(138) 



mentary principles in the course of the ensuing decomposi- 

 tion. Therefore, it is nearer the facts that two years' crops 

 or culture, for market or removal, would require one year's 

 growth of some manuring crop to replace, and to maintain 

 undiminished or increasing the productive power of the fit-Id.. 

 The poorest, and also the cheapest, of such manuring crops 

 will be the natural or " volunteer " growth of weeds on 

 lands left cultivated, and not grazed; and the best of all 

 will be furnished in the whole product of a broadcast sown 

 and entire crop of your own most fertilizing and valuable 

 field peas. 



" Thus, of each manuring crop, (as of all others), or of 

 the fertilizing matter thus given to the land, the cultivator 

 has contributed but five parts to the land, or its previous 

 manuring, and the atmosphere has supplied fifteen parts. 

 If, then, the cultivator, by still more increasing his own 

 contributions, will give ten parts of alimentary matter to 

 the land and crop, there will be added thereto from the at- 

 mosphere in the same three- fold proportion, or thirty parts, 

 and the whole new productive power will be equal to forty. 

 And if the soil is fitted by its natural constitution, or the 

 artificial change induced by calcareous or other applications, 

 to fix and retain this double supply of organic matter, the 

 land will not only be made, but will remain of as much 

 increased fertility, under the subsequent like course of re- 

 ceiving one year's product for manure for every two other 

 crops removed. But, on the other hand, if more exhausting 

 culture had been allowed, instead of either increased or 

 maintained production, or if the crops take away more or- 

 ganic matter than nature's three-fold contributions will 

 replace, then a downward progress must begin, and will 

 proceed, whether slowly or quickly, to extreme poverty of 

 the land, its profitless cultivation, and final abandonment. 

 In this, the more usual case, the cultivator's contributions 

 of aliment (obtained from the soil), are reduced from the 

 former value, designated as five, first to four, and next sue- 



