July, 1912.J 



55 



Scientific Agriculture. 



1. Ignition and extraction with boil- 

 ing water exercise a considerable effect 

 on the availability of the phosphate. 



2. That insoluble calcium phosphate is 

 markedly less effective in the growth of 

 oats than insoluble iron phosphate. 



3. That this difference in efficiency is 

 not apparent in the case of swedes and 

 peas. 



The results as a whole are in accord 

 with the conclusions of Soderbaum and 

 Prianischnikoff ; the former found tbat 

 not much phosphoric acid is available 

 for the oat plant, and the latter, that 

 even in pure sand lupins can use apa- 

 tite, though Gi aminese fail to do so. 



THE DIRECT ASSIMILATION OP 

 INORGANIC AND ORGANIC 

 FORMS OF NITROGEN BY 

 HIGHER PLANTS. 



Hutchinson, H. B. and Miller, N. H. J. 

 (Lawks Agricultural Trust). 



The Journal oj Agricultural Science, Vol. 

 IV.. Pt. 3, pp ; 282-302 + Plate 1 + Tables 

 4. Cambridge, January, 1912. 



(Bulletin of the Bureau of Agricultural 

 Intelligence and of Plant-Diseases, 3rd 

 Year— Number 4, April, 1912.) 



It is now known that any nitrogenous 

 compound applied to the soil will, sooner 

 or later, under ordinary conditions, be 

 converted into nitrates, and if it can be 

 shown tbat from certain types of 

 nitrogen compounds plants can directly 

 obtain all the nitrogen they require, and 

 that of such types some are more favour- 

 able than others, the results cannot fail 

 to throw some lighc on the synthetical 

 process in plants. 



The conclusions so far reached may be 

 summed up as follows : 



According to Molisch, M. Schultz, Per- 

 ciabosco and Rosso, nitrates are assim- 

 ilated by different plants when in suffi- 

 ciently dilute solutions ; further, plants 



supplied with nitrogen in potassium 

 nitrate solutions or as ammonium 

 salts, contain a distinctly higher per- 

 centage of nitrogen thau plants grown 

 with nitrate. Other inorganic com- 

 pounds of nitrogen — amidosulphonicacid, 

 hydroxylamiue, hydrazin sulphate, and 

 azuiinide— have given negative results. 

 As regards organic compounds the 

 majority have given negative, or at 

 most uncertain results. 



In the investigations described in this 

 paper, as in the previous ones, the seeds 

 were sterilised by a mercuric chloride 

 solution under reduced pressure, and the 

 plants (peas) were grown in Woulffe's 

 bottles with th9 usual mineral substances 

 in about 1 litre of water. The nitro- 

 genous compound was added iu such 

 quantity as to supply about 80 mg. of 

 nitrogen. The garden soil experiment 

 gave no positive results. 



It was found that the soil in the bottles 

 had become infected and contained con- 

 siderable amounts of ammouia. 



The various compounds may be divided 

 into the following group according to 

 their availability, or otherwise, as direct 

 sources of nitrogen for peas : 



I. Readily assimilated : Ammonium 

 salts; Formamide ; Acetamide Urea. 

 Barbituric acid ; Alloxan ; Humus. 



II. Assimilated : Glycine ; a— Amino- 

 propionic acid; Guamidine hydrochlor- 

 ide ; Cyanuric acid ; Oxamide ; Peptone. 



III. Doubtful or not assimilated : Hip- 

 puric acid ; Trimethy-lamine para — Ura- 

 zine ; Hexamethyl-eneteramine) ; Ethyl 

 nitrate; Propionitiile ; Hydroxylamine 

 hydrochloride ; Methyl carbonate. 



IV. Toxic : Tetranitromethane. 



The results so far obtained are not 

 sufficiently numerous to make it possible 

 to trace any connection between the 

 assimilability or the reverse of the 

 nitrogenous compounds and their con- 

 stitution. Apart from humus, which as a 

 mixture, cannot be said to have a con- 

 stitution, the best results are obtained 

 with urea and barbituric acid, the former 

 assimilating rather more nitrogen than 



