206 The Bothamsted Grass Experiments. 



the application of the ammonia-salts was the means of turning 

 to account some of the accumulated residue of the mineral 

 constituents supplied in the dung, the limit of the imme- 

 diately available supply was very soon reached, the remainder 

 becoming less and less rapidly recoverable. It was, in fact, 

 retained in a condition so slowly available as to be of but 

 little effect in increasing immediate crops, and, therefore, of 

 but little practical value, except as a storehouse against 

 exhaustion. 



Two points only now remain for consideration, namely, the 

 character of the second crops, and the influence exercised by 

 the nature of the season upon the produce of hay. Both of 

 these are matters of high practical interest. 



THE SECOND CEOPS. 



So far the produce of the first crops only, of each year, 

 has been taken into account. The estimated amounts of 

 second 'crop, on each plot, in each season, are collected in 

 an elaborate table in an appendix to the paper published in 

 the Philosophical Transactions. But the general character 

 and bearing of the results are sufficiently brought to view 

 in an abstract table, too extensive to be reproduced here, 

 in which are recorded the figures for a selection of the 

 plots only, representing very characteristically different con- 

 ditions of manuring. The plots for which the results are so 

 given are : 



Plot 3. Unmanured every year. 



Plot 7. Mixed mineral manure (including potash), without 

 nitrogenous manure, every year. 



Plot 9. Mixed mineral manure (including potash), and 

 4001b. ammonia- salts, every year. 



Plot 11. Mixed mineral manure (including potash), and 

 SOOlb. ammonia-salts. 



Plot 14. Mixed mineral manure (including potash), and 

 nitrate of soda containing the same amount of nitrogen as 

 the ammonia-salts on plot 9. 



