Purdue University professor of agronomy Bob Nielson says the effects of climate change on crops are amplified if the ground had poor soil structure.

Maize growers will need to take better care of their soil if they are to continue to grow crops that are climate change resilient.

It the soil is well cared for, it will drain faster in floods and allow plants to spread their roots further to find moisture if it is dry.

Achieving this was a huge challenge, visiting agronomy professor Bob Nielson told farmers at the Foundation for Arable Research's (FAR) annual field day at their research site at Tamahere.

Supplied Waikato and Bay of Plenty maize growers suffered from severe flooding this year.

Over time, a better soil structure improved crop yields and reduced yield variability from year-to-year, he said.

READ MORE:

* Dairy farmers should expect to pay higher maize feed prices this season

* Waikato maize season on track despite cooler early summer

* Flood swallows up Bay of Plenty farms and crops

"In the bad times, the crop is more resilient and the yield does not decrease as much."

The effects of extreme weather would be amplified on the soil if there were factors such as compaction already affecting crop growth.

"If we can mitigate those and reduce those, that's going to allow the crop to grow a little more vigorously and therefore be more resilient to the extremes of the weather that you and I can't predict or control."

Nielson is a professor of agronomy at Purdue University in Indiana, the United States and had spent a week in New Zealand talking to farmers at FAR events.

Whether farmers believed in climate change or not had become a moot point because they were having to deal with its consequences, he said.

"These extremes are becoming more normal. When we maybe think back at normal weather - there's no such thing."

The challenge for growers and agronomists was to work out how to keep growing maize crops in this new environment, he said.

"How do we face this? How do we grow crops that are resilient to these extremes in weather that you and I can't predict?"

In Waikato, farmers were hit by severe flooding in April and record rainfall in August and September. Now many were worried about a potential drought.

He said Indiana maize growers had just had a similar season to Waikato growers. Soon after their crops were planted, farmers experienced successive bouts of rain and cold weather, resulting in growers having to replant two to three times.

"We had more acres of corn replanted this year than we have ever had before."

The biggest limiting factor for those growers was poorly drained soils and too much rain, he said.

He recounted his experience visiting Ukraine earlier this year, a country which had a reputation for having some of the richest, deepest soils in the world.

While those farms existed in drought prone areas, he assumed the quality of the soil was superior enough for crops to cope. Instead, he saw maize under severe heat stress due to massive soil compaction caused by aggressive tillage practices.

"Here's the richest area on Earth in terms of agricultural productivity, and its brutal and not to badmouth Kiwis, but we have seen our share of soil compaction in the fields we have been in. We're all guilty."

He also advocated switching to reduced or no tillage. It slowly improved soil quality and drainage capabilities over the long term.

Other options for farmers included using maize hybrids that were bred to be more resilient to environmental stress. FAR was working through trials around the country to test different hybrid varieties in different conditions.

The challenge for farmers was to identify and reduce factors that lead to crops stress from climate change.

New technology in GPS yield maps and drones with cameras could help solve this challenge. Farmers could use the tools to help identify early if their crop had problems and calculate the potential yield loss, he said.

"Crop diagnostics is best done fresh, when the evidence is there, when the symptoms are there and it's a lot more easier to identify the cause."