374 The Land and Its Treatment 



2. The tillage, of maintenance should occur, at least as 

 frequently as ouce in ten days for the best market-garden? 

 conditions. Surface-tillage enables the land to drink in 

 the water of rainfall. It also saves the soil water by 

 hindering evaporation : it maintains a loose and dry layer 

 that acts as a mulch to the moister soil beneath. The 

 depth of this mulch must be determined by the character 

 of the soil, kind of crop, frequency of tillage, and char- 

 acter of tools; but, as a rule, from three to four inches of 

 loosely stirred earth is sufficient. It also solves the diffi- 

 culty of weeds. 



The soil in the surface-mulch is relatively dry, and it 

 is moved so often that roots do not secure a foot-hold in 

 it. It is therefore out of use for the time being as a 

 source of plant-food ; but it is more useful as a conservator 

 of moisture than as plant-food. Its nutriment comes into 

 use when it is turned under the following season, and it is 

 also carried down by the rains, particularly by those of 

 spring and fall. 



All tillage of preparation — all fitting of the land — 

 should be completed before the crop is put in: thereafter, 

 only the surface-mulch is to be kept in repair. But many 

 times the preparation-tillage is not completed in its season, 

 and the land must be fitted after the crop is sown by 

 means of deep and heavy cultivating; it is usually a loss 

 of effort and efficiency when preparation-tillage and main- 

 tenance-tillage must be performed at the same time. 



The rainfall of the growing season is often insufficient 

 for the crop. The plants draw on the moisture stored in 

 the soil by the winter rains and snows. Therefore, it is 

 exceedingly important to save this winter rainfall, and this 



