Soil Carbon Update

The Carbon Positive project has now completed the first of six seasons and in this season grew sweetcorn for McCains, testing three different growing systems.

Added one year ago

The Carbon Positive project has now completed the first of six seasons and in this season grew sweetcorn for McCains, testing three different growing systems.

The purpose of the trial is to try and regenerate soil carbon in soils used for intensive field cropping and is based at LandWISE Microfarm, Ruahapia Road, Hastings.

The trials include growing conventional, regenerative and a hybrid system (taking the best of both systems) and achieving sustainable and commercial outcomes.

Because there is no defined system for regenerative field cropping in New Zealand currently, it is about learning and testing ideas guided by a well-developed science plan and drawing from the experience and learnings of a wide range of practitioners.

Baseline testing included visual soil assessments, worm count monitoring and soil carbon sampling.

Soil Carbon samples indicated soil carbon is evenly distributed throughout the trial block at 0-15 cm and 15-30 cm and more variable, yet still significant at 30-60 cm. There were also soil carbon stocks at 60-90 cm depth. The graph below shows total soil carbon tested.

There is 115 tonne per ha of soil carbon to 90 cm depth across the trial site. This is lower than average for NZ agricultural soils which have stocks of 100 tonne per ha in the top 30 cm. There is scope for soil carbon to both increase or decrease in the trial plots as a result of the treatments imposed during the trial. Soil carbon levels will be measured again after three years and six years of cropping.