o 



00 MANUKES AisD THEIIl APPLICATION. 



the roots of plants penetrate and absorb nourishment, which 

 they carry up into their stems and leaves. This part of the 

 riches of the soil having served as food finds its way in whole or 

 in part into the manure heap, and in due time is spread upon 

 the surface of the land. There are other agencies at work which 

 determine this transference from below upwards, some of them 

 due to the work of the farmer and others quite independent of 

 his exertions. Among the former may be mentioned drainage, 

 subsoil cultivation, and others which I shall refer to hereafter; 

 while among the latter are capillary attraction, by which salts 

 in solution are carried up from considerable depths and concen- 

 trated upon the superficial soil, and the slow but constant 

 working of the humble earthworm, whose castings, derived often 

 from great depths, have recently been shown by Darwin to be 

 capable of renewing in a few years the entire surface of the 

 soil. 



It will be seen that in the lateral and vertical transference of 

 the soil no addition whatever is made to the total amount of 

 wealth it contains. There is a certain amount of nitrogenous 

 matter brought down to the soil from the air by rain, but the 

 mineral matter which forms so important a part of the food of 

 plants receives no increment ; on the contrary, it is being con- 

 tinually diminished. All that the farmer puts into or expends 

 ■upon the soil is his work. He ploughs, harrows, and cultivates 

 his land, and thus increases the amount of the surface of the soil 

 which is exposed to weathering — that is to say, to the solvent 

 and ameliorating action of air, rain, sun, and frost, which hastens 

 the disintegration and decomposition of the soil, and causes its 

 locked up treasures to become more readily suitable for the 

 nourishment of crops. His whole energies are devoted to 

 extracting from the soil as rapidly as possible all its available 

 wealth for the production of corn, beef, mutton, milk, cheese, 

 poultry, eggs, or other saleable products. If the soil were inex- 

 haustible, this kind of farming might go on for ever ; but common 

 experience teaches us that there is a limit to the fertility of soils, 

 and that in the case of our long-cropped soils that limit is easily 

 Teached. We know that if we go on cropping land continually 

 we shall soon have a crop not worth lifting, and reason tells us 

 that though we adopt ever so many expedients for extending 

 this term of fertility the end must come some time. Forty years 

 ago Liebig brought this fact very forcibly before the attention 

 of farmers, and there was no place where his warnings were 

 better understood and regarded than in this country. 



But there are still very many who do not believe this fact, 

 and who maintain that a judicious system of rotation and hus- 

 banding of the resources of the farm is quite sulficient to enable 

 agriculture to be carried on, and that progressively. Where a 



