On the Theory of Manures. 11 



.bably all have partly that power, seem also evident : the exact 

 tabular data of the quantities in crops and manures may not, 

 therefore, be a perfect guide, and we may not always reap 

 benefit in proportion to the quantity furnished ; yet, generally 

 speaking, manures containing much nitrogen are found to 

 have a powerful effect ; the exceptions will be best learned by 

 practice. 



As urine, and other liquid drainings of the farm-yard, and 

 those furnished domestically, which are so rich in nitrogen, are 

 too frequently allowed to run to waste, the necessity of collect- 

 ing these substances and depositing them in the compost heap, 

 with plenty of humus earth, which in many places abounds to 

 so great an extent, cannot be too much inculcated. 



Peat earth is plentiful in many situations, and has long been 

 known as capable of fermenting and becoming as good as manure, 

 if mixed with it. Sawdust of deciduous plants (hard wood) 

 rots also, and is good for composts ; that of fir wood is found 

 to decay very slowly, from the insolubility of the resinous sub- 

 stances, which might, perhaps, be helped to dissolve by mixing 

 with the alkalies of wood-ashes, in which they are soluble. 

 Where leaves can be collected, and clippings of hedges, they are 

 excellent for composts ; also the stems, leaves, and roots of 

 garden plants and weeds, in fact all the haulm and refuse of 

 the garden. The straw of grain crops, the stems of potatoes, 

 turf, and scourings of ditches (avoiding those places where 

 there is much deposit of iron from the water), are all capable of 

 yielding humus to the manure heap. Even the roots of couch 

 grass, and other root-weeds, if well fermented, are capable of 

 adding to the bulk and value of the manure heap ; and almost 

 all vegetable and animal refuse, which cannot be more beneficially 

 employed. They should all be collected, a layer of these sub- 

 stances and earth put below, and alternate layers of hot ferment- 

 ing dung and these put together, watered if needed, and too 

 much wetness thrown oflP by coverings open at the ends and 

 sides. There should be most of the humus earth in the bottom 

 and around the outsides, the fermenting substance will not then 

 escape so much. A proper state as to moisture, neither too wet 

 nor too dry, is very necessary to be attended to, substances be- 

 ing found to putrefy incomparably more quickly when moist, 

 than either wet or dry. Heat should be encouraged by loose 

 strawy matter, to allow the admission of air, and when too 

 great the heap should be turned over to allow it to cool. When 

 too loose and dry it burns and gets white, and a proper degree 

 of consolidation and moisture is necessary. The drainings of 

 the dunghill should not be encouraged by too much wetness 

 being allowed to fall on the heap, but provision should be made 

 for collecting all that comes away, and throwing it on again, 



