Land is tilled, sowed, and harvested for horticultural crops to grow.
Repeated cultivation and harvesting of the soil can result in increased surface run off in areas surrounding streams and rivers, carrying high sediment loads and nutrients , especially following heavy rain.
Excess nutrients from fertiliser applications are more likely to end up in waterways when soils 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 any nearby waters. Nutrients, herbicides, and pesticides are less likely to contaminate waterways when riparian vegetation is maintained as a buffer between the land and the adjacent stream, river, or estuary.
Plant pest control
Farmers are encouraged to consider an integrated pest management programme involving biological (e.g., crop diversity), mechanical (e.g., weeding), and cultural (e.g., using traditional methods) controls. Chemical pesticides are only recommended as a last resort when crops are threatened or pest levels are high. If chemicals are necessary, specific new-generation chemicals are preferable because they 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 water ways via runoff or from direct spraying around waterways (spray drift). The toxicity of these chemical contaminants depends on the type and quantity 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). Rotating crops and incorporating organic matter back into the soil will add nutrients and structure to help prevent disease and reduce fertiliser wastage. Good soil structure and stability reduces surface erosion and decreases surface water run-off with associated chemical contaminants, nutrients, and sediment.
Irrigation and abstraction
Some cropping operations rely on water abstraction for irrigation of crops. 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 the particular crop to reduce the risk of fertiliser runoff or nutrient leaching from soils to groundwater, both of which can lead to the subsequent contamination of streams. Pesticides and herbicides in waterways are often associated with cropping or horticultural activity.
Areas or “hot spots” on farms and orchards 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 areas
- uncontrolled dumping or land filling of chemical containers or other waste products
- nutrient solution storage facilities.