72 CALIFORNIA VEGETABLES. 







The use of winter storm water often results in a con- 

 siderable contribution to the fertility of the soil in the 

 form of silt and other materials rich in plant food. 



HOW MUCH IRRIGATION IS NEEDED? 



It is impossible to answer this question exactly for any 

 crop, but it can be approximated more nearly for an or- 

 chard or vineyard or a field crop than for a garden, which 

 should be held up to its maximum of free water nearly 

 all the time. Evidently the requirement for gardening 

 is greater than for any other cropping. How much water 

 will be required to hold any piece of land up to its best 

 estate of moisture, depends upon the plant grown, the 

 soil and subsoil, the slope and exposure, the local heat 

 and dryness of the air, the rainfall, etc. The quantity 

 can, then, only be determined for each piece of ground 

 with the' data of its conditions and environment, and the 

 observing man will allow the plants to tell him by their 

 vigor and speed of growth how the supply suits them. 



Ardquate Use of Water Essential. Beyond any theo- 

 retical computation of the amount of water needed, it is 

 one of the plainest teachings of California experience 

 that good, thorough soaking of the ground is the secret 

 of satisfactory results. Surface sprinkling without pene- 

 tration is a delusion even in lawn growing. It gives the 

 impression of moisture when the roots of the plant may 

 be famishing in dry ground. Pouring on water from a 

 watering pot, though it be once every day, will make 

 a brick to inclose the plant stem and roots if the soil be 

 prone to bake. On larger scale work it has been fully 

 demonstrated that for productiveness a small piece of 

 ground thoroughly soaked with water and then as thor- 

 oughly cultivated on the surface to kill weeds and pre- 

 vent the waste of moisture into the air by evaporation, 

 is preferable to twice the surface only half watered. One 

 very thorough wetting, with good cultivation, will pro- 

 duce better results than several superficial waterings. 



