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Tasmanian Institute of Agriculture

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Basic principles for successful crop production

Water on

  • correct irrigation system design and operation
  • VRI and sprinkler technology (e.g. dry packs) to manage variable water holding capacity and zones that don’t need water (e.g. roads, uncropped areas)

Water off

  • Paddock layout (direction of run) integrated with surface drainage
  • Sub-surface drainage according to soil type

These aspects are influenced by soil structure, which is heavily influenced by how the soil is managed. Be aware of irrigation by-passing topsoil, surface sealing and compaction, among other issues.

Some directions towards better soil management

If at all possible:

  • Don’t drive on the soil – i.e. controlled traffic. Guidance helps, but not sufficient on its own. Match implement working widths. Integrating harvest is a challenge in mixed cropping systems, but entirely achievable in grains.
  • Don’t disturb the soil (or at least minimise disturbance) – zero-till, strip-till, min-till. Manage traffic to reduce the need for tillage.
  • Keep something growing/covering the soil at all times (i.e. residue retention, cover crops). Organic matter is important for structure, biology, aeration, infiltration, nutrient retention, internal drainage, soil resilience.

Cover crops

  • Manage as you would a cash crop. Be aware of pros and cons of livestock in a cropping rotation, particularly with respect to winter grazing.
  • Use the cheapest mix that does the job you want. Use a legume for nitrogen, use a tap rooted species or a vigorous grass for ‘biological tillage’, etc.
  • Leave it on the surface to minimise erosion and maintain root channels in the soil. Biofumigants must be incorporated for benefits.

Building and maintaining structure

  • Traffic (both machines and livestock) compacts soil.
  • Tillage destroys internal channels, aggregates, roots and fungi.
  • The less traffic and less tillage, the easier it is to build structure.
  • Subsoil manuring for dense clay subsoils – jury out on benefits for irrigated crops, but if you do it, need to manage traffic afterwards.