Closely connected with cultivation is the practice of scattering straw or other litter over the ground. Such artificial mulches are very effective in reducing evaporation. Ebermayer found that by spreading straw on the land, the evaporation was reduced 22 per cent; Wagner found under similar conditions a saving of 38 per cent, and these results have been confirmed by many other investigators. On the modern dry-farms, which are large in area, the artificial mulching of soils cannot become a very extensive practice, yet it is well to bear the principle in mind. The practice of harvesting dry-farm grain with the header and plowing under the high stubble in the fall is a phase of cultivation for water conservation that deserves special notice. The straw, thus incorporated into the soil, decomposes quite readily in spite of the popular notion to the contrary, and makes the soil more porous, and, therefore, more effectively worked for the prevention of evaporation. When this practice is continued for considerable periods, the topsoil becomes rich in organic matter, which assists in retarding evaporation, besides increasing the fertility of the land. When straw cannot be fed to advantage, as is yet the case on many of the western dry-farms, it would be better to scatter it over the land than to burn it, as is often done. Anything that covers the ground or loosens the topsoil prevents in a measure the evaporation of the water stored in lower soil depths for the use of crops. Depth of cultivation