36 . VERTICAL FARMING 



legumes is also' drawn from the soil air. This air circulates 

 through voids or pores which are stopped up by excesses of 

 free water that cannot drain away. Such a condition stops 

 the actions just described, and must be guarded against by 

 keeping free water drained away from the active feeding zone 

 of the roots. When the water table is within the reach of the 

 deeper roots, small feeders are sent down to or near the water 

 surface and drawn from the moister soil there. 



Cultivation and Yields. The easiest soil to plow or cultivate 

 is one that has all excesses of free water drained away, and has 

 dried a little so that it will crumble rather than break in lumps. 

 A wet, soggy soil is not only hard to cultivate, but the very act 

 of working it injures instead of being a benefit. The air i? 

 worked out, and the air spaces themselves are closed by the 

 process, and the granulation is destroyed. A very dry soil 

 breaks up cloddy, and the condition produced by plowing it 

 when it is in this condition is sometimes nearly as bad as if it 

 had been plowed wet. The proper storage of capillary moisture 

 by good cultivation is the only safeguard to maintaining the 

 proper tilth of the soil and to prevent puddling or the forma- 

 tion of clods. 



The aim of the farmer is to produce crops at a profit. Water 

 is the cheapest article he has to handle, and is at the same time 

 one that allows itself to be handled almost at will, but becomes 

 a serious drawback if allowed to take its own way. It must be 

 there as a food and a carrier of other foods, as a control of 

 the temperature of the soil, and to insure the proper granu- 

 lation of the soil. Everything that can be done to the soil in the 

 way of getting rid of excesses of free water and holding the 

 maximum of capillary water will make itself known in the 

 increased yields it affords. 



Erosion. Erosion or washing steals plant food. If bad, it 

 takes the whole of the surface soil away. An excess of water 

 often causes damage by erosion. In addition to taking away 

 valuable plant food and the cultivated top soil, erosion leaves 

 the fields cut up and rough and exposes material that requires 



