a32 The W()J>urn Pot-Culture E.vperime7its, 1910-11-12. 



These fignres again are very striking and show that the 

 toxic effects produced by the repetition of magnesia treatment 

 in 1911 are removed by growing the seed again in normal 

 soil. Not only is this so, but the grain previously treated with 

 magnesia would seem to have retained some of its early 

 advantage, as the crop is somewhat above the "no treatment." 

 Moreover it is noticeable that the grain that gave in 1911 the 

 highest nitrogen when treated with magnesia, now gave the 

 lowest nitrogen when planted in ordinary soil. 



Whatever n:ay be said in respect of the "fixing" of type by 

 biological considerations, I cannot help feeling that the present 

 work has shown that there is another side to the question also, 

 and that when such changes as those described above have 

 been seen iu the case of the Cambridge wheats, alike as regards 

 yield, character and composition of grain, as the result of 

 increasing or decreasing the proportions of magnesia to lime in 

 the soil, it cannot be urged that the nature or composition of 

 the soil is without influence as a determining factor. 



(b) The addition of Lime. 

 Having tried the addition of magnesia to a soil poor in this 

 constituent, it was thought well to reverse the nature of the 

 enquiry, and to see whether a soil in which the magnesia 

 naturally dominated over the lime would be improved by the 

 addition of lime. That this is not without practical importance 

 is seen by references which I have made of recent years in my 

 Annual Reports (Annual Report of Consulting Chemist, 1908, 

 page 306 ; 1909, page 8.50) in this Journal, and in which I have 

 dealt with certain soils which have shown inability to carry 

 satisfactory corn crops. In the analyses of these I have found 

 no evidence of actual deficiency of necessary plant food, the 

 one unusual feature being the great predominance of magnesia 

 over lime. The institution of the experiments just recorded 

 led me to think whether possibly the excess of magnesia 

 present had to do with the want of fertility, and I accordingly 

 set the new experiment on foot. For this purpose 1 took a soil 

 from the red clay loam land of Herefordshire, about which 

 complaint was made that it would not grow corn well. This 

 soil, on analysis, showed lime "83 per cent., magnesia 2*29 per 

 cent. In one case the natural soil was used, in a second case 

 lime was added to bring the percentage of lime up to 1*25, in a 

 third to 1*5() per cent., a fourth to 1"75 per cent., a fifth to 2*0 

 •per cent., and in a sixth to 2"25 per cent., or practically equal 

 quantities of lime and magnesia. 



1. Experiment of 1909. 

 The first year's experiments (1909) are given in Journal 

 R.A.S.E., Vol."?], 1910, pp. 317-8, but the results will l)e set out 



