The Science of the Soil 121 



surfaces. Many of these are protected from the glaring sun by hairs, 

 spines, bristles, or by a waxy "bloom", consequently the amount of 

 moisture given off from their surfaces is very small. 



Movement of Water in the Soil. We have already seen (p. 118) that 

 the deeper a soil is cultivated the more water it will absorb, no matter 

 what its character may be. This water sinks down and down until it 

 comes to a level where water is always standing. This water level or 

 water table may be from 3 to 150 ft. beneath the surface, and may be 

 taken to represent the reserve supply locked up in the soil. It is obvious 

 that all the rain that falls does not reach the water table, because it is 

 waylaid en route and absorbed by the particles of soil. And it must be 

 remembered that although more rain falls in the hilly districts, the soil 

 on the hillsides is not moistened so deeply as that in the lowlands and 

 valleys. In the latter places, apart from the natural annual rainfall, a 

 good deal of extra water is obtained when the rivers and streams overflow 

 their banks at floodtime. When the fields and meadows are flooded to a 

 depth of 1, 2, or 3 ft., many hundreds of tons of water are thus spread 

 over the land, and a very large quantity of it must sink downwards to the 

 water table if the soil is in a porous condition. 



Water Lost by Weeds. Many growers do not appreciate the quantity 

 of water that is stolen from the soil by weeds. After all, weeds are plants 

 outcasts of the horticultural world, but they must live, if allowed to 

 remain on the ground. Being more vigorous in their nature than culti- 

 vated plants, they need large supplies of moisture to keep them going, 

 and they transpire through their leaves at least as freely as do cultivated 

 crops. It therefore follows that if an acre of ground, carrying, say, 

 40,000 Lettuces or 10,000 Cabbages, is allowed also to carry a crop of 

 weeds between, the amount of water taken up from the soil and evapo- 

 rated in the course of the season will be probably twice as great as if 

 no weeds were allowed to grow. The commercial gardener should there- 

 fore decide whether it is cheaper and better for him to allow weeds to 

 grow and steal the moisture and food from his Cabbages, Carrots, Beets, 

 Lettuces, and fruit trees or bushes, or whether it is more remunerative 

 to spend money in keeping the weeds down, and thus conserve the mois- 

 ture and food for his crops. The sensible grower will, of course, spend 

 money in labour for hoeing by hand or machine between his crops, because 

 he knows he will not only keep his crops clean, healthy, and steadily 

 growing with the moisture he is conserving, but also because he knows 

 that freshening up the surface of the soil means more food for the roots 

 of his plants, fewer insect pests in the soil, greater absorption of rain and 

 dew, and consequently crops that are likely to sell more quickly and fetch 

 higher prices than those that have been neglected. 



During the summer months it is not at all uncommon to see the ground 

 between rows of fruit trees and bushes, and between vegetable crops, full 

 of weeds. These are not only robbing the air of carbonic acid gas (see 

 p 108). but also the ground of moisture, and leaving it in a parched and 



