22 minute read
Effluent
from Dairy Farmer February 2021
by AgriHQ
Thinking outside the box
By Cheyenne Nicholson
A system used in Africa for water has provided a Southland farmer with the perfect solution for the farm effluent system.
Having an effluent application setup that breaks down, is difficult to move and frequently costs money to repair can quickly leave you up an effluent creek without a paddle.
This was the situation Southland farmer Edwin Mabonga found himself in 10 years ago. Today, he has what he deems “the perfect setup” that saves him time and money. The investment has paid for itself many times over, he says, and best of all, his staff are happier shifting the irrigator as it’s not a big burden on them.
Edwin, his wife Fungai and their two children emigrated to New Zealand 18 years ago, with their third child being born here. The Mabongas are sharemilking for an equity partnership of which they are partners. The 270-hectare farm borders the Aparima River in western Southland. The farm comprises 200ha owned by the partnership, with a further 70ha lease and an 85ha runoff for young stock, and milks around 850
Kiwicross cows.
While NZ might be chalk and cheese with Zimbabwe, where Edwin hails from, it’s his experience with irrigation there that helped him form the solution for his effluent application problems here.
“Ten years ago when I first came to this farm, we were running into a lot of issues with effluent application. We had K-Lines for effluent application, and every time you shifted them something broke, the hose would get a kink or something else would go wrong. They were a right pain, and it got to the point where the staff weren’t happy moving them,” he recalls.
Wanting to decrease the repair bills, make life easier on staff and find a more efficient solution for effluent application,
Edwin put his thinking cap on. A hard hose coil irrigator ticked all the boxes for him. The system has a 50m radius Edwin Mabonga works on a farm in Southland, which is vastly different from Zimbabwe, but his experience there has helped find solutions for effluent application.
cover and 300-metre of hose, which allows effluent to be spread over a large area, can be used for water and effluent irrigation and is simple and easy to move – and it works every time you go to shift it.
“Having lived in Zimbabwe, I’ve worked a lot with irrigation. I used this system for water in Zimbabwe so I thought, ‘yep, this should work as a solution for effluent spreading too,’ so I made some enquiries,” he says.
While the idea was great in theory, there were a few hurdles to overcome.
Firstly, the company selling the hard hose coil irrigator weren’t all that keen on selling it for the use of effluent spreading at the time. Secondly, the shareholders of the farm weren’t keen on investing the money required for a new system. Throw in the low application rate of their council consent for effluent and it started as an unlikely option.
“The shareholders weren’t keen to spend money on another system. I managed to convince them that this idea had merit and better suited our values of good environmental management. They have been happy with the decision and their $26,000 investment,” he says.
While the initial upfront cost of the new system is large, Mabonga says it’s
paid for itself over the past 10 years in savings on repair bills. While he says that K-Lines are cheaper by far, the ongoing costs soon mount up, and he often urges farmers to look beyond the initial setup cost of any system on-farm.
“Maintenance-wise, we’ve had the same equipment for 10 years and have had basic services (done), but that’s it. It’s paid for itself many times over and true to my word, the shareholders haven’t heard anything else about effluent – only how great the system is,” he says.
The farm had council consent for low application rates of effluent, 10mm instantaneous application, 50m away from waterways. In order to get council to sign off on the new system, Edwin had to put the new system through its paces to ensure it was capable of low application rates.
“We can get it down to 4mm, which is far better than K-Lines can do. We put a GPS on it as well; if it’s within 50m of a waterway the pump won’t start, so it’s a failsafe option. You can mark boundaries on it via GPS to stop it going into areas you don’t want as well,” he says.
The Southland farm had an effluent spreading system that frequently broke down but has been replaced with a hard hose coil irrigator.
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With a river bordering the farm, good management practices across the board are imperative and having the safeguard of the GPS system gives him peace of mind.
The hard hose coil irrigator is a selfwinding setup that is moved via tractor from one paddock to the next. Capable of effluent and water irrigation, the multipurpose system is utilised heavily at targeted times of the year.
Drawing from the 35-day storage effluent ponds, effluent is applied to paddocks where soil moisture levels are needing a boost.
“We have soil probes in two locations. One on the light freer draining soils and the other on the heavier clays. We can easily adjust the amount that goes on based on what the soil needs, as long as it’s within our consent. It’s all linked up to a computer that controls the rate that it goes,” he says.
This has been a massive win for them in the summertime, where they can often dry out. Though this season they haven’t had to use it much, with soil moisture levels holding at good levels, the grass is growing well without too much additional help. Another big win has been a drop in metabolic problems at calving time.
“Because we can apply such low levels of effluent we are able to calve in any paddock. With old systems, we’d typically shy away from using the effluent paddocks,” he says.
“The spread of the effluent is wide and at first glance it looks like you’re putting
a lot of effluent on, but you’re not.” n
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Stir well, achieve more
Effluent ponds and storage tanks lot less value from your resource. are a significant part of any 2. The accumulation of solids reduces effluent management system, the volume of storage available. In after all, they’re storing all those some cases this can become a council essential nutrients that will later be used compliance issue as most councils for fertilisation of crops and pastures. will have minimum requirements for
However, to truly maximise the value of effluent storage. the stored effluent there are a few things 3. You will eventually need to drain the to keep in mind. pond and get a contractor in, or spend
If effluent is left sitting in a pond or time digging out the solids yourself. tank the solids will inevitably sink to the This can be costly, inefficient, and is bottom and crust and debris will form less effective than simply stirring well. on the top, separating out the essential nutrients. Prolongs the life of your pump and
To maximise the value of your effluent irrigator it is vital the effluent is thoroughly mixed Thoroughly mixed effluent reduces prior to pumping to ensure a consistent strain on your pump, and you’ll be far mix of nutrients is being pumped out less likely to experience blockages, so and spread evenly over pasture. your entire system is more likely to run
For farmers monitoring the level of smoothly. nitrogen and other nutrients in the effluent, it also ensures more accurate Reduced odour results for testing and analysis. Aerating the pond gets the biology
Additionally, with a well-stirred pond of the pond working, which will greatly you will also achieve these benefits: reduce the odour.
No solids accumulation at the bottom of the pond
There are a number of issues with solids accumulating at the bottom of the pond/tank: 1. As the solids sit at the bottom of the pond or tank they lose their nutrient value, meaning by the time you dig them out to spread you are getting a
Aesthetics
Everybody wants to have an enviable looking farm, and a well-stirred pond is a much better look than crust and vegetation.
Tip: It is essential to stir before pumping so the sediment can be mixed with water. It can be difficult to tell just how much is accumulated at the bottom, and it is too late to mix if you’ve already pumped down to the sludge.
Achieving a thorough effluent mix
To create a stirring action that will get the entire pond swirling, you need to create a strong horizontal flow of water with sufficient velocity to carry the suspended solids.
A consistent speed of approximately 0.8 metres per second will stop solid particles from dropping out of suspension, and the only way to do this is by creating a strong horizontal thrust.
This is where a shore-mounted electric stirrer is recommended as they are able to provide the right combination of angle, power and speed to churn up the entire pond.
In the past, floating vertical stirrers were promoted for having low power requirements, however these are not recommended for the following reasons: 1. Having a vertical shaft, the solids are merely pushed away from the propeller and will then slow down and drop out of suspension in the water, so they never end up being effectively mixed.
Moving the stirrer around the pond will only shift the solids from one area to another, so nutrients are not getting mixed in and therefore don’t
Effluent ponds and storage tanks contain essential nutrients that can be used to fertilise crops and pasture.
end up leaving the pond. 2. While some floating effluent stirrers may have low power requirements, a lot of the time these need to be run constantly to achieve any results. 3. In terms of safety, it is always better to keep electricity out of water, and not have the need for anyone to venture out onto an effluent pond should the stirrer require maintenance.
Another option, which has been suggested in the past, is using a pumptype stirrer.
In theory these stirrers should work, however in reality you would need a massive pump, or even several pumps to even come close to what a shoremounted stirrer can achieve. n “If effluent is left sitting in a pond or tank the solids will inevitably sink to the bottom and crust and debris will form on the top, separating out the essential nutrients.”
Bruce’s Slurry Tanker Exceeded Expectations
Bruce Baggott and his son Lyn run a 850 cow dairy farm in Cust, Canterbury. His underground effluent management system was working well, with effluent being pumped from the concrete storage pond through to a travelling irrigator…in fact, you could say it was working too well!
‘Our nutrient levels were too high from all the effluent being spread to just the one area. We wanted to get the nutrients to all available areas and also to the run-off.’ - Bruce Baggott Essentially, Bruce’s effluent nutrients were going to waste because there was too much for the soil to soak up. Bruce did a lot of research into different brands of slurry tanker, but he felt Nevada’s features were a cut above the rest, so he ordered a 10,000L tandem axle. ‘The double safety protections are special to these – it’s a great reason to buy one.’ He also liked that Nevada slurry tankers included the unique RainWaveTM spreading applicator, which promised a wider, more even and controlled spread with minimal wind drift. In fact, since having the slurry tanker, Bruce and Lyn say the tanker has exceeded their expectations. ‘There’s only so many nutrients the soil can take up, and when nutrient levels are too high, the soil becomes locked. This can actually end up causing metabolic problems with the cows.’ - Lloyd Thomas, Nevada Effluent Management Specialist Bruce and Lyn couldn’t be happier with their investment, saying they’re now able to spread under pivots and other areas they couldn’t previously reach with the irrigators. ‘It’s far more versatile. We can spread in areas we couldn’t reach before.’ - Bruce Baggott ADVERTISEMENT
‘That RainWave is a huge advantage over other tankers. It’s exceeded our expectations. We were surprised how fast it loaded. We envisioned it being a chore, but it’s a fast, easy job.’ Lyn Baggott
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Unique set of challenges
By Ross Nolly
A Taranaki couple have peace of mind with their new irrigation system, which combined with their cropping policy gives them a dual strategy for coping with dry summers.
The word “coastal” is an understatement when it comes to describing where Taranaki farmers Larry and Caroline Charteris farm.
Their 85-hectare farm at Tataraimaka, 11 kilometres south of Oakura in North Taranaki, is a proverbial “stone’s throw” from the beach. Their property overlooks a stunning seafront with only a narrow country road separating them from the beach.
Their proximity to the coast also provides a unique set of farming challenges. For Larry and Caroline coping with dry summers is an annual expectation. They continually seek out ways to mitigate their dry stress periods and have implemented strategies that help combat their climatic challenges.
They bought their 54ha farm property in 1983 and in 1994, they sold the upper 28ha to buy an adjacent 64.7ha beach block to create their present 85ha (80ha effective) farm.
We merged the two blocks and retained the two cowsheds with the thought of building a new shed in the middle of the farm. The lower 12-aside herringbone cowshed sits on the roadside directly opposite the beach. The original upper shed is a 16-aside herringbone situated one kilometre up the road,” Caroline says.
“We wanted to milk through one new shed, but it never became economically viable for us to do that. So, right from the beginning we employed a 25% sharemilker on the lower block and it’s worked very well.”
The Charteris’ winter 260 cows and during mid-summer they milk about 245 cows to produce 106,000kgs of milksolids. They run two herds – a Friesian herd on the bottom block and son Daniel Son Daniel who manages the upper block and the Jersey herd with his parents Caroline and Larry Charteris who milk 245 cows on their 85-hectare farm at Tataraimaka, 11 kilometres south of Oakura in North Taranaki.
manages a Jersey herd on the top block with similar numbers in each.
When the time arose to upgrade the farm’s effluent system, they attended many field days searching for a system that suited their farm and soil type. They wanted a simple system that would be sustainable and give them peace of mind by knowing that their farm effluent would never enter their waterways.
They chose the Clean Green Effluent System (CGES) and installed the system at the top cowshed in 2018.
The CGES consists of a weeping wall with two chambers (bunkers) to retain the effluent solids. A centre chamber is utilised as a liquid pump chamber.
The liquid from the pump chamber is pumped to a greenwash storage tank and the effluent in the weeping wall is contained in a concrete lined bunker. The solids are retained in the bunker and removed with a digger annually.
The system also has two 30,000-litre storage tanks. One is dedicated to containing greenwash for external yarding, and is usually full. The secondary tank contains green water awaiting distribution to land.
The recycled liquid is used to wash the external yard via the automated backing gate system. The wash water and effluent then returns to the weeping wall for refiltration. This has significantly reduced water use and also saves time.
Effluent is pumped from the storage tanks and distributed each night through a low-rate, low-depth application system using K-Line pods. The system allows controlled application to land at low-rate, low-depth application rates of 0.25mm (in 24-hours), thereby eliminating nitrate leaching, ponding or runoff.
“The K-Line flexible hoseline and sprinkler pod system spray is more of
a mist than a heavy spray. We use four pods to irrigate our flat paddocks to prevent any runoff or leaching,” Larry says.
“It’s a much-diluted product that’s spread over a greater area and it practically removes any user error. You can barely tell whether any effluent has been applied. “The economies of scale for a farm of our size are perfect.”
The farm has a 30ha irrigation platform and both cowsheds are connected to the system, but the lower shed still retains its singular system and tank for irrigation. If there is significant rainfall, the lower shed’s system is diverted into the CGES by simply turning a tap.
“Before we installed this system we always worried about blockages. But The Clean Green Effluent System installed in 2018 is simple and sustainable. now we don’t have any, because the solids have been removed and left at the bunker,” Caroline says. to be pumped and drastically reduces and use the electricity night rate. There
“The system needs minimal the associated maintenance issues and are no bad odours when the effluent maintenance. Our sandy soil is a running costs. is spread on the paddocks, which nightmare for pumps and sand traps. “It’s a simple system because the pods eliminates any concerns about the With this system, the bunker is the only need to be moved weekly, unless it’s system affecting neighbouring lifestyle sandpit. Our pumps will last longer been raining, then we move them more block owners. because the sand and solids are often,” Caroline says. The system provides extra moisture deposited in the bunkers,” Larry adds. “During a dry summer we also move and nutrients, which in turn helps them
Each bunker is cleared out in March the pods more frequently to spread the drought-proof their property by growing on alternate years, after the turnips and irrigation. We bought an extra set of pods more grass. That vegetative cover chicory have been grazed off. The solids to have a set at either end of the farm. protects and grows the humus layer, are applied to the cropping paddocks. Then it’s just a case of turning on the which prevents the soil from drying out The dry, almost composted effluent is hydrant to wherever it’s needed.” and is the key to getting paddocks to last applied before the grass is sown and in They believe that solid separation is the longer. Larry’s words, “it’s just like rocket fuel for best way to lower the concentration of “Cover is king,” Larry says. new grass.” effluent. It also gives them more control “Surviving on short rounds may be
During summer the cooling water is as to where and when it’s applied. The the modern way, but we find that if we run to the weeping wall to add water full bunker spends the summer drying have cover during summer along with to the pods. In winter and spring this out, so the contractor has less material the other inputs, we can get through any water is diverted for stock water. This that is easier to shift and spread. stress period. If you don’t have the cover, reduces the amount of water that needs The system pumps operate at night you’re really up against it.” The System 3 farm grows a limited amount of crops as a summer-proofing measure. This season they have put in 2ha of turnips, 1ha of green-feed maize for the Friesians, and 3.5ha of chicory for the Jerseys. They will also plant 2ha of oats during winter to help them kick into spring. The oats and turnips are for the Friesians. This year they are using green-feed maize to get bulk into their cows during the summer stress period. Dry summers are something they have had to contend with for most of their farming career. They have previously never been big utilisers of cropping due to their farm’s sandy soil type. Their new cropping strategy combining the newly-installed effluent system is a dual The effluent system consists of a weeping wall with two chambers (bunkers) to approach at managing summer dry retain the effluent solids. A centre chamber is utilised as a liquid pump chamber. periods. n
Researcher Grant Rennie shows his cutting and nutritional trial of bananas as a fodder crop.
Bananas idea pays off
By Hugh Stringleman
A Northland trial of growing bananas as a forage crop is showing better than expected results.
Northland dairy farmers A SMASH field day was held on the Graeme and Carol Edwards farm to highlight the banana trial, are investigating bananas as possible use of sexed semen in a a forage crop with cutting breeding plan, and provide an overview trials and nutrition measurements by of the new effluent system.
AgResearch. Edwards said different sources of
Stems in the small banana plot near more reliable supplementary feeding the farm dairy are drip irrigated by will be needed now it appears annual effluent water high in potassium after rainfall has reduced from 1800mm to an upgrade of the effluent system 1200mm. incorporated a weeping wall to separate The banana plot was first planted in solids. November 2018 with 65 stems of the
The Edwards’ 125ha effective farm popular Misi Luki variety, being hardy at Opouteke, near Pakotai in mid- and disease resistant.
Northland, runs 250 high BW cows on A survey taken 22 months later showed once-a-day milking on their System 2 near eight stems per plant and an property. estimate of 10kg/plant dry matter.
A preliminary estimate showed that Annual production was then potentially about 4% of the land planted calculated at 16 tonnes/ha DM at planting to bananas could use all the green water, density of 1600 stems/ha and at 20t/ha optimise storage and avoid unconsented for 2000 plants. discharges, and provide a large This was when Grant Rennie from supplementary fodder source. AgResearch Ruakura got involved with a grant from Our Land and Water Science Challenge.
He listed the possible benefits of using bananas as a forage crop: -High summer growth rates for increased resilience of forage supply during dry periods. -High nutrient demand could potentially change whole-farm nutrient cycling. -Potential for cut and carry or strip grazing for animals. -Deep-rooting and drought tolerant, with water stored vertically in stems.
In September last year, Rennie began trial cutting and analysing of the banana vegetative matter.
He cut all main stems but left at least four stems per plant over 500mm high, including no more than four over one metre and no more than two over two metres.
Cutting was to harvest the fodder
soluble sugars and starch and do they have other properties? What proportion of NDF is effective, by promoting rumination with long, stringy fibre? Edwards says cows were happy eating the leaves, but struggled with the stems. Local farmer Murray Douglas, who has a family dairy farm in Brazil where many types of tropical fodders are used, says chopping the stems into chunks may help the cows. The first plan for the bananas included harvesting the fruit for commercial sale, but that required skills and manual labour Edwards did not have. The change of tack to cattle fodder would mean less cultivation than traditional crops like turnips, lower soil carbon loss, reduced environment risks Northland dairy farmer Graeme Edwards has a small banana plot nourished by from effluent irrigation and more reliable effluent water. cropping in the summer. “We can set this up in a way that if an organised banana industry develops and promote tillering growth, but also low crude protein mean for nitrogen in the region, we could switch to fruit mindful of the amount of plant matter uptake from effluent? What are the production,” Edwards says. n that can be harvested before regrowth was suppressed.
Because of their thickness and length, the stem was found to have two-thirds of the dry matter in a plant on average and therefore in any given plantation area.
Figures showed 18% dry matter in the leaves and 10% in the stems, but metabolisable energy has not yet been measured.
The first assay using NIR spectroscopy found that crude protein was low in the leaf and very low in the stem, that NDF fibre was low in both leaf and stem and that soluble sugars were moderate in the leaf and high in stems.
“This is not what we had expected and will require validation with wet chemistry, but this may mean the forage is better than originally anticipated,” Rennie says. Green water from the effluent system is pumped to a trickle system for the
The questions raised were: What does bananas.
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