48 



Burning Land for Manure. 



the above-quoted instance, but that the amount of the active 

 ones was beyond all comparison greater in the sample of un- 

 exhausted soil.* 



I shall conclude these extracts by the following quotation from 

 the same paper: — The dormant and active portions may both 

 be comprehended under the designation of its available consti- 

 tuents, whilst those which, from their state of combination in the 

 mass, can never be expected to contribute to the growth of 

 plants, may be denominated the passive ones." 



Every soil which is capable of yielding an abundant crop of 

 any kind of plant, after fallowing, must be assumed to possess 

 in itself an adequate supply of all the ingredients necessary for 

 its support in an available condition ; but it is plain that these 

 could not have existed in an active one, or such interval of rest 

 would not have been required for rendering them efficient. 



Seeing that the inorganic constituents of plants exist in the 

 soil in three different states, which may be termed passive, avail- 

 able, and active, and that in one of these only (the active) are they 

 of service to the husbandman, it is evident that all operations 

 which will convert the first and second into the third state will 

 be of advantage to his labours. 



When a chemist has to analyse a mineral that is refractory — in 

 other words, of difficult solubility by the ordinary agent — it is a 

 common practice to submit such a mineral or other matter to the 

 agency of heat, which sometimes wholly, but generally partially, 

 has the desired effect ; the remaining intractable matter, or the 

 whole substance, if found on subsequent trial unchanged, is mixed 

 with some alkali, as lime, soda, or potash, and again submitted 

 to the fire, on the withdrawal of which the constitution of the 

 matter under investigation will mostly be found so changed as to 

 become soluble in the ordinary solvents. It is, however, neces- 

 sary to be borne in mind, that the total solution of aluminous 

 and silicious soils is only obtained by treating the same with an 

 excess of alkali ; such an amount of alkali as is necessary for the 

 purpose is never found in soils, and the process is only mentioned 

 in order that the farmer may the more easily comprehend the 

 true 7'ationale of the action which takes place during the process 

 of burning land for manure. 



From the preceding observations the reader will be prepared 

 for the information that the benefit of burning land for manure 

 will be found most beneficial on such soils as contain the largest 

 amount of the necessary mineral constituents of plants, in what 

 has been previously alluded to as existing in a passive state, and 



* See Table, p. 240, vol. vii,, of Journal of the Royal English Agricul- 

 tural Society. 



