70 



MONTHLY JOURNAL OF AGRICULTURE. 



known enters in a still larger proportion than 

 the -phosphate of lime into the composition of 

 the grain. 



The Alkaline Phosphates, although not ori- 

 ginaUy found in nature, m-e important ele- 

 ments of the seeds of grain, of j)eas, beans, 

 &c. A rational farmer must provide them in 

 sufficient quantities to those plants which re- 

 quire them for their development, from know- 

 ing that human excrements increase the pro- 

 duce of grain in a far gi-eater proportion, be- 

 cause they contain alkaline phosphates, than 

 the aminal excrements, in which they do not 

 exist. 



The Alkalies — potash and soda — must be 

 constituents of eveiy rationally composed ma- 

 nure, because by them the original iertile 

 condition of the fields is preserved. A soil 

 which contains the alkalies in too small a 

 quantity is, perhaps, fertile for grain; but is 

 not necessarily so for timiips or potatoes, 

 ■which require a great quantity of alkali. By 

 supplying an alkaline manure, fallows or the 

 cultivation of those plants which are gi-ovni 

 during the time of fallowing, become less ne- 

 cessary. 



Sulphate of Potash is a constituent of all 

 plants, although in small quantity, as well as 

 common salt and chloride of potassium, which 

 are found in milk in rather a large proportion. 

 Tlie salts of lime, especially gypsum,, are im- 

 portant nourishment lor the leguminous plants. 

 Silica is never wanting in all sorts of soils — 

 it is a constituent of all rocks, by the decom- 

 position of which all productive soils are 

 formed, and the Cerealia find it everywhere 

 in sufficient quantity, and in a foi-m capable 

 of being taken up by the plants, if the alka- 

 lies are provided wherever they ai'e present 

 in too small quantity. 



Salts of Ammonia. — It may be regarded 

 as certain that the nitrogen of the plants is 

 derived either from the ammonia of the at- 

 mosphere, or from the manure which is pro- 

 vided in the shape of animal fluid and solid 



excrements, and that nitrogenous compounds 

 exercise an effect on the growth of plants 

 only in so far as they give up their nitrogen 

 in the form of ammonia during their decom- 

 position and decay. We may, therefore, 

 profitably replace all the nitrogenous sub- 

 stances with compounds of ammonia. 



Decaying vegetable matters, which con- 

 tain carbon, are usefiil to the fields in so far 

 as they j>rovide a source of carbonic acid ; 

 but they are quite dispensable in manure, if 

 it be rationally combined, as the atmospheric 

 air is an mexhaustible source of carbonic acid, 

 from which the plants derive theii- carbon,?, e., 

 if in the manure, the mineral substances are 

 provided which are necessary for the assimi- 

 lation of the carbonic acid. These ai-e the 

 substances which together give fertility to the 

 soil ; but, although each of them may, under 

 certain circumstances — viz., where the soil is 

 defective, or where it is not indifferent to the 

 plant to take up one instead of the other, as, 

 for instance, may be the case wth soda in- 

 stead of potash — mcrease the fertility, no one 

 of them can be regarded as manure, accord- 

 mg to the common meaning of the word, for 

 the simple reason that only all of them, in. 

 certain proportions, will fulfill the purpose 

 ibr which the common manure is applied. 

 This pui-j3ose is the restoration or an increase 

 of the original fertility, and by manure we 

 must replace all the constituents of the plants 

 which have been taken away in the harvest, 

 or which are contained in the plants wliich 

 we are desirous to cultivate. 



What, then, are the constituents of the soil 

 which we remove by the straw, seeds, tuber- 

 culous roots, stalks, &c., of ovu- plants of cul- 

 ture ? It is obvious that we must know these 

 first, ui order to restore them in sufficient 

 quantities. To this we answer, by giving the 

 analysis of the ashes of plants and their seeds. 

 Hundred weights of the ashes of the follow- 

 ing plants contains — 



In these analyses silica has not been taken 

 into accoimt, as it is found in all soils, and 

 need not be supplied. One hundred weight 



of the ashes of potatoes, and the seeds of the 

 following plants, contain — 



(166) 



