Category Archives: Farm Dairy Effluent

Protocols for Compliance Checks of Farm Dairy Effluent Irrigators

Leave a Reply

I spent a day with staff from a regional council discussing farm dairy effluent application. In particular, they were interested in protocols for monitoring  the performance of travelling irrigators. They need efficient and acceptable ways to monitor compliance with regional plan rules and resource consent conditions.

It is an interesting topic.

travelling effluent irrigator

For the purpose of effluent application, the regional council has defined high and low risk soils, and different consent conditions apply. And of course, there are variations on conditions depending on when consents were issued, the location of the site and so on. And some consent conditions apply to nutrient loadings, including both 24 hour and annual time frames. Yet others relate to soil moisture status, and others to applied depths.

We discussed a lot of things:

  • soil water physics; including application depths, rates, and uniformity 
  • surface ponding and over-land flow or run-off
  • the Farm Dairy Effluent System Design Code of Practice and Design Standards,
  • the Irrigation Evaluation Code of Practice,
  • current approaches for assessing dairy effluent irrigators
  • results from system evaluations
  • accuracy and confidence of monitoring results

Then we went out to a farm and physically measured travelling effluent irrigator performance. And we debriefed.

And so to a protocol: what elements are required?

A protocol needs to be:

  • recognised – look for existing procedures and processes that are suitable
  • defensible – ensure sufficient sampling and fair statistics
  • cost-effective – be efficient, not overly time consuming 
  • meaningful – so everyone can understand the process and the outcomes

Most, if not all, of these are available. The Irrigation Evaluation Code of Practice and the Farm Dairy Effluent System Design Code of Practice and Design Standards, cover field sampling, statistics and standards reasonably well.

But they were not developed as tools to audit performance of Farm Dairy Effluent irrigation performance (equipment and management) against the full range of regional plan rules and individual resource consent conditions that are found within one region, let alone across the country.

And as a country, we still have not agreed on how to assess surface ponding, or interpret our findings. What is acceptable in what environments, and over what time frames?

 

 

Excessive surface ponding

6 Replies

I’ve worked a lot and with many people on irrigation efficiency and on application of effluent to land. We keep coming up against the question, “What actually constitutes surface ponding?”

I’d love to get some agreement on this.

In the last year or so:

  • I’ve heard that ponding only applies to durations lasting 4 hours or more, and I’ve heard it applies to anything from a few minutes duration.
  • I’ve heard it has to be at least a pretty big area and I’ve heard anything at all counts.
  • I’ve been told the Environment Court determined any duration mattered. A regional council had applied a four hour minimum when assessing ponding, but the court said the consent said ‘no surface ponding’ and that meant no surface ponding.
  • I’ve seen lots of it and I’ve seen evidence that excessive application rates are problematic – both for irrigation and for land applied effluent.

There will almost always be some surface ponding; even drip systems micro-pond. So applying a concept of excessive surface ponding seems better. But what is excessive surface ponding?

Excessive surface ponding – defined

In the interests of sparking debate, I propose a definition of excessive surface ponding:

“Excessive surface ponding means the presence of surface water pooled in contiguous areas of greater than 0.04m2 found, one hour after application starts,  at more than four of forty sample points selected at random over at least 25% of the application area, with each point being more than two metres apart.”

  • Surface water pooled may need definition, but I’d say means clearly visible puddling – i.e. not just wet soil
  • contiguous areas means connected
  • 0.04m2 (about 20x20cm) is bigger than a hoof print (my first intent) but is maybe too small – the auction starts now, your bids please . . .  .
  • one hour after the start of application covers both travellers and stationary nozzles but is the time right?
  • Four of forty sample points means 10% and hopefully is a big enough sample that is not too onerous to take
  • Random is random – let’s specify a method e.g. tossing a 0.25 m2 quadrat or ring backwards over your head with your eyes shut having spun twice clockwise
  • 25% of the application area means you have to look around a bit
  • More than 2 m apart spreads it out a bit and avoids sampling landing in the same contiguous, but relatively small, pond. Pick a number (and justify it!)

I don’t know that I agree with my proposed definition.

For a start, I’ve watched high application rate water (and effluent too) disappear very rapidly, and upon digging significant holes, couldn’t find sign of it in the rootzone. So maybe, if you can’t see ponding for more than 10 minutes, that’s when you should get worried!?

Please, have a think, then post a comment below. Let’s try to have a reasoned and enlightening debate!

Regards

Dan

Effluent irrigator calibration

Leave a Reply

New guidelines and worksheets for calibrating farm effluent irrigators have been posted on the Page Bloomer site.

Additions to the IRRIG8Quick series, two options are offered for effluent systems. Both are for travelling irrigators; one for irrigators with less than, and one for those with more than, 15% overlap between adjacent run-to-run passes. (It is likely that most people will find the under 15% overlap is ok. And there may not be very much difference between them for most systems.)

We are aware that farmers are using a range of effluent application irrigation systems, but by far the most common are small travelling irrigators with rotating booms. You can download the guidelines and worksheets here>

What is involved?

The guidelines show how to lay out catch cans (buckets) to catch applied effluent, and how to perform calculations to determine the amount (rainfall depth equivalent) of effluent applied and its uniformity (evenness). There are interpretations to guide assessment of your results. The worksheets are designed to make recording and analysing your measurements easy.

What is different to normal irrigation calibrations?

A series of methods for calibrating other irrigation types is available on the irrigation calibration page. They are designed to help you calibrate normal, clean water irrigation systems.

Normal irrigation is used to avoid drought stress, and there is a focus on potential under-application. It is used when the available soil moisture is getting used up. The standard uniformity measure looks at the lowest collected volumes and compares them to the overall average applied. 

Effluent is nutrient and biology rich with a need to focus on potential over-application. And it might be applied when the soil is already pretty wet. So the uniformity measure compares the highest collected volumes with the average.

The normal irrigation guidelines do not have nutrient application built into the templates. But with a little thought and a look at the effluent guidelines, you can work out what to do! 

Results from surveys

Page Bloomer Associates completed a national survey of farm dairy effluent applicators (SFF 07-016 Canterbury Dairy Effluent Efficiency Application) and results are now available on the site under “Projects”. Click here for more>

We also ran a workshop for dairy farmers in the Toenepi Catchment study area where we trialed the IRRIG8Quick methods. Thanks to those farmers, we have a better set of guidelines and worksheets for you to use! The results can be viewed here>