PLANT FOOD AND SOIL FERTILITY 



29 



and more than one-half of it said to be wasted. The presence 

 of nitrogen, phosphorus, and potassium in manure does not 

 represent its entire value. When mixed with soil, it increases 

 the water-holding capacity if the soil is light, and promotes 

 granulation if the soil is 

 heavy. At the same time 

 it brings into the soil count- 

 less bacteria that are use- 

 ful in liberating or making 

 available plant food, par- 

 ticularly nitrogen. 



How to prevent loss of 

 nitrogen from manure. - 

 Since manure is of so much 

 value, all possible measures 

 should be taken to prevent its waste. In order to make 

 clear a means of preventing or reducing the losses of nitrogen 

 from manure we need first to consider what takes place in an 



ordinary pile of manure 

 when it is left in the 

 open. In such cases 

 decay and putrefaction 

 rapidly occur through 

 the action of bacteria. 

 Among the final results 



Diagram of a concrete pit for storing ma- . . . 



nure. If the pit is water-tight there will be of this action IS the 



little loss of plant food, especially if the change of nitrogen COm- 

 manure is kept well packed. 



pounds into simpler ones 



known as nitrates. Nitrates are quite soluble and are, there- 

 fore, easily washed away as the water from rains passes 

 through the heap. Nitrates in the lower part of the pile 

 that do not escape in this way may be broken up by other 



