4: On-farm management options for soil compaction (continued) Management option Approximate cost Longevity Mechanism Suitable locations and soils Likelihood of success/ reliability Associated benefits/ drawbacks Shallow ripping $250/tine (few $/ha over cropping program) Annual, if traffic is not controlled; longer if traffic is controlled longer points on the seeder to dig deeper to about 15cm Can large area with a small change in productivity compared with deep ripping where a small area is treated for a large return Suitable on most compacted High (provided tine breakout is high enough) Soil may be more susceptible to compaction if not carefully managed Increased risk of wind and water erosion Management needed to limit recompaction If compaction is very deep, production will be limited by underlying compaction Soil inversion $100–120/ha + significant cost in time Lasts until recompacted through machinery movement Some sands self-compact under wetting and drying Breaks up layers of compacted soils to a depth of 30–35cm Deep sandy earths, pale deep sands and sandy gravels Should not be used on shallow duplex or soils with abundant rock or cemented gravel High Reduction of weed burden Incorporation of lime or clay or other soil amendments, although buried in layer and not mixed well Overcome soil water repellence Potential increase in wind and erosion Difficulty of seeding into loose soil Exposure of low pH soils Crusting and surface sealing if higher clay content subsoil is brought to the surface Management needed to limit recompaction and deeper compaction can remain below the ploughing depth. Rotary spading $150/ha + significant cost in time Lasts until recompaction through machinery movement Some sands self-compact under wetting and drying Breaks up layers of compacted soils to a depth of 25cm Deep sandy earths, pale deep sands and sandy gravels Should not be used on shallow duplex or soils with abundant rock or cemented gravel High Incorporation of lime, clay or other soil amendments Reduction in weed burden Overcoming soil water repellence Increased risk of wind and water erosion Difficulty of seeding into loose soil Management needed to limit recompaction Deep compaction can remain below the depth of spading, which may need to be removed by deeper ripping. Gypsum Dependent on soil characteristics and management Stabilises soil aggregation Use on sodic soils Not effective on sand Moderate
Table 6: On-farm management options for dryland salinity Management Option Approximate cost Longevity Mechanism Suitable locations and soils Likelihood of success/ reliability Associated benefits/ drawbacks Productive use of saline land Cost of enterprise As long as the option remains in place saline-affected areas for potentially profitable options such as feed (e.g. saltbush) for livestock or carbon farming Marginal areas around saline areas Reliable, if established in the right areas Dryland salinity is not resolved, but can reduce spread or rate of spread Reduces risk of waterlogging, wind and erosion Perennial plant options to prevent salinisation Cost of establishment ($100-150/ha) Lost income from cropping on land allocated to perennials Income from perennials is driven by the profitability of the livestock enterprise. It is at best marginally profitable Benefits retained for as long as perennials remain Planting deep-rooted perennials can increase use and reduce groundwater recharge Medium- to areas Areas adjacent to saline land Only protects the land on which it is located Little benefit to surrounds Dryland salinity is not resolved Encroachment is slowed where perennials are planted Reduces risk of waterlogging, wind and erosion Farm forestry Cost of trees and maintenance of trees Benefits are retained while trees are in place Planting trees for commercial forestry and/or carbon sequestration Areas of relatively fresh groundwater, transmissive localised aquifers, and slopes greater than 4% Only protects the land on which it is located Little benefit to surrounds Diversified income Stabilisation of soil Livestock husbandry Potentially improved water quality Reduced waterlogging Carbon sequestration Engineering solutions High cost of engineering works Benefits are retained while drains are in place Low to moderate Limited benefits beyond the Off-site impacts of drained water (often highly acidic or high in toxic metals) Salt-tolerant crops Cost of new seed Annual Allows for continued profitable cropping Mildly affected saline areas Low to moderate Does not address the problem Retirement of land Cost of fence ($3500/km at contract rates) Benefits are retained while land is excluded Area is fenced and natural regeneration allowed to occur Most successful when topsoil remains High Regenerates well if fenced off and excluded Reduces land degradation from salt accumulation Less salt washes downstream Reduced risk of wind and water erosion Increased biodiversity In the long term, can provide grazing land
Table 7: On-farm management options for phosphorus – nutrient status and export Management Option Approximate cost Longevity Mechanism Suitable locations and soils Likelihood of success/reliability Associated benefits/ drawbacks Use soil tests to inform decisions Based on a 30-paddock farm, ~ $2500–3100 for the 1st year to develop whole farm nutrient maps Annual Provides a map of soil nutrient status Whole-farm nutrient mapping Optimise soil P levels on-farm, minimising off-farm P flow. All High Allows for identification and treatment of other nutrient deficiencies or excesses Effective fertiliser use $10/ha Annual Applying optimal fertiliser rates Accurate placement Split applications Not applying when rains forecast Optimise soil P levels on-farm, minimising off-farm P flow All locations Moderate Reduces cost to farmer Increases productivity Use perennial pastures to increase water use and reduce erosion $100–150/ha for establishment Annual Deeper rooted perennials use more water and have lower P requirements Medium- to areas Particularly areas prone to rapid Moderate Can increase productivity, depending on farm However, likely to be less profitable than cropping Vegetated buffers near waterways Up to $6000/km Long term Buffers reduce the off-farm nutrient load entering streams Vegetated buffers remove P attached to eroded soil Areas close to streams Low for soils Moderate for hill slopes, draining loam and clay soils Increased biodiversity Reduced sediment Increased aesthetics Increased farm value Soil amendment (Alkaloam or clay) $70–280/ha A long time (at 10 years for nutrient retention and water repellence and many more for moisture retention) Reduce movement of P off-farm An alkaline residue from bauxite processing with significant P retention properties Reduces P loss by 30–60% Claying is likely to have similar effects as well as improved soil wetting but at higher application rates than Alkaloam where dissolved P from farming moves into waterways and areas that are water repellent Usually higher rainfall sandy soils High for sandy soils Rapidly increased soil pH Increased plant growth Reduced non-wetting Improved water-holding capacity of the soil May need to increase rates of P application Improve stock management around feedlots and sheds $75–100 per source Annual Management of manure and high P source on the farm All High Improved animal health
Conclusion The information in this report is presented at a state level, and therefore provides high level guidance. It is intended to be read in conjunction with the report card which gives a detailed summary of the trends for natural resource themes, which are considered the highest priority for the state. The metrics and ratings provided are a starting point or reference for discussion regarding investment decision making. References Ghadim A 2000, ‘Water repellency: a whole farm bio-economic perspective’, Journal of Hydrology, vol. 231–32, pp. 396–405. Abrahams, M, R & Peek, C 2004, ‘Profitability of drains to reclaim saline land is driven by wheat production’, 1st National Salinity Engineering Conference, 9–12 November 2004, Perth, Western Australia. ABC 2013, ‘Mouldboard plough makes a modern comeback’, Australian Broadcasting Corporation, Australia, viewed 4 June 2013, Ali, R & Filmer, M 2008, ‘Role for drains in controlling salt’, Farming Ahead, April 2008, no. 195. Alston, J 2011, ‘Global and US trends in agricultural R&D in a global food security setting’, OECD Conference on Agricultural Knowledge Systems: Responding to Global Food Security and Climate Change Challenges, OECD, Paris, 15–17 June 2011, viewed 11 September 2013, Australian Dryland Salinity Assessment 2000, ‘National Land and Resources Audit: a program of the National Heritage Trust’, viewed 10 June 2014 Baldock, J 2009, ‘Building soil carbon for productivity and implications for carbon accounting’, Agribusiness Crop Updates, 24–25 February 2009. Barrett-Lennard, EG & Shabala, SN 2013, ‘The waterlogging/salinity interaction in higher plants revisited — focusing on the hypoxia-induced disturbance to K+ homeostasis’, Functional Plant Biology, vol. 40, pp. 872–82. Barrett-Lennard, EG 2003, ‘The interaction between waterlogging and salinity in higher plants: causes, consequences and implications’, Plant and Soil, vol. 253, pp. 35–54. Bathgate, A & Byrne, F 2007, ‘The economic value of fencing and improving saline land: a supplementary analysis to the Economics Theme of the Sustainable Grazing