195 



^ The yield, however, was maintained for twenty years considerably 

 ligher than that on the unmanured soil. Continuous manuring of 

 wheat at the rate of 14 tons per acre annually for forty years resulted 

 in an average increase of yield from year to year of one-fourth bushel 

 per acre, or a total of about 10 bushels in forty years. While it is true 

 that there is a constant increase in the productiveness of soil on which 

 barn yard manure is applied regularly, it is not as great as the amounts 

 applied would seem to justify. This is chiefly due to the fact, already 

 explained, that the nitrogen is largely converted into slowly available 

 forms. 



SUMMARY. 



(1) Barnyard manure is the most important manurial resource o£ 

 the farm and should be carefully saved and used. It represents fer- 

 tility drawn from the soil and must be returned to it if productiveness 

 is to be maintained. In many cases it has been demonstrated that the 

 Talue of the manure obtained in cattle feeding represents largely, if not 

 entirely, the profit of feeding. 



(2) There are sound scientific reasons for the high esteem in which, 

 this manure is held. It contains all the fertilising elements required 

 by plants in forms that insure plentiful crops and permanent fertility 

 to the soil. It not only enriches the soil with the nitrogen, phosphoric 

 acid, and potash which it contains, but it also renders the stored-up 

 materials of the soil, more available, improves the mechanical condition, 

 of the soil, makes it warmer, and enables it to retain more moisture or 

 to draw it up from below. 



(3) The amount and value of manure produced by different kinds of 

 farm animals may be judged from the following figures, calculated te 

 1,000 pounds of live weight : Sheep, 34.1 pounds of manure per day, 

 ■worth 7.2 cents ; calves, 67.8 pounds, worth 6.7 cents ; pigs, 83.6 pounds, 

 worth 16.7 cents; cows, 74.1 pounds, worth 8 cents, and horses 48.8 

 pounds, worth 7.6 cents, basing calculations of value on market prices 

 of commercial fertilisers, which probably gives results much too high. 

 Making liberal allowance for these and other considerations, Prof. Roberts 

 estimates that the value of the manure produced on a small farm carry- 

 ing 4 horses, 20 cows, 50 sheep and 10 pigs during the seven winter 

 months amounts to about $250. 



(4) The urine is by far the most valuable part of the excreta of 

 animals. It is especially rich in readily available nitrogen, which rapidly 

 escapes into the ail if special precautions are not taken to prevent its 

 loss. It is also rich in potash, but deficient in phosphoric acid. It 

 should, as a rule, be used in connection with the solid dung, the one thus 

 supplying the deficiencies of the other and making a more evenly 

 balanced manure. 



(5) Barnyard manure is a very variable substance. The more impor- 

 tant conditions which determine its composition and value are (I) age 

 and kind of animal, (2) quantity and quality of food, (3) proportion of 

 litter, and (4) method of management and age. Mixed barnyard 

 manure properly cared for may be assumed to have the following com- 

 position : Water, 75 per cent ; nitrogen, 0.57 per cent ; phosphoric; 

 .acid, 0.3 per cent ; potash, 0.57 per cent. 



(6) Mature animals, neither gaining nor losing weight, excrete prac- 



