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