Low-rate effluent application

What

Over-application of effluent onto paddocks can have harmful effects on water quality due to the high concentration of contaminants including phosphorus, nitrogen, and microbes in the effluent. Low-rate application of effluent can therefore help to reduce the contaminants getting into groundwater and waterways.

Why

Low-rate application of effluent can be done by using temporarily fixed sprinklers that pump out effluent at rates of approximately 4-8 mm/hr to the soil. Some sprinklers can also release effluent on an instantaneous basis depending on the soil moisture. These systems make sure effluent doesn’t get over applied to paddocks which could result in ponding or the nutrients from the effluent leaching into the groundwater.

Low rate (upper) and high rate (lower) effluent application systems.
Image sources: Progressive Rural Trade Services and Waikato Regional Council.

References

Houlbrooke, D. J., Horne, D. J., Hedley, M. J., Snow, V. O., & Hanly, J. A. (2008). Land application of farm dairy effluent to a mole and pipe drained soil: implications for nutrient enrichment of winter-spring drainage. Soil Research, 46(1), 45-52.

McLeod, M., Schipper, L. A., & Taylor, M. D. (1998). Preferential flow in a well drained and a poorly drained soil under different overhead irrigation regimes. Soil Use and Management, 14(2), 96-100.

Monaghan, R. M., & Smith, L. C. (2004). Minimising surface water pollution resulting from farm‐dairy effluent application to mole‐pipe drained soils. II. The contribution of preferential flow of effluent to whole‐farm pollutant losses in subsurface drainage from a West Otago dairy farm. New Zealand Journal of Agricultural Research, 47(4), 417-428.

Monaghan, R. M., Houlbrooke, D. J., & Smith, L. C. (2010). The use of low-rate sprinkler application systems for applying farm dairy effluent to land to reduce contaminant transfers. New Zealand Journal of Agricultural Research, 53(4), 389-402.

Muirhead, R. W., & Monaghan, R. M. (2011). Impacts of direct faecal inputs and effluent management practices on microbial water quality.