Cropping activities

The land used to produce crops is usually flat to gently rolling so it can be tilled, sowed, and harvested.

The land used to produce crops is usually flat to gently rolling so it can be tilled, sowed, and harvested.

Alternating cropping with pasture rotation can ease the effects of soil compaction or, conversely, the effects of tillage on soil degradation. However, repeated cultivation and harvesting of the soil on a farm can result in increased surface runoff in areas surrounding streams and rivers, carrying high sediment loads and nutrients, especially following heavy rain.

Excess nutrients from fertiliser applied to crops and pasture are likely to end up in waterways when these are cultivated to the water's edge. Herbicides and pesticides used on crops to control weeds and insect pests are chemical contaminants that have the potential to leach through the soil and pollute nearby waters. Nutrients, herbicides, and pesticides are less likely to contaminate waterways when riparian vegetation or a grass edge is maintained as a buffer between the land and the adjacent stream, river, or estuary.

Here are some on farm activities to consider.

Plant pest control

Farmers are encouraged to consider an integrated pest management programme involving biological and mechanical controls. Chemical pesticides are only recommended as a last resort when crops are threatened or pest levels are high. When chemicals are necessary, specific new generation chemicals should be used that have a lower environmental persistence and are less toxic than those used in the past. Excess spray residue accumulates and binds to sediment particles which may end up in waterways via runoff or from direct spraying around waterways. The toxicity of these chemical contaminants depends on the type and quantity that are applied.

Crops and soils

Sustainable and sensible land and water management results in greater profitability and environmental improvements. Good soil structure can be maintained through regular soil testing to determine optimal soil health and by preventing compaction by minimising tillage (ploughing, ripping, or turning of the soil). Crop rotation and incorporating organic matter back into the soil will add nutrients and restore structure, which in turn will prevent disease and reduce waste from excess fertiliser application. Good crop and soil management will improve soil structure and stability which reduces surface erosion, and decreases surface run off and the associated chemical contaminants and sediment.

Irrigation and abstraction

Some cropping operations rely on abstraction for irrigation. Irrigation systems may be permanent or semi-permanent, including pop-up systems, fixed above-ground drip and micro systems, and pivot or laterally moving machines.

Irrigated water should be applied to match the needs of a crop otherwise any excess will be lost to groundwater. Irrigation may increase the risk of fertiliser runoff or nutrient leaching which can lead to the subsequent contamination of stream water, in particular nitrate leaching. Pesticides and herbicides in waterways are often also associated with cropping or horticultural activity.

Areas or 'hot spots' on a cropping farm that are likely to contain concentrations of residual agrichemicals and therefore require careful consideration/control measures include:

  • spray storage sheds
  • spray equipment wash down areas
  • bulk fuel storage
  • bulk fertiliser storage sheds
  • uncontrolled dumping
  • pesticide contamination of waterways by spray drift.