IMPORTANCE OF ORGANIC MANURES 



155 



may be markedly effective through the changes which they cause in 

 the chemical equilibrium of soils, both directly and through their 

 effects on the micro-organisms of the soil. 



ORGANIC MATTER IN FERTILIZATION 



Indissolubly linked with the question of fertilizers on soils is that 

 of organic matter. No soil can be, or remain, fertile for any length 

 of time without organic matter. By organic matter we mean, in this 

 connection, residues of plants like the tops, roots, or stubble, and 

 the excrements of animals. The reasons for the importance of 

 organic matter to soils may be stated popularly as follows : 



1st. It is the chief source of the soil nitrogen which is needed 

 by plants. 



2nd. It furnishes the element carbon as a source of energy, as 

 coal serves for the engine, for certain important bacteria which 

 alone have the power of adding nitrogen from the air to the soil; 

 and for other bacteria and fungi which are concerned in changing 

 essential substances in the soil from an insoluble and otherwise un- 

 usable form to a soluble and usable one. 



3rd. It improves the water-holding power of sandy soils by 

 giving them more water-holding surface, and, incidentally, prevents 

 them from becoming packed and hence relatively impervious to 

 roots and to air. 



4th. It improves the heavy clay soils by giving them a more 

 crumb-like and porous structure and hence tends to prevent water- 

 logging and allows of freer movement of air and roots. For the 

 same reason it prevents baking of the soil and renders tillage much 

 easier. 



The foregoing statements must render clear the outstanding im- 

 portance of keeping soils well stocked with organic matter and the 

 question naturally arises, how can this best be done? By applying 

 to the soil and incorporating therewith any and all quantities of the 

 following materials that the economic conditions in a given orchard 

 or vineyard will permit: 



Horse, cow, sheep, goat, hog and chicken manures. 



Green manures, meaning the plowing under in spring of a winter 

 grown crop, preferably a leguminous crop like melilotus, burr clover, 

 or vetch. 



Pruning from trees and vines. 



Apple, grape, and other fruit pomace and cannery waste. 



Grain straws preferably composted, and similar materials. 



How to Apply Organic Matter. Animal manures should be 

 broadcasted, or put on the soil with a manure spreader. They 

 should then be plowed under or thoroughly cultivated in. Green 

 manures should be thoroughly plowed under. Prunings of various 

 kinds should be cut up into small pieces, spread evenly over the 

 surface of the ground and then plowed under. Fruit pomace and 



