Publication Date

1993

Description

The focus of this paper is a framework for determining the soil and land properties and processes which are critical to managing grasslands in an ecologically sustainable manner. Essential to the discussion is the development of concepts which allow description of the stability, resilience and sustainability of the agroecosystem as a whole as well as the land resource base. The regions of Australia with arid, semi-arid and seasonally dry environments are defined and related to the dry environments of the world. This provides a background for a brief consideration of major vegetation types and soils within the dry environments of Australia. Selected Australian grasslands in the wet­dry tropics, the semi-arid/arid temperate rangelands, and the summer dry pasture-cropping zone are examined to determine the effects of agricultural land use. These examples illustrate that management-induced change to critical soil and land properties and processes is a major cause of extensive land degradation and decline in primary productivity. In areas of extensive pastoral activity, the changes primarily result from our inability to manage grazing pressure under the highly variable climatic regime which characterises ·1he continent. We conclude that many current farming and grazing systems are not sustainable. Although solutions to many problems seem self-evident, the tendency in Australian agriculture is 10 solve one problem and create another. Consideration is given 10 the fundamental deficiencies in our understanding which result in this being so. 11 is proposed that the basic cause for failure to implement sustainable farming systems is lack of understanding of the water, energy and chemical equilibria operating in our landscapes and a capacity to predict the ways these will be altered by management, Australian grazing and farming practices have not been designed at the outset 10 take account of the unique environment and there has been a focus on short-term soil-plant-animal productivity without consideration of the consequences for other components of lhc ecosystem. In practice we must learn 10 develop farming systems in the context of the ecosystems in which they are cast, that is, to incorporate existing nutrient and hydrological cycles, pest-predator relationships,and biotic diversity into the production process, It is suggested this is also true for other dry regions in the world. While existing knowledge must be increasingly applied, substantial research is necessary to develop ecologically sustainable systems. The scientific problems that must be solved are many, complex and difficult. The solutions to the problems that confront us, however, are not only technically demanding but also require a specific orientation and coordination of research, development and extension activities.

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Soil Characteristics and Processes Critical to the Sustainable use of Grasslands in Arid, Semi-arid, and Seasonally Dry Environments

The focus of this paper is a framework for determining the soil and land properties and processes which are critical to managing grasslands in an ecologically sustainable manner. Essential to the discussion is the development of concepts which allow description of the stability, resilience and sustainability of the agroecosystem as a whole as well as the land resource base. The regions of Australia with arid, semi-arid and seasonally dry environments are defined and related to the dry environments of the world. This provides a background for a brief consideration of major vegetation types and soils within the dry environments of Australia. Selected Australian grasslands in the wet­dry tropics, the semi-arid/arid temperate rangelands, and the summer dry pasture-cropping zone are examined to determine the effects of agricultural land use. These examples illustrate that management-induced change to critical soil and land properties and processes is a major cause of extensive land degradation and decline in primary productivity. In areas of extensive pastoral activity, the changes primarily result from our inability to manage grazing pressure under the highly variable climatic regime which characterises ·1he continent. We conclude that many current farming and grazing systems are not sustainable. Although solutions to many problems seem self-evident, the tendency in Australian agriculture is 10 solve one problem and create another. Consideration is given 10 the fundamental deficiencies in our understanding which result in this being so. 11 is proposed that the basic cause for failure to implement sustainable farming systems is lack of understanding of the water, energy and chemical equilibria operating in our landscapes and a capacity to predict the ways these will be altered by management, Australian grazing and farming practices have not been designed at the outset 10 take account of the unique environment and there has been a focus on short-term soil-plant-animal productivity without consideration of the consequences for other components of lhc ecosystem. In practice we must learn 10 develop farming systems in the context of the ecosystems in which they are cast, that is, to incorporate existing nutrient and hydrological cycles, pest-predator relationships,and biotic diversity into the production process, It is suggested this is also true for other dry regions in the world. While existing knowledge must be increasingly applied, substantial research is necessary to develop ecologically sustainable systems. The scientific problems that must be solved are many, complex and difficult. The solutions to the problems that confront us, however, are not only technically demanding but also require a specific orientation and coordination of research, development and extension activities.