MANURES. 257 



purchasing them should be guided by other considerations than 

 those o( general vAuG. The probity of the manufacturer, and the 

 care with which his subordinates carry out his instructions, have so 

 much to do with the value of the product of any establishment, 

 that purchases from each should be made according to more infor- 

 mation than it would be safe or proper to give'^in this book. 



Peruvian guano^ when purchased from the regular agents of the 

 Peruvian government, or from any thoroughly honest dealer, may 

 be depended on as an extremely valuable manure for certain pur- 

 poses, but it must always be used with great judgment and discre- 

 tion. Its valuable constituents are so perfectly prepared for the uses 

 of vegetation, that even so small a dressing as loo pounds per acre, 

 evenly spread over the land, produces such a marked effect on 

 early vegetation as to give nearly all crops a start so rapid that 

 they are enabled to take up with great vigor from the soil itself 

 such plant-nutriment as it may be able to offer. Probably, even 

 in addition to Its influence as an easily assimilated food, it acts as 

 a solvent of certain elements of the soil, and makes them much 

 more readily available. The result is, in many cases, that a soil, 

 which, in its natural condition, would furnish the mineral food 

 for only a small crop, will, with this slight assistance, furnish 

 the mineral matter required for a very much larger crop, the 

 mineral matter taken up being many times greater than that 

 contained in the guano. Herein lies, probably, the only secret of 

 what is called the "exhausting" influence of Peruvian guano, for 

 up to this point (the raising of the crop) no injury has been done. 

 The final result of the cultivation must depend on the judgment 

 and care of the farmer. If, elated by the excessive production or 

 tempted by an exceptionally high price of the crop in market, he 

 sells off from his farm all that has been produced by the aid of the 

 guano, the land must inevitably suffer in consequence ; but if the 

 crop be consumed on the farm, or in any manner so made use of 

 that its mineral ingredients are returned to the soil on which it 

 grew, it will be found that the effect of the guano has been per- 

 manently beneficial. 



In improving waste land with the aid of a stock of cattle to 



