53 



Cost of ap]ihiin(j water. 



Irrigation head used by one irrigator miner's inches. . 163 



Number of acres irrigated by one man in one day acres. . 5 



Cost of one irrigation per acre. . $0. 44 



Cost of season's irrigation do $1. 07 



An idea of the methods employed may perhaps best be conveyed by 

 a brief description of the irrigation of two staple crops in difierent 

 parts of the State, viz, a grain crop grown in the Gallatin Valley and 

 an alfalfa crop grown in the Yellowstone Valley. 



IRRIGATING BARLEY IN GALLATIN VALLEY. 



The land for a crop of barley in the Gallatin Valley is usually 

 plowed in the fall just after harvest and is permitted to lie without 

 further cultivation until the following spring. About the first of May 

 the surface is usually dry and it can then be leveled, harrowed, and 

 seeded. In that section the average rainfall for the two months of 

 April and May is nearly 4.5 inches, enough for the needs of the plant 

 until it is 5 to 7 inches above the ground. The barley crop reaches 

 this stage the latter part of June and is then ready for the first irriga- 

 tion. Assuming that the head ditch is already constructed and 

 properly cleaned out, the first thing to be done is to mark out the 

 laterals and furrow them out with a ditch plow. The marking out is 

 often omitted, but when done the grade allowed in fields that have 

 been carefully leveled is about 0.5 inch to the rod or, when a 100-foot 

 chain is used, 0.2 foot to 100 feet. The laterals are spaced 60 to 80 feet 

 apart, although the narrower space is to be preferred. Each one con- 

 nects with the head ditch and is terminated about 50 feet from the 

 lower border of the field. A dammer drawn by one horse follows the 

 ditch plow and forms the earth checks, which are spaced about 60 feet 

 apart. Canvas dams provide the most convenient check for the head 

 ditch. By their use a stream of 75 to 125 miner's inches is divided 

 between two neighboring laterals and the small areas lying between 

 the supply ditch and the first checks are irrigated. The checks of 

 earth are then broken with a long-handled shovel and the water flows 

 in each lateral until it encounters the next check, where it is held until 

 . the next space is irrigated. In this way each of the strips lying 

 immediately below each lateral is watered. A thorough irrigation 

 consists in saturating the soil to a depth of 1 foot. In some seasons 

 one irrigation will suffice. In dry years two v.-aterings usually pro- 

 duce the largest yields. Sometimes the second irrigation is light, 

 only part of the full supply required to saturate the soil being used. 

 A volume of water equal to a depth of 6 inches spread evenly over the 

 surface is usually sufficient, when there is no waste, for one thorough 

 irrigation. When the land is uneven or not properly leveled-or when 

 it is broken up by ravines, there is usually considerable waste and it 



