REGULATING THE EVAPORATION 159 



amount lost during the first weeli, over 60 per cent 

 occurred during the first three days. Cultivation 

 should, therefore, be practiced as soon as possible 

 after conditions favorable for evaporation have been 

 established. This means, first, that in early spring, 

 just as soon as the land is dry enough to be worked 

 without causing puddling, the soil should be deeply 

 and thoroughly stirred. Spring plowing, done as 

 early as possible, is an excellent practice for forming 

 a mulch against evaporation. Even when the land 

 has been fall-plowed, spring plowing is very bene- 

 ficial, though on fall-plowed land the disk harrow is 

 usually used in early spring, and if it is set at rather a 

 sharp angle, and properly weighted, so that it cuts 

 deeply into the ground, it is practically as effective 

 as spring plowing. The chief danger to the dry- 

 farmer is that he \^ill permit the early spring days 

 to slip by until, when at last he begins spring culti- 

 vation, a large portion of the stored soil-water has 

 been evaporated. It may l^e said that deep fall 

 plowing, by permitting the moisture to sink quickly 

 into the lower layers of soil, makes it possible to get 

 upon the ground earlier in the spring. In fact, un- 

 plowed land cannot be cultivated as early as that 

 which has gone through the winter in a plowed 

 condition. 



If the land carries a fall-sown crop, early spring 

 cultivation is doul^ly important. As soon as the 

 plants are well up in spring the land should be gone 



