Identifying and managing risk factors for salt-affected soils: a case study in a semi-arid region in China

Soil salinization and desalinization are complex processes caused by natural conditions and human-induced risk factors. Conventional salinity risk identification and management methods have limitations in spatial data analysis and often provide an inadequate description of the problem. The objectives of this study were to identify controllable risk factors, to provide response measures, and to design management strategies for salt-affected soils. We proposed to integrate spatial autoregressive (SAR) model, multi-attribute decision making (MADM), and analytic hierarchy process (AHP) for these purposes. Our proposed method was demonstrated through a case study of managing soil salinization in a semi-arid region in China. The results clearly indicated that the SAR model is superior to the OLS model in terms of risk factor identification. These factors include groundwater salinity, paddy area, corn area, aquaculture (i.e., ponds and lakes) area, distance to drainage ditches and irrigation channels, organic fertilizer input, and cropping index, among which the factors related to human land use activities are dominant risk factors that drive the soil salinization processes. We also showed that ecological irrigation and sustainable land use are acceptable strategies for soil salinity management.

Environmental risk assessments for transgenic crops producing output trait enzymes

The environmental risks from cultivating crops producing output trait enzymes can be rigorously assessed by testing conservative risk hypotheses of no harm to endpoints such as the abundance of wildlife, crop yield and the rate of degradation of crop residues in soil. These hypotheses can be tested with data from many sources, including evaluations of the agronomic performance and nutritional quality of the crop made during product development, and information from the scientific literature on the mode-of-action, taxonomic distribution and environmental fate of the enzyme. Few, if any, specific ecotoxicology or environmental fate studies are needed. The effective use of existing data means that regulatory decision-making, to which an environmental risk assessment provides essential information, is not unnecessarily complicated by evaluation of large amounts of new data that provide negligible improvement in the characterization of risk, and that may delay environmental benefits offered by transgenic crops containing output trait enzymes.

The search for new pasture plants to achieve more sustainable production systems in southern Australia

Increasing the proportion of the landscape planted to deep-rooted perennial pasture species is recognised as one of several remedial actions required for the control of dryland salinity in southern Australia. The widespread use of perennials in farming systems is limited at present by the lack of well-adapted perennials that can be grown to reduce recharge in a landscape where drought, soil acidity, temporary waterlogging, infertile soils and unrestricted grazing prohibit the use of many species. The range of plants adapted to salinity also needs to be expanded to stabilise and ameliorate soils already degraded by rising watertables and to increase the profitability of grazing discharge regions within the landscape. This paper describes the steps involved in a national forage screening and breeding program initiated by the Cooperative Research Centre (CRC) for Plant-based Management of Dryland Salinity1, seeking to expand the range of perennial and or salt-tolerant forage plants that can be incorporated into farming systems of southern Australia. It describes the target environments, soil constraints, farming systems and the criteria being considered when assessing the potential of new plants, including assessment of the weed risk posed by introducing new species. This paper forms an introduction to a special issue which presents the outcomes of the pasture species field evaluation and plant breeding program conducted by the CRC.

An environmental weed risk assessment model for Australian forage improvement programs

Many plant species with agronomic potential have been introduced for livestock forage and have subsequently become weeds of natural ecosystems, or ‘environmental weeds’. Stringent border quarantine procedures introduced by Australia in 1997 ensure few high weed risk species are now imported into the country; however, there are no protocols for assessing and managing weed risk in use on a national scale ‘post-border’ (i.e. once a plant species is in the country). Environmental weed risk management in forage improvement programs aims to minimise the risk that new species and cultivar introductions will be invasive in natural ecosystems. We describe an environmental weed risk assessment (EWRA) model specifically aimed at assessing the weed potential of exotic and native forage species. The EWRA model predicts and ranks species for weed risk by assessing invasiveness, impacts and potential distribution. Assessments are based on published evidence, experimental observations and intuitive responses from experienced pasture researchers, in collaboration with weed experts. This model specifically addresses the need for environmental weed risk management in forage improvement programs.

The systematic collection and characterisation of herbaceous forage species for recharge and discharge environments in southern Australia

Australian temperate pasture Genetic Resource Centres (GRCs) co-ordinated a major program to introduce and screen herbaceous forage species. This program aims to expand the environments where such species could reduce recharge and manage discharge for the control of dryland salinity in southern Australia. The sustainability of agriculture, in Australia especially, depends on continued access to new germplasm to enable plant breeders to continue crop and forage improvement. The GRCs supported the selection and identification of promising new legume, grass and herb species as part of a national pasture evaluation program. In total, 671 species and 21 non-species-specific genera were identified as having potential to increase water use profitability of recharge lands and to improve the productivity of saline lands across a diverse range of agricultural environments in southern Australia. Through a series of activities, 201 of these species, representing legumes, herbs and grasses were identified as promising. These were then disseminated for evaluation in a range of environments across southern Australia. The progress of selected species was monitored and germplasm of the most promising 11 species and three leguminous genera was targeted for intensive acquisition and characterisation as the basis for selection and breeding. In addition to the identification and dissemination of promising species of immediate potential, a comprehensive collection of 544 native and exotic, wild and cultivated pasture species was conserved and is now available to service future plant improvement programs.

A decision framework for natural resource management: a case study using plant introductions

One means of anticipating and, thus, preventing natural resource problems, such as those that may arise from plant introductions, is to use effective decision frameworks. This paper argues that such frameworks are typified by 4 elements. These are clear goals explicitly linked to cultural values, key questions that scope problems and management options, application of appropriate analytical tools, and the connection of authority for decisions with responsibility for outcomes. These elements are explored here. Trade offs are an inevitable part of decisions concerning natural resource management, including those relating to plant introductions. Benefit-cost and multi-criteria decision analyses are useful in this regard, but must be applied using methods that ensure all the relevant cultural values and management options are explored. Some recent proposals concerning the assessment of plant introductions do not always adequately frame decision issues. Ecological risk assessments can be used to define an acceptable level of risk concerning the negative impacts of introducing new biota, and, combined with an appropriate benefit-cost or multi-criteria analysis, provide the suite of analytical tools to make effective decisions concerning plant introductions. Effective decisions are more likely when the authority to make decisions and the responsibility for unforeseen outcomes are closely linked.

Potential of current perennial plant-based farming systems to deliver salinity management outcomes and improve prospects for native biodiversity: a review

Existing perennial plant-based farming systems are examined within 4 climatic zones in southern Australia (western winter rainfall, south-eastern low to medium rainfall, south-eastern high rainfall and northern summer rainfall) to assess their potential to improve the management of dryland salinity. If profit is to be the primary driver of adoption, it appears that the available options (lucerne and other perennial pastures, farm forestry, saltland pastures and forage shrubs) will fall short of existing hydrological targets with the exception of the higher rainfall zones. In the 3 eastern zones, the need to preserve fresh water flows to permanent river systems places limitations on the use of perennial plants, while the higher proportion of regional groundwater flow systems increases response times and heightens the need for regional coordination of effort. In the western zone, the prevalence of local and intermediate ground water flow systems increases effectiveness of individual action. Research into new perennial land use systems has been characterised by an emphasis on water use over profit resulting from poor dialogue between paddock, farm and catchment scales. Exploring the water use implications of land use systems that are potentially viable at farm scale is a more promising approach than focusing on the opportunity cost of catchment scale intervention. Perennial plant-based farming systems present both threats and opportunities to native biodiversity. The major threat is the introduction of new environmental weeds. The opportunities are potential improvements in vegetative cover, food sources and habitat for the native biota, but only where nature conservation goals can influence the structural complexity, composition and location of new land use systems.