MAINTAINING FEllTILITY OF LAND 187 



ing up the supply. Sometimes the stalks an; burned. 

 This may occasionally be desirable, but one should be 

 very sure of it before he destroys such valuable material. 



In a few sections in the western part of the United 

 States, wheat is harvested with a combined harvester and 

 thresher that leaves the straw scattered over the field. 

 When this is plowed under without burning, it furnishes a 

 large amount of humus-making material. In parts of 

 the western wheat country, where grain cannot be safely 

 left standing until it is dry enough to thresh, the threshing 

 is done from the shock or stack. Here the straw is often 

 burned. It is difficult to get this straw to rot in a region 

 of short rainfall. It is, however, a serious waste to burn 

 it, and, if possible, it should be worked down by stock 

 and then spread very thinly on the land as a top dress- 

 ing, or be saved in some other way. In this region, as 

 well as in most of the country, the problem of organic 

 matter is a serious one. 



122. Farm manure as a source of organic matter. 

 About 40 per cent of the organic matter that is fed to 

 animals is returned in the manure, and all of the bedding 

 used is so recovered. 



Heiden found that 47 per cent of the dry matter fed 

 to a horse was recovered. A full-grown steer returned 

 56 per cent of the dry matter of the feed. 1 



R. E. Deuel fed 46 cows for one week and weighed and 

 analyzed feed, bedding, and manure. The cows had been 

 on the same ration for some time previous to the test. 

 He found 45 per cent of the dry matter and 43 per cent 

 of the organic matter of the feed eaten was recovered in 

 the manure. 



Young animals, lean animals, or those that are produc- 



1 Feeds and Feeding, W. A. Henry, 7th edition, pp. 34 and 265. 



