Early Tillage to Conserve Moisture 147 



over plowed fields when a considerable evaporation has taken 

 place from the wet surface, and which, on account of the shrink- 

 age and of the salts brought to the surface by the soil water, tend 

 to close up the soil pores, and thus interfere with the proper 

 entrance of air to it, which is essential to the best results. Roll- 

 ing in such cases will seldom do much good, except where the 

 ground was left somewhat uneven at the time of seeding, either 

 by the drill ridges or by those left by the harrow, or unless there 

 are many small lumps, which the rolling tends to break down, 

 forming from them and the ridges, or both, a thin mulch. The 

 harrowing in such cases has a wider range than rolling, and is 

 often likely to be more effective. But neither of these treat- 

 ments should be given except when the soil of the field is dry 

 and crumbly at the surface, for otherwise no mulch will be formed, 

 and the effect would be to increase rather than diminish the loss 

 of water from the soil by surface evaporation from it. 



4. Early Tillage to Conserve Moisture 



It has already been pointed out that tillage to 

 conserve moisture is most useful in humid climates 

 when it is applied as early in the season as the condi- 

 tion of the soil will admit. But the case is stated in 

 the most general terms when it is said that tillage, 

 to save moisture, should be given to the soil just as 

 soon after the wetting of the surface as it is possi- 

 ble to do so without puddling or otherwise injuring 

 its texture. 



Let it be fully understood that tillage to save soil 

 moisture is concerned almost wholly with the saving 

 of that which has penetrated the soil to a depth exceed- 

 ing that of the mulch developed by stirring, As a 

 thoroughly effective soil mulch cannot be readily made 

 having a depth less than 2 to 3 inches, it follows that 



