186 DRY LAND FARMING 



young plants that spring from them sufficiently to pro- 

 tect them at least measurably well -from the harmful in- 

 fluences of drought. 



The season may influence the depth to which seed 

 should be sown by the amount of moisture which it puts 

 into the soil or withholds from the same. In times of 

 prolonged drought, the soil, other things being equal, 

 dries to a greater depth than when the weather is the 

 opposite in character. This, of course, influences the 

 depth to which seeds must be buried, if they are to grow. 



The nurse crop and sowing. In humid areas the 

 rule is to sow grasses and clovers on land which 

 will also sustain a grain crop the same season. The 

 grass crop is thus established without losing the crop 

 of one season in order to establish it. In some instances 

 this would not be practicable in semi-arid regions. If 

 two crops are sown thus, there' is a contest between them 

 for moisture during the period of growth. The grain 

 crop, that is, the nurse crop, makes the more vigorous 

 growth, and, therefore, it gets the larger share of the 

 moisture to the injury of the other crop in proportion 

 as its power exceeds that of the other to draw on the 

 moisture in the soil. The nurse crop also weakens the 

 other crop by its shade in proportion as it is strong or 

 weak. Moreover, while the nurse crop is maturing, its 

 draughts upon soil moisture are unusually large, leaving 

 so much less for the grass or clover crop at a critical 

 time. The hazard is present that when the nurse crop 

 is harvested the plants will succumb to the hot sun 

 which shines down upon them at that season from a 

 torrid sky. In humid areas these influences are also 

 operative, but not to the extent, save in a few instances, 

 of destroying the crop that is being nursed. 



It may be legitimate in dry areas to use a light nurse 

 crop (1), when sowing certain grasses for making pas- 

 tures of more or less permanence, and (2) when the soil 



