FERTILITY AND HUMUS IN DRY AREAS 419 



But the opposite result will follow when it lies in the 

 soil without decaying, as it does sometimes when buried 

 in the form of stubble, of dry grass on sod land or of 

 strawy manure. Because of such burial and the adverse 

 results that have followed, the prejudice has arisen which 

 prevails to a very considerable extent in dry areas against 

 the application of farm manures. If straw must be bur- 

 ied, as when strong stubbles are plowed under, the aim 

 should be to disc the soil before it is plowed, that the 

 stubbles may be mixed with the soil before they are 

 buried, and then to pack the soil where it will stand 

 such packing after it is plowed. The direct burial of 

 heavy stubble by covering it in a shallow furrow, in the 

 eastern portions of the semi-arid area, where heavy 

 stubble is frequently produced, has led to the ruin of 

 many a grain crop. The stubble thus lying in the bot- 

 tom of the furrow has prevented the ascent of soil mois- 

 ture and also the downward penetration of the roots. 

 Why, then, does the plan of burying the straw of grain 

 that has been headed meet with so much favor? Because 

 (1) its deep burial is usually followed by the bare-fallow, 

 which gives it time to decay ; (2) because in its decay it 

 encourages all the processes of bacterial life which are so 

 helpful to crop production ; (3) because of the plant food 

 which it furnishes in its decay, much of which is brought 

 up from the subsoil while the crop that produced the 

 straw has been in process of growth, and (4) it makes 

 the soil more porous and therefore more easily and ef- 

 fectively worked for the prevention of evaporation. The 

 burning of stubble, like the burning of straw, is a most 

 baneful process. 



Organic matter in the soil furnishes food to plants 

 in a readily available form. The plants that are buried 

 have gathered food from, the soil through the wide dis- 

 tribution of their roots, and by processes that have been 

 slow in their action. When the organic matter thus 



