492 On the Growth of Barley hij different Manures, Sfc. 



84 lbs. more of straw, = 93 lbs. more of average total produce, 

 than by the rape-cake alone. 



The addition of both superphosphate of lime and " Mixed 

 Alkalies'^ to the small amount of ammoniacal salts, increased the 

 result by 405 lbs. of corn, 729 lbs. straw, = 1134 lbs. total in- 

 crease ; but their addition to the larger amount of ammoniacal 

 salts only increased the produce by 198 lbs. corn, 882 lbs. straw, 

 = 1080 lbs. total increase. The addition of the same full mineral 

 manure to the rape-cake did very much less. Thus the combi- 

 nation gave 2 lbs. less corn and only 90 lbs. more straw than the 

 rape-cake alone. 



From all that has been said as to the very much increased luxu- 

 riance of growth where the double amounts of nitrogen were 

 applied by manure, it will be sufficiently clear, that these appaiently 

 less results of both given amounts of nitrogen and of mineral ma- 

 nures, when the former — the nitrogen — was employed in so large 

 an amount, was due in reality, not to the inaction of the manures, 

 but to the over-luxuriance they induced in the earlier stages of 

 growth, and the consequent falling of the crop and loss of final 

 result. It is obvious, therefore, that tlie numerical results of 

 Series 4, do not at all fairly represent the intrinsic productive 

 values of the different combinations. 



That over-luxuriance, and not the contrary, was the cause of 

 the failure, is evident from the fact, that although the rape-cake 

 used alone gave more increase than the ammoniacal salts alone, 

 when they were respectively used with superphosphate of lime 

 and superphosphate of lime and the *' Mixed Alkalies" together 

 (which increased the produce with smaller supplies of nitrogen), 

 then the rape-cake, which when alone was the most active, gave 

 less results than the ammoniacal salts. 



The general conclusions from a review of the results of Scries 4 

 are, that with an excessive amount of nitrogenous manure, the 

 immediate return of crop from a given amount of the expensive 

 manurial constituent — available nitrogen — will be much dimi- 

 nished ; that the proportion of straw will be greater — an expen- 

 sive end to which to devote such costly means ; and lastly, that 

 the addition under these circumstances of a liberal supply of 

 certain otherwise effective mineral manures, may be quite inade- 

 quate to counterai;t the injurious effect ; their tendency being then, 

 as seasons go, still more to increase the straw in greater propor- 

 tion than the corn. 



From a review of the whole of the results relating to the action 

 of special manures upon the barley-crop — taking the average of 

 six successive years of growth by each, on land in an agricultural 

 sense somewhat exhausted — we learn — 



