Crops were grown successfully across 34 sites that suffered serious silt incursion during Cyclone Gabrielle, a study shows.
Hawke’s Bay researcher Alan Kale, who worked with colleague Diana Mathers, said the study was aimed at growers to support their recovery and that of the land impacted by silt.
“We found that land covered by sludgy clay-based silt could grow good vegetable and arable crops in the next season, with minimal additional effort.
“However, the story was considerably different for land covered by sandy silt. Crops grown on this land did not thrive,” Kale said.
The study looked at the recovery of silt-covered land at 34 different sites in Hawke’s Bay and Wairoa.
The study was managed by the Foundation for Arable Research with funding from the Ministry for Primary Industries, North Island Weather Event Fund and Vegetable Research and Innovation.
Kale said initial conclusions from the study showed cropping on silted sites in the Heretaunga Plains was very successful.
No extra pest and disease inputs were required.
Some fields had an extra side dress applied, otherwise fertiliser practice was as normal.
Most sites grew and produced crops at or above normal pre-cyclone levels, and current season non-silt crops.
Generally, growers were comfortable to return to normal cropping cycles on these sites.
The exception was the sandy silt type sites, where at one site the sandy silt layer severely impacted maize plants growth and yield by preventing roots reaching the soil below.
Kale said some extra remedial cultivation was required to deal with silt.
“Once you can, stir the silt up to help with the drying process.
“The silt holds onto moisture. Be prepared to wait longer between cultivation passes.
“Post harvest, growers still report needing a longer gap between cultivation passes.
“Extra ripping was often reported as the flooding created a tighter profile.”
The study covered sites where arable, seed, market gardener, processing and cucurbit crops were grown.
“The whole idea of the study was to create a body of knowledge that could be used immediately, as well as in future similar flooding events. We believe we have achieved this outcome.”
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