and for loams. Experience will, in time, 

 develop these methods in their most favorable detail; it seems worth 

 w T hilo here to point out to parties interested that this difference between 

 adobe land and loam should never be lost sight of, nor the experience 



