210 Fruit-growing in Arid Regions 



heavy, fall irrigation is one of the best ways of wetting such 

 land. Figure 57 shows an apple orchard on heavy soil 

 well furrowed for irrigation. 



Sandy soils take water freely, and the furrows should 

 be closer together and the rows not so long as in the 

 heavier soils. In the heavy soils the water moves more 

 freely laterally, and in lighter soils the movement is down- 

 ward. The longer the rows, the larger should be the head 

 of water. The upper end of the orchard is sometimes 

 over-watered by trying to run a small head of water 

 through long rows in sandy soils. It is better to water 

 a few rows well than to try to spread the water over the 

 whole orchard the same day. The length of time the water 

 is allowed to run will depend entirely on the soil. The 

 orchardist must learn to understand his soil and know 

 how long it will take to wet it. Provided the free water 

 does not come too near the surface, heavy waterings at 

 greater intervals are always to be preferred to light and 

 frequent irrigations. Figure 58 shows a pear orchard 

 on sandy soil well furrowed out for watering. Figure 25 

 shows a common mistake of furrowing near the trees only. 

 With the sandy soil it is not so important that the water 

 be kept off the surface, but flooding should be avoided 

 if possible, especially if the ground is bare. 



Frequency of Irrigation 



Soil conditions and the treatment the orchard receives 

 between times will determine how often it must be irri- 

 gated. Sandy soils, as a rule, require more frequent 

 irrigations, especially where they have good drainage. 

 Orchards that are sparingly tilled require more frequent 



