Soil & Erosion Management
There are a diverse range of soil types present throughout the Hawke’s Bay region. Knowledge of your properties soil types and characteristics is essential for their sustainable management and long-term agricultural profitability.
S-maps are available online here. S-map is the new national soils database. When completed, it will provide a seamless digital soil map coverage for New Zealand.
Other Soil Maps
Soil maps and a soil book of the Heretaunga & Ruataniwha Plains are available. These describe soil type, characteristics, formation and ‘best management’ guidelines. Thematic maps covering available water capacity, compaction, drainage, frost, permeability and wind erosion susceptibility are also available. Call Paul Train and Maddy McLean in the Land Management Team for more details - 0800 108 838.
Hawke's Bay Soils
Across Hawke's Bay, many different types of soils have evolved. A knowledge of these soils is critical to understanding the growing environment for your trees, crops and pasture. While soils are complex, there are some basic things you need to understand.
About Erosion and Slips
Hawke’s Bay region is regularly affected by intense storms, and predictions are that these will increase with climate change. As well as the damage done to property, storms often cause slips on our thin soil.
Slips remove all topsoil and much subsoil leaving a very poor surface for pasture growth, and putting productive use back. The biggest challenge is replanting this lower fertility soil to return to economic production. A mix of hardy pasture species, fertiliser, soil conservation planting and careful management are needed.
This information has been prepared for farmers by HBRC's land management advisory team. Farmers can contact their land management advisors directly for advice for their own land.
What can be done?
Over-sowing and top dressing with careful management helps to improve the recovery of slip scars. Resting an erosion area for at least a season is ideal but may be difficult to achieve when feed demand arises. However the results of this work are very worthwhile as well as providing an opportunity to establish soil conservation poplar and willow poles. While many farmers may find the need to re-grass slips as soon as possible, better value may be gained by repairing fences if funds are limited.
We can help with funding through the Regional Landcare Scheme for farmers wanting to plant soil conservation poplar and willow trees during winter.
HBRC's Land Management Advisors can assist with information on soil conservation planting and slip recovery. Contact us on 06 835 9200 or 0800 838 108.
Trials in the Wairarapa hill country show the recovery rate of pasture on slips can be improved by over sowing and top dressing (with at least maintenance rates of superphospate and sulphur but not nitrogen). Pasture production on these areas was 2.5 times greater after 5 years than on untreated slips.
Storms often remove all topsoil and much subsoil leaving a very poor surface for pasture growth.The biggest challenge comes back to what varieties of plants will take to this lower fertility soil types. Essentially legumes are the most successful establishers in low organic matter sites. These come in the form of white clover, sub clover, and even a touch of annual clover will be beneficial.
In terms of grasses, ryegrass will make an excellent bulker to the mix, but most likely won’t give the best persistence in this lower fertility situation. Cocksfoot will give a certain amount of success. Agri Plus recommends the following mix : Blend of Perennial Rye Grass & clover 10kg/ha; Subclover 6 kg/ha;Cocksfoot 6kg/ha; Balensa clover 4 kg/ha.
Trials in the Wairarapa suggested the following mix: Cocksfoot 6kg/ha; White Clover 3 kg/ha; Lotus pedunculatus 2kg/ha.
Plantain is another species that has the ability to cover the ground very quickly on hard sites so could be worth considering for small patches of bare ground.
How long does it take for slips to recover?
There are 2 types of bare ground on hill country after a storm: slip scars and slip debris.
- Slip scars are usually very hard and steep and will grass over very slowly.
- Slip debris although very rough is easily converted back into high production but will include initially many weeds.
Pasture growth only reaches 70 to 80% of original production after 30 years on slip scars. Most of this recovery takes place within the first 10 years. Research has shown recovery time can be shortened by 20 years with the right management.
Technical information available
Thanks to Horizons Regional Council (which dealt with severe storm damage in 2004), there are also a series of handouts and technical papers available below in related documents. (or contact your land management advisor).