On the Top- Dressing of Wheat. 



203 



mildew. These two serious faults, it now appears, may be cor- 

 rected by mixing with the nitrate a moderate quantity of common 

 sea-salt — which, when used in heavy doses, destroys the life of 

 grass — and may therefore be readily supposed to counteract the 

 dangerous suddenness of vegetation that nitrate produces. Thus 

 common salt may prevent mildew, and is known certainly, on some 

 soils, to strengthen the straw. The nitrate was sown as directed 

 at the rate of one cwt. per acre, mixed with one cwt. of common 

 salt ; but this quantity was not given at once, being divided as 

 enjoined into two doses, applied at a fortnight's interval and in 

 showery weather. It was so applied to a 10-acre piece of white 

 wheat, a portion thereof being, however, passed over. The whole 

 produce has been threshed out already, in order to test the effect ; 

 a portion was top-dressed, not with nitrate, but guano. The result 

 is as follows — 



Value"! 



Bushels ' Increase' Cost of ^ °^ j 

 per Acre, in Bushels. Dressing. Increased 



Produce. , 



s, s. d. 



Undressed 21 



Guano, 2 cwts. 24 3 20 15 0 "" 



Nitrate, 1 cwt., and salt, 1 cwt. . 25^ 4^ 17 22 6 



The other trial was made on an 8 -acre piece of red wheat 

 following barley. The wheat had begun to appear very blue and 

 spindling, notwithstanding a good coat of dung given it in the 

 autumn, to make up for cross cropping. The improvement was 

 immediate, and has stood the test of threshing, for the account is 

 as follows. Two acres were threshed, one on each side adjoining 

 the half acre in the middle on which no nitrate of soda was sown. 



Value 



Bushels Increase Cost of per Acre pj-ggt 



per Acre, in Bushels. Dressing. increased P^r Acre. ] 



. Produce. 



s. s. s. 



Undressed ... 19? 



Nitrated . . . 27i 8| 17 42 25 



The profit on this piece is certainly more than the value to 

 rent of the land, which is a poor blowing sand. The theory of this 

 action is now clearly established by Mr. Lawes's experiments, for 

 nitrogen, whether as ammonia in guano or whether in a nitrate, 

 is proved to be the food generally wanted by wheat. Mr. Way 

 informs me that nitrogen is now rather cheapest in guano, but it 

 does not appear to be so effective as a top-dressing, possibly be- 

 cause in guano it is volatile and not so in nitrate. Clearly as 

 there is no limit to the beds of nitrate in the plains of Peru, it 

 will be a great advantage if we can thus hope to deal with the 

 most unfortunate monopoly of guano, for with a large demand 



