Mar. 2, 1908.] Agricultural Gazette of N.S.W. 201 



The humus in the soil is the ingredient which is most subject to alteration 

 and destruction, and under dry conditions it is more or less rapidly destroyed. 

 As soon as it has lost its moisture and become dry it is rapidly burnt out 

 by the combined action of sun and air. So that it is exactly in those circum- 

 stances where its presence is most essential that it is most liable to destruction, 

 and the necessity for renewing it most urgent. 



The presence of humus in the soil also tends to improve the texture of the 

 soil, hghtening it and loosening it. and preventing compaction of the surface, 

 so that it is of special value in the amelioration of stiff soils. 



It is the principal source of nitrogen in the soil, and by its decay under 

 the influence of soil organisms, ammonium salts and nitrates are produced, 

 which are the forms in which this important element is assimilated by the 

 plant. It is of interest to remember that the humus of arid or semi-arid 

 regions is richer in nitrogen than that of the moister districts. This is a point 

 of great importance with reference to the potential fertility of these soils. 

 In point of fact from a variety of causes acting together, the soils of the dry 

 climates are richer in plant food of all kinds than are the soils in regions of 

 greater rainfall, consequently nothing but the absence of water prevents 

 these from being extremely reproductive. There is, therefore, no problem 

 which exceeds in importance that of retaining in the soil the little moisture 

 that it receives, and any operation that succeeds in arresting even partially 

 the unavoidable loss of that moisture deserves the highest consideration. 



Methods of supplying Humus. 



There are three ways of supplying humus to soils in need of this constituent, 

 namely by the application of generous additions of farmyard manure (in 

 cases where this is available), by the application of compost manure, and by 

 green-manuring, or the ploughing under of a quickly growing green-crop 

 (leguminous for choice). We will discuss these separately. 



Farmyard Manure. 



Except in some dairies or such farms on which the animals are stall-fed, 

 the material known as farmyard manure is nothing more than the solid 

 excrements of animals, and does not contain either the urine or the vegetable 

 matter used as bedding which is the characteristic of farmyard manure 

 made and used in Europe and colder countries. 



Owing to the absence of vegetable matter such manure has very little 

 value in the formation of humus, and it is probably most economically used 

 in the compost heap. 



The Compost Heap. 



The compost heap is a most valuable adjunct to the farm, and it is a very 

 great pity that it is not more frequently to be found. 



A heap or pit can be made very economically, and is of special value in 

 that it utilizes all sorts of vegetable and animal refuse, which would otherwise 

 be wasted, and converts it into a valuable manure, rich in vegetable matter 

 and eminently suited for soils low in humus or subject to droughty conditions. 



