South Coast Sandplain WA – Environmental Issues
The most widespread environmental issues that have arguably the biggest impact on agriculture include soil resource management issues such as soil acidity, water repellence, wind erosion, compaction, and loss of organic matter (Table 1). These have the potential to impact greatly on the soil resource and agricultural production in both pastures and cropping. Other issues of significance include secondary salinisation and nutrient loss (primarily phosphorous) which have significant implications for the health of both waterways and farmland.
These issues affect both pastures and crops. They result in poor production and lack of persistence. Solutions for many of these include perennial pastures and where cropping is severely compromised by these issues in mixed cropping and livestock properties perennial based pasture systems can be a profitable and sustainable option.
Resource management issues like wind erosion and salinity are key drivers for the adoption of perennial farming systems in the region. The right plant can, and has, turned what has been an unproductive and difficult to manage soil into a highly productive pasture.
Table 1: Resource management issues and possible solutions/adaptions.
|Sub soil acidity||Leaching of nitrates, product removal plus many soils were likely acidic before clearing||Liming at up to 2t/ha (100NV equivalent), delayed and split application of nitrogen, planting of acid tolerant pastures and crops||This map shows the areas at moderate to high risk of subsoil acidity|
|Water repellence||Tillage, natural occurrence of wax’s and oils in the soil.||Application of suitable clay at up to 150t/ha, furrow seeding, soil wetters. Planting of spreading perennial pastures.||This map shows the areas at moderate to high risk of water repellence|
|Wind erosion||Ground cover falling to below 50% prostrate stubble or 30% standing stubble||No till, wind breaks, perennial pastures on areas highly susceptible to wind erosion. Management of stock to maintain adequate ground covers.||This map shows the areas at moderate to high risk of wind erosion|
|Compaction||Vehicle movement and livestock||Tramlining, Deep ripping, use of deep rooted perennials (lucerne)|
|Waterlogging||Shallow clay layers and water tables.||Use of waterlogging tolerant perennials (kikuyu, phalaris, tall fescue), engineering solutions including contour and W banks and raised beds.|
|Secondary salinity||Excess recharge leading to high water tables.||Use of salt tolerant pastures and shrubs, use of high water use perennials throughout the catchment.|
|Phosphate leaching||Application of excess phosphorous in low PBI soils||Soil testing and application of correct amounts of phosphate fertilisers, Split application of fertilisers, Use of deep rooted perennials.|
- Soil Guide; A hand book for understanding and managing agricultural soils. Bulletin 4343, DAFWA July 2001.
- Managing South Coast Sandplain Soil to Yield Potential. Bulletin 4773, DAFWA October 2009.
- Soil acidity: a guide for WA farmers and consultants. Bulletin 4784, DAFWA November 2009.
- Saltland Genie