488 ORGANOLOGY. 



From tliis we are naturally led to a closer observation of cultivated 

 plants. I have already shown that irrigated meadows which are not 

 manured yield yearly a much larger amount of nitrogen than lands under 

 tillage. Hence it appears improbable that cultivated plants should re- 

 quire nitrogen from the manure which is supplied to them, since the 

 same sources from which wild plants receive that element are open to 

 them also. I believe that it is more than probable that plants under 

 culture are as entirely independent of manure, so far as it contains ni- 

 trogen, as wild plants themselves. The experiments of Boussingault, 

 against which no objection can be made, seem to prove this. Boussin- 

 gault is an experienced practical agriculturist, a distinguished naturalist, 

 and a superior chemist. The great number of his experiments, and their 

 extreme simplicity, leave no room for objections. Boussingault culti- 

 vated the plants which he observed in the usual method, and made most 

 accurate investigations as to measure and weight ; and these he places 

 before us instead of guesses or fancies. r ihe results which he obtained 

 as to the weight of produce, the quantities of manure, &c., agree in the 

 main with those of experienced German agriculturists, and exhibit a 

 medium between their extremes. An objection which has been put forward 

 by Liebig, that the nitrogenous matters of the manure evaporate during 

 the process of drying (at 110 C.), might have had some weight, had he 

 established the fact by experiment. The ammonia of manure is either 

 disengaged and volatile, or it is not volatile at 110 C. In the last case 

 the objection is at once answered, and I believe this to be the fact with 

 the generality of the ammoniacal salts contained in manure ; but in the 

 first case, that portion of the salts of ammonia which is volatile is not 

 directly taken up by plants, but is dispersed in the air by the ploughing 

 and turning about of the soil. The manure is not immediately or con- 

 tinually supplied to each plant commencing vegetation ; it is put into the 

 ground, often some time before the seed, turned about as the soil is 

 turned, and thus most probably its action extends over the four, five, or 

 six years consumed by a rotation of crops. It must be at once seen that 

 by the second or third year the earth will hardly contain any remnant 

 of the ammonia salts supplied to it with the manure. Now the inde- 

 pendence of the nitrogen in plants of what they receive from manure, is 

 proved by the fact that the amount produced is not larger the first year, 

 and then gradually decreasing, or the contrary ; but it depends rather 



wert of rye, and 6,852 of barley ; in the whole, about 40,000 million Ibs. of dry 

 organic substance, which was more or less directly produced from the soil: and it would 

 be impossible to allow that more than 1,000,000 Ibs. of dry organic substance 

 could have reached the soil in the form of manure. A similar calculation may be made 

 for St. Petersburg. What needs to be done is the laying a basis for a new science, 

 which, by means of most accurate measurements, weights, and analyses, shall supply 

 commercial statistics, and the elements of a national economy, in those forms of matter 

 which constitute the food of plants and animals. We cannot tell how important might 

 be the result, for the benefit of mankind, if we could once be placed in circumstances 

 that should enable us to subject to calculation, and thence also to control, the escape 

 and influx of the elementary substances, their interchange between sea and land, and 

 between both and the atmosphere. Happy would be the country, and sure to carry 

 agriculture to the greatest perfection, which should learn the means of regulating the 

 quantity of the organic elements (carbon, hydrogen, oxygen, nitrogen) in proportion 

 to its area, which should possess the art to draw upon the inorganic stores of the atmo- 

 sphere, and thereby to spare all waste, and multiply the means of fertilising the earth 

 to export its superfluity of some elements, and to import those of which larger supplies 

 would be beneficial. 



