CROPS AND CROP TILLAGE. 35 



tegratiiig wheat straw, a good supply of soil moisture, high soil 

 temperatures, and the presence of alkaline bases to combine with the 

 nitric acid produced. 



ORGANIC MATTER LOST BY OXIDATION. 



In view of the importance of organic matter in maintaining the 

 fertility of these dry-farmed soils there is a strong incentive to avoid 

 excessive losses by direct oxidation. 



In maintaining the clean sunnner fallow previously described, it 

 is necessary to keep the upper 8 inches of the soil thoroughly stirred 

 to form the surface mulch. This portion of the soil, being very dry 

 and well aerated, is kept in a condition which is most favorable to 

 "burning out" the organic matter which it contains." The loss of 

 organic matter in this way can not very well be avoided, for an effect- 

 ive surface mulch is necessary to prevent the loss of moisture from 

 the lower soil. It is possible, however, to very greatly reduce the 

 loss due to oxidation by deep plowing, which increases the depth of 

 the surface soil in which the nitrification and nitrogen fixing can 

 take place. These processes go on very slowly, if at all, in the soil 

 below the furrow slice, so that deep plowing is very necessary to the 

 best results in dry farming, not only as a factor in securing and con- 

 serving soil moisture but also in promoting the activities of the 

 various organisms that work in the loosened soil and help to make it 

 productive. 



DBY FARMING SUPPLEMENTARY TO IRRIGATION. 



With a few exceptions, the irrigated sections of the Great Basin are 

 surrounded by arable lands which are either too high to be economic- 

 ally irrigated or too extensive to be irrigated with the available 

 water supply. In the gi'eat majority of cases these lands receive 

 rainfall enough for the production of some special crops even when 

 it is insufficient to support farm homes or even for the growth of 

 wheat and alfalfa with the best of tillage. 



It is very doubtful whether a settler would be safe in attempting 

 to make a home and start a farm on even the more promising of these 

 dry lands. At the present time almost all the farming on the dry 

 lands is done in connection with some irrigation farming. In many 

 cases the farmer has little more than his garden and orchard under 

 ditch, but it is at least enough to insure him fruits and vegetables 

 for his table, and, if need be, a little forage for his stock in the event 

 of a severe and protracted drought. 



This plan of utilizing the unirrigable dry lands is much safer for 

 the individual and is also much better for the community. Farming 



oStorer, F. H. Agriculture, 2: 28-29, 1902. 

 103 



