134 BOARD OF AGRICULTUEE. [Pub. Doc. 



4 per cent of magnesia, and about 35 per cent of lime in 

 the form of calcium carbonate. In regard to the phos- 

 phoric acid of wood ashes, there seems to be a lack of 

 definite knowledge as to its assimilability, and it is possibly 

 much inferior to soluble phosphoric acid (mono-calcic phos- 

 phate) and perhaps also to even other less valuable forms. 

 While upon some farms and for certain crops the lime of 

 the wood ashes may have little or no value, and with 

 a few plants work positive injury, yet on many of our 

 New England farms and for many of our important crops 

 it imparts, frequently, more benefit to the lands than the 

 potash which they contain. This great value of the lime 

 has been abundantly demonstrated during the last three or 

 four years in all parts of Rhode Island. Similar results 

 have just been obtained, particularly in connection with the 

 use of sulfate of ammonia, by Professor Phelps at Storrs, 

 Conn., and by the New Hampshire station at Durham. 

 Director Voorhees of the New Jersey Experiment Station 

 bears testimony to similar experience in certain sections 

 of his own State, and wonderful benefit is also reported to 

 have been observed at Wellesley, Bolton and Westminster, 

 Mass. In recent experiments conducted at the Rhode 

 Island Experiment Station a gain of al)out 7 per cent in 

 the crop has resulted from the use of magnesia ; and it is 

 not improbable that its use, particularly in connection with 

 certain crops, may yet be found to result in more general 

 benefit than is customarily supposed. Let us therefore 

 divorce our minds at once from the unfortunate and fiilla- 

 cious idea that we must apply to our soils only the three 

 so-called " essentials," — potash, phosphoric acid and nitro- 

 gen. Having done this, and then having examined the soil 

 as to its probable need of lime and magnesia, and con- 

 sidered the crops to be grown, we are in position to know 

 with some definiteness whether it is better economy to use 

 wood ashes to supply our potash, or to depend upon the 

 German potash salts, supplemented, as may be required, by 

 lime or magnesian lime. 



Another excellent though limited source of potash is the 

 ash of cotton-seed hulls. These contain on an average about 

 22 per cent of potash, 8 to 9 per cent of phosphoric acid 

 and from 9 to 10 per cent each of lime and miignesia. 



