Land assessment

The early settlers, seeing the new lands through European eyes, found it difficult to make valid assessments or to come to terms with land that quickly changed so bewilderingly from lush vegetation on apparently fertile soils to withered pastures on bare, drought stricken earth. Land that was first surveyed for initial settlement, sale or lease was described only in general terms as 'sandy' or 'clayey'. As the settlers gained experience they gradually developed a local folklore in which soil fertility and agricultural potential was associated with the occurrence of certain trees and shrubs.

By the middle of the last century the lack of valid and precise criteria for measuring natural resources led to disastrous attempts to over extend cultivations into unsuitable marginal lands and these experiences resulted in the first development of scientific methods of using natural vegetation as a guide to climatic boundaries. In particular, Goyder's use of natural vegetation to delimit areas of South Australia for arable farming was a major advance.[51] The importance of seasonal weather patterns and their association with particular crops became generally recognised and with this recognition came the development of State, and later Commonwealth, meterological stations. The establishment of station networks was particularly important for the longer term understanding of the Australian environment and for scientific land assessment, and it coincided with the consolidation of rural settlements between about 1870 and 1910.

Prior to the turn of the century soil and land descriptions were based on simple and variable criteria but, between 1900 and 1910, the first use of standardised soil and land descriptions appeared. Using practices that were already common in the United Kingdom and North America, soils were classified and compared on the basis of their geological parent materials rather than on their pedological characteristics. The need to survey soils and to establish soil mapping units came primarily with the introduction of irrigated horticulture along the Murray and Murrumbidgee Rivers from the 1880s onwards. Techniques of soil definition were largely imported from the United States as part of the whole irrigation technology, which had no counterpart in United Kingdom or European experience.

By the 1930s sufficient information had accumulated about Australia's soils, climates and vegetation to enable Professor Prescott to attempt the first map of Australia's soils and for Dr. Griffith Taylor to assess the possible potential of the continent for future development. Both were broad-scale assessments of Australia's land resources but both were important scientifically and politically since they emphasised the environmental limitations of the Australian continent in terms of European based landuse practices.

Between 1928 and 1931 it was suggested in Britain that continuous air photography should be used as a means for assessing land resources in 'underdeveloped countries'. This technique does not, however, appear to have been used for other than cartographic survey in Australia at that time. Most emphasis in land assessment was still on climate; Prescott and Trumble's P/E (precipitation/evaporation) ratio was a major concept which linked climatic conditions and crop production, and led eventually, through Penman's and Thornthwaite's work in the USA, to the development of a number of soil moisture availability measures in Australia during the 1950s and 1960s.

Australian Academy of Technological Sciences and Engineering