592 The Lois Weeclon Plan of Growing Wheat. 



would be obtained in the average of seasons on such soil by the 

 ordinary means of farming-. 



But turning now from the effect of the mineral constituents to 

 that of assimilable nitrogen in manures, we have in these simple 

 experiments the best answer — namely, that of direct contrary 

 fact — to those who would endeavour to persuade the farmer, that 

 because the soil itself contains hundreds of times more nitrogen 

 than the largest crop of wheat, therefore the comparatively small 

 quantity which is added in an ordinary dressing of manure can 

 have little or no effect. We shall recur to the subject of the 

 nitrogen in soils further on, should our allotted time permit it. In 

 the mean time let it be prominently noted, that whilst the minerals 

 alone gave a total increase of only 438 lbs., the ammoniacal salts 

 alone gave 2573 lbs. of increase ! And again, whilst the addition 

 of minerals to ammonia gave an increase of 1368 lbs., the addi- 

 tion of ammonia salts to minerals, on the other hand, gave an 

 increase of 3503 lbs. ! 



There can now be little difficulty in deciding, that it was no 

 deficiency of available mineral food merely, which prevented the 

 plant for itself, or the soil in the first instance for it, from 

 acquiring a sufficiency of available and assimilable organic con- 

 stituents for the growth of a very much larger crop than was in 

 fact obtained from this expensively cultivated land. It was, on 

 the other hand, notwithstanding the " inexhaustible " supplies of 

 the atmosphere, and notwithstanding the enormous amount of 

 nitrogen in the soil in some form — it was, notwithstanding these 

 — a deficiency of available and assimilable nitrogen toithin the soil, 

 which restricted the full action of the obviously available minerals, 

 and which hence restricted the produce also, to an amount below 

 the average of farming. Whilst, only make up this deficiency of 

 available nitrogen, and the produce is increased to once and a 

 half or twice as much. 



It appears, then, that the same means Avhich afforded the Rev. 

 Mr. Smith his early success on the soil at Lois Weedon, were 

 quite incompetent to yield a similar result on the soil at Rotham- 

 sted. Nay, these same means, notwithstanding that in our case they 

 were much more costly than either Mr. Smith had found them, or 

 than the common fallow which we tried by their side, did not 

 even attain, for the Rothamsted soil, those mechanical conditions, 

 without which the necessary action between soil and atmosphere 

 could not be expected to take place. We think it indeed very 

 doubtful whether, even if all the more recent improvements in 

 the plan could have been fully carried out at Rothamsted, a 

 result would have been obtained there at all equal to that at Lois 

 Weedon. Certain it is, that soils and subsoils, which may equally 

 be included as " c%e?/ " or " heavy" or ^' loamy,'" vary almost 



