The Deterioration of Manures. 
3 i 
Fresh sheep manure particularly should not be spread upon the 
land under our. conditions, but rotting about six months, or at 
most a year, is all that is necessary to put the manure in fine condition 
for immediate assimilation by plants. 
Recapitulation. 
The main facts brought out by the deterioration experiment are 
as follows: 
Manure under our conditions does not lose in weight as rapidly as 
in more humid regions. The sheep manure lost 32.5 percent in weight 
in about 15 months, and 56.7 percent in a little over two years. 
About half (48.6 percent) of the total nitrogen was lost during 
the first 15 months, and 68 percent was lost in two years. The total 
nitrogen sustains the heaviest loss of any of the elements of plant fer¬ 
tility in semi-arid climates. 
The phosphoric acid decreased 42 percent in 15 months, and 59 
percent in two years. The loss in weight seems to fairly represent the 
loss of phosphoric acid. 
The great difference between manures in semi-arid and humid 
climates is expressed in the potash. Practically all who have con¬ 
ducted experiments along this line mention potash as the most easily 
lost of the three elements of plant food, and that it is lost by leaching. 
Our manures retain the potash, probably due to the light rainfall. In 
the first 15 months no loss was found. The second year an absolute 
loss of 35 percent of the potash occurred. That the potash in fresh 
manure is soluble was demonstrated by experiment. Air-dried sheep 
manure lost 17.8 percent when washed with water, which represents 
a loss of 43.7 percent of the potash, 22.6 percent of the phosphoric 
acid, and 39.0 percent of the nitrogen. 
From the 23 analyses of sheep manure, we learn that they con¬ 
tain on the average 13 percent less moisture than an average of sheep 
manures in moist climates. 
The phosphoric acid remains at about one percent of the dry mat¬ 
ter irrespective of the age of the manure. 
The potash in this series of samples increases from an average of 
4.4 percent in the fresh manures to 6.3 percent in the one-year-old 
samples, and remains at about this figure for several years, which 
corroborates the summarized statement in regard to the potash in the 
deterioration experiment. 
There is a large loss of total nitrogen during the first two years. 
Almost the whole of this loss is due to a loss of free ammonia, which 
is produced in large amounts by the action of uro-bacteria. 
