463 ANNUAL REPORT OF THE Off. Doc. 



the soil and which acts as a blanket to prevent the rapid escape 

 of moisture into the atmosphere. The principles involved in this 

 case are quite similar to those described in the case of tillage and 

 plowing. The water is prevented from escaping because the mulch 

 distributed upon the surface soil prevents the immediate contact 

 with it of the hot, dry winds; these affect first and directly the 

 mulch itself, which protects and cools the surface. The use of 

 mulches for small areas is very helpful, and while not practicable 

 on large areas it can be made of practical value in gardens and 

 orchards and for special purposes. 



Growing crops are regarded as of use, also, in conserving mois- 

 ture, though in a different way, particularly in the humid climates, 

 since a soil well covered with a crop will absorb proportionately 

 more of the rainfall than one lying bare, largely because it prevents 

 surface drainage. Furthermore, the rapid escape of the w^ater in 

 the atmosphere is prevented because, as in the case of the other 

 forms, the winds do not come in immediate contact with the soil, 

 thus more of the moisture passes off through the crop rather than 

 directly into the atmosphere. In the case of crop mulches grown 

 as a catch for the primary purpose of covering the soil between 

 the regular crops of the rotation there is a further advantage in 

 that the vegetable matter accumulated by them is incorporated 

 with the soil, which is materially improved because of the intro- 

 duction into it of a substance which in itself, as already pointed 

 out, has a higher absorptive power. This vegetable matter as it 

 decays becomes what is known as "humis," a substance which exer- 

 cises a very important influence upon the productive power of the 

 soil. 



Burning Straw a Wasteful Practice. 



In many section® of our country, particularly in those States 

 which possess soils rich in fertility elements, it is the custom to 

 burn straw and other refuse vegetable matter. This is a bad prac- 

 tice, for even if it is not needed for improving the productive power 

 of the soil in respect to other elements, if it is used as a mulch and 

 incorporated with the soil it would assist very materially in retain- 

 ing moisture for crops during the period of insufficient rainfall. If 

 the straw is not needed for bedding and other purposes it should 

 be distributed over the land, serving first as a mulch and then incor- 

 porated with the soil, thus improving its absorptive and retentive 



power. ■ ■■''!'•■; i 'l'":|^:^| 



The Effect of the Eolling. ' 



Kolling the soil is another means by which moisture may be 

 conserved, though the results of the use of this tool should be 



