368 INORGANIC ELEMENTS OF MANURES AND CROPS. 



illustration of other particulars. My farm, I may say, by way of 

 preliminary, is an ordinary establishment ; the lands which have 

 been brought by a system of rational treatment to a very satisfactory 

 state of fertility, are not rich at bottom and originally, and they fall 

 off rapidly if they have not the dose of manure at regular intervals, 

 which is requisite to maintain them in their state of productiveness. 

 My first business was to determine the nature and the quantity of 

 the mineral substances contained in my manure ; and with a view to 

 arrive at this information, I burned considerable quantities of dung 

 at different periods of the year, mixed the ashes of the several in 

 cinerations, and from the mixture took a sample for ultimate analysis 

 The mean results are represented by : 



(Carbonic 2.0 



Acids -^ Phosphoric 3.0 



(Sulphuric 1.9 



Chlorine 0.6 



Silica, sand 6G.4 



Lime 8.6 



Magnesia 3.6 



Oxide of iron, alumina 6.1 



Potash and soda 7.8 



100.0 



But our farm-yard dung is not the only article we are in the habit 

 of giving to our land ; it further receives a good dose of peat-ashes 

 and gypsum. I here recall to the reader's mind that the mean com- 

 position of prat-ashes is this : 



Silica 65.5 



.Alumina 16.2 



Lime 6.0 



Magnesia 0.6 



Oxide of iron 3.7 



Potash and soda 2.3 



Sulphuric acid. 5.4 



tnilorine 03 



100.0 



In the system lul lowed at Bcchclbronn, the farm-yard dung laid 

 upon an acre contains '2(\ cwts 3 qrs. of ashes. On our clover leas 

 we spread the fir.sl year 7 cubic feet of turf-ashes ; and in the begin- 

 ning of spring of the second year, we lay on as much more, say 14 

 cubic feet, in nil weighing about 2 tons. I do not take the 8 cwts. 

 of gypsum wliicli, in conformity with usage, the second year's clover 

 generally receives, because 1 believe this addition to be perfectly 

 useless after the very sufficient dose of peat-ash which we employ. 



The whole of the mineral substances given to the land in the 

 course of five years per acre is as follows, viz. : Ashes contained in 

 the manure and in the peal-ashes, 7()'3 1 lbs.; consisting of phos- 

 phoric acid DO Ih.s., 8iil|iluiric acid 'M)l \hs , cldoiine 4.5 lbs., limt* 

 532.5 lbs., magnesia 135. (j lbs., potash and siula 339 lbs., silica aii'l 

 sand 4030 lbs., oxide of iron, &c., 353 lbs. 



It is therefore easy to perceive, from the preceding data, tliat 

 what with the manure ami the ashes it receives, the land is more 

 than suj)plied with all \ho minenil sub.slances re<|iiire«l bv the sev- 

 eral crops it produces in the course of ifie rotatmn. Lti us cast '^ 



