606 



SCIENCE. 



[N. S. Vol. XX. No. 514. 



of four each, ' strongly contrasted in their 

 native productive capacities, in order that 

 strongly marked difPerences might be dealt 

 with.' The dressings of barnyard manure 

 used were at the rate of five, ten and fifteen 

 tons per acre. The crops grown were 

 potatoes and corn, with a series of unmanured 

 check-plots between, in each case. 



The crops from each series of plots were 

 weighed, mostly both in the green and in the 

 dry condition; and concurrently, the kinds and 

 amounts of soluble salts extraetable by water 

 from the soils of each of the plots before and 

 at different intervals after the application of 

 the manure, were determined according to the 

 delicate methods used in the investigations of 

 aqueous soil extracts.* Moreover, the amounts 

 of the several substances contained in the soil 

 extracts, present in the sap of the plants them- 

 selves, were likewise determined, in order to 

 ascertain the relations between the soil solu- 

 tions and the substances taken up by the crops. 



It is not easy for the outsider to detect any- 

 thing reprehensible in this well-considered 

 plan of operations. It seems to be admirably 

 conceived for the determination of the relation 

 of -the soil solutions to plant nutrition and 

 crop production under normal, practical condi- 

 tions. The details given regarding the actual 

 carrying out of the experiments are equally 

 unexceptionable, except as concerns some 

 points in respect to which, apparently, there 

 was interference of some sort with the plan ; 

 e. g., in the matter of making chemical anal- 

 yses of the stable manure used at the several 

 localities. But however regrettable, this and 

 some other omissions, apparently imposed by 

 superior authority, do not vitiate, to any ma- 

 terial extent, the conclusions arrived at by 

 King. 



The plan and methods of experimentation 

 being thus unexceptionable so far as any one 

 examining the record given can judge, the only 

 question remaining is whether the conclusions 

 deduced from the experimental results are 

 justified, and whether these are in conflict with 

 practical or scientific experience, or with com- 

 mon sense. Of these conclusions it will be 



- Bulletin No. 22, Bureau of Soils. 



best to give the chief ones in the words of the 

 author. 



After giving, on page 5, a table showing the 

 percentage relations of crop yield under dif- 

 ferent fertilizations, he says : ' It will be seen 

 that in the case of the poorer soils there is a 

 percentage difference of 46 between the yields 

 of the fiiteen-ton subplots and those to which 

 nothing has been added; but a difference of 

 only eighteen on the stronger soils.' Recal- 

 culating these results on the next page so as to 

 show their relations more clearly, he adds : 

 ' These results show that both relatively and 

 absolutely, adding fertilizers to the poprer soils 

 has had a greater effect than the same treat- 

 ment with stronger soils.' Farther on, after 

 giving- a table of the several yields of water- 

 free shelled corn, he says : " It is here seen that 

 on the four poorer soils, there is a systematic / 

 difference in the yield of water-free shelled 

 corn, closely related to the fertilizers applied 

 to the soil. The group of four stronger soils 

 do not show, throughout, this systematic rela- 

 tion." Photographic views of the corn on the 

 growing plots show these differences clearly in 

 the growth of the plants. 



The only criticism that could be, perhaps, 

 made of the work leading to these conclusions 

 from an outside point of view, is that they 

 are so clearly and thoroughly in accord with 

 all former experience, both practical and ex- 

 perimental, that they are largely foreseen. 



Then follows the record and discussion of 

 corresponding experiments with potatoes, 

 which yield practically the same results and 

 conclusions. 



Then are given the results of analyses of 

 leachings of the same soils upon which these 

 crops had been grown. The results are pre- 

 sented in a table, from which " it is very clear 

 that the effect of different amounts of stable 

 manure applied to these soils * * * has been 

 such upon the recovery of the water-soluble 

 salts as to enable the same treatment to re- 

 move different amounts from different fertili- 

 zations. * * * There is a clear quantitative 

 relation, too, between the yields and the salts 

 recovered, these (the former) increasing 

 where the essential ingredients of plant food 

 are higher." 



