44 THE FARMERS'" HANDBOOK. 



Humus. 



In the first place is to be remarked the deficient amount of humus matter! 

 The absence of moisture is equally noticeable, but although the comparative 

 figures given probably represent very nearly the proportionate amounts as 

 compared with other soils, the individual figures are not altogether trust- 

 worthy, since the amount found in the soil on arrival in the laboratory is by 

 no means always an indication of its condition in situ. The soils were, 

 however, invariably dry, and the average probably very nearly represents the 

 average contents of the soils if determined on the spot. The humus deficiency 

 is, however, a definite one, and has to be taken seriously into account in any 

 scheme for the improvement of these soils. It is due, of course, to the 

 absence of moisture and the burning action of the sun. Moisture is neces- 

 sary for the decay of vegetable matter. This defect will be remedied by 

 irrigation ; firstly, by deposition of the silt which is carried in suspension by 

 even the clearest river water, and which contains a certain amount of organic 

 matter; and, secondly, by supplying the necessary moisture to enable the 

 decay of vegetable matter to proceed. 



Capacity for Water. 



The next point of importance is the capacity of these soils for water, that 

 is to say, their water-retaining power. These figures represent the percentage 

 amount of water which the soil is capable of holding. This property depends 

 partly upon the amount of humus present, which has a very high capacity 

 for holding water, and partly upon the mechanical condition of the soil, the 

 relative proportions of coarse and fine sand and clay. It is noticeable that 

 the light sandy loams (those soils in which the amount of clay does not 

 exceed 12 or 15 per cent.), have a very low retentive power for water. The 

 average of these soils is, however, about the same as it is for similiar light 

 sandy loams in other parts of the State. This is true, also, of the soils in 

 which the clay content is higher — in the loams and heavy loams. With the 

 increase in decayed vegetable matter, which will be .one of the results of 

 irrigation, this retentive power for water will be considerably improved. This 

 is exemplified in the case of the soils from the Richmond River and other 

 places, where the increased humus content has increased the water-holding 

 capacity of the soil enormously, although the proportions of sand and clay 

 are, on the average, the same as in our western soils. This characteristic 

 of the soil to absorb and to retain moisture is one of the very greatest 

 importance in determining their fertility; and although the average of the 

 soils examined from the semi-arid regions is lower in this regard than the 

 average of soils from other parts of the State, it must be borne in mind that 

 these soils are for the most part sandy soils, and only fairly comparable 

 with similar sandy soils from other parts. 



The average water-holding capacity of the loams and heavy loams will be 

 found to be quite as high as that of the same class of soils from other places. 

 It is, I think, a matter of congratulation that we are able to assure ourselves 

 that in this important particular the soils in our drier districts are in no 

 way inferior to those of more favoured regions. 



Mineral Plant-food. 



A second very striking peculiarity in these soils is the large amount of 

 mineral plant-food present. It will be seen, on comparing them with the 

 County of Cumberland soils, for example, that they contain about three 

 limes the amount of lime and potash, and twice as much phosphoric acid. 



