440 ANNUAL REPORT OF THE OfE. Doc. 



Stead calcium nitrate; the potassium in the nitrate having been re- 

 placed by calcium and the potassium having become fixed. This 

 process is known as fixation. We notice that the potassium is fixed 

 and the nitrate passes through the soil by combining with another 

 basic element which forms a soluble salt with it, and therefore can- 

 not be fixed. It has been shown by experiment that this fixation 

 is due to zeolitic minerals or silicates, humu® and carbonate of lime, 

 and that it is greatest in heavy clay soils and least in sandy soils. It 

 i» one of the most desirable properties and can be developed in sandy 

 soils by adding humus and carbonate of lime. If it were not for this 

 property the soil in regions of heavy rains would become sterile. 

 The fertilizer which undergoes fixation still remains available, es- 

 pecially in soils containing a large amount of humus derived from 

 farm manure and leguminous plants. 



FARM MANURE. 



Farm manure is the most valuable and at the same time one of the 

 most variable compositions produced on the farm. It varies as do 

 the animals that iDroduce it, and as the foods with which they are 

 fed, and to a certain degree as the absorbents that are used to absorb 

 it. Not onl}^ have the animals, the foods and absorbents so great 

 an influence on its composition, but the methods of preserving and 

 composting it, have more influence on its fertilizing value than all 

 combined. Leaching is the greatest agency of loss in manure. When 

 horse manure is thrown on a loose pile, subject to the agencies of the 

 atmosphere and leaching, it will loose as high as 60 per cent of its 

 fertilizing value in six months. Another agency of loss is injurious 

 fermentation. In the manure pile as in the soil aerobic and anaero- 

 bic fermentation is going on, the former by bacteria requiring an 

 ample supply of air or oxygen for their work, the latter the entire 

 absence of this element. In the manure pile conditions favorable 

 for anaerobic fermentation should prevail, whereas in the soil aerobic 

 should and must be encouraged, because they render plant food 

 available and the anaerobic unavailable. 



To secure anaerobic fermentation the manure pile must be so 

 constructed that air is excluded, water retained, both that which is 

 contained in the manure, and that which it may become necessary to 

 add when lengthy droughts prevail. Manure produced under cover, 

 as in stables, hae all necessary conditions, namely compactness, ex- 

 clusion of air, a sufficient amount of water, prevention of leaching, 

 and favorable environment for anaerobic fermentation. But what- 

 ever composting, sheltering, etc., may do for manure, the best and 

 most economic method is to haul it directly from the stable to the 

 field, because no leaching occurs, it mixes with the soil, and is in 

 position for aerobic fermentation to act on it, it produces conditions 



