20 



MONTHLY JOURNAL OF AGRICULTURE. 



plant. A number of the most important ag- 

 ricultural operations, especially the mechan- 

 ical, exercise an intiuence on the fertility 

 of the fields only thus far, that they remove 

 the impediments which are ojiposed to the 

 assimilation of the mineral food into the veg- 

 etable organism. By plowing, fur instance, 

 the sutface of the iield is made accessiljle to 

 air and moisture. The nutritious elements 

 contained in the soil in a latent state, acquire, 

 by these operatiou.s, the pro]>crties necessary 

 for their ti-ansmission into the jilants. It is 

 easy to conceive the useful influence which, 

 in this respect, is exercised on the produce 

 of the fields by the care and industry of the 

 farmer. But all these labors and etforts do 

 not increase the amount of mineral elements 

 in the field : in rendeiing soluljle in a given 

 time a larger quantity of the insoluble sub- 

 stances, and obtaining by these means a richer 

 crop — the time is merely hastened in vvliich 

 the soil becomes exhausted. 



The expeiience of centuries has shown 

 that, with the aid of nranure, of the excre- 

 ments of animals and man, with which we 

 supply those fields which have ceased to pro- 

 duce crops of gi'ain, &c., serving as food for 

 man and animals, in a sufficient quantity, the 

 original iertility can again be restored ; an 

 e.xhausted field, which scarcely yielded back 

 the seed, is made to produce a twenty and 

 more fold crop, according to the proi^ortion 

 of the manure provided. 



Regarding the mode of action of manures, 

 it has been observed that all excrements do 

 not exercise an equal inlluence on plants. 

 The excrements of sheep and cattle, for in- 

 stance, increase in most fields the crop of 

 roots and lierbaceous plants to a lar greater 

 degree than those of man and birds, (guano.) 

 The latter act far more favorably on the pro- 

 duction of gi-ain crops, especially if they are 

 added to the animal excremeuts, and are 

 given to the fields at the same time. 



A field, for example, which has lost its fer- 

 tility for potatoes and turnips, but on which 

 peas and beans still thrive, becomes far more 

 iertile, by a supply of the excrements of 

 horses and cows, for a new crop of potatoes 

 and tuniips, than by manuring it with the 

 excrements of man or with guano. 



The most accurate experiments and analyses 

 have pointed out that the excrements of man 

 and animals contain those substances to the 

 presence of which the fertility of the soil is due. 

 The fertilizing ]iower of manure can be deter- 

 mined by weight, as its effect is in a direct 

 ratio to its amount in the mineral elements of 

 the food of plants. The truth of the result 

 of these chemical analyses nuist be evident to 

 every one who inquires into the origin of ex- 

 crements. 



All the excrements of man and animals are 

 derived from the plants of our fields; in the 

 oats and hay which serve as food for the 

 horse, in the roots which are consumed by a 

 cow, there is a certain quantity of mineral 

 ingredients. A horse, in consuming 15 lbs. 



(68) 



of hay and 4^ lbs. of oats per day. consumes 

 21 ounces of those substances which the hay 

 and the oats took fron. the fields ; he con- 

 sumes annually 480 lbs. of these constituent 

 elements of the soil, but only a veiy small 

 portion of them remains in his body. If a 

 liorse, during one year, increases 100 lbs. m 

 weight, this inci'ease contains only 7 lbs. of 

 th(jse mineral substances which were con- 

 tained in the food. But what has become 

 oi'the 473 lbs. which we caimot detect iu Ixis 

 body ? 



The analysis of the fluid and solid excre- 

 ments which the horse gives out daily, shows 

 that the ingi'edients of the soil which do not 

 remain in the body of the animal are con- 

 tained in its excrements ; it shows that in an 

 adult animal, which from day to day neither 

 increases nor decreases in weight, the amount 

 of the mineral ingredients of the excrements 

 is equal in weight to the mineral ingredients 

 of the ibod. 



As with the horse, so it is with all animals. 

 In all advlt animals the excrements contain 

 the ingredients of the soil according to the 

 quantities and relative proportiojis in which 

 they are contained, in their fond. 



The mineral substances of the food which 

 have remained in the body of the animals, 

 and served to increase their weight, are I'ound 

 again in the bones and excrements of man, 

 who consimies the flesh of these animals. 



The excrements of mdii contain the ele- 

 ments of the soil, of bread or of grain, of 

 vegetables and meat. 



These discoveries explain, in a most simple 

 and satisfactoiy manner, the fertilizing effect 

 which manure jiroduces on our fields. 



It is now obvious why manure renders 

 again fertile the exhausted fields ; why, by 

 its means, their productiveness can be aug- 

 mented ; why the latter is in a direct ratio to 

 the quantity of manure administered. 



The exhaustion of the soil by subsequent 

 crops, its decrease in fertility, is produced by 

 the gradual removsil of the minei'al elements, 

 in a soluble state, which are necessary for the 

 develojnnent of our cultivated plants. By a 

 supjily of manure they are again restored to 

 the state suited to serve as nourislunent to a 

 new vegetation. 



If the fiupjdy of the removed elements of 

 the soil, by means of manure, be suflicient, 

 if the qiumtity tfiken away he restored, the 

 original fertility reappears ; if the supply be 

 greater, the produce increases ; a defective 

 supply gives a smaller pi'oduce. 



It is now explained why the ilifferent kinds 

 of manure exercise an unequal eftect upon the 

 fields. 



The excrements of man and guano, contain- 

 ing especially the mineral ingredients of grain 

 and of meat, exercise far gi'eater influence on. 

 the amount of produce of grain in a field in 

 which these ingredients are wanting, even if 

 those of the leaves and stalks are present in 

 sufficient quantity, than the excrements of an 

 animal wliich feeds on roots or green fodder. 



