July, 1909.] 



El 



Scientific Agriculture. 



partial sterilization of the soil such as 

 cau be produced by heat or the use of 

 certain volatile antiseptics. 



The following remark of Hall indicates 

 how much there is yet to learn legarding 

 the questions of fertility and infertility, 

 and how far we still are from being able 

 to control the soil : — " The soil is such a 

 complex medium— the seat of so many and 

 divers interactions, chemical, physical, 

 and biological — and is so unsusceptible 

 of synthetic reproduction from known 

 materials, that experimental work of a 

 crucial character becomes extremely 

 difficult, and above all requires to be 

 interpreted with extreme caution and 

 conservatism." 



There is here evidently intended a 

 gentle reprimand to the American scien- 

 tists for propounding theories which 

 must be considered "not proven;" and 

 yet it is evident that Hall himself is 

 travelling along the same line of thought 

 though his caution will not permit him 

 to dogmatize. 



The conclusion of the whole matter, 

 from an agricultural point of view, 

 emphasizes the necessity for specific 

 knowledge of the habits of cultivated 

 plants, and (to use Hall's expression) their 

 " idiosyncraeies " — knowledge only to be 

 derived through experiment and experi- 

 ence. 



FERTILIZER ACTION. 



(Prom the Journal of the Board of A gri- 

 culture, British Guiana. Vol. II., 

 No. 3, January, 1909.) 



Mr. A. D. Hall, of the famous Rotham- 

 sted Experiment Station, which for over 

 half a century has been the scene — as 

 it was the pioneer— of continuous agri- 

 cultural experiments on an agricultural 

 scale, contributes to the American 

 Journal " Science," of November 6th, an 

 important and most informing paper on 

 " Theories of Manure and Fertilizer 

 Action " which was read by him as a 

 lecture at the Graduate School of Agri- 

 culture, Cornel University, in July, 1908. 

 While summing up the present state of 

 knowledge on this vital matter, the 

 English expert finds occasion to criticise 

 adversely the new and revolutionary 

 theory, recently advanced by Messrs. 

 Whitney and Cameron, that the benefi- 

 cent action ot fertilizers is really due to 

 their destructive effect on the toxins or 

 poison excreted by the roots of plants 

 in the soil (which it is alleged tend to 

 accumulate to a harmful degree if the 

 same crop is continuously grown on the 

 same plot of land) and not to their 

 modifying influence on the quantity 

 



and quality of the plant-food. The 

 paper is too long for reproduction here, 

 and a brief summary only can be given ; 

 but this may serve to draw attention to 

 a valuable contribution to the science of 

 Agriculture, 



Commencing, as is natural, with 

 Liebig, Mr. Hall neatly re-states the 

 German chemist's theory of the action 

 of manures thus : — " The proper fertilizer 

 for any particular crop must contain 

 the amounts of nitrogen, phosphoric 

 acid, potash, and other constituents 

 which are withdrawn from the soil by a 

 typical good yield of the plant in 

 question," and proceeds to show from 

 Rothamsted experiments on wheat, 

 barley and swede turnips that the theory 

 is inadequate to explain the results 

 observed. Thus wheat and barley 

 though taking identical amounts of 

 phosphoric acid from the soil are quite 

 differently affected by phosphoric acid 

 as a fertilizer ; the effect on the former 

 being of quite secondary importance, 

 but in the latter comparing with that of 

 the all-essential nitrogen, For both 

 plants the addition of potash counts for 

 little or nothing, although wheat with- 

 draws 29 lbs. of that constituent from 

 each acre of soil, and barley 56 lbs. 

 Evidently the soil is able to supply all 

 the requirements of the plant for potash 

 in spite of the large amounts which the 

 crop removes ; and it is here, as Mr. 

 Hall says, that Liebig's theory fails — it 

 takes no account of the soil and the 

 enormous accumulation of plant-food 

 therein contained. " A still more note- 

 worthy example is provided by the 

 swede turnip crop ; the analysis of a 

 representative yield would show it to 

 withdraw from the soil about 150 lbs. 

 per acre of nitrogen, 30 lbs. of phosphoric 

 acid, and 120 lbs. of potash, Yet the 

 ordinary fertilizer for the swede crop 

 will consist in the main of phosphatic 

 material with but a small quantity of 

 nitrogen and rarely or never any potash. 

 These differences in manurial require- 

 ments are, as the lecturer points out, 

 correlated with the habits of growth of 

 the plants. The wheat possesses a very 

 extensive root system and a long period 

 of growth, hence it is specially well 

 fitted to obtain whatever mineral con- 

 stituents may be available in the soil ; 

 barley is a spring sown crop, but being 

 shallow-rooted and having only a short 

 growing season, the plant experiences a 

 difficulty in satisfying its requirements 

 for phosphoric acid ; the swede is sown 

 late in the season after a very thorough 

 preparation of the soil, so that the 

 nitrification aloue of the nitrogenous 

 residue in the soil is capable of furnish- 

 ing almost all the large amount of 



