CH. x] Cake-fed DniU) 179 



soil open and to facilitate drainage and the action of 

 winter frost. The harmful effect on the soil nitrates 

 alreadj^ noted (p. 171) is not produced to any notable 

 extent during this season of the year; the straw has had 

 time to become disintegrated, and its reactive con- 

 stituents to decompose, before the spring comes round. 



On the other hand spring applications of long manure 

 suffer from certain disadvantages; there is the possi- 

 bility of loss of nitrate and on light land or in dry dis- 

 tricts the undecomposed straw may open up the soil too 

 much and cause loss of water. These disadvantages do 

 not operate in wet districts. 



Short manure can be used at almost any time of the 

 year and is therefore necessary for many garden pur 

 poses. 



The distinction between cake-fed dung and ordinary 

 dung produced by store cattle has already been dis- 

 cussed. Cake-fed dimg, as shown on p. 172, is richer in 

 nitrogen than dimg produced on hay and roots only, 

 and is even better than the figures indicate because the 

 extra nitrogen is largely in the form of ammonia and 

 amides produced from the liquid excreta. These com- 

 pounds readily change to nitrates in the soil and so give 

 rise to increased crops. Some of the data obtained at 

 Rothamsted are given in Table XII. 



On the heavy soil at Rothamsted and the similar soil 

 at Garforth the advantage of the cake feeding was not 

 seen after the second year ; experiments on other types 

 of soil would be needed to discover how far this effect is 

 general. 



The two most striking physical effects of farmyard 

 manure on the soil are the improvement in tilth already 

 referred to, and the improvement in the water-holding 



122 



