SUBSURFACE DRAINAGE RETURN ON INVESTMENT

The first year of South Coast NRM’s Subsurface Drainage Return on Investment Trial, wrapped up with the 2021 harvest. The past twelve months have seen us install 3km of subsurface drainage in a waterlogged paddock in the Neridup region, to the east of Esperance. A good growing season and high rainfall have provided us with enough data to begin the critical analysis of this drainage system and its value. 

The trial paddock grew canola in 2021 and this susceptible crop yielded 56% more in the drained site compared to the paddock average. Accounting for yield penalties, we can estimate a preliminary yield benefit due to subsurface drainage of 25 – 50%. With canola currently priced at $980/t, this has translated to an increase in profit of up to $745/ha. Over the following year, we will be taking this yield increase and comparing it against the costs of installation to assess a preliminary return on investment. South Coast NRM are also excited to announce that in the second year of the trial we will be expanding the project by including two additional subsurface drainage systems into the Esperance trial. 

The same Subsurface Drainage trial is also being run in the Cranbrook region, by the Stirlings to Coast Farmers Group. This trial also had a successful first year and saw a 1t/ha yield benefit in their trial zone. Read more about the Esperance and Cranbrook trials in the latest issue of Farm Weekly South Coast NRM and Stirlings to Coast Farmers Help Develop Waterlogging Strategies”