88 



The number of furrows into which the irrigating head may be divided 

 will depend much on the character of the soil and grade of furrows. In 

 some cases one half a miners' inch or even less may be run into each fur- 

 row while for some sandy soils it is necessary to use 3 or 4 miners' inches 

 in order that the water will reach the lower end of the furrow and not be 

 all absorbed at the upper end. On tight soil a small stream must be used 

 in order that it will run slowly in the furrows and give time for the water 

 to percolate into the ground without a waste at the lower end. To prevent 

 the upper end of the furrows from receiving too much water it is always 

 desirable to begin with a large stream into each furrow and rush the 

 water to the lower end, then reduce the size of stream to obtain an even 

 distribution. 



With furrows 330 feet long, 6 feet apart, and a British Columbia miners' 

 inch to each furrow, the time which the water must run to give an average 

 depth of water on the soil of 6 inches is about 10 hours. Depending on the 

 nature of the soil and length of the furrow, the time the water is run into 

 the furrows varies from 4 to 48 hours. Prof. R. W. Fischer, of Montana, 

 found that on the clayey loams of the apple orchards on the east bench of 

 the Bitter Root River, it requires from 12 to 18 hours to moisten the soil in 

 furrow irrigation, 4 feet deep and 3 feet sideways. 



5. Prevention of Losses of Water Applied; and Cultivation. 



The losses which occur in the application of water to the soil are: 



1st. The losses due to unequal distribution of water iu the soil caused 

 by deep percolation and waste at the upper end of the fields, unequal 

 division of water between furrows, and excessive use of water which is not 

 retained by the soil. 



2nd. Loss from neglect, because of careless irrigation which allows 

 waste in the low places and at the ends of the furrows, causing injury to 

 roads and adjoining orchards or farms. 



3rd. Loss by evaporation of the water in the furrow itself and especial- 

 ly of the soil moisture from the wet soil. 



The remedies to minimize the losses due to unequal distribution of 

 water in the soil and the waste due to deep percolation have been fully 

 discussed in the preceding pages. The loss from neglect can be largely 

 prevented by care. The losses due to evaporation can be lessened by apply- 

 ing the water in deep furrows and by thorough cultivation. 



Irrigation with deep furrows places the water well below the surface 

 and does not wet the surface soil to the same extent as with shallow fur- 

 rows; this decreases the evaporation loss and permits cultivation of the 

 orchard soon after irrigation. It also encourages deep rooting which Is 

 always desirable except where the soil is very shallow. 



Cultivation is one of the most important factors not only to prevent 

 evaporation, but to improve the condition of the soil. To prevent evapora- 

 tion the soil should.be cultivated immediately after each irrigation. Pro- 

 fessor Fischer, Horticulturist for the Montana Agricultural College, states 

 that as a general rule orchards should be cultivated every ten days during 

 the growing season until about August 1st. Cultivation should stop at that 

 time, especially in young orchards in order to induce the trees to mature, 

 thus putting them in better condition to endure freezing temperatures in 

 the early fall and winter. He describes the process of cultivation in 

 Montana as follows: 



