Short Term Effluent Management in a Changing Tasmanian Climate — YRD

Short Term Effluent Management in a Changing Tasmanian Climate (1043)

Louise Murphy 1 , Scott Birchall 2 , Rachel Brown 3 , Mark Boersma 1 , James Hills 1 , Alistair Gracie 1 , Steven Emmett 1
  1. Tasmanian Institute of Agriculture, Burnie, TAS, Australia
  2. AgSystems Design, Shepparton, VIC, Australia
  3. Landly, Port Sorell, TAS, Australia

While some regions of Australia such as WA plan to reuse effluent as an adaptive measure to reduced rainfall, in other regions such as northern Tasmania, increased rainfall may lead to greater risk of off-site pollution through surface run-off. To prevent run-off, a condition of dairy farmer licencing in Tasmania, management of dairy farm effluent will need to undergo practice change to accommodate forecasted rainfall increases. While primarily devised for mitigation, the potential of Short Term Effluent Management (STEM) as an adaptive tool to manage the risk of off-site effluent pollution during high rainfall periods is discussed. STEM is the frequent distribution of effluent triggered by soil moisture deficit below a threshold. Here, effluent is only applied where a soil moisture deficit increases the probability of soluble nutrients entering the profile, these then being less available for surface run-off events. STEM may also provide the flexibility to allow the timing and volume of application to assist in preventing nutrients from being leached through the profile by excessive irrigation or forecast rainfall events. To successfully reduce effluent pollution using STEM, we suggest that determining a suitable tank volume with the capacity to retain sufficient volumes is fundamental to achieving flexibility for the storage of effluent during extended rainfall periods. Additionally, to determine if STEM can be used as an adaptive practice, more information is required on its influence on the fate of minimally retained effluent and associated nutrients once applied to pasture.

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