Soil mapping project praised

Southern Cross Produce field manager Jesse Malcolm inspects an organic carrot crop near Woodlands...
Southern Cross Produce field manager Jesse Malcolm inspects an organic carrot crop near Woodlands. PHOTO: SUPPLIED
A Southland vegetable grower is singing the praises of a project mapping soil types to help them make better management decisions.

Southern Cross Produce in Woodlands grows about 20ha of carrots and about 80ha of parsnips, more than half of all the parsnips sold nationwide.

Southern Cross Produce managing director Matthew Malcolm said the temperate Southland climate and good soils result in higher crop yields with low disease pressures compared to many other regions.

When the company was offered the opportunity to take part in a case study as part of the Hedgehope Makarewa Catchment Group’s Understanding Our Land to Drive Change project, it happily got on board.

The project, funded by Thriving Southland, uses state-of-the-art technology to map the landscape and its interaction with water quality and greenhouse gas emissions.

Land and Water Science in Invercargill had worked alongside the catchment group to create content, which used airborne radiometric data to improve and refine existing soil maps, and data from a drone survey to create high-resolution hydrological layers for people to access.

The project work also involved “ground-truthing” to validate the accuracy of the radiometric data.

Mr Malcolm said the mapping would be particularly useful for the growing organics market, where traceability was even more important.

As one of the case study properties, it was really beneficial to add the new information to their tool box. The data confirmed a lot of what they had learned from running the operation over the years.

Areas of the property with heavier soils could be grazed or planted as appropriate and it was useful to know exactly where one soil type turned into another type.

Ultimately, they wanted to be good custodians of the land, he said.

“It’s a good add-on and we want to be more conscious of what happens in the wider area, and making sure we are doing the right things.”

The Makarewa River and its tributaries have been mapped and divided into seven sub-catchments, because of the level of detail. Four case study properties have been selected to give insights on their landscape susceptibility and resilience as a cross reference of the land-use, elevation and location within the whole catchment.

Land and Water Science founder and director Clint Rissmann said the property specific information provided insights into landscape susceptibilities.

The mapping showed the catchment had highly variable landscapes, and this meant a one-size solution for water quality and greenhouse gas mitigations would not fit all, he said.

Hedgehope Makarewa Catchment Group project lead Tim Campbell, who also works for Land and Water Science, said the catchment contained quite a diverse range of industries.

“It was great to gain an insight into horticultural land-use, understanding what their landscape susceptibility challenges are in their industry, and as a community how we can support them with a project like this.”

The mapping had given Southern Cross Produce more insight into the biodiversity of their soils, the soil drainage properties on their farm, and would help to inform farm planning, including freshwater farm plans.

“It’s about providing tools and resources so they can make these decisions,” Mr Campbell said.

Thriving Southland catchment co-ordinator Sarah Thorne said the project had been three years of hard work by the catchment group.