EPA ensures farmers meet effluent management responsibility

A dairy cow will dump up to 15 per cent of its daily manure output on the concrete yard of a dairy farm. It is then washed into effluent ponds. Managing this issue is important.

Biosolids - appropriately treated environmental sludge - and liquid effluent are potential resources that can be beneficially utilised in agriculture, helping to reduce emissions and fertiliser costs on farm.

According to Dairy Australia, 10-15pc of manure created by each cow on a daily basis is washed from dairy sheds into holding ponds, so reusing effluent can be a beneficial tool on farms.

Dispersing treated effluent across paddocks in instantly-usable liquid form or as a biosolid incorporated into the ground to act as a slow-release fertiliser helps save cuts costs of bought-in fertiliser.

The organic matter of effluent provides soil-conditioning properties and improves soil moisture and nutrient-holding capacity.

With a high nitrogen level, effluent provides productivity gains from pasture responses, which can result in increased production.

Using effluent as valuable source of nutrients

Hans van Wees, a sharefarmer at Tinamba in central Gippsland, Vic, utilises a purpose-redesigned 10-megalitre dam and irrigation system to manage effluent and utilise it for pasture growth.

Washdown water and effluent flow into a large solids trap at the side of the dairy. The trapped solids, when dry, are spread over nearby paddocks. The liquids are pumped into a dam, which is located about 300 metres from the dairy.

A stationary pump mixes the dam water to prevent slurrying.

When Mr van Wees wants to apply the effluent water to the paddocks, he opens a release valve into an irrigation channel connected to the dam.

The effluent water is then pumped into one or two other channels and diluted with irrigation water - at a rate of one part effluent to two parts irrigation water.

Mr van Wees can irrigate 120 hectares directly from this dam or shift the effluent to another dam further down the property and irrigate other paddocks from there.

The capacity of the effluent dam means there is no runoff or flow over into paddocks and consequently no effluent running off the farm in wet weather.

The backup dam further down the property provides double insurance.

Mr van Wees said the system returned fertiliser savings of 100kg/ha of single superphosphate over 120ha.

Jeanette Severs, Queensland Country Life, 22 November 2023.

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