78 SUCCESSFUL FARMING 



Experiments at several experiment stations show that the nitrogen in 

 manure is much less readily available than that in either nitrate of soda or 

 sulphate of ammonia. Because of this fact, barnyard manure when used 

 for certain truck crops is sometimes supplemented with available forms of 

 nitrogen. In such cases it is not advisable to mix the chemical forms of 

 nitrogen with the manure. Such mixture is likely to result in a loss of 

 available nitrogen through denitrification in the manure pile. It is best, 

 therefore, to apply the chemical form of nitrogen by itself, preferably 

 some time after the manure has been applied. 



Physical Effect of Manures. Barnyard and stable manure improves 

 the physical condition of heavy soils by increasing their tilth and making 

 them easier to cultivate. It improves loose, sandy soils by holding the 

 particles together and increasing the water-holding capacity. It, there- 

 fore, has the reverse effect on these two extremes of soil. 



Manure tends to equalize the supply and distribution of water in 

 the soil and renders the soil less subject to erosion and injury by winds. 

 Experiments conducted by Professor King at the Wisconsin Experiment 

 Station show that manured land contained eighteen tons more water per 

 acre in the upper foot of soil than similar land unmanured, and thirty- 

 four tons more in the soil to a depth of three feet. 



Biological Effect of Manure. Farm manures introduce into the 

 soil a variety of bacteria and ferments. These help increase the supply 

 of available plant food. Barnyard manure sometimes causes denitrifi- 

 cation in the soil. By this process, nitrogen is set free in a gaseous form 

 and may escape. This is likely to be most serious as a result of changing 

 nitrates in the soil into other forms and therefore reducing the available 

 nitrogen supply. Experiments show that this occurs only in exceptional 

 cases and generally when unusually large applications of manure have 

 been made. On the other hand, experiments in considerable number indi- 

 cate that applications of manure may actually favor nitrification and aid 

 in the formation of nitrates. At the Delaware Experiment Station it 

 was found that soil liberally manured and producing hay at the rate of 

 six tons per acre contained several times as many bacteria as were found 

 in the same soil which had but little manure and was producing hay at 

 the rate of about one ton per acre. 



The Value of Manure. The value of manure depends: (1) upon 

 the class of animals by which it is produced; (2) upon the age of the 

 animals producing it; and (3) upon the character of feed from which 

 produced. Animals that are used for breeding purposes or for the pro- 

 duction of milk or wool retain a larger proportion of the plant-food con- 

 stituents of the food they consume. This will be found in their products, 

 whether it be the young animals to which they give birth or the milk or 

 wool produced by the cow and sheep respectively. Young animals that 

 are making rapid growth use a portion of the plant-food constituents, 

 and this is built into the tissues and bones of such animals. Old animals 



