Agricultural landscape

The Lower Herbert, near Ingham, is one of Queensland's largest sugarcane-growing regions. For over a century, it has been the primary source of employment and is at the heart of the local community. The uniqueness of the region sitting across the wet and dry tropics makes it highly suitable for growing sugarcane.

Extensive historical clearing in the Lower Herbert region has removed many wetlands and vegetation on floodplains, especially Melaleuca forests. This vegetation once slowed water, retaining and filtering water while holding sediments and nutrients on the land.

With less vegetation, intense rainfall runoff flows more freely over the land. This, combined with intense cropping across large areas, has heightened the risk of floodwaters washing fertiliser and pesticide off the paddocks into the catchment. This makes it more challenging for growers to manage fertiliser and pesticide runoff from paddocks.

Environmental challenges

Growers rely on fertilisers and pesticides for productive crops, yet they can unknowingly be lost to waterways and groundwater. Research spanning decades reveals that fertilisers and pesticides from cropping lands are prone to moving off paddocks in elevated concentrations, especially during the initial heavy rain of the wet season.

As a perennial river, the Herbert supports diverse freshwater species. This includes barramundi, jungle perch, sooty grunter, and freshwater shrimp. High pesticide levels can diminish macro-invertebrates, a crucial food source for these fish. The wetlands in the Herbert basin are frequently overwhelmed with aquatic weeds, and when combined with high nutrient levels, can result in low oxygen levels and fish kills.

While concentrations of fertiliser and pesticide are higher in waterways closest to paddocks, river plumes in the wet season can also extend along the coast to cover inshore reefs and seagrass meadows – exposing these ecosystems to terrestrial runoff.

In this region, the Herbert River discharges into the Hinchinbrook channel, a highly productive estuary with abundant marine life, seagrass meadows, and mangrove habitats. Flood plumes often reach offshore to popular recreational fishing locations like Pelorus Island, the Brook Islands, and Goold Island. The sediment and nutrients carried by these plumes can potentially impact these ecosystems, often leading to higher levels of macroalgae overgrowth on coral reefs, lower coral coverage, and less new coral growth.

Reducing runoff can improve farm productivity

The loss of pesticides and nutrients through runoff from farms can be costly for growers. When more fertilisers and pesticides run off paddocks, input efficiency decreases, and overall productivity lowers. Making good land management decisions benefits both the farm and the environment, including:

• Effective use of machinery reduces ground compaction, enhancing water infiltration for better soil health. 

• When precision technology is used to apply fertilisers and pesticides, the use and cost of these products are reduced.

• Using rotational cropping, such as legumes, improves soil health and structure. This reduces the reliance and cost of synthetic fertilisers. 

• By accounting for organic nutrients added to the paddock, such as fallow crops and mill mud, synthetic fertiliser application rates are lowered. This strategy optimises fertiliser rates, which can increase crop yields and reduce input costs.

Research has shown co-benefits in the adoption of many progressive farming practices, which not only improve farm productivity and profitability effectively but simultaneously address water quality concerns.

How can growers adopt improved practices?

The Herbert Basin is one of the most extensively monitored catchments for water quality. Data collected and communicated back to growers by extension staff and scientists has led to steady improvements in water quality.

The Lower Herbert region sits on the boundary between the wet and dry tropics, meaning there are more diverse microclimates and distinct soil types. This diversity means more customised management practices are needed for relatively small areas, highlighting the need for extension providers to test various management strategies across different sections of the region before growers commit to change.

Growers are adjusting their practices using a range of management strategies, including:

• Sensor technology: Using sensor-based technologies throughout the stream networks, 'hotspot areas' and key fertiliser loss periods can be identified. Growers can respond by carefully managing application methods and product choices.

  
  

• Understanding peak fertiliser losses: Peak runoff losses occur during initial heavy rainfall when new cane crops are fertilised. The real-time monitoring helps growers match higher fertiliser losses with specific farming practices for timely adjustments.

  
  

• Improving soil health: Growers are trialling multispecies rotational crops and the application of targeted mill mud as alternative fertiliser inputs. This improves soil health and structure, while reducing the reliance and cost of synthetic fertilisers.

  
  

• Pesticide and fertiliser management: Growers carefully manage application methods and product choices. For fertilisers, this includes timing, rates, placement, and product selection. For pesticides, it involves timing, product choice, and strategic application. Machinery can allow for precise application.·        

Mitigating paddock runoff continues to be a significant challenge for growers, largely due to changes in natural floodplains and years of monoculture farming practices. However many growers persist in their innovation to adopt improved farming techniques while maintaining a profitable farm.