Baseline Sampling Project
It has been over a year since Cyclone Gabrielle caused devastation to many parts of the North Island, however the impact of the flood is still being felt by many, as people rebuild homes and businesses.
As the water subsided, a group of us began a baseline study, sampling soil and sediment across Hawke’s Bay, Tairawhiti, and Northland, aiming to build on studies completed after previous flood events such as the 2004 Southern North Island storm, which focused on returning to pastoral production. The focus after Cyclone Gabrielle, and of the baseline sampling project, was to better understand sediment characteristics deposited across the landscape, capture information that could help growers make decisions, and help in the recovery of highly productive land and elite, versatile soils, which grow a range of high value fruit, vegetable and arable crops. This LandWISE project was funded by the Ministry for Primary Industries, and work was completed alongside a large group of organisations including AgResearch, Massey University, Hawke’s Bay Regional Council, Gisborne District Council, Plant and Food Research, Vegetable Research & Innovation Board, and Vegetables NZ.
As part of the baseline sampling project 155 samples were collected from 116 sites. Over 70 farmers and growers engaged with the project. Data was collected along a 50 m transect, with 3 sampling points along the transect. Data collected included:
- Sediment Depth
- Soil nutrient analysis (fertility)
- Visual Soil Assessment (VSA)
- Bulk Density
- Sediment Texture
- Earthworm abundance and species
- Contaminants (select few sites)
Results from the baseline sampling are available in the full report, available on the LandWISE website.
Repeat Sampling
With support from MPI and the Vegetable Research and Innovation Board, we have been able to develop a study to revisit and resample a select few sites around Hawke’s Bay. The aim of this study is to understand the impact of sediment deposition and different management decisions on the soil, and impact on crop production the following season.
These sites have been paired by location, sediment texture and sediment depth, but have been managed differently (e.g. sediment incorporated vs sediment left on the surface). 10 sites were revisited in the spring, 6-months after the flood, with soil or sediment analysis completed in the same way as the initial baseline testing. This autumn, 12 months after the cyclone, we are revisiting these 10 sites and six others. Eight of the selected sites have been planted in vegetables, and crop yield and quality data are being collected in addition to the soil measurements.
We have revisited nine sites so far this autumn. Hand harvests were completed in two blocks in sweetcorn and one of tomatoes. The remaining sites were planted in grass. We will report on this work at the LandWISE Conference in May.