104 TjIdk' lie<iiiir<iii< Ills of Cirlniii Sails 



ainniouia and nitrates produced, do not give corresponding increases 

 in crop. 



(6) Certain physical chan(.'es aiso (iconr alxnit f]ii' partial sterilisa- 

 tion point. 



Par'I' TT. Jjime Jipqinrcmcnla for Netilralisalion Purjwses. 



(1) The method described for the determination of the lime require- 

 ments of the soil is based on the absorptive capacity of the soil for 

 calcium carbonate (present in solution as bicarbonate), which is the 

 chief form coming into operation in the field. 



(2) The comparative tests of various soils to which (|uantities of 

 lime had been added previouslv, showed proportiniinte dimiinition of 

 the lime requirements. 



(3) The method possesses the advantage over several others sug- 

 gested in that it indicates no absorption in the case of neutral soils. 



(4) Soils showing a positive lime requirement according to this 

 method have been found to respond distinctly to the a])|)iieation of 

 carboimte {a) by increased ammonia and nitrate production in laboratoiy 

 experiments, and (6) by greater plant growth in ])ot culture and lield 

 work. 



(•■j) The application of lime to field soils is reflected in decreased 

 lime requirements and increased crop production even after a prolongeil 

 period (upwards of 17 years). 



(6) The values of calcium oxide and carbonate have been shown to 

 be identical provided that the lime requirements (for neutralisation 

 purposes) are not fully satisfied. After the neutral point is reached 

 calcium oxide exercises its specific effect. With an acid Woburn soil 

 the returns in plant growth were pioportional tn the reduction in 

 acidity. 



(7) An application of carbonate to a soil exercises a marked effect 

 in accelerating the process of ainmom'fication, and to a lesser degree 

 nitrification. 



(8) The results of an acidity, or lime requirement, test and not 

 those of determinations of free carbonate should be taken into con- 

 sideration when the needs of any particular soil are concerned. 



(9) In the case of soils on the same geological formation a definite 

 relation between soil reaction and natural flora has been traced. The 

 occurrence of certain plants on acid soils appears to be determined by 

 their capacity of resistance to acidity. 



