With two early storms causing significant erosion in parts of Western Australia earlier this year, some producers may be looking at unproductive and uncovered sandy areas with increasing trepidation.
It’s the type of situation that Woodanilling farmer John Pickford experienced in the 1990’s on an area with deep pale sands.
“It’s really beach sand, very fragile,” John said. “In the deepest parts there is 50 feet of white sand (15 m), a bit of gravel in it, and then it touches down on a tight clay. It wouldn’t grow enough cover and would blow even when it wasn’t grazed.”
John’s solution was tagasaste (Chamaecytisus palmensis), a drought-tolerant fodder shrub adapted to pale deep sands in areas that receive over 325 mm of annual rainfall.
John direct seeded approximately 27 hectares of tagasaste in rows 6-8 metres apart, the equivalent of a single row 50 kilometres long.
“The tagasaste has stabilised this area and has been highly productive on a very poor piece of soil. The deeper the soil the better. In my opinion it needs to go down at least three metres so it needs a situation where there is no rock, tough clay or water. It’s very deep rooted.”
The Department of Primary Industries and Regional Development’s (DPIRD) Perennial Pastures for Western Australia (Chapter 8) publication states that the soils should be at least one metre of well-drained soil to persist and be productive, with deeper sand better for plant growth. While it can grow on fine-textured soils, they can restrict root growth and increase the risk of waterlogging, which along with salinity is something tagasaste doesn’t tolerate. So, planting in one metre of soil comes at some risk especially if waterlogging is likely.
Tagasaste grows rapidly after the break of season, especially in April and May when temperatures are warmer compared to winter. Highest growth rates occur in spring. Over these months animal growth rates can match those for green annual pasture. DPIRD provides an example of cattle growth rates of 1.0-1.8 kg/head/day on tagasaste with a dry matter digestibility (DMD) of 70-82%. After spring, palatability steadily declines over summer and autumn as stress produces tannin-like compounds that interfere with protein metabolism in the rumen, leading to protein deficiencies even though crude protein is never below 10-15%.
“Sheep really like it. They come straight in and start eating it. We graze it when we need it, but autumn is one of the best times (when pastures are establishing). However, there’s no doubt that if it’s been dry for a month or more, they won’t touch it. I gather the tannins rise in it protects itself, but as soon as you get 10 mm or similar it freshens up (and is more palatable). Flowering also reduces feed value.”
Tagasaste can tolerate hard grazing by sheep but need to be rested every six weeks before new buds emerge. Because cattle don’t graze as tightly as sheep and so don’t remove new buds, they can be successfully set stocked.
John tends to have his shrubs cut mechanically every 18 months or so, so it stays within reach of sheep. However, this is less of a requirement for cattle.
The other benefit John sees with tagasaste is its ability to use water.
“Much of this site is lower than the creekline so it is a perfect recharge site. We’re trying to use that water because our neighbour’s paddock across the road is badly salt-affected and I think it’s been very effective. Piezometers on the edge of it here have completely dried out.”
One final benefit was the pleasant sounds of birds whistling around the shrubs on a glorious spring morning.
For more information, download Perennial Pastures for Western Australia from the DPIRD website.Tags: Fodder shrub