Lets stop the spread

Let’s stop the spread (of topsoil)

The constant push for agricultural production puts pressure on primary producers, who often have little time to restore, repair and prepare the ground between crops.

Large, fast, heavy farm equipment is a great time saver, but can damage valuable soil structure leaving it compacted, stripped of organic matter and with reduced water infiltration capacity. One solution is planting a short-term Autumn cover crop to provide protection from erosion between cash crops. Above ground, cover crop plants reduce rain splash impact, and this increases with increasing plant height. Below ground, the roots bind the soil, reducing the potential for erosion.

Typically, during the summer season, there is exposed ground as vegetable crops are at various stages of growth without full row closure; this leaves topsoil vulnerable. The recent ~100 mm rainfall event in early February caught many by surprise, and highlighted the issue.

Other benefits include improved soil structure provided by decaying plant matter leaving spaces for infiltration and improved water holding capacity. Valuable soil organisms increase that improve soil biology; more nutrients are retained. Weed suppression can be achieved and with improved plant health and disease pressure reduces.

Key management considerations

Cover crops can help protect steep paddocks during times of expected high rainfall,

Planning for cover crops should include identifying suitable species, when to plant, how and when to deal with plant residue,

Cover crops cost approximately $140/ha.

This has been estimated as one tenth of the value of soil potentially lost due to erosion if no erosion control is used –$1,000/ha for soils left fallow in autumn and winter.

Longer term cost savings include reduced fertiliser, chemicals, fuel and irrigation requirements.

The NRM team at Cradle Coast Authority have recently completed various trials on steep terrain in north-west Tasmania, where seasonal cover crops were used to protect bare fallow autumn and winter soils from erosion. The results from road-testing on a commercial scale, together with crop growth stage monitoring display, has provided a robust guide for future implementation. Many producers are getting on board.

Please get in touch to learn more about the program and how it can complement your cropping regime. Contact project coordinator Ali Dugand at adugand@cradlecoast.com.

This project is supported by the Cradle Coast Authority, through funding from the Australian Government’s National Landcare Program.

P r i o r t o t h e n e x t c a s h c r o p , r e m e m b e r t o :

Reduce the crop (by either herbicide or mulching) when it is just below knee height or at the first sign of flowering.

Cover crop growth stage monitoring display (note greater root depth down to 600 mm, compared to above ground height of ~300 mm) – August.

Cover crop trial species Tic beans, peas, lupins and oats, prior to termination – August.