Effects of Nitrate of Soda. 119 



vision of mineral constituents within the soil, the amount of 

 produce is more dependent on the supply by manure of 

 available nitrogen, than of any other constituent. The 

 question has been discussed as to how much ammonia, or its 

 equivalent of nitrogen in some other form, will, on the 

 average, be required to yield a given amount of increase of 

 wheat or barley grain, and its proportion of straw. It was 

 concluded that, on the average, about 51b. of ammonia (or 

 its equivalent of nitrogen) were required to yield one bushel 

 of increase of wheat, and its proportion of straw, whilst 

 only 21b. to 2Jlb. of ammonia are required to produce one 

 bushel increase of barley, and its straw. In other words, 

 whilst it required 51b. of ammonia in manure to yield 611b. 

 of wheat grain, and 1051b. of straw = 1661b. of total pro- 

 duce, it only requires from 21b. to 2Jlb. to yield 521b. of 

 barley grain and 631b. of straw = 1151b. of total produce. 

 Or, for the production of lOOlb. increase of total produce of 

 wheat, it required 31b., and for the production of lOOlb. 

 increase of barley (containing a larger proportion of grain, 

 but about the same amount of nitrogen), it required only 

 from l|lb. to 21b. of ammonia in manure ; that is to say, it 

 required much more ammonia to yield a given amount of 

 increase when applied in the autumn for wheat, than when 

 in the spring for barley. 



In connection with the action of nitrate of soda, it must 

 not be overlooked that a given surface of soil has much less 

 power to retain either nitrate of soda, or other nitrates, 

 than ammonia, and so far their nitrogen is, coder is paribus, 

 more liable to loss by drainage. Yet when frequently used 

 on the same land, such was the effect of the nitrate, or of 

 its products of decomposition, aided by increased develop- 

 ment of root, in causing the disintegration, and so increasing 

 the porosity and surface of the clay subsoil, that there 

 would appear to have been not only a greater retention of 

 moisture in an available form by the subsoil, rendering the 

 growing crop more independent of drought, but also a 



