528 NATURE AND PROPERTIES OP SOILS 



n 



feet of the animals. It must not be spread on the manure 

 until the stock are out of the way. Since manure is unbal- 

 anced as to phosphorus, the agricultural value of kainit is 

 slight. When applied, it is generally used at the rate of 50 

 pounds to the ton of manure. 



Acid phosphate is partially soluble and will not only react 

 readily with the ammonia but will tend to raise the phos- 

 phorus content to the proper point. From 40 to 80 pounds 

 of acid phosphate are generally recommended to a ton of 

 average farm manure. It should not be allowed to come into 

 contact with the feet of farm animals. 



Eaw rock phosphate, or floats, is a very insoluble compound, 

 and consequently reacts but slowly with the soluble constitu- 

 ents of manure. Carrying such a large percentage of phos- 

 phorus, it tends to balance the manure and to raise its agri- 

 cultural value. It is supposed that the intimate relationship 

 between the phosphate and the decaying manure increases the 

 availability of the former to plants when the mixture is added 

 to the soil. The reinforcement is usually at the rate of 75 

 to 100 pounds to a ton of manure. 



Experimental data have shown that these various rein- 

 forcements have no particular effect on the nature, function, 

 and number of the bacterial flora. Their conserving influ- 

 ence, if any, when the manure is exposed, might be in check- 

 ing leaching and in preventing loss of ammonia. The follow- 

 ing figures from Ohio experiments ^ show how slight this con- 

 serving effect is.„ The reinforcement was at the rate of 40 

 pounds to the ton. (See Table CXIX, page 529.) 



It is immediately evident that kainit and gypsum do not 

 conserve the manure, and, although acid phosphate and floats 

 show some influence, it is slight and evidently well within the 

 experimental error. The principal benefit from reinforcing 

 manure, if any, must, therefore, be as a balancing agent. The 



*Thoriie, C. E., and others, The Maintenance of Fertility; OHo Agr. 

 Exp. Sta., Bui. ISa, p. 206, 1907. 



