Farm advice: Effluent ponds – how much storage do you need?

By: Logan Bowler, DairyNZ environmental extension specialist and effluent management expert


Logan Bowler from DairyNZ discusses the many factors to take into account to determine how much storage your farm requires

I’m a firm believer that you can’t do a good job if you don’t have the right equipment, and the same applies to managing effluent on farm.

No matter how well you manage your effluent storage pond, if it’s too small, you’re going to struggle.  

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So, just how much storage do you need? Everyone’s requirements are different depending on their farm. Just because your neighbour has a certain sized pond, doesn’t mean that’s the right fit for you. 

If you’re considering installing or upgrading your effluent system, there are a number of factors to take into account to determine how much storage your farm requires. These include shed water use, herd size, season length, and application depths, which we’ll look at in more detail in the next column. But the biggest factor to take into consideration is your soil type.

If you have high-risk soils, your storage requirements will be significantly more (five to six times more) than those with low risk, as you won’t be able to irrigate as frequently.
High-risk soils are those that exhibit surface run-off and/or preferential flow. While low risk are well or moderately well-drained soils on slopes less than seven degrees. 

If you’re not sure if your soils are high or low risk, there’s a pocket guide available on the DairyNZ website to help you identify the soil risk for effluent irrigation on your farm.  

Soils and future-proofing key factors for farmer

Soils were a key factor Waikato dairy farmer Ian Taylor took into account when determining what sized pond to install on his farm. Ian, who farms 440-cows on consolidated peat soils in Puketaha, decided to put in a pond with a plastic liner that exceeded his requirements.  

"I thought I’d err on the side of caution and go bigger. I went for a pond twice the size that I needed, at 2100 cubic meters.

"I didn’t want to end up building a pond that was too small, so I built one as big as I could in order to future-proof any changes that might come in later or down the track."
Ian did a lot of research before deciding on what size and type of pond he would install to determine what system was best for his farm and team.

He says he chooses a relatively simple system as he wanted to reduce operator error.
He recommends farmers consider all their options and use soil experts to determine whether they have any low-risk soils.

"There can be a three- to five-fold difference in the size of the pond depending on whether you have high or low-risk soils."

Ian says having the right infrastructure in place makes effluent management less stressful. "I can now relax knowing in wet weather we can pump into the pond."

If you’re considering installing or upgrading your effluent system and you’re not sure where to start, there’s some great information on the DairyNZ website. There’s also the free Dairy Effluent Storage Calculator to help you get a better idea of how much effluent storage you need.

I also highly recommend using an accredited effluent system design company. After all, it’s a big investment, so you want to make sure it’s done right.

For more information to help you make the right decision when installing or upgrading your effluent system, or for a list of accredited effluent system design companies, visit dairynz.co.nz/effluent. 

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