CULTIVATION 101 



A strong solution of plant food in the soil is a necessary 

 condition for the growth of young plants which are only 

 able to absorb a comparatively small quantity of water. 

 In this small quantity of water they must find much food, 

 which cannot be the case if they get too much irrigation 

 water. To save the crops from being irrigated, the land 

 is fassed equally whether there is little or much irrigation 

 water available, whether the soil is wet or dry. Low- 

 ly ing, wettish land really requires more fassing than dryer 

 soil, not to save water, but to render further irrigation 

 unnecessary. Fassing prevents loss of water, hardening 

 and shrinking of the soil in the following way : when the 

 surface of the soil is exposed to the hot dry air water is 

 rapidly evaporated from its surface. As the surface layer 

 dries it draws on the water below which rises up by 

 capillarity. Hence a constant stream of water is moving 

 up the soil to be evaporated and lost. By fassing, the 

 capillarity is stopped and therefore the loss of water. The 

 loose layer of soil on the surface is separated from the 

 undisturbed soil by large air spaces across which water can- 

 not pass by capillarity. This loose layer is soon desiccated, 

 but it protects the lower undisturbed surface from the 

 drying effect of the hot air. In the same way, the surface 

 evaporation is reduced when the soil is shaded by plants 

 or when covered with a layer of tibn or other loose material. 

 When the surface water is saved by fassing, the soil does 

 not become so hard, it contracts less and there are fewer 

 or smaller cracks. Plants cause a great loss of deep soil 

 water which is evaporated from the leaves, but this and 

 fassing causes the soil to shrink more gradually and more 



