LIME 



189 



244. Effect of lime on tilth. — A clay or loam soil when in 

 acid condition tends to become compact and difficult to till. 

 The addition of lime to soil helps to bring about a granular 

 formation of the small particles, and to give the soil better 

 tilth. This effect has previously been noted in § 46. 



245. Effect of lime on bacterial action. — Some of the 

 most beneficial bacteriological processes are greatly favored 

 by an abundant supply of lime in the soil. Important among 

 these are the various processes involved in the formation 

 of nitrates from organic forms of nitrogen. It seems also 

 to be associated with the operation by which some legumes, 

 for instance alfalfa, secure nitrogen from the air. The in- 

 creased supply of easily available nitrogen is often reflected 

 in the yield and nitrogen content of the crops, as well as in 

 the percentage of nitrates in the soil. This is illustrated by 

 an experiment in which alfalfa was raised on plats of land 

 one of which was limed liberally and the other not limed. 

 The hay was weighed when cut, and was then analyzed, 

 as were also the weeds growing with the alfalfa. The soil 

 was sampled and the nitrates determined. The soil was also 

 allowed to stand for ten days at an optimum water content 

 and a temperature suited to the production of nitrates, 

 at the end of which time the quantities of nitrates formed 

 were determined. The results are shown in Table 40. 



Table 40. — The Effect of Liming Soil on the Yield and 

 Composition of Alfalfa Raised on It, and on Its Nitri- 

 fying Power 



