120 Repokt f)F Farmers' Institutes 



TREATED ROCK vs. RAW ROCK AND BASIC SLAG 



Professor G. W. Cavanaugh 



The choice of commercial phosplioric acid seems to be limited to 

 acid-phosphate and ground rock phosphate. It depends largely 

 under what conditions they are to he nsed, which one should be 

 chosen. In general, where organic matter is low in the soil, or 

 can be supplied only in limited amounts by cover crops and 

 manures, it seems advisable to use the acid-phosphate. Where 

 the organic matter in the soil is high, or for use in composted 

 stable manure, the cheaper rock phosphate may ])e recommended. 



Acid-phosphate may be indirectly beneficial, through the action 

 of its gypsum, in making the soil's potash available. 



Acid-phosphate may be useful on acid soils. 



ADVICE AS TO POTASH 

 Professor G. W. Cavanaugh 



The potash situation is simple though unsatisfactory. The 

 only sources seem to be (a) the potash in the soil, (b) in wood 

 ashes and (c) small amounts in the hands of some dealers. While 

 there are some efforts being made to obtain potash in this country, 

 these have not yet materialized in a commercial way. For the 

 present the principal source seems to be the native supply in the 

 soil. This quantity varies with localities and types of spil. 



Eight samples of soil were recently obtained from Jefferson 

 county through the cooperation of the county agent. The samples 

 were analyzed for potash. Following are the results : 



Sample 1 2.46 per cent KoO 



Sample 2 2 . 62 per cent KoO 



Sample ?> 1 . 78 per cent KoO 



Sample 4 2.32 per cent KoO 



Sample 5 3.16 per cent KoO 



Sample 6 2 . 87 per cent K,0 



Sample 7 1 .91 per cent K^O 



Sample 8 1.81 per cent K'O 



