Friday, March 29, 2024

Keeping water use to a minimum

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When the Welch family looked at a new effluent system as part of constructing a new dairy and feedpad they wanted one which minimised water use. 
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“Every drop of water going into the effluent pond is a drop you have to get
rid of,” Brent Welch says. Brent is in charge of their 400 hectare farm milking 750 cows.

His father, Harry, was a large maize grower in the Tuakau area, south of Pukekohe, for 20 years as well as running a poultry operation and a sheep and beef farm. The 400ha block at Mangatawhiri was used for maize growing but with a downturn in profitability it was decided to switch to dairying.

“There’s not a lot of money in maize,” Brent says.

So they decided to make a change.

While drainage and some sub-division had been done, generally the land was a blank canvas on which fencing contractors could start work and races could be laid. Two herds were bought in to start with, one from Otorohanga and one from Paeroa.

“We’ve added to them as we’ve gone along,” he says.

“They say any cow can do 400kg milksolids (MS) so we call them any cows.”

They’re predominantly Jersey and Brent is using Jersey semen from CRV Ambreed.

Calving date is July 19 with empty cows carried over into a small winter-milking herd.

There was a block of 70ha on the farm which was milking 170 cows through a 16-aside herringbone. 

“We milked 320 cows through it in our first season,” Brent says.

“We double cupped it and put 750 cows through last season. People said we were mad.”

The old dairy was decommissioned last year with the new 60-bail rotary with Milfos plant up and running in October. It’s fully automated with milk meters measuring fat, protein, volume and conductivity, automatic cup removers and scales at the drafting gates. The cows soon got used to the new dairy with their noticeably laid-back nature meaning some of them are now reluctant to get off the platform.

“If they’re not content you’re not going to get production,” Brent says.

The four farm staff work a six-days-on, two-days-off roster with just one living onfarm.

“And someone in the family will jump in when needed,” Brent says.

It’s a family operation, with brother Malvin in charge of the 200,000 laying hens next door, sister Julie, an accountant, in charge of the books and another sister Andrea helping her out as well as raising the young chickens.

The in-dairy feeding system feeds the herd from 1kg/cow of supplements up to 3kg/cow immediately after calving. After milking they go out on to the large uncovered feedpad which with the dairy yard totals 4900m2 in size. It was built at the same time as the dairy with a Universal feedwagon used to top up feed bins with a mix of palm kernel and some of the 1000 tonnes of grass silage the herd is fed each year. 

About 500t is made on the farm and the rest on two other dairy farms the Welch family has owned for the past three years, just down the main Auckland to Coromandel highway. Both run 320 cows with about 200,000kg MS being produced through two herringbone dairies, one 18-aside and the other 20-aside.

The submersible pump sends effluent up to the larger pump in the shed.

“There are no solids in the pond so there’s no need to attempt to stir it.”

He believes this is saving up to $20,000 a year in electricity costs.

“And as there are no solids in the pond irrigation equipment will not block and fail.”

Liquid runs out the bottom of the sludge bed and into the 82.5m by 55m storage pond. It tapers down from the sides to be 5m deep in the centre and has a marine-grade rope and netting system 6-7m out from the edge when the pond is full in case a person or animal falls in. An extra security precaution will be deer fencing on all sides.  

The pumping system uses a 3kW pump on a crane submerged in the pond and an 18.5kW pump on the shore in a pump shed. 

“The pump is controlled by a variable speed drive which means it will only use the electricity required for the particular duty at one time,” Verheij says.

It can irrigate 60,000 litres per hour.

Brent hasn’t connected up his two travelling irrigators with permanent lines yet, deferring the estimated $100,000 cost. With a lot of pipework already on the farm and the effluent system costs up to $400,000 already he’s using temporary lines to feed the irrigators. A K-line system hasn’t yet been installed.

“It was costly and we had spent so much money here,” he says.

“Then there’s the drop in payout that hasn’t helped.” 

About 150ha can be reached by the travelling irrigators but the Welch family would like to extend this as much as they can. Where effluent can’t be applied they make full use of poultry manure which means they don’t buy in any fertiliser to spread apart from on their summer crops which receive a 12-10-10 mix of nitrogen, phosphate and potassium.

About one tonne/ha/year will go on straight from the poultry sheds in two applications. 

“It fosters microbial activity and builds worm numbers,” Brent says.

“And like a small amount of nitrogen it boosts grass growth.”

Cows need to be stood off for 28 days, the same requirement as when effluent is applied. And because of some heavy soils on the farm the Welchs have a little-but-often application policy on some areas. So far the new effluent system has been relatively maintenance free. 

A rubber liner was chosen for the pond because it has fewer seams than polythene. And because the southern end of the pond needed to be built above ground the risk of any settling was clearly kept in mind.

Key Points

Location: Mangatawhiri, southeast of Auckland

Owners: Welch Egg Company

Area: 400ha

Herd: 750 Jerseys

Dairy: 60-bail rotary with Milfos plant, milk meters, automatic cup removers, weighing and drafting

Production: 300,000kg milksolids

Supplements: 1-3kg/cow of pellets fed in the dairy, palm kernel and 1000 tonnes of grass silage fed on uncovered feedpad.

Green water checklist

  • Incorporating recycled green water for yard washdown at the farm dairy generates significant benefits for farmers in reduced water use and less effluent storage required. Here is a checklist for farmers’ green water requirements. 
  • Yards must be washed after every milking
  • Yards must be free of residual sediment after every wash and kept clean 
  • The yard must be concrete with no surface cover and rinsed with clear water if necessary to remove any residual sediment
  • The system must be completely separate from the freshwater washdown system
  • The water recovery system must be of a design that will consistently deliver water that does not contain excessive sediment or offensive odours and is acceptable to the farm dairy assessor
  • Recycled wastewater must not carry any offensive odour either during or after application
  • Recycled wastewater is only to be used on the yard or pad area. It must not have any contact with the milking area or with the milk receiving-storage areas 
  • The recycled system can only be used if the raw milk is not intended for the manufacture of unpasteurised dairy products
  • The recycled water must be a low-pressure fixed design, such as a gravity operated flood wash
  • The green water system must not include hand-held hoses
  • If pumped, delivery method must be no greater than 300mm above the yard surface
  • The recycled wastewater system must be supported by an effluent system that is compliant with the local regional council rules 
  • The farm must have an operative nutrient management plan. 
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