E. J. Russell and E. H. Richards 519 



relative to the total change. The final losses of nitrogen, therefore, 

 are not so great as appears from the shrinkage of the heap, although 

 on the absolute they are generally greater than the losses from the 

 covered heaps. 



The non-nitrogenous constituents of the dry matter thus appear 

 to suffer relatively more than the nitrogen compounds as the result 

 of exposure. The residt seems to be fairly general : it was obtained by 

 Maercker at Halle in 1897, and in Scotland by Berry. 



* This experiment is really a comparison between manure stored under the animals 

 in the "Tiefstall," and manure thrown out daily on to two heaps, one exposed and one 

 sheltered. The figures for the loss of nitrogen are absolute determinations, the loss from 

 the " Tiefstall " manure being only 13 per cent. The values for dry matter loss, on the 

 other hand, are relative only and simply represent the excess over and above the losses 

 in the " Tiefstall." The result shows that the losses of nitrogen have been greater than 

 those of dry matter. See Landw. Jahrhuch. 1898, 27, 215 



Direct field experiments have shown that the exposed heaps have 

 less crop producing power than the sheltered heaps. Our own are 

 recorded on p. 505: 10 tons of the sheltered manure (the compact 

 bullock manure, stored three months) gave an increase over the control 

 of 76 % in the yield of potatoes, while an equal dressing of the exposed 

 manure gave only 44 % increase : for the corresponding loose heaps 

 the increases were 73 % from the sheltered, and 57 % from the exposed 

 manure. This was on equal weights of the final manure : had we taken 

 equal weights of the original manure we should have expected even 

 more striking results because of the difference in dry matter. The 

 1916 experiments with potatoes, and both experiments with wheat, 

 give similar results. In like manner Berry found that 30 tons of the 

 sheltered manure gave an increase of 57 % in yield of potatoes, and 

 45% 'of turnips, while an equal dressing of the exposed manure gave 

 only 49 % increased yield of potatoes, and 38 % of turnips, again using 

 equal weights of final, and not of original manure. 



Effect of summer storage. The nine months experiments lasted over 

 the summer, and the columns in Figs. 5 and 6 show how serious the 

 losses were then. The question is one of great practical importance on 

 farms where there is much grass land in proportion to arable, and 



