16 



FARMERS BULLETIN 797. 



lime requirement. On the unlimed areas with a low lime requirement 

 15 per cent more plants winterkilled than on the limed areas ; on those 

 with a high lime requirement the increase in winterkilling was 33 

 per cent. In the fall of 1914 the hay cut from the limed areas ex- 

 ceeded that from the areas with a low lime requirement by 600 pounds 

 per acre and exceeded that from the areas of high lime requirement 



by 4,000 pounds per 



'M 



acre. In July, 1915, the 

 increase in hay yield 

 on the limed areas over 

 that from the areas with 

 a low and with a high 

 lime requirement was 

 2,300 and 9,400 pounds 

 per acre, respectively. 

 The area of high lime 

 requirement returned a 

 small yield in 1914 and 

 no hay in 1915. 



In spite of the fact 

 that sweet clover is as 

 sensitive to soil acidity 

 as red clover or alfalfa, 

 a large percentage of 

 the acreage thus far 

 seeded in the eastern 

 half of the United 

 States has been com- 

 posed of acid soils, and 

 this soil acidity un- 

 doubtedly is responsi- 

 ble for a very large per- 

 centage of the failures 

 with sweet clover in 

 this section. Where 

 sweet clover is to be 

 sown on acid soils a suf- 

 ficient quantity of lime 



should first be applied to at least neutralize the acids in the soil to 

 a depth of 6 inches. An application of 1 ton of burnt lime or 2 tons 

 of finely ground limestone will usually be sufficient for this purpose. 

 Fields have been noted where sweet clover was making a fair 

 growth on apparently acid soils. Such fields usually are rich in 

 humus or phosphorus and are exceptional cases rather than the rule. 



FIG. 7. Sweet-clover plants, showing the effect of lime 

 upon their growth. The plants at the left represent 

 the average growth on the unlimed portion of a field ; 

 the plants at the right show the average growth on 

 the limed part of the same field. 



