Phosphorus and Sediment Loss Management:
The Essentials for a Winter Management Plan
Planning
- The manager should understand the environmental risks associated with phosphorous, sediment and effluent run off and likely sources of these
- Critical nutrient source areas and other high run off risk areas need to be identified and nutrient/sediment losses from these appropriately managed.
- Put a plan in place to reduce P and sediment losses from critical source and other high risk run off areas
- Develop a winter fodder crop management plan before you order the seed
Cultivation and Location of crops
- Minimum or no till cultivation techniques should be used when high risk of run-off or flooding of cultivated paddocks
- Winter forage crops should be located in areas of lowest risk from flooding, soil loss and land damage
- Lighter soils are often located near waterways and heavy soils have higher pugging and run off risks. Management needs of each is different
Tracks and Laneways
- Laneways should be located away from waterways and use buffer strips to avoid direct runoff of stormwater or effluent
- Laneways alongside waterways (and water races) are designed for lane run-off to be directed away from the waterway
- Runoff from tracks approaching waterway crossings should be diverted away from the waterway. Use bunds or reprofiling in high risk locations
- Runoff from tracks on sloping country is particularly high risk – try to intercept and divert away from waterways
Grazing Practises
- Where practical cattle should be grazed on and off fodder block
- Strip next to riparian margin grazed last when break feeding winter feed crops
- Where possible graze from top of slope to bottom using crop as buffer strip
- Keep welfare issues in mind
Margins and Buffer Strips
- Vegetated buffer strip of sufficient width to filter any runoff is left between grazed fodder crop blocks and waterways.
- A strip may need to be several metres wide to be effective – key factors are slope, crop and soil.
- The steeper the slope the wider the strip.
- Drains are shaped to minimise risk of bank erosion
- Drain cleaning is undertaken in a manner that minimises sediment losses, ideally outside of fishing season.
Fertiliser Use
- No super-phosphate application in high risk / rainfall months i.e. June-September.
- Regular soil tests (at least 2 yearly) must be undertaken as aid to determining P needs
- P fertiliser application rates based on Advisor’s recommendations and designed not to exceed optimum Olsen P level
- Slow release P fertilisers are used where risk of P loss from conventional P fertilisers are high
- GPS technology used for precise application of all P fertiliser spread
Key Points
- Phosphorus (P) is an essential plant nutrient but a high-risk pollutant in the aquatic environment. You should be keeping it where plants can use it and out of waterways. Good for your pocket and good for the environment.
- When P is bound to soil particles it is relatively insoluble. If you manage soil and sediment loss, you largely manage your P loss; BUT
- Superphosphate fertilisers are very soluble for about the first six weeks – so have a high risk of being leached in the time following application. Do not apply soluble P fertilisers when there is a risk of heavy rain no applications during winter months.
- There is a high P load in faeces – keep crap out of waterways.
- Tracks, laneways and crossing points are high risk areas that concentrate sediment and crap – focus attention on managing run off from these.
- Winter forage crops are very high risk. Manage crops carefully. Plan your winter-feeding areas and – apply all the rules for grazing and buffer strips.