Table 7: On-farm management options for phosphorus nutrient status and export – Approximate cost Longevity Mechanism Suitable locations Likelihood of Associated benefits/ Management and soils success/reliability drawbacks Option Use soil tests to Based on a Annual Provides a map of soil nutrient All High Allows for identification and treatment of inform decisions 30-paddock farm, ~ status other nutrient deficiencies or excesses $2500–3100 for the 1st Whole-farm nutrient mapping year to develop whole Optimise soil P levels on-farm, farm nutrient maps minimising off-farm P flow. Effective fertiliser $10/ha Annual Applying optimal fertiliser rates All locations Moderate Reduces cost to farmer use Accurate placement Increases productivity Split applications Not applying when rains forecast Optimise soil P levels on-farm, minimising off-farm P flow Use perennial $100–150/ha for Annual Deeper rooted perennials use Medium- to Moderate Can increase productivity, depending on pastures to establishment more water and have lower P areas farm increase water requirements Particularly areas However, likely to be less profitable than use and reduce prone to rapid cropping erosion Vegetated buffers Up to $6000/km Long term Buffers reduce the off-farm Areas close to Low for soils Increased biodiversity near waterways nutrient load entering streams streams Moderate for hill slopes, Reduced sediment Vegetated buffers remove P draining loam and clay Increased aesthetics attached to eroded soil soils Increased farm value Soil amendment $70–280/ha A long time (at 10 Reduce movement of P off-farm where High for sandy soils Rapidly increased soil pH (Alkaloam or clay) years for nutrient retention dissolved P from An alkaline residue from bauxite Increased plant growth and water repellence and farming moves into processing with significant P Reduced non-wetting many more for moisture waterways and retention properties Improved water-holding capacity of the soil retention) areas that are water Reduces P loss by 30–60% May need to increase rates of P application repellent Claying is likely to have similar Usually higher effects as well as improved soil rainfall sandy soils wetting but at higher application rates than Alkaloam Improve stock $75–100 per source Annual Management of manure and All High Improved animal health management high P source on the farm around feedlots and sheds
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
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