Building up the Fertility of the Soil. 755 



BUILDING UP THE FERTILITY OF THE SOIL. 



By A. Baguley, B.Sc, F.I.C. 



By fertility of the soil is meant useful productiyity. We have to 

 recognize many limitations in useful productivity- due to various 

 causes, such as latitude, altitude, proximity of the sea or other water, 

 aspect, slope, position, sub-soil, etc. These aifect productivity in the 

 quantity and kinds of crops that can be grown with profit, and 

 generally do not admit of modification in building up the fertility 

 of the soil. This process, carried to completion, however, makes 

 possible a very much wider and more profitable range of crops. 

 Properly done it increases the certainty of the crop, and always it 

 enables the agriculturist to succeed with a minimum rainfall. 



These advantages, together with the general low level of inherent 

 fertility in the soils of our country, make this matter one of import- 

 ance and interest. It is not enough to maintain fertility. We must 

 increase it to a notable degree. To do that safely and uniformly we 

 have to follow faithfully a few physical and chemical principles which 

 universal experience indicates. 



Building up fertility is clearly associated with additions to the 

 soil. Other corisi derations are no less important and must have 

 attention if success is to be attained; such are, tillage, drainage, 

 weeding, and harvesting. But in addition to these necessary opera- 

 tions, we have to provide for the full supply of food and stimulation. 

 By increasing the amount and availability of plant food we build up 

 the fertility of the soil. 



Usually several, sometimes all, of five essential things are lack- 

 ing. These are : — 



I. Humus. — This term includes the remains of plant and animal 

 life, decayed to a stage far beyond recognition. It is usually dark 

 brown or black in colour, porous and absorbent of water and gases. 

 In this property and in composition it resembles charcoal. The power 

 which soils have of deodorizing and purifying dirty water may be 

 attributed largely to the humus they contain. Humus is not soluble 

 in water, but as oxidation proceeds it jaelds organic acids which are 

 useful solvents of soil material. It imparts mellowness to soil and 

 relieves the harshness belonging* to grit and sand. It provides home 

 and food for iu numerable micro-organisms which use it as a source 

 of energy, oxidizing atmospheric nitiogen, which thus becomes 

 capable of nourishing crop-plants. 



Humus suffers loss and diminution in several ways : (a) By 

 oxidation in the soil; this is a leg-itimate loss, and the humus in 

 undergoing it serves its purpose. The process is rather rapid owing 

 to the high mean temperature ; it is increased by tillage operations 

 and by the use of quicklime, (b) By the activities of various creatures 

 such as ants, worms, larvae, and others, (c) By natural agencies as 

 fires, floods, and winds. Organic material is carried off and lost or 

 destroyed. Sometimes a fertile soil is overlaid by gravel and sand 

 or it may be washed away. 



