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Novel tillage practice to increase yields

28 September 2004

Tillage rotation, a novel tillage regime that has the potential to improve compacted subsoil, increase yield and economic return while still enabling farmers to use their existing seeding points, is the focus of a study by the South Australian Research and Development Institute (SARDI).

SARDI senior technical officer, Mr Rick Darling says, “Tillage rotation is one of the lead cost effective technologies currently used to address subsoil problems of cropping land and is readily acceptable to land users. It also adds to the record of current knowledge, innovations and issues in theory and practice to dealing with subsoil issues.”

Mr Darling was speaking today at the 4th International Crop Science Congress in Brisbane. The Congress has brought together over 1000 delegates from 65 countries to focus on the key issues for cropping systems that provide food, feed and fibre for the world.

Most southern Australia cropping land has shallow compacted subsoil with low organic matter. Severe erosion and degradation including compaction of these soils occurred in the last 100 years when the land was intensively cropped to wheat following a cultivated long fallow. There has not been an attempt to remove subsoil compaction economically other than by deep ripping, which was and remains a costly exercise with benefits lasting for only a season or two.

As part of a Grains Research and Development Corporation (GRDC) funded project, David Malinda, SARDI senior research scientist, and his research team including Mr Darling, set up a field experiment to develop a new tillage regime to test the benefits of varying tillage depths. The aim was to reduce compaction and increase the depth of soil exploitable by plant roots and improve yield and yield quality.

Mr Darling reported that the results strongly show that tillage rotation reduces soil strength, roots grow deeper in the subsoil, the uptake of water, nutrients and organic carbon is improved, and the crops produce consistent economic returns for each year compared with no-till and conventional cultivation. Tillage rotation also changed some subsoil chemistry and biology.

SARDI scientists recorded an economic return with tillage rotation over conventional cultivation in the red-brown earth with an average (6 years) gross margin of $50/yr/ha over conventional cultivation.

“Tillage rotation is an improved form of conservation farming system and is now recognised as a viable concept for sustainable agriculture due to its comprehensive benefits in economic, environmental and social sustainability,” Mr Darling said.

“We believe that tillage rotation technology (progressive tillage) is the way to go to economically rehabilitate compacted soils. However, tillage rotation is not so effective in soils with very low subsoil water holding capacity and high salts concentration,” he said.

“We found that by removing compaction in such soils, the topsoil dries up quicker mainly through evaporation, causing plants to suffer from moisture stress.”

Work continues to check and countercheck the effect of vertical progressive tillage (tillage rotation) using different seeding points, in contrasting soil types, in crop production.

The research findings have been well received in Australia and overseas by farmers, extension workers and scientists. The next phase of the work concentrates on technology to rehabilitate degraded subsoil using different tool designs at locations with contrasting soil types.

In addition, vigorous extension of this technology will be pursued.

4ICSC would like to thank all its supporters including the following major sponsors:
AusAID, CSIRO, Pioneer Hi-Bred International and QDPI

More information:
Cathy Reade, Media Manager, 4th International Crop Science Congress
Mobile: 0413 575 934

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