1278 CEREAI^S AND PULSE CROPS 



ammoniacal salts and nitrate, between the sulphate and carbonate of mag- 

 nesium, and between the different ammoniacal salts, tend to disappear. 



In some cases the ammoniacal salts may produce a crop equal to that 

 obtained with the nitrates, and if, under many other circumstances, the ni- 

 trate still retains an indisputable superiority, the fact is probably due to 

 a poisonous action of ammoniacal salts on the growing seedlings. An expla- 

 nation has been offered for the specificallj^ favourable action of the am- 

 moniacal salts by connecting it with the acid physiological character of 

 the latter. Both in the chloride and the sulphate, the cation NH^ is 

 alone absorbed and utilised by the plant, while the anions CI or SO4 are onh' 

 partly fixed, and hence there results a progressive increase of acidity in 

 the plant substance, which is quite sufficient at this stage to produce an 

 action injurious to growth. On these h'nes the favourable effects of magne- 

 sium carbonate in the series : phosphates, ammoniacal salts, might be ex- 

 plained, as likewise the superiority of the slag with large lime contents over 

 the other phosphate manures, etc. All that is here in operation would be 

 merely the neutralising power of the two carbonates, that of magnesia and 

 that of lime. 



The following facts however conflict with this h3-pothesis : 



i) The sick plants were young ones, and so small as yet that it cannot 

 be certain that fhey had absorbed nitrogen to an extent capable of notice- 

 ably influencing the composition of their substance. 



2) If the weight of the dry substance of the 3 weeks old seedlings 

 which grew in one vessel be taken as equal to 6 grms., there will be in all about 

 24 grms. of green substance. Out of 24 grms. of fresh substance there is 

 0.144 grni. of nitrogen, corresponding to 0.375 grm. of hydrochloric acid, 

 which would require 0.51 grm. of calcium carbonate for its neutralisation. 

 Bone meal, however, contains calcium carbonate in the proportion of 1.26 

 grms, more than twice what is required, and in spite of this it does not suf- 

 fice alone to counteract the injurious action of the ammoniacal salts. 



3) Finally, it was observable that ammonium nitrate, though physio- 

 logically a perfectly neutral salt, produces the same effects as magnesium 

 chloride and sulphate, though to a less extent. 



Thus the hypothesis of a progressive acidification of the substance of 

 the plants must be dismissed, and it is more in keei)ing with the facts to 

 assume that what really takes place is a poisonous action of the ammoniacal 

 salts exerted direct on the plant. 



Recent experiments appear to show that the carbonates of calcium 

 and magnesium promote the processes of nitrification by bringing about the 

 transformation of the injurious ammoniacal salts into nitrates which are 

 not injurious : hence their beneficial action. 



971 - Oat-growing in the State of Washington, United-States. — schafer e. g. and Gai- 

 nes E. F., in State CullcL;e of Washini;ton, A<^nct(llurn! F.xpen'ment Sta-lion, Pullman, 

 Washington, BullctinNo. 129, 13 pp., 3 fig. I'ullnian, March 1916. 



After wheat, oats are the most important grain crop cultivated in the 

 State of Washington. During the ten-year period which closed in 1914, the 

 average annual production was 1.1 629 253 bushels ; the average area oc- 



