5

Leaching nutrients are not just an environ-mental issue, they are also a waste of money. So why not use them to grow crops?

A big area of concern is nitrogen from the urine of cows grazing winter forage over rela-tively small areas but at high stocking rates. The key word here is ‘winter’. There are parts of the country where establishing crops in winter has traditionally been considered too difficult.

However, trials are showing that even in Southland, a catch crop can be planted to mop up excess nitrogen after winter grazing and to provide extra feed.

Cereals such as oats have proven to be the best catch crop. They are large seeds and can handle the rugged winter conditions better than grass. They also deliver a worthwhile amount of good quality feed.

Dr Peter Carey is a field scientist at Lincoln University’s research arm Lincoln Agritech. As part of his PhD project he investigated catch crops and now he has funding through

the Sustainable Farming Fund (SFF) for a research programme called Catch Crops for Reduced Nitrate Leaching.

This trial has up-scaled from trial plots to paddocks on real dairy farms. Its focus is on nitrate leaching after dairy grazing, mainly in South Island areas that typically have high winter rainfall.

The farm trial started in July 2018 and will continue until 2021.

Winter feed is usually kale or fodder beet, grazed from June to the end of July. During that time a lot of cows deposit a lot of urine.

“An equivalent of 300 kg of nitrogen per hectare is being applied in the middle of winter to bare soil in the urine of cows. The

FIELD TRIALS REINFORCE VALUE OF CATCH CROPS AFTER WINTER GRAZINGCATCH CROPS ARE A CLEVER WAY

TO CONVERT A PROBLEM INTO A

RESOURCE.

05

PLOTS LAID OUT FOR FIELD TRIALS OF WINTER-SOWN CATCH CROPS.

Call 0800 274 5245biostart.co.nz

THERE’S CASH IN CROP TRASH

Digester speeds up the decomposition of

crop trash recycling valuable nutrients

and organic matter back into the soil

faster and more efficiently, resulting in a

more fertile seed bed.

BIOS 013 Digester advert - Rural Contractor.indd 1 18/2/19 8:35 pm

A SPECIAL EDITION OF THE RURAL CONTRACTOR & LARGE SCALE FARMER

ISSUE 186 2019

THE PROFESSIONALS GUIDE TO CULTIVATION AND CROP ESTABLISHMENT

ISSUE 185 FEBRUARY/MARCH 2019

FEATUREWhat’s new in Tillage and Seeding Equipment

PROFILELong contracting career

now winding down

EQUIPMENTDemo convinces family JCB is the one

as seen in...RURAL CONTRACTOR & LARGE SCALE FARMER GroundBreaker 2019 Issue 186

NEW READERS

NZ Rural Contractor is available free of charge to readers who qualify under the publisher’s criteria and who supply proof of occupation (printed letterhead, business card, invoice etc) and to others via subscription and payment of the $68.00 inc GST annual NZ Subscription. Australian Subscription $108.50, Rest of World $172.50.

If you are not a registered reader, but would like to receive a regular bi-monthly copy, fill in the details of your contracting or farming business below.

FEATURE

Bale Wrappers, Bale Handling

Equipment and Telehandlers

ISSUE 175 OCTOBER/NOVEMBER 2017

NEWS

John Deere uncorks

5R Series tractors

TECHNOLOGY

Claas combines and tractors

on the medal podium

A SPECIAL EDITION OF THE RURAL

CONTRACTOR & LARGE SCALE FARMER

ISSUE 186 2019

THE PROFESSIONALS GUIDE TO CULTIVATION AND CROP ESTABLISHMENT

ISSUE 185 FEBRUARY/MARCH 2019

FEATUREWhat’s new in Tillage and Seeding Equipment

PROFILELong contracting career

now winding down

EQUIPMENTDemo convinces family JCB is the one

ISSUE 174 2017

A SPECIAL EDITION OF THE RURAL

CONTRACTOR & LARGE SCALE FARMER

GOLD

GREEN TOT H E P R O F E S S I O N A L S G U I D E T O H A Y A N D S I L A G E M A K I N G

ISSUE 185 FEBRUARY/MARCH 2019

FEATUREWhat’s new in Tillage and Seeding Equipment

PROFILELong contracting career now winding down

EQUIPMENTDemo convinces family JCB is the one

CONTRACTOR Main contracting services offered: Equipment operated Make, Year, Model

SUBSCRIBERTo subscribe to NZ Rural Contractor & Large Scale farmer, please enclose a cheque for: $68.00 (NZ), $108.50 (Australia), $172.50 (Rest of World) – made payable to Agri Media Ltd.

Name:

Company:

Address:

Email:

Rapid No.

Phone: Post Code:

Please sign here if you wish to receive a regular copy of this publication and send the form together with proof of occupation or cheque to AgriMedia Ltd, P.O. Box 37-151, Christchurch, Freepost No. 114059.

Sign: Date:

Total farm Ha.:

No. of sheep:

No. of dairy cows:

No. of beef cattle:

Area in arable crop:

LARGE SCALE FARMERSubscription criteria for owners/sharefarmers:

Dairy milk over 600 cows Sheep & Beef 12,000+ stock units Cropping over 250 ha in arable

potential for leaching nitrogen as nitrate is high.”

Winter grazed land is usu-ally left fallow until spring, which allows excess nitrogen to leach out and end up in ground or sur-

face waters. A catch crop can suck up some of that vulnerable nitrogen.

In Canterbury, either direct drill-ing or cultivating land for oats in July or early August has been the most successful catch crop. It is harvested as green crop in November and then the paddock can either go back into pasture or into another winter forage crop.

This last winter was mild in

the South Island and oats were drilled in July. When they were harvested in November, they yielded 10 tonnes of DM per hec-tare.

“It’s a win/win,” Peter says. “Not only is it reducing environ-mental issues, it is also produc-ing dry matter. A catch crop also puts residues on the surface which reduces further damage from uncovered soil.”

The trials in Southland includ-ed the use of a Farmax spader in combination with a seed drill (See story Page 8). This type of machine can get onto wet pad-docks straight after harvest or grazing to mix up the top lay-ers of soil, consolidate, and drill seeds, all in one pass.

The crop sown with the spader yielded twice as much as the conventionally cultivated trial as it could be drilled six weeks earli-er. It was the first year a machine of this type had been used for establishing catch crops, and Peter will use it again on other sites, to show its usefulness.

Further results will be out soon but overall Peter is encouraging farmers to consider catch crops.

“I think we will see it become a regular part of winter rotations after winter forage,” he says.

Plant and Food Research soil and crop scientist Dr Brendon Malcolm is also involved in the SFF trials. He was part of the Pas-toral 21 programme that funded Peter’s previous work, which measured leaching using lysim-eters.

A lysimeter is an undisturbed column of soil contained within a drum, 500 mm in diameter and 700 mm deep. It is used to meas-ure leaching at the bottom and the release of gases at the top under different applications of fertiliser and urine.

Brendon says Peter’s work shows that leaching under urine patches could be reduced by up to almost 50 percent with a catch crop. Ultimately, how effi-cient the catch is depends on the season (mainly the timing and amount of rainfall), the soil type, and the performance of the crops under actual field conditions.

The lysimeter is useful to get an idea of what is happening at a conceptual level; the next step is field trials to see what the prac-tical issues are for farmers to implement the ideas.

Catch crop field trials began in 2015 and have continued every year since. The plots are mainly in Canterbury, but also in Wai-kato, and have more recently

TECHNOLOGY

06

DRILLING A COVER CROP AFTER CULTIVATION DURING CATCH CROP FIELD TRIALS IN CANTERBURY

1. Do not delay. Get the catch crop in as soon as possible after grazing.2. Try not to over-cultivate. Direct drilling is ideal because the more you cultivate the greater the risk

of releasing more nitrogen via mineralisation.3. Use a winter-active cereal and sow at relatively high rates. Aim for 300 plants/m2. This will help

reach canopy closure as early as possible, which maximises the ability of the crop to mop up N and reduce drainage.

dr brendon malcolm has three main recommendations for farmers considering catch crops:

ON-FARM TRIALS SHOW THE ABILITY OF CATCH CROPS TO REMOVE HIGH LEVELS OF NITROGEN LEFT OVER FROM ANIMALS GRAZING WINTER CROPS.

TECHNOLOGY

707

been set up in Southland.Brendon’s and Peter’s teams

are working together on the rep-licated SFF on-farm trials.

“Part of our ongoing work is to develop computer models that can be used to get an idea of the average impacts of catch crops on leaching,” Brendon says.

They test the model against dif-ferent scenarios and add in more factors. For example, what hap-pens if you delay the planting of the catch crop? What are the dif-ferences between regions, soil types, rainfall and drainage?

With field trials and more lysim-eter trials the model becomes more sensitive and more useful to more farmers.

The trials also address how catch crops might fit into crop rotations.

“To get the full production ben-efit of the catch crop, leave it in until November even though that means potential delays getting in the next crop,” Brendon says.

Another option Brendon and Peter are looking at is to add grass seed with the cover crop oats so it is already established when the oats are harvested as green feed. Some farmers are already experimenting with this.

Brendon says he would not normally advocate the use of a spader on wet soils because it intensively works the soil (although not as much as a rotary hoe). But farming is about balancing the trade-offs and it is not always possible to direct drill

after heavy pugging.When the ground is wet, con-

ventional cultivation may smear the soil, or not be possible at all. Cultivation also requires more passes, compared to the one pass with the spader-drill combi-nation.

“It is exciting to see what hap-pens with the spader. Part of our work is looking at the physical condition of the soil before and after the spader and comparing it to more conventional practices.”

The big difference the South-land trial has shown so far is in the increase in crop with the spader because it was planted so much earlier.

“Conventionally drilled crops were already running out of nitro-gen and running out of biomass because the nitrogen was lost before the crop could pick it up.”

For Brendon, this is not just about environmental issues; it is also about productivity and tight-ening up the nitrogen cycle. He has worked out that the cost of growing oat catch crops is 3 to 10 cents per kg of DM, by using the nutrients that might otherwise have been lost in leaching.

THIS TRIAL AT GORE SHOWED THAT COVER

CROPS CAN HELP SOUTHLAND FARMERS

RECOVER FROM WINTER GRAZING AND ADD DRY

MATTER INTO THEIR SYSTEM.

Trimble GPS:

GPS Control Systems Ltd www.gpscsl.co.nz 0800 874 625 www.trimble.com/agriculture

Trimble Autopilot self-steering systems provide centimetre repeatability from planting to harvest with any field pattern, and extends your operating hours with incredible precision. Seed, fertiliser, and crop protection all go in precisely the right spot. You’ll save time, fuel, and inputs, while reducing operator stress and fatigue.

NZ-RTK is making centimetre accuracy easier and more reliable with the largest agriculture RTK network in New Zealand - available to most manufacturers of GPS systems. For more information see www.rtk.co.nz.

Call us for sales, and real technical support.

Everyone is telling you to be more productive - we will show you how...

John Ahearn

0800 874 625john@gpscsl.co.nz

Wade Riley

021 874 602wade@gpscsl.co.nz

Russell Van de Laak

021 874 622 russell@gpscsl.co.nz