;J74 BOARD OF AGRICULTURE. [Pub. Doc. 



affected by drought and in the increased power of the deeper 

 soil to obtain moisture by capillary attraction from below. 



The insufficiency of aeration alone to supply moisture in 

 amounts large enough to sustain ordinary vegetation is often 

 shown by drained peaty soils, which, though of the most 

 porous and absorbent nature, are not only incapable, dur- 

 ing seasons of prolonged drought, of acquiring moisture by 

 aeration (absorption from the air above), but are equally 

 incapable of receiving it by capillarity (absorption from the 

 water table below). The difficulty with such soils is that 

 the size of the pores is so large and their volume so great 

 that, while permitting the greatest possible degree of aera- 

 tion, they are incapable of lifting water to a sufficient height 

 by capillary attraction, and so remain dry. The same is 

 true of soils composed of or underlaid by coarse sand or 

 gravel. They too admit of the highest degree of aeration, 

 but have little capillary power ; whence it appears that it is 

 the extremely porous soils of whatever material — that is, 

 those best adapted for aeration — that suffer most in time 

 of drought. 



Well-drained soils, then, are not so effectively benefited 

 in a dry time through the moisture which they absorb from 

 the air as through that which they permanently retain below 

 the effective action of evaporation and above the water table, 

 supplemented by that absorbed from below through capillary 

 attraction. 



Such soils, whether too exclusively of peat or of coarse 

 sand, may be improved by processes which tend to compact 

 them so as to reduce the size and volume of their pores, 

 thus diminishing aeration and increasing the moisture ob- 

 tained by capillary attraction. In the case of well-drained 

 peat soil heavy rolling after sowing or planting is often an 

 effective aid to the germination of the seed. In dry times 

 grass seed sown on such land will often be found to sprout 

 and grow in the deep foot-prints of men and horses, while 

 elsewhere no growth may appear until copious rain has 

 fallen. Another method is by increasing the compactness 

 and weight of peat by adding to and mixing with it either 

 tine sand, clay or marl, or a combination of them, which 



