76 FIELD, FOREST AND FARM 



our stables and poultry-yards. A cart-load of dung 

 becomes at the farmer's .pleasure, after passing 

 through one sort of plant or another, a crop of peas 

 or beans, a basket of fruit, or a loaf of bread. Hence 

 this fertilizer is a very precious thing which nothing 

 can replace and which must be utilized to the very 

 utmost. The nourishment of us all depends on it. 

 Enriched with this fertilizer, the soil produces, we 

 will say, a first harvest of wheat. But wheat with 

 its bunch of short and fine roots, has drawn only 

 upon the upper layer of fertilizing material, leav- 

 ing intact all that the rain has dissolved and carried 

 down into the lower layers. It has performed its 

 mission admirably, it is true; it has made a clean 

 sweep and converted into wheat all the fertilizer 

 contained in the layer of soil accessible to its roots, 

 so that if wheat were sown a second time no harvest 

 would be obtained. The soil, then, is exhausted on 

 the surface, but in its underlying strata it is still 

 rich. Well, what crop shall we choose for the utiliza- 

 tion of these lower strata and the production of still 

 further supplies of food? It cannot be barley, oats, 

 or rye, since their little fibrous roots would find noth- 

 ing to glean in the surface soil after the first crop 

 of wheat. But it will be lucerne, since this plant 

 will send down its roots, each as thick as your finger, 

 to the depth of one, two, or even three meters, if need 

 be, and give back the fertilizer in the form of for- 

 age, which, with the help of the animal that feeds 

 on it, will be converted into nutritious meat, valuable 

 dairy products, excellent wool, or, at the very least, 



