THE WATER-COST OF DRY MATTER 141 



foods, reduced the rate of transpiration, but did not 

 diminish the water-cost of the resulting dry matter. It 

 does not follow, therefore, that on alkali soils, such as 

 occur frequently in the arid West, crops may be produced 

 at a lower water-cost than on soils containing less soluble 

 matter. Whether or not water is saved depends entirely 

 upon the composition of the alkali. In places, the alkali 

 consists largely of nitrates, potassium salts and other plant- 

 foods; but, ordinarily, alkali lands contain the chlorides, 

 sulfates and carbonates of sodium and other substances 

 of a non-nutrient character. Crops grown on the usual 

 alkali lands are not only injured by the high concentra- 

 tion of the soil solution, but they are produced at an exces- 

 sive cost of water. 



The irrigation farmer who wishes to make the best 

 use of a limited quantity of water must keep steadily in 

 mind the necessity of maintaining the soil, constantly, 

 in a very fertile condition. 



100. Cultural operations. It is well understood that 

 thorough plowing, frequent cultivation and other correct 

 cultural operations accelerate soil solubility and favor 

 bacterial activity in the soil. Nitrification, the conversion 

 of the soil nitrogen into nitrates, is especially fostered by 

 proper soil tillage. This treatment given soils should, 

 therefore, affect quite distinctly the water-cost of crops. 

 Few experiments have been made on this subject, but 

 those available bear out this belief. At the Utah Sta- 

 tion, a number of pots containing soils of varying degrees 

 of fertility were sown to corn. Half of the pots were 

 properly cultivated, and the others received no culti- 

 vation, throughout the growing season. The transpira- 

 tion ratio was invariably smaller on the cultivated than 

 on the non-cultivated soils. On College loam, the ratios 



