Relation of Soils to Moisture and Air 57 



from which it can be taken to water the market gardens on 

 the flats by running the water slowly between the rows of 

 vegetables. With high-priced products like those of the 

 garden it is often, even in humid districts, profitable to 

 provide some means for watering in dry weather. With 

 the introduction of cheap gasoHne engines for pump- 

 ing water to elevated tanks this can often be accom- 

 plished even on lands that cannot be watered from 

 streams. 



In some sections, especially in Europe, on high-priced 

 lands, the sewage flow from the cities has been utilized in 

 the production of great crops of grass. The sewage flows 

 over the surface and the surplus water is carried off by a 

 system of imderdrains. Irrigation for general farm crops 

 in our humid sections is still in the future, but will come 

 with the increase in population and the value of the farm- 

 ing lands. In one large institution of over five hundred 

 inmates, in this country, the sewage is disposed of on a 

 five-acre lot of grass. The sewage is received in a general 

 cesspool from which porous tiles radiate in all directions, 

 and below these are Hnes of drainage tiles to carry off the 

 surplus water, which flows almost entirely purified by 

 the absorbent power of the soil, into a stream below. 

 The field cuts very heavy crops of grass. 



It is probable that the overhead system, imitating a 

 rainfall, will be the one most generally used by market 

 gardeners. One market gardener's farm in North Caro- 

 lina has now eighteen acres irrigated in this way. The 

 overhead sprinkling pipes can also be used for the distri- 

 bution of fertihzers dissolved in the supply tanks and can 

 thus be distributed in the most uniform and readily avail- 



