110 The Rothamsted Barley Experiments. 



the greater, the greater the amount of ammonia-salts 

 applied as manure ; that (after autumn sowing) the quantity 

 was very much greater in the winter than subsequently in 

 the spring and summer; that, indeed, the winter drainage, 

 after sowing ammonia-salts in the autumn, may often 

 contain from two to three parts (and sometimes much 

 more) of nitrogen (in the form of nitrates and nitrites) 

 per 100,000 parts of water. Calculation showed that, for 

 every one part of nitrogen per 100,000 parts of drainage, 

 there would be a loss of 2Jlb. of nitrogen per acre for every 

 inch of rain passing beyond the reach of the roots. Inas- 

 much as a given surface of soil possesses much less capacity 

 of absorption for nitrate of soda, or its products of decom- 

 position, than for the ammonia of ammonia-salts, it follows 

 that heavy rains soon after sowing would carry away in the 

 drainage water more nitrogen from a dressing of nitrate of 

 soda than from an equivalent dressing of ammonia-salts 

 In one case, after a heavy dressing of nitrate of soda in the 

 spring, Dr. Voelcker examined the drainage waters, and 

 found 5*83 parts of nitrogen per 100,000 of water, corres- 

 ponding to a loss of 131b. of nitrogen per acre, per inch of 

 rain so passing. Owing to the much less loss by drainage 

 in the case of spring than of winter sowing, there was not 

 only more increase in the immediate crop from a given 

 amount of nitrogen applied in the spring for barley (or oats) 

 than in the autumn for wheat, but there was also much 

 more effect upon succeeding crops, from the at first 

 unrecovered amount, in the case of the barley than in that 

 of the wheat. Respecting the fate of the nitrogen supplied 

 as manure in ammonia-salts, or in nitrate of soda, it is 

 probable that the whole of this element is either recovered 

 in the immediate increase of crop, or retained in the soil in 

 a very slowly available condition, or drained away and lost. 

 Owing to the slow decomposition of the nitrogenous organic 

 matter of rape-cake and farmyard manure, their nitrogen is 

 less rapidly available than that of ammonia-salts or of 



