FERTILIZERS. 259 



more necessaiy to fertility, and there is no substitute for phosphoric acid. Plants may obtain 

 lime from the carbonate, sulphate or phosphate : it is, I believe, only from this single mineral, 

 the phosphate of lime, that phosphoric acid is obtained ; and as its quantity in the soil is al- 

 ways exceedingly minute, its artificial supply can never be lost to the soil — in the end it will 

 tell, and the fertility of the land will continne the longer, in consequence of any supply of it 

 which a farmer may see fit to give. I have always spoken of this substance as one of the 

 expensive fertilizers : if, then, the immediate eifects of a manure of a known composition does 

 not tell upon the crop at its first application, it does not follow that its application will be lost, 

 especially when the substance is essential to the constitution of ail plants. 



6. Wood and Coal Jlshes. 



Wood ashes being derived directly from plants, they must always form an important appli- 

 cation to all crops ; they are, in a measure, similar to the foregoing mixed saline fertilizer, al- 

 ready recommended, only they are more complex in their constitution, and hence, better fitted 

 to meet the general wants of vegetation. The general constitution of the ash, of most culti- 

 vated plants, may be ascertained by consulting the second volume of the Agriculture of New- 

 York. Three important substances are always present, though variable in quantity in different 

 plants, and different parts of the same plant : thus potash, soda and phosphoric acid are always 

 present. Lime enters largely into the constitution of the bark, and sometimes the wood : oak, 

 beech and hickory contain lime in very large proportions, as 70 per cent and more. One of 

 the best modes of applying ashes is directly to the young growing plant. Maize is remarkably 

 benefited by the application of a single handful of ashes, when two or three inches high ; and 

 sown upon wheat or the cereals, or upon meadows, its effects are immediate and quite durable. 

 Leached ashes, though less valuable, exert immediate good effects upon the same crops. There 

 is some danger of applying leached ashes too abundantly ; in that case, the surface of the 

 ground becomes compacted and hard : indeed leached ashes form walks in gardens almost im- 

 pervious to weeds, and hence we may well suppose that this form of ashes is well adapted to 

 loose sandy soils, and that they will correct, in a measure, this quality. Still there is a limit 

 to their use, even upon this kind of soil, for it is agreeable to the principles of good husbandry 

 that all excesses in the application of any one susbtance should be avoided ; and the advantages 

 of large quantities of fertilizers, added at one time, are far less than when given the soil in di- 

 vided doses, at wide intervals of time. 



Anthracite and bituminous coal ashes must be regarded as weak fertilizers : they contain 

 lime, magnesia, a trace of phosphoric acid and alkalies. Upon grass lands experience proves 

 that they possess considerable value, especially if the soil is argillaceous ; but they can not be 

 useless upon sandy soils, though, mechanically, Ihey will be inert. About one-third of their 

 matters are moderately active in promoting vegetation. Ashes from the mineral coals should, 

 by no means, be wasted, although they will not pay for transportation, except for short dis- 

 tances around our cities and large towns. 



Peat ashei^and soot possess valuable properties : they contain ninrc potash and jihosphates 



