CANE SUGAR. 



9. The determinations of potash soluble in 1 per cent, citric acid and in 

 200th normal hydrochloric aoid showed that cultural operations have made 

 probahly available more potash each year than is required for the growth of the 

 sugar cane, the original samples yielding potash at the rate of 262 Ibs. and 

 278 Ibs. per acre to a depth of eight inches, those not manured with potash 

 salts during ten years at the rates of 376 Ibs. and 500 Ibs., and those which 

 received potash salts in addition to nitrogenous manures at the rates of 357 Ibs. 

 and 530 Ibs. 



10. Judging from the solubility of the lime in the soil in 200th 

 normal hydrochloric acid, cultural operations set free in a soluble form more 

 lime than the crops utilized, the original soil yielding lime to the solvent at 

 the rate of, in round figures, 3400 Ibs. per acre to a depth of eight inches, 

 while the samples taken after ten years' cultivation yielded at the rate of 

 3800 Ibs. The soils which received in July, 1891, slacked lime, supplying in 

 round figures 6700 Ibs. lime per acre, yielded to the acid in 1902 a mean of 

 5000 Ibs. per acre, thus indicating after ten years' cultural operations a 

 retention in the uppermost layer of the soil of only 1200 Ibs. of added lime 

 in a readily soluble form. 



11. The action of the lime on the solubility of the potash in the upper- 

 most layer of the soil appeared well marked, the samples from the not-limed 

 land yielding to 200th normal hydrochloric acid at a mean rate of 460 Ibs. 

 potash per acre to a depth of eight inches, while those from the limed land 

 yielded at the mean rate of 640 Ibs. 



Finally, as a result of these analyses and experiments, Prof. Harrison lays 

 down certain precise and formal propositions of the greatest value to the 

 agricultural chemist responsible for the economic manuring of large areas of 

 sugar cane. These may be summarized as under : 



1. Soils which yield -007 per cent, phosphoric anhydride to 1 per cent, 

 aqueous citric acid with five hours' continuous shaking will not as a rule 

 respond to manurings with phosphates. 



2. Under similar conditions soils yielding '005 per cent, to '007 per 

 cent, will benefit as a rule by phosphatic manurings. 



3. It is advisable to apply heavy dressings of slag-phosphates or lighter 

 ones of super or basic phosphates to soils yielding less than -005 phosphoric 

 anhydride. 



4. Soils yielding *008 per cent, potash can be regarded as containing 

 under the usual system of cultivation sufficient available potash for the needs 

 of the sugar cane. 



5. If the potash lies between '005 per cent, and -008 per cent, it is 

 doubtful if the application of potash salts will result in remunerative returns. 



6. Where the potash falls below *005 per cent, it is advisable to add 

 potash salts in the manures. 



58 



