Technology

FARMERS WEEKLY – farmersweekly.co.nz – September 5, 2022

Technology FAR lays out better ways of growing maize

Annette Scott TECHNOLOGY

Maize

MAIZE growers facing increasing production costs need to refi ne their production systems. So says Foundation for Arable Research (FAR) senior researcher maize David Densley, who cited more extreme weather events and warmer temperatures as reasons for maize growers to continually adapt their production systems to be more resilient or face falling yields.

Densley led a series of FAR maize workshops throughout the North Island and Canterbury at which discussion focused on maize agronomy practices that could help growers improve profi tability.

The yield potential from modern maize genetics is signifi cantly higher than what maize growers are currently achieving, with no yield improvement for maize grain or silage production over the past 10 years.

Anecdotally, grain yields of 1618 tonnes a hectare and silage yields of 26-28t/dry matter/ha are being achieved.

Densley said even though paddock variability exists, typically maize growers’ management practice continues to base all inputs and management on averages, with blanket applications for a paddock.

He did acknowledge that a small number of future-focused growers are dividing their paddocks into management zones using precision agriculture technology such as electro magnetic (EM) soil survey mapping, extensive soil fertility testing, remote sensing vegetation mapping using satellites and drones and previous yield map information.

Weather data to determine evapotranspiration (ET) rates during the 2021-22 maize production season showed the total ET was 469mm, compared with the 20-year average of 417mm. This meant crops needed 52mm more moisture to achieve the same yield.

During the critical grain fi ll period the estimated maize yield loss when drought stress persists for four or more consecutive days is about 3%-9% yield loss per day of stress.

Weather data also showed that soil temperatures in October are not much higher than the longterm average.

“So, if growers’ strategy is to plant earlier to beat soil moisture stress during fl owering, the October soil temperatures aren’t helping much,” Densley said.

An increasing number of maize growers are using no till or strip till to prepare and plant maize crops, rather than turning the soil over using conventional cultivation.

They also utilise cover crops and catch crops over winter, which

LEND AN EAR: FAR senior researcher maize David Densley says maize growers need to continually re ne and adapt their maize production system or face the prospect of falling yields.

include nitrogen-fi xing legumes to reduce nitrogen inputs.

These farmers are applying variable-rate lime and using variable-rate seeding rates for plant population, as well as deep N sampling to better match inputs with productivity.

Densley recommended all farmers adopt pre-side-dress deep N sampling, which does not require precision agriculture technology.

Some growers have tried no till using old systems and thinking and it hasn’t worked so they have abandoned it.

David Densley FAR

The cost of carrying out the sampling, which measures plant available soil nitrogen levels to a depth of 60cm, is more than covered by savings in applied nitrogen and also provides environmental gains with reductions in nitrogen loss and greenhouse gas emissions.

He suggested that farmers trial deep N sampling to gain some trust and apply side dress nitrogen based on the results.

“Some growers have tried no till using old systems and thinking and it hasn’t worked so they have abandoned it.

“The planter becomes very important when adopting no till in particular, as the objective is to place the seed into the soil at a uniform depth to achieve emergence uniformity and that requires a different skillset and equipment.”

How to E-Check your emissions

Annette Scott TECHNOLOGY

Emissions

ARABLE farmers unsure about how to calculate their greenhouse gas emissions number can learn more through a series of workshops being run by the Foundation for Arable Research (FAR) during September.

Numbers will be generated using E-Check, a simple and straightforward online calculator, purpose-built by FAR researcher Dirk Wallace for arable farmers.

All farmers are expected to know their GHG emissions number by the end of this year, with more than 60% of arable farmers in FAR’s 2021 survey yet to do the calculations.

As well as developing E-Check, FAR environment team members Turi McFarlane, Dirk Wallace and Diana Mathers have been gathering data on arable farms’ GHG emissions.

A pilot study involving 26 mixed arable farms in Canterbury, Manawatu, Southland and Otago using the Overseer emissions calculator showed total farm emissions ranged from 2024 to 6139kg CO2e/ha (carbon dioxide equivalent per hectare). This was made up of 41% methane, 26% carbon dioxide, and 33% nitrous oxide.

Livestock is often a major driver of GHG emissions, with 93% of arable farms indicating that they run a mixed cropping and livestock operation.

McFarlane said a number of agricultural-based GHG emissions calculators have been approved by He Waka Eke Noa (HWEN) to help growers meet this year’s target, but it’s important to appreciate there are some key differences between calculators.

E-Check has been designed entirely with the arable industry in mind and is aligned to biological emissions considered by HWEN.

“E-Check is simple and for most farmers it will take less than 20 minutes to calculate, depending on the level of detail farmers want to include.”

E-Check is a spreadsheet-based GHG calculator that farmers can use to input easy to access information on farm size, fertiliser applied and livestock moving on and off farm, to calculate a farm’s GHG number.

For livestock, E-Check calculates livestock emissions on a daily time step, so the number of days farmers hold stock for is important.

MAKE IT COUNT: FAR environment team member Turi McFarlane says there are key di erences between GHG calculators. MORE:

For more information on E-Check and the Greenhouse Gas Farm Planning go to: www.far.org.nz/environment To register for a workshop near you, email admin@far.org.nz.

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