WestVic Dairy News - November 2010 Edition
Highlights from Pasture Recovery Field Day
By Nadine Markham, DPI Colac
Pugging prevention, damage assessment and strategies, drainage and soil fertility were among the topics discussed at recent Pasture Recovery Field Days held in southwest Victoria.
The days, held as a response to wet conditions in the region this season, were attended by more than 80 people.
Funded by Dairy Australia, the field days featured several speakers including Peter Notman, Richard Gloyne, Michele Ryan, Nadine Markham, Glen Cain and Neil Palmer.
The following is a summary of some topics covered.
Successful Pugging Prevention Strategies
Pasture damage can be reduced through farm management and grazing practices such as:
- Focusing on achieving a high pasture cover across the farm from the start of the autumn break through regular applications of nitrogen, leaf- stage grazing and the efficient use of supplements.
- Having feed in the paddock allows the practice of on/off grazing where cows are able to get their fill more quickly. The grazing between two to three leaf (for perennial ryegrass) ensures a well-developed perennial ryegrass root system that can help bind the soil together, and together with a higher pasture cover, contribute greater soil strength.
- Filling cows with hay and silage before grazing paddocks also appears to reduce the amount of damage occurring due to cow traffic. For those farms without feed pads, farmers feed hay or silage on tracks and laneways. In some cases farmers would practice on/off grazing by leaving gateways open for cows to leave paddocks once that had eaten their fill.
Assessing Damaged Paddocks
Although most farmers employed management practices to reduced pugging damage, it was difficult to avoid this season.
Department of Primary Industries (DPI) dairy officers Michele Ryan and Nadine Markham outlined an objective way to assess the severity and extent of damage across the paddock, to then determine if remedial action was required.
Strategies to Address Pugging Damage
Peter Notman from Notman Pasture Seeds spoke of the importance of:
- Renovating no more than 20 per cent of the farm area to avoid running short of feed in the following season.
- When selecting paddocks for renovation include those containing annuals as well as the most damaged areas.
- Understanding details of the many summer crop alternatives ranging from brassicas, chicory, and millet through to sorghums and sowing what works for you and fits in best with your system.
- Having a planned end date for whatever crop is sown to ensure that the paddock is resown by a set target date ready for winter production.
- Knowing that over-sowing pasture programs are generally more reliable if conducted in autumn.
Waterlogged Soils and Drainage Solutions
Richard Gloyne from Draintech covered a number of key points during his segment. Some of these included:
- Soils lose their strength as they become progressively wetter, increasing the potential risk of damage to soil structure through compaction. Compaction is the process by which soil aggregates are pushed closer together, resulting in smaller pore spaces, which tends to prolong waterlogging. Compaction can be avoided or reduced by keeping animals and machinery off wet areas.
- Overcoming waterlogging usually involves a combination of both surface and subsurface drainage.
- Surface drainage is often the cheapest form of drainage and can be effective in removing surface water. Issues arise with surface drainage, when drains are not properly maintained and water movement is impeded.
- Sub-surface drainage aims to remove excess water, occupying the macropores in the soil profile by lowering the watertable. In a properly-installed system, it takes between 24 to 48 hours for excess water to drain away. Grazing is recommended when the water table is about 30cm below the surface.
- Subsurface drainage typically costs between $1500 to $2000 per hectare depending on gradients, soils type and rainfall. This is a significant capital investment; therefore an assessment needs to be made as to whether drainage will improve overall farm performance to a level that will allow the drainage costs to be recouped over time.
- Drainage should be planned carefully on a whole farm basis with a drainage expert as the design greatly influences the efficiency and final cost of the installation. Before considering draining a wet area, your local Catchment Management Authority should be contacted for advice as a permit may be required.
Soil Fertility levels
Given the good growing conditions at the start of the season and the high rainfall events resulting in the leaching of water soluble nutrients, such as potassium, nitrogen and sulphates, soils tests are recommend to assess the impact of the wet seasonal conditions on the nutrient status of soils.
Glen Cain and Neil Palmer from Webber and Chivell reported seeing soils tests with a notable reduction in sulphur levels. Glen commented that this was probably the reason for why trials conducted by Weber and Chivell were showing slightly better responses to sulphur coated urea compared to straight urea, this season.
For more information, a copy of the notes or to enrol in a Feeding Pastures For Profit program please call Michele Ryan, Warrnambool DPI on 03 5561 9914 or Nadine Markham, Colac DPI on 03 5233 5525.
