62 CALIFORNIA VEGETABLES 



Permanent Ditches. The use of permanent ditchers was for- 

 merly very common in the irrigation of sloping garden ground and 

 is still somewhat observed. These ditches are drawn very nearly 

 on contour lines, only just enough fall being given to move the 

 water slowly. When the slope is nearly uniform the ditches are 

 almost parallel and they are distanced according to what is known 

 of the movement of water by seepage down the) slope in each par- 

 ticular soil. The plantings are made on the plan of each strip 

 securing its moisture from the ditch above and water is admitted 

 occasionally or kept running almost continuously according to the 

 needs of the particular crop or the leakiness of the ditch. The out- 

 flow from the ditch, after traversing backward and forward its full 

 length, is carried to an alfalfa patch below and thus utilized. These 

 permanent ditches serve a good purpose in saving hillsides from 

 washing as they catch the/ surface storm water before it has a chance 

 to acquire much headway and carry it down gently. Where the 

 soil favors such distribution very good results are attained with 

 these ditches, but the tendejncy is to use the ditches too long and 

 allow them to become cemented by action of water and deposit of 

 slime. Besides thejy grow weeds and distribute seeds if their banks 

 are neglected. In most cases it is better to employ less permanency 

 breaking up the ground and locating new ditchers at shorter in- 

 tervals of time. 



Lowland Irrigation by Seepage. Another form of irrigation 

 by means of permanent ditches is that practiced on reclaimed lands 

 along thq interior rivers. When the rivers are swollen from sum- 

 mer melting of snow in the high Sierra, the water is brought to the 

 land by flood-gates in the levees. When the rivers are low ve,lry 

 capacious pumping plants are used the same serving at other times 

 to drain the lands when they are too wet from the rainfall or seep- 

 age. The soils of these reclaimed lands is loose and prone to dry 

 out because of their lack of capillarity, so that at times irrigation is 

 as necessary as on uplands. The water is distributed by means of 

 small, rather deep, ditches from which moisture readily extends as 

 the water moves out over the\ clay bottom which underlies most of 

 these lands and makes it possible to hold the water up within reach 

 of the roots of the plants. With rich land, high heat and ample 

 moisture just below the surface the growth is almost marvelous. 

 On these lowlands flooding the surface frequently seriously in- 

 jures the plants by sun scald. 



