552 PROCEEDINGS OF SECTION G2. 



6.— TASMANIAN AGRICULTURE, WITH SPECIAL REFERENCE TO 

 THE SOILS OF THE COUNTRY AND THEIR TREATMENT. 

 By H. J. COLBOURN, Department of Agriculture, Tasmania. 



(Abstract.) 



The climatic conditions of a country have to be considered in 

 reference to its soils. The temperature conditions of Tasmania are 

 chiefly affected by altitude and have reference to liability to night 

 frosts. Tasmania is just outside the zone for successful culture of 

 the vine. 



The rainfall of Tasmania shows a greater relative difference 

 than its temperature, and shows great extremes between the east 

 and west, being very scanty upon the former and abundant upon 

 the latter. Pulverising the surface soil to a depth of two or three 

 inches is found an effective means for retaining moisture in the soil, 

 and the districts of light rainfall would further do well to keep the 

 surface of their soils in a pulverised condition in order to prevent 

 rain from running off the surface when it comes, and rather en- 

 courage it to sink to the moisture-retaining reserves of the sub-soil. 



Much good would result from growing varieties of crops suitable 

 for semi-arid conditions, but seed must not be imported from the 

 warm localities of the mainland, but rather from the cooler districts. 

 Success has attended the importation of seed oats from Canada to 

 Tasmania. 



Soils require an abundant supply of humus to promote moisture 

 retention and render them readily penetrable by the roots of crops. 

 The requirements of the latter in this respect must be considered, as 

 crops like wheat and clover require a firm seed, but whilst potatoes, 

 turnips and barley prefer one that is friable. Virgin soils are fertile 

 because they contain much humus, but the sub-soil cultivation 

 exerted by the roots of trees must be considered. Tree roots go 

 deep, and in the process of decay leave channels for water and the 

 roots of crop to travel down. After a time these channels close, 

 hence the conditions for fertility are later on not so good. Deep- 

 rooting crops should be employed to imitate the action of tree roots 

 as far as possible. Humus, in decaying, produces carbon dioxide, 

 which, dissolved in water, increases the solvent action of the 

 water. This depletes the soil of its lime, which should be regu- 

 larly apphed at proper intervals wherever high farming is 

 practised. Humus is best furnished by ploughing in green crops,, 

 and lime should be applied at this time to promote decay of 

 humus and correct tendency to acidity which freshly ploughed 

 in vegetable matter exhibits. Leguminous crops should be used 

 for ploughing in, because these supply nitrogen to the soil. 



Powdered limestone is a suitable form of lime to apply when 

 the soil is deficient in organic matter. For this purpose the purer 

 the form of limestone employed the better, as the presence of 

 silicate of lime retards the assimilation of lime by most plants. 

 Powdered limestone improves the permeability of clay soils to 

 water. 



