Scientific Agriculture. 



234 



[March, 1910, 



fying organisms in consequence much 

 reduced in numbers. Hence it would 

 appear that the nitrogen which the 

 grass is obtaining is that of the ammo- 

 nium salts of the manure. Inasmuch, 

 however, as the experimental evidence 

 supplied by previous workers is not 

 conclusive, Messrs, Hutchinson and 

 Miller have carried out a series of 

 experiments, admirably planned and 

 conducted, to settle the matter once 

 for all. 



The experiments, to be conclusive, 

 must be carried out in soil or sand in 

 which nitrification is precluded, and it 

 is not the least interesting part of their 

 woi k that the authors named have suc- 

 ceeded in growing various plauts, such 

 as Wheat and Peas, in media from 

 which bacteria of all kinds were ex- 

 cluded. The seeds were first sterilised 

 by means of mercuric chloride, they 

 were germinated on sterilised agar, and, 

 when sufficiently advanced, the seed- 

 lings were transferred to sterilised cul- 

 ture vessels containing soil, sand, or 

 water, to which either ammonium sul- 

 phate or nitrate of soda, or both, was 

 added. 



The results prove that in the cases 

 of Wheat and Peas, plants grow just 

 as well when supplied with ammonium 

 salts, under conditions which preclude 

 all possibility of the nitrification of 

 these salts to nitrates, as they do when 

 provided with nitrogen in the form of 

 nitrates. 



Incidentally, Messrs. Hutchinson and 

 Miller make an ingenious suggestion to 

 account for the striking fact that legu- 

 minous crops are so much richer than 

 others in organic nitrogen. They 

 observe that plants supplied with nitro- 

 gen in the form of ammonium salts tend 

 to be richer in nitrogen than those 

 which receive nitrates. They suggest, 

 very plausibly, that this is due to the 

 ammonium salts being converted readily 

 into organic compounds, such as aspara- 

 gine, which substances will not interfere 

 with further absorption of ammonium 

 salts from the soil. When, on the other 

 hand, nitrates are supplied, they tend 

 to accumulate as such in the tissues of 

 the plant, and a condition of equilibrium 

 between soil and plant-tissues with res- 

 pect to nitrates being established, fur- 

 ther absorption of nitrates is hindered. 



Applying these considerations to legu- 

 minous plants, they point out that the 

 nitrogen supplied to the plant by the 

 activity of the nodule-organism is prob- 

 ably in the form of an ammonium 

 compound ; that, as a matter of fact, 

 asparagine occurs in considerable quan- 

 tity in the tissues of the root neighbour- 

 ing on the nodules ; and, therefore, 



there is nothing to hinder the absorp- 

 tion by the plant of as much combined 

 nitrogen as the nodule or organism is 

 able to provide. 



Lastly, turning to the practical side 

 of the question, it appears to be fairly 

 well established that not all crops are 

 alike in their preference for a parti- 

 cular form of nitrogen. Potatoes thrive 

 somewhat better when supplied with 

 ammonium salts. Maize and Paddy Rice 

 prefer ammonium salts during their 

 e irly stage of growth, but later do 

 better with nitrates. Mangolds and 

 Buckwheat give a better yield when 

 supplied with nitrates than when pro- 

 vided with sulphate of ammonium. 

 Mustard, Oats, and Barley are indif- 

 ferent, growing equally well with ni- 

 trates or ammonium salts. 



Speaking generally, the best results 

 are obtained when nitrogen is supplied 

 in both forms. The last point deserves 

 to be emphaised, for, as has been shown 

 by Mr. Hall, the continued and exclu- 

 sive use of one or other of the two chief 

 nitiogen-containing artificial manures, 

 nitrate of soda and sulphate of ammonia, 

 sets up unsatisfactory soil conditions. 



We welcome the work of Messrs. 

 Hutchinson and Miller, both because of 

 its intrinsic value and because it is a 

 manifestation of the energetic manner 

 in which soil and other researches are 

 being conducted at Rothamsted under 

 the able direction of Mr. Hall. We 

 should like to see the investigation ex- 

 tended to embrace the chief garden and 

 field crops, and would suggest that 

 some of the horticultural colleges should 

 carry out the work on the lines so ex- 

 cellently laid down in the paper which 

 we have been considering. 



It should be the function of a station 

 such as Rothamsted to deal, as it does, 

 with the broad principles of the sciences 

 of agriculture and horticulture. It 

 should be the function of the smaller in- 

 stitutions to develop in detailed manner 

 the discoveries made at the national 

 station, so that they may yield the 

 maximum of service to those engaged 

 iu the practice of agriculture and of 

 horticulture. 



THE TREATMENT OF ACID SOILS 

 FOR RUBBER AND OTHER 

 CUL TIVATIO NS. 



By J. B. Carruthers. 



(From the Agricultural Bulletin of the 

 Straits and F.M.S., VIII., No. 1.) 

 A series of experiments have been 

 begun by the D partmeut of Agri- 

 culture on some low lying flat land 



