A VISIT TO IIOIIIA.M.STKI). 255 



take along witli tlicni jilots 3 and 10, is as follows: — Plot 3, tlie 

 natural soil, was deficient especially in nitrogen, and for the want 

 of that constituent the crop was \niable to make use of the 

 mineral matter that was present to the extent that it ought to 

 have clone. In plot 10 this deliciency was made up l)y the addi- 

 tion to the natural soil of 400 lbs. ammonia salts, and the crop 

 rose (.luring the first twelve years from an average of 1H\ to 22^ 

 bushels per acre. This addition of nitrogenous manure enabled 

 the plant to make full use of the mineral food contained in the 

 soil, for there was plenty mineral food in the natural soil, but for 

 want of nitrogen the plant could not assimilate it. It is not 

 surprising tlien that the addition of minerals (plot 5) to such a 

 soil should have produced very little effect. As soon as 

 ammoniacal salts were added (phit 6), the plant was able to utilise 

 not only the original mineral food in the soil, but also a large 

 amount of that which had been added. That it was not able to 

 do so entirely is seen from the increase obtained on plots 7 and 

 8 l)y the further addition of ammonia salts. 



The small increase of croji on plot 8 over that on plot 7 

 shows that the limit of profitable nitrogenous manuring on that 

 soil has been passed — that in fact there is now an excess of 

 nitrogenous food in the soil, and that to obtain a large increase 

 of crt)p a further application of mineral salts is needed. The 

 probability is, however, tliat any increase of crop by that means 

 would be small in proportion to the increase of manure. "We 

 are plainly taught by these results that in ordinary soil there is 

 a deficiency of nitrogen, and that without the application of some 

 kuul of nitrogenous manure the soil cannot raise crops to the 

 extent to which its mineral wealth entitles it, and that there is 

 a certain ratio between the nitrogenous and mineral matters in 

 the soil which is most economical, enabling the plant to make 

 equal use of both ; that, moreover, even when that ratio is main- 

 tained, there is a limit to the quantity of well-adjusted manure 

 which it is profitable to put upon the soil. 



As to the kind of nitrogenous manure ])est suited to supply 

 the natural deficiency, ammoniacal salts are here again compared 

 with corresponding amounts of nitrate of soda, and, as in the case 

 of the grass and the barley experiments,the advantage lies with the 

 nitrate of soda, especially in the produce of the second twelve years. 

 I'lots 7 and 1 5 are both manured in the same way — the former 

 being manured in spring, and the latter in autumn. The slight 

 deficiency in the crop on plot. 15 may be due to the loss of some 

 of the ammonia salts from the soil during the Avinter fallow. 



Tliat there is in time a great loss to the soil of anmionia is 

 brought out very strikingly on plots 16, a and h, wliich received 

 annually for twelve years the very large application of 800 lbs. 

 ammonia salts, with the usual amount of mineral manures, and 

 produced annually on an average 39^ bushels of wheat. If this 



