No. 7. DEPARTMENT OF AGRICULTURE. 239 



same statement is made in all parts of the country in places where 

 clover has thriven in the past, and the difficulty in getting clover 

 seems to be very general. Two years ago I was requested to address 

 the farmers of East Tennessee at their annual convention in the city 

 of KnoxA'ille on the Southern Cowpea. After I had concluded 

 my address a farmer took the rostrum, and in a very emphatic way 

 declared that he did not want the pea, and that the clover was the 

 crop for him, I interrupted him, and told him that I had not said a 

 word against clover, but would like to know why they did not grow 

 it, for I had ridden the day before down the beautiful limestone 

 valley of the Tennessee from Asheville to Knoxville, in the month 

 of May, and had not seen one decent field of clover? The audience 

 of 2,500 of the best farmers of East Tennessee applauded loudly at 

 this, and manv of them told me afterwards that the man who was so 

 fond of clover utterly failed to grow it as most of them did. I told 

 them then, and would repeat it now, that I believe the failure of 

 clover, where it formerly succeeded, is due to one of two causes, 

 either the exhaustion of elements in the soil needed by clover, or 

 soil acidity, which is death to the bacteria that live on clover roots 

 and get nitrogen for it from the air. Generally both conditions are 

 present where clover fails. The farmers in Bucks county have been 

 running their lands in timothy to sell hay in the market of Philadel- 

 phia, year after year till the hay crop is too small to pay before 

 breaking the land again. The long and exhausting rotation is the 

 chief trouble, and the soil has become acid thereby. Many years 

 ago I took a farm in Maryland just south of the Pennsylvania line. 

 It was a beautiful limestone valley, and the soil was fertile and well 

 supplied with humus, but one field was pointed out to me as being 

 clover sick. 



I never took much stock in the clover sick idea, and I gave that 

 field a good dressing of lime, and never saw finer clover than grew 

 on it the next year. The soil was simply in an acid condition, and 

 the lime restored the conditions in which the bacteria throve again. 



The most thoughtful men in all parts of the country are fast com- 

 ing to the conclusion that the constant use of the dissolved phos- 

 phate rock, or acid phosphate as it is called, has been the cause of 

 soil acidity in many sections. We were not at first disposed to ac- 

 cept this, because we knew that manufacturers of acid phosphate 

 were very careful not to have any free sulphuric acid in their goods, 

 as it would interfere with the drilling of the article. But the inves- 

 tigations of the Ohio Experiment ■Station seem to throw further light 

 on the matter. Dr. Thorne, the Director, believes that the effect of 

 the acid phosphate in creating acidity in the soil comes from the fact 

 that the soluble phosphoric acid is taken up rapidly by the crops, 

 and the suljthuric acid is set free and at once combines with the 

 lime in the soil, and forms lime sulphate, which does not sweeten 

 the soil as the carbonate does. The soil, being thus robbed of lime, 

 becomes acid and clover fails to thrive until lime is again added. 

 He has found too that when the pulverized phosphate rock or "floats" 

 is used in connection with stable manure it rapidly becomes avail- 

 able to plants and the use of this pulverized rock will entirely do 

 away with the difficulty attending the use of the dissolved rock, 

 in case the soil is well supplied with humus-making organic matter. 

 Here again we see the importance of humus. The old long rota- 



