VEGETABLE GROWING IN NEW SOUTH WAlks. .13 



The Effects of Tillage. 



It may be convenient at this stage to remark that the effects of cultivation 

 upon the soil are numerous and complex, but they are of such importance 

 that the vegetable grower should acquire at least a general impression of 

 what they are, and of their close relation to the success of any agricultural 

 or horticultural enterprise. 



Left to itself, land usually produces abundantly if the rainfall is a fair one, 

 but the vegetation is not of the class that is desired by civilised man, .and it 

 is therefore the rirst business of the grower to destroy the class of vegetation 

 the soil is, naturally producing, and to make its decay a means by which more 

 desirable plants can be raised. The object, therefore, is to destroy that which 

 is already growing upon the land, and to turn it under so that it will be out 

 of the way of subsequent operations. In that position it will decay, or 

 humify, thus improving the physical qualities of the soil, and providing the 

 crop with plant-food. 



It is one object of ploughing that it may be possible at a later stage to 

 reduce the surface soil to a fine tilth by the use of harrows and cultivators, 

 and it sometimes happens, especially on new land, that though that which 

 previously grew on the surface has been effectively turned under, the finer 

 implements cannot be employed until a second ploughing at right angles to 

 the first has been given. A fine seed-betl must ever be kept in view as one 

 of the objects of tillage. 



Another effect of ploughing is to enable moisture, , whether supplied 

 naturally or artificially, to sink through the surface soil into the subsoil 

 where it may be retained. Soils vary much in their capacity to hold moisture 

 while yet remaining arable and in good physical condition, and on the other 

 hand, plants also show a considerable range of adaptability. It is possible 

 for a soil to contain from 20 to 25 per cent, of water and yet not be too moist 

 for cultivation, while on the other hand plants are able to maintain themselves 

 and grow when the soil contains only 6 to 8 per cent, of moisture. 



The storage capacity of a soil is so much increased by deep cultivation that 

 this becomes one of the chief reasons for subsoiling. If a heavy rain falls on 

 land that has only been worked 4 inches deep the tilled soil is in danger of 

 being water-logged. On the other hand, land that has been worked to a 

 depth of 12 inches can absorb a much larger rainfall without becoming too 

 wet, simply because the deep working has provided such a large quantity of 

 loose friable soil to take up the moisture. Just as a large sponge will hold 

 more water than a small one, so a big bulk of tilled earth will hold more 

 water than a small bulk of it. The surface of a deeply worked soil can be 

 loosened sooner after rain than that of a soil that has only been superficially 

 worked. Moreover, the disadvantages of shallow ploughing are increased by 

 the readier loss of moisture ; partly because so much is retained near the 

 Mirface within reach of sun and wind, and partly because in most situations 



