68 AUSTRALIAN AGRICULTURE. 



depth as roots penetrate, or even to still greater depth. A 

 leading object of soil cultivation is to maintain it in such 

 condition that rain and air can penetrate freely ; that as 

 small quantity as possible of rain water may run over the 

 surface. It is, in reality, as necessary to have the soil in a 

 workable mechanical state as to have sufficient and the 

 right sort of plant food for the crops we are endeavouring to 

 make. To understand these conditions, and to help in 

 bringing the soil into the state that roots can develop and 

 feed most effectively, is amongst the most valuable experi- 

 ences of agricultural knowledge. For instance, we may 

 have a soil containing such a proportion of clay matter or 

 clayey substances that during wet weather it becomes plastic 

 or sticky like clay, and which, in dry weather, may become 

 hard, like brick material, and quite unfit for working. Or, 

 going to the other extreme, we may have such a heavy 

 proportion of sand in a soil that, during dry weather, it 

 becomes a loose heap of sand grains which will throw off 

 rain, and yet absorbs the sun heat so freely that the roots 

 of plants, and even the plants above ground are scorched 

 and burned. Both these conditions are mechanical, and the 

 skill of agriculture comes into action in making the best 

 use of the conditions which have to be dealt with. The 

 stiff soil, though the most likely, by far, to be rich in plant 

 food, is the more difficult for treatment in this climate. 

 Where heavy frost would swell and break up the clayey 

 inass.we would plough up such soil rough in autumn, possibly 

 while the land was soggy wet, and allow the frost of winter 

 to " cure and sweeten " it. But where there is no frost, the 

 treatment is different. Heavy liming would, unless it were 

 already fully supplied (not a likely condition in Australia) 

 come into the first course of treatment. Then surface, 

 rooting crops, like maize, sorghum, etc., or such fruit as 

 apples or pears would be suitable. Our object being in all 

 the methods of treatment followed, to keep the soil open- 

 that air and rain may penetrate, and that the roots of crops 

 may spread and find what they require. Unless this latter 

 condition exists, neither rich grass, nor trees, nor field 

 crops, nor vegetables can prosper, and the good qualities of 

 manure are lost. With sandy soil, after breaking it loose 



