Development and evaluation of an on-farm sediment pond - Aussie Pineapples

Development and evaluation of an on-farm sediment pond

Research Topic 5: Management of erosion and sedimentation
Trial number: 05-WB-03

Fertilisers and pesticides are major inputs in pineapple production. There are increasing concerns about their potential environmental impact, so managing these inputs has never been more important. The industry is located in the coastal areas of Queensland for its warm climate, well-drained soils and limited exposure to cold winters and frost.

The high rainfall events and predominantly sandy loams in this coastal area pose a soil erosion risk which coupled with their proximity to sensitive environmental areas such as the Great Barrier Reef and Moreton Bay Marine Park are a challenge for growers.

The key issues of concern are off-farm deposition of sediment, pesticide and nutrient. Sediment has been identified as a primary element impacting aquatic species and their habitats. Sediment deposited onto reefs can smother corals and interfere with their ability to feed, grow, and reproduce.  Sediment can also act as a carrier for pesticides such as diuron.  Pesticides such as diuron directly kill marine vegetation such as sea grasses which are important parts of the food chain.  High levels of nutrients in the water can have a negative impact on aquatic environments, for example by causing blue green algae blooms. 

It is important for pineapple farmers to manage their fertiliser and pesticide programs efficiently and reduce losses of soil, pesticides and fertilisers from the farm. Measures include only applying amounts that will be used by the crop, reducing the movement of soil and water across the farm and as far as possible retaining them on the farm so they are not contaminating the environment. This demonstration trial focuses on a redesign of the traditional silt trap into a shallow sediment pond and evaluating its capacity to reduce fertiliser and pesticide in water leaving the farm. 

  1. To capture the first 25 mm rainfall per hectare. The reason is that the first 25mm of run off is generally considered to contain 75% of the fertiliser and pesticides likely to run off the field.
  2. Evaluate the potential to degrade pesticides in the soil and water run-off through greater exposure to heat and sunlight in a shallow, broad sediment pond.
  3. Monitor the levels of pesticides and nutrients in the water and sediment to see if they drop over time.