82 CALIFORNIA VEGETABLES 



to grind an inch or two of the surface to powder. The free move- 

 ment of air through this shallow layer at least in our summer air 

 with its exceptional thirst, will proceed with evaporation from the 

 too thinly covered compact portion and the loss of moisture will be 

 only a little less rapid and complete than if the surface had not been 

 disturbed at all. The same, thing will happen if the surface layer 

 be only coarsely broken to a still greater depth: the passage of air 

 through the clods will be free enough to draw off the moisture and 

 the soil will dry out to a degree which will bring distress to plants 

 which good cultivation would have maintained in vigorous growth. 

 It is plain then that the earth mulch must be fine enough and deep 

 enough to serve its intended purpose and for this no arbitrary rule 

 can be laid down except that the coarser the soil by nature or the 

 coarser the particles by cultivation the deeper the mulch must be. 

 The practical test is easy ; if the pulverized layer become dry and 

 if on brushing it aside with the foot, the firm surface is hard and 

 more or less dry also, the mulch is not effective and its character 

 must be improved. 



Steps by Which Conservation is Attained. The foundation for 

 a satisfactory moisture-conserving tilth is laid with the plow during 

 the fall or winter preceding the summer during which it is to be 

 maintained. Though plowing has been considered as a factor in 

 opening the soil to receive and store moisture it is also considered 

 in its conservation. To do this the plow must be used when the soil 

 is in the best condition not only for turning but for disintegrating 

 by the crushing action of the mold board so that the soil particles 

 shall lie closely upon the firm portion and not form large air spaces 

 which minister to drying out. Plowing when the soil is unfit results 

 in clods, which are every way hateful in the garden, and in air" 

 spaces, which are objectionable, as shown. Even when the soil is in 

 reasonably good condition, late plowing, if left rough and open to 

 dry winds, will form clods in all except the loosest soils, conse- 

 quently all late plowing should be at once well harrowed. 



The next step in the assurance of a good earth mulch is the 

 early use of the cultivator. It will not do to allow the harrowed 

 soil to crust by rains and then trust to some later rain to loosen and 

 rescue the young plants from its embrace. Just as soon as the soil 

 arrives in condition after a rain, stir the surface well and the crust 

 will not be formed, and this must be done just as often as crust- 

 forming conditions recur. In this way the soil surface is constantly 



