40 



THE MOISTURE SUPPLY 



Lateral ditches, connected with the main ditches by gates, 

 conduct the water to each field or garden. The time at which a 

 man may secure water from the main ditch that is supposed to 

 supply his land is determined by law or agreement rather than 

 by the needs of his crops. Lateral or sublateral ditches carry the 

 water along the highest parts of each field. From the laterals 

 it is distributed over the fields or gardens to be watered. To be 

 irrigated readily the land should slope gradually and uniformly 

 in at least one direction from a given lateral. 



Methods of Irrigating. — There are various methods of applying 

 the irrigation water to the growing crop, but they are usually 

 some form of either flood or furrow irrigation. Flood irrigation 



Fig, 21. — Narrow tooth cultivator — a good tool for conse^^dng moisture. 



is extensively used for alfalfa and sowed grains, but much less 

 frequently for vegetable crops planted in rows. Furrow irrigation 

 of vegetables is much more common, though if very shallow furrows 

 are made and a large amount of water turned in, it frequently 

 breaks out of the furrows, so that in some parts of the field the 

 effect is much the same as if flood irrigation had been employed 

 (Fig. 18). Flooding is admissible with certain vegetable crops, 

 but detrimental to others, such as celery. 



A field of vegetables planted in rows is prepared for irrigation 

 by making shallow furrows at the proper intervals by means of 

 suitable attachments on tillage tools (Fig. 19). If the rows are 



