THE JOURNAL 



OF THE 



BOARD OF AGRICULTURE. 



Vol. XIIL No, 2, 



r6f/iAY.i906 ' 



MAY, 1908. 



THE USE OF WASTE ORGANIC SUBSTANCES 

 AS MANURES. 



There are several ways in which a manure may be beneficial,, 

 but in general most manures serve one or more of four purposes^ 

 which are : — 



1. To increase the supply of plant food, either directly or 

 indirectly, through the solvent action of the soil. 



2. To improve the mechanical condition of the soil. 



3. To hold up water in the soil and so ensure a constant 

 supply for the plant. 



4. To favour the growth and work of micro-organisms on 

 whose activity the productiveness of the soil to a certain extent 

 depends. 



Mineral substances, with the exception of lime and basic slag, 

 chiefly serve one function only, supplying plant food ; but 

 organic substances, like dung and the products described in the 

 following pages, act beneficially in all the directions enumerated 

 above. They furnish plant food, but the proportions are not 

 well balanced, and somewhere in the rotation the proper 

 mineral substances have to be added if the best results are to 

 be obtained. They have a marked effect on the mechanical 

 condition of the soil : a heavy soil is lightened both by their 

 mere presence and as a result of their decay ; and a light 

 soil is improved by the cementing action of the glue-like 

 colloidal humus to which they give rise. A good tilth is 

 difficult to secure without organic matter. 



One of their most valuable properties, and one in which they 

 far surpass artificial manures, is their remarkable power of hold- 

 ing water. The water supply in many soils is insufficient for 



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