438 



MR. J. B. LA.WB8, DB. GILBERT, AND UK. PTJGH ON 



paratively large amount of Nitrogen, is one of the best preparations for tin- aftergrowth 

 of wheat. On the other hand, it is equally true that fallow — one important effect of 

 which is to accumulate within the soil the available Nitrogen of two or mere yea 



the growth of one — and adding nitrogenous manures, have eaeh much the same effect in 

 increasing the produce of the Cereal crops. 



B. — Yield of Nitrogen per acre when "Wheat is grown in alternation with 



Beans, or with Fallow. 



The striking and interesting fact, that the growth (and removal from the land) of a 

 highly nitrogenized Leguminous crop, and fallow, have each the effect of increasing the 

 amount of produce, and with it the yield of Nitrogen per acre, of a succeeding Cereal 

 crop, is briefly illustrated by the summary of direct experimental results given in the 

 following Table : — 



Table III. 



Showing the Amount of Nitrogen obtained per acre, in "Wheat grown consecutively, in 

 Wheat alternated with Beans, and in Wheat alternated with Fallow. 



Period of Experiment ten years, 1850 — 1859 inclusive. 



It is seen, then, that ten consecutive crops of beans, without manure of any kind, 

 gave an average annual yield of Nitrogen, per acre, of 34-7 lbs. ; and ten consecutive 

 crops with "mineral" but without nitrogenous manure gave an average annual yield, 

 per acre, of 51-1 lbs. 



During the same period, ten consecutive crops of wheat without manure of any 

 kind gave annually 2 3- 4 lbs. of Nitrogen, or less than half as much as the beans 

 with mineral but without nitrogenous manure. Again, extending over the same 

 series of years, five crops of wheat alternated with fallow gave, taking the average of 

 the five years under crop, 43-9 lbs., and on the average of the ten years. 21 - 9 lbs. per 

 acre, per annum, of Nitrogen. , That is to say, the wheat alternated with fallow gave, 

 taking the average of the five years of its growth, nearly twice as much Nitrogen 

 annually as the wheat grown after wheat in the same seasons. The total Nitrogen 

 obtained, per acre, over the ten years, was, however, pretty much the same in the two 



