84 DRY LAND FARMING 



sionally cloudbursts occur, and when they do the rain 

 falls in sheets. When it falls thus much of the water is 

 lost to the soil, much of the soil is also removed to lower 

 levels and the gullying of the land becomes more pro- 

 nounced. The aim should be, of course, to prevent such 

 loss as far as this may be found practicable (see p. 128). 

 The loss from the third source mentioned is seldom 

 serious, as prolonged and heavy rains seldom occur in 

 dry areas. 



Functions of water in soils. These include: (1) dis- 

 solving plant food in the soil ; (2) carrying the food 

 dissolved to the plant, and (3) maintaining proper growth 

 in the plant. These functions can only be found at their 

 best in soils of proper texture, well supplied with the 

 elements of plant food, free from matter hurtful to plant 

 growth and in proper condition as to tilth ; water must 

 also be present in sufficient quantities in the soil and 

 subsoil. 



Plants take their food from the soil through the 

 roots. These cannot appropriate the food unless it is 

 held in solution. The water which surrounds the soil 

 grains in the form of a film dissolves the food so that 

 the plants can feed upon it. When the plant food is 

 thus liberated in excess of the needs of the plants or at 

 a season when plants are not growing, it is carried down 

 in solution in the gravity water. Should this gravity 

 water reach the water table below, it is much liable to 

 be carried away in the drainage water. Should it be 

 absorbed in the lower soil along with the capillary wa- 

 ter, it may be again carried to the area where the roots 

 of plants feed in the upward movement of the capillary 

 water, and it may also be reinforced by plant food lib- 

 erated in the lower levels that have been reached by 

 moisture. 



The food solutions are carried to the plants through 

 the root hairs which ramify through the pore spaces of 



