Run-off from either rain fed or irrigated blocks can cause increased soil erosion, loss of productivity, loss of agricultural chemicals and unforeseen off-site impacts. Agricultural chemicals can also attach to soil particles which can further increase stream pollution.

Growcom’s Hort360 South East Queensland (Hort360 SEQ) project is working with growers in the Lockyer Valley, Scenic Rim and Sunshine Coast hinterland to promote sustainable management practices with a specific focus on reducing erosion and concentrated runoff from sediment, nutrient, herbicide and pesticides.

The following information has been developed to give a snap shot of how to alleviate some of these issues.

RIPARIAN

  • Refrain from cultivating close to stream banks.
  • Improve vegetation diversity and structure through both vegetation planting and natural regeneration.
  • Undertaking remedial works where appropriate to address problems at specific sites eg. subsurface drainage.
  • Providing off-stream stock watering points to minimise any degradation of the stream bank.
  • Avoid pumping installations where there are steep vertical bank sections or eroding banks.
  • Locate infrastructure so that it does not interfere or compromise the stability of the riparian zone.
  • Re-route or capture surface flows which erode stream banks.
  • Monitor riparian buffers to ensure that green vegetation of appropriate width is maintained in response to changing riparian conditions.
  • Protect stream banks with vegetation, especially in areas where flood flows re-enter the stream.

RUNOFF – INFRASTRUCTURE

  • Maintain maximum ground cover where possible, and avoid intensively cultivating or leaving soil bare during the wet season.
  • Keep waterways or flow channels grassed or vegetated.
  • Design farm infrastructure to allow natural drainage lines to function so that natural flows are unimpeded.
  • To avoid any damaging increase in flood heights and velocity, align structures such as fences and roads so there is no channelling of floodwaters.
  • Design head ditches, crop furrows and tail drains to minimise impact on flood flow concentration and flow direction.
  • Grow crops in strips at right angles to the water flow to spread the flow and reduce velocities, allowing silt to be deposited.
  • Design paddock size and layout taking into account capability of the land type and landform.
  • Design above ground structures (roads, buildings, water storage ring tanks) to minimise concentration, diversion or restriction of flood flows.
  • Construct and maintain water storages to prevent leakage.

RUNOFF – INFIELD

  • Avoid cultivating soil to a very fine tilth – this will maintain surface roughness and reduce erosion caused by surface run-off.
  • Apply irrigation at rates and amounts appropriate to the plant and available water capacity of the soil.
  • Where practical, refrain from irrigating when storms are likely, so that fields will be able to absorb a high proportion of stormwater.
  • Plant green manure or cover crops to increase soil organic matter levels for improved soil structure, stability and fertility.
  • Maintain grass strips between rows of tree crops to prevent collection of silt from inter row surfaces.
  • Retain stubble and trash to protect the soil surface – this will slow sealing of the surface, keeping it open and able to absorb water.
  • Mulch bare surfaces and/or minimise periods of exposed bare soil.
  • Avoid tillage where possible during times of the year when heavy rainfall events are likely.
  • Permanent bed systems can improve soil structure and stability by maintaining or improving soil organic matter levels.
  • Use contour banks to intercept run-off on sloping land.
  • Leave harvest remains on-site until the site is next required.

RUNOFF – OUTFIELD

  • Design and maintain tail drains with sufficient capacity to hold first-flush stormwater.
  • Incorporate contours or mounds to slow water flow across slopes.
  • Safeguard production areas by protecting from upstream water flow impacts.
  • Grass drainage lines, waterways and field surroundings to filter silt and agricultural chemicals and decrease water flow from cultivated areas.
  • Use sediment traps or ponds where practical.
  • Identify flood prone land that is subject to erosion.
  • Construct artificial wetlands to capture and reduce the impact of sediment loss.

SOIL CHEMISTRY

  • Avoid the use of chemicals if rainfall is predicted or imminent
  • Establish crops using good quality water and then use poor quality water once they have passed the most sensitive stage.
  • If the water table is not high, consider flushing irrigation with good quality water to wash salts beyond the root zone.
  • Avoid excess irrigation or any action that will raise water tables.
  • Use surface or subsurface drainage to lower water tables.
  • Avoid developing naturally waterlogged or saline soils.
  • Avoid developing areas with high water tables.
  • Install subsurface drains and reuse water if suitable.
  • Maintain deep-rooted crops or vegetation to reduce deep drainage and use subsoil water.
  • Conduct leaf testing.

SOIL MANAGEMENT

  • Calibrate and maintain fertiliser application equipment.
  • Conduct soil mapping.
  • Conduct soil testing.
  • Use moisture monitoring probes.
  • Adopt zonal application by soil type.
  • Do nutrient budgeting and recording.
  • Avoid cultivating steep slopes, natural drainage lines or for weed control.
  • Cultivate at correct moisture content.
  • Use low till techniques.

Hort360 SEQ is funded by the Department of Environment and Science.