Dr Bob Nielsen, an agronomist at Purdue University, Indiana, said he appreciated 2017 had proven to be very much the case for NZ farmers, and maize farmers in particular had worn the brunt of extreme patterns in the past year.
A frequent visitor to this country, Nielsen addressed maize growers at a recent Foundation for Arable Research maize day on the group’s northern research farm, near Hamilton.
Areas like Bay of Plenty had experienced more than 50% above their annual rainfall pattern for the first 10 months of 2017, only to have moisture levels plunge to record lows as an early summer dry struck.
Growers in eastern Bay of Plenty had struggled with crops almost impossible to harvest under flood conditions, only to see this season’s crops stagger through a very dry period after germination.
In the United States growers had also faced equally challenging conditions, with many growers having to replant at least once this season, and in some cases three times after cold, rainy conditions.
“These extremes are becoming normal, and we can think back nostalgically to what normal was, but the big challenge for us as growers is ‘how do we face these, and grow crops that are more resilient?’” Nielsen said.
Accepting that such events were the new normal, Nielsen and his fellow researchers had been working to better identify what crops’ “yield limiting factors” (YLFs) were that amplify the uncontrollable effects of climatic events.
“For us in Indiana, one of our biggest YLFs is poor drainage and too much rain. It has been about installing drainage to remove water from fields as fast as we can.”
A key focus for Nielsen and researchers has been to improve the care and health of the soil, in turn increasing the robustness of the crops within it under extreme conditions. Better drainage has, over time, delivered increased earthworm populations and better structure, minimising the period that intense rainfall events will impinge on crop growth.
Nielsen suggested the adoption of low-tillage systems also offered a pathway to soil restoration, reducing pan formation lower down in the profile and the loss of topsoil.
“You will see, over time, some yield increase but just as importantly you will see less year-to-year variability.”
He admitted being shocked during a recent visit to Russia’s deep black-soil region near Ukarine. Despite a soil depth of 10-20 metres, and being among the richest topsoils on Earth, farms in this region were experiencing severe drought issues thanks in part to aggressive tillage techniques resulting in extreme compaction of the topsoil layer.
“They were just brutal with it. You would have expected with such deep soil you could get through a drought.”
Nielsen welcomed the arrival of unmanned aerial vehicles (drones) and GPS-enabled yield mapping as two tools to help identify a crop area’s weaknesses.
“With these kinds of spatial data sets we can better identify faults and develop a better crop from the get-go.”
He acknowledged drone mapping was still in its infancy in the US.
