SWEET CLOVER: GROWING THE CROP. 15 



Thus it appears that lime is essential for the maximum growth of 

 sweet clover in this region. 



The reason for the exceptional growth of sweet clover in north- 

 central Kentucky is undoubtedly the fact that these soils contain 

 an abundant supply of limestone. The Kentucky Agricultural 

 Experiment Station states that this area is the only portion of the 

 State where sweet clover is being grown with genera] success without 

 applying lime. 



Soils on which sweet clover is aggressive are almost invariably 

 alkaline or but slightly acid. This plant is often found in valleys of 

 streams in localities where the soils are supposedly acid, but such 

 streams generally have their origin in limestone areas or flow through 

 limestone regions, and calcium carbonate is thus deposited in these 

 valleys during flood periods with the sedimentary deposits from flood 

 waters. Sweet clover often appears in deep cuts along highways or 

 railroads in localities where the soil is known to be acid and where 

 sweet clover has not previously grown. In many of these cuts the 

 acid soil has been removed and neutral or alkaline subsoil exposed, 

 or limestone has been used in ballasting or road making and the dust 

 has blown on the exposed soil. It is a very common occurrence to 

 find sweet clover making an abundant growth along macadamized 

 roads from which the wind has scattered the finely pulverized lime- 

 stone. 



An application of burnt lime or finely ground limestone has made 

 the difference between success and failure in most experiments which 

 have thus far been conducted on decidedly acid soils. (Fig. 7.) 



A number of sweet-clover experiments were performed on acid soils 

 and on adjacent plats or fields of the same type of soil that had re- 

 ceived applications of limestone varying from 1 to 4 tons to the 

 acre. There was a marked difference in the stands obtained and in 

 the growth of the plants on the limed and unlimed areas. In some 

 cases the difference in growth was so marked that the last round of 

 the lime spreader could be distinguished at some distance from the 

 plats. The stands were much heavier on the limed areas and the 

 plants made from two to three times more growth than those on the 

 unlimed plats. Yields of hay were doubled on soils that received only 

 sufficient limestone to neutralize the acids in the surface soil, although 

 the yields were further increased when more limestone was added. 



Mr. AY. E. Watkins, county agent of Allen County, Kans., made 

 counts of the number of plants which winterkilled during the winter 

 of 1914-15 on given areas of limed and unlimed soil. It was found 

 that from 15 to 35 per cent more plants winterkilled on the unlimed 

 soil than on the limed areas. That portion of the unlimed field on 

 which the fewest plants winterkilled was found to have the lowest 



