284 



Kansas State Board of Agriculture. 



FIG. 221. Reasonable preparation of the land is very essential with small 

 water supplies. 



THE QUANTITY OF WATER TO APPLY. 



The quantity of water to apply per irrigation will depend largely 

 upon the season. Irrigation in Kansas is supplemental to the natural 

 precipitation, consequently more water is needed in some years than 

 others. Other factors also enter in, such as the character of the soil and 

 the head of water used. Sandy soils require more water than the heavier 

 loam soils. For instance, less water is required for an upland region 

 than for the sandy valleys. In the valley districts, or sandy loam soils, 

 about 6 inches of water is applied for each irrigation, and in some cases 

 as much as 9 inches are used. In the upland areas 2.5 to 6 inches are 

 applied for each irrigation. Where the alfalfa is irrigated twice about 

 2.5 inches are applied for each irrigation. Under extreme conditions on 

 the sandy lands alfalfa may receive as much as 36 inches of water an- 

 nually. However, under the best farming conditions in the valleys 24 

 inches annually should be sufficient, and in the upland areas from 12 

 inches to 20 inches should be ample for a season. 



THE HEAD OF WATER TO USE. 



The amount of water available for farm irrigation is known as the 

 "head of water." A small amount is, therefore, a "small head" and a 

 large quantity is a "high head." Where the water must be pumped the 

 farmer must usually content himself with a small head of water, and 

 where small heads must be utilized the greatest care is necessary in ap- 

 plication. Irrigation water is lost by seepage, evaporation and deep 

 percolation. When the water is applied in small quantities seepage is 

 relatively large, a high percentage evaporates, and a considerable portion 

 percolates so deep in the ground as to be beyond the feeding roots of the 



