CHAPTER Vn. 



ARTIFICIAL MANURES, AND IRRIGATION. 



253. The class of salts, as manure, is to be distinguished 

 from the salts called mineral manures, by this circumstance, 

 that they contain large portions of peculiar animal products 

 called urea and uric acid. These afford ammonia in large 

 quantity by their decomposition. Having considered the 

 relative value of the two classes of manure, those composed 

 of salts, and of salts and geine, that consisting chiefly of 

 geine is now to be explained. 



254. First and foremost in this class, is swamp-muck, 

 mud, or peat. This class includes, also, dry leaves, dry 

 vegetables of all sorts ; ploughing in of green or dry crops, 

 irrigation. These are fruitful topics. The principles only 

 of their action can be pointed out. The application of the 

 principle must be left to the farmer. The why of things has 

 been or will be shown ; the how must be deduced from the 

 why by practical men. 



255. Peat is too well known to render it necessary to say 

 that it is the result of that spontaneous change in vegetable 

 matter, which ends in geine. Peat is, among manures 

 consisting chiefly of geine, what bone-dust is among manures 

 consisting of animal matter. Peat is highly concentrated 

 vegetable food. When the state in which this food exists is 

 examined, it is found not only partly cooked but seasoned. 



256. Peat consists of soluble and insoluble geine, and salts. 



(206) 



