72 



MONTHLY JOURNAL OF AGRICULTURE. 



in which they are fiimished by Nature — that 

 a field manured by it resembles the primitive 

 state of America and Hungary, this assertion 

 "Will not be found exaggerated. It is certain 

 that stable dung contains no alkaline phos- 

 phates, but Nature does not furnish these to 

 the plants even in the most fertile soil, al- 

 though we find them in large quantity in all 

 the seeds of wild plants. It is obvious that, 

 notwithstanding theu- absence from the soil, 

 the phosphates are foi-med in the organism of 

 the plants, and they are produced from the 

 phosphate of lime and magnesia and the sup- 

 phed alkalies, by an exchange of the elements 

 of each. The alkalies are necessary for 

 forming alkaline phosphates, which cannot 

 originate in the phosphate of lime alone. 

 Both together are present in stable dung. In 

 human excrements and in guano, the alkaline 

 carbonates are entirely wanting. The prac- 

 tice of the former, in some places, of supply- 

 ing to the field not pure guano, but a mixtiu-e 

 of it with gypsum, shows clearly that the 

 phosphates of alkaline bases are really formed 

 on the organism of the plants fi-om the phos- 

 phate of lime and magnesia, because this mix- 

 ture (guano and gypsum) contains less phos- 

 phate of potash or soda than the guano itself; 

 or, in certain proportions of gypsum, no alka- 

 line phosphates at all ; the soluble phosphates 

 in the guano decomposing the gj'psum into 

 phosphate of lime and magnesia, and into sul- 

 phate of potash. I am far from asserting that 

 ■we should not provide the fields with alka- 

 line phosphates ; the excellent effect of the 

 guano and of the human excrements is too 

 well known to question it, and we perceive 

 from this fact that plants are in this respect 

 like domestic animals which, with a normal 

 food, are healthy and strong, but do not fat- 

 ten. On the contraiy, we know that if we 

 prepare the food of these animals artificially, 

 80 as to render it more easily digested and 

 assimilated, they are enabled to consume, in 

 a given time, a gi-eater quantity of it, by 

 which all their parts increase in weight. The 

 same happens with plants : if we give them 

 their nourishment in a state most appropriate 

 for assimilation, their capability to attract the 

 gaseous elements from the atmosphere in- 

 creases and their development is accelerated. 

 If we recollect that the favorable effect of 

 guano upon our fields depends on its amount 

 of ammoniacal salts, of alkaline phosphates 

 and the other mineral constituc7its of the seeds, 

 but that it is deficient in alkalies, the princi- 

 pal constituents of the herbs, straw and roots, 

 it is easily imderstood why the opinions of 

 farmers on the value of guano as a manure 

 are so very different. On a soil which is de- 

 fective in alkalies its effect is small ; on a soil 

 rich in them it increases the produce in a re- 

 markable degiee ; but, as I have ah-eady ob- 

 served, the continued application of guano 

 must gradually diminish the fertility of our 

 fields for a number of plants, because the ele- 

 ments of those organs, of the leaves, stalks, 

 roots, &c., without which the plants cannot 

 (1G8) 



be developed and cannot produce seeds, ai-e 

 taken off in the harvest without any restora- 

 tion of them. I think it, therefore, certain 

 that the stable dung can replace the guano to 

 a certain degree, but not vice versa. A ra- 

 tional agriculturist, in using guano, cannot dis- 

 pense with stable dung. 



During my excursions in England, I have 

 repeatedly directed the attention of the agri- 

 cultiu-ists, as Messrs. Pusey and Miles will, 

 perhaps, recollect, to the necessity of sup- 

 plying the alkalies, and not merely the phos- 

 j)hates and other salts ; by a partial supply 

 the equilibrium of fertility is not restored, 

 and if we supply guauo alone, we do not 

 act wisely, because we consume our capital 

 by rich interests, and leave to our children an 

 exhausted soil. 



And now the principles above-mentioned 

 must guide us in the manufacture of an artifi- 

 cial manure. If they ai-e neglected — if the 

 artificial manure is defective in one or two of 

 the necessaiy ingredients — the fanner, in ma- 

 king use of it, will, in a very short time, dis- 

 cover the fact by the injury he will have 

 sustained. 



In the manufacture of an artificial manure^ 

 it must be kept in view that the application 

 of stable dung, of human excrements, and of 

 guano, is attended with a gi-eat loss, in con- 

 sequence of the too great solubilitj' of their 

 most efficacious constituents; and this must 

 be prevented by artificial means. This is evi- 

 dent, if we remember those counti'ies whence 

 guano is derived. It is known that the col- 

 lection and preservation of the excrements on 

 the African islands, and the coasts of Peru and 

 Chili, depend upon the scarcity of rain iu 

 those countries. The best sorts of guano con- 

 tain, in fact, more than one-half of their weight 

 of soluble salts, which, if exposed to the rain, 

 are in exactly the same condition as, under 

 similar conditions, a heap of salt. They dis- 

 solve iu water, and are removed. Some 

 months of rain would deprive those countries 

 of all then" riches. The remainder would 

 have lost the greater part of its fertilhzing 

 power. Such effects, however, take place 

 upon the guano with which our fields are 

 nmiuired. Only a small portion of its effica- 

 cious salts produce the beneficial effect they 

 are capable of doing, the greater part being 

 caiTied off by the rain. The stable dung is, 

 in this respect, in the same condition as guano ; 

 indeed, its piincipal compounds are already 

 in a dissolved state, and, therefore, are carried 

 off more easily than those of guano. 



A covering for those places in which stable 

 dung is preserved, in order to shelter it fi'oni 

 the effects of the rain, has been regarded in 

 GeiTuany as essential for presen'ing its ma- 

 nuring power. In consequence of the expe- 

 rience that the soluble elements of stable dung 

 are the most efficacious, it has, in some cases, 

 been drawn rut with water, and it has been 

 found advantageous to carry only this fluid 

 to the fields. I need only refer to the forego- 

 mg analyses of the urine of animals, iu order 



