When farmland is flooded by seawater

Coastal North Island New Year storms

Published on Tuesday, January 09, 2018

What happens to farmland which has been flooded by seawater?

  • The impact will depend on how long the crop or pasture is covered by seawater. If it’s only for a short time – up to 48 hours – and gets good rainfall, grasses should bounce back. 
  • Rain is needed to wash the salt away. It’s likely the saltwater was diluted by the rains during the storm which measured up to 70mm.
  • The last similar event in the areas was 15 July 1995. This was during winter, there was plenty of rain to wash out, and pasture recovered well over a three month period.

Pasture and soil

  • Salt should wash away fairly quickly with rainfall. The more porous the soils the quicker it washes out.
  • Pasture dies after three days without oxygen. Overseas studies on inundation suggest:
    • 24-48 hours most pasture will recover, some discolouration
    • 48-96 hours most of the grass will die but some stems survive, clover survives
    • After 96 hours all pasture dies and requires renewal.
  • Most of the area impacted now falls in the 24-48 hour category; some pooling remains and those areas have surpassed 96 hours.
  • Your soil/texture profile affects how much seawater can impact it. Clay soils have low penetration (1-2cm); sandy soils have higher penetration (up to 15cm). This is good news for many farmers whose soil is marine clay. Near Kaiaua there is more sand-based soil.
  • Soils are not expected to become sodic.

Animal health:

  • Precautionary approach of deferring grazing until after the next heavy rainfall. 
  • Ensure stock have access to fresh clean water.
  • Talk to your vet if there are any concerns.

Actions farmers can take:

  • If it’s possible to pump seawater off, do so.
  • Make a feed budget. Consider there may already be feed shortages in the area and take this into account.
  • You may need to offload stock – make a plan and make decisions early.
  • Talk to your accountant about possible tax flexibility or other standard income assistance for you/workers.
  • Talk to your farm consultant if your pasture has been covered for several days or longer - will there be a need to regrass?
  • Talk to your farm consultant about soil testing for sodium or conductivity. Some consultants may be able to offer this as a rapid field test.
  • Talk to your local Rural Support Trust who are working with regional councils, CDEM, MPI and agri-business.

Read a more detailed analysis by Matthew Taylor, Soil Scientist and Diffuse Contamination Specialist at the Waikato Regional Council

 

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News & Alerts

Drought tax relief measures

Tax relief and support measures extended to farmers in medium-scale drought areas

Thursday, January 18, 2018

Author: Terri Anderson

https://www.beehive.govt.nz/release/tax-relief-drought-affected-farmers

https://www.beehive.govt.nz/release/further-support-struggling-farmers.

 

Detail of what may be available can be found on the Work and Income drought page: https://www.workandincome.govt.nz/eligibility/emergencies/rural-assistance-lower-north-island-and-west-coast-drought-2018.html including Rural Assistance Payments.

Please share this information and encourage farmers in affected areas to talk to their accountants and advisors.

Share with your rural professional contacts so they are aware of the current challenges due to poor spring and dry early summer. Farmers and families may benefit from help revising their budgets. Some who are badly affected - particularly lower-order sharemilkers and contract milkers - may be eligible for entitlements such as Working for Families https://www.workingforfamilies.govt.nz/ so your help to make their accountants / advisors aware is appreciated.

Your local Rural Support Trust is available and Federated Farmers' Feedline is open to both memb ers and non-members: https://www.fedfarm.org.nz/FFPublic/Adverse_Events_Farmer_Support_and_Feedline.aspx

MPI, DairyNZ and B+L NZ also have good information for getting through droughts and dry weather.

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Summer BBQ: 10 Feb 2018 Glen Murray Hall

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Friday, January 19, 2018

Author: WandaLeadbeater
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Protecting your farm from Mycoplasma bovis in drought-affected areas

Sunday, January 14, 2018

Author: Terri Anderson

With a number of farms in drought-affected areas, there is concern about the movement of animals for grazing or getting in supplementary feed from other regions.

The pdf has advice for keeping your farm safe. More infomrmation is available on MPI's website https://www.mpi.govt.nz/protection-and-response/responding/alerts/mycoplasma-bovis/#whatucando

 

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Drought classification extends to Grey and Buller

https://www.beehive.govt.nz/release/drought-classification-extends-grey-and-buller

Sunday, January 14, 2018

Author: Terri Anderson

Minister for Agriculture and Rural Communities Damien O’Connor has extended the medium-scale adverse event classification to the drought-hit Grey and Buller districts of the South Island’s West Coast.

These are the first South Island additions to the medium-scale event, which was announced for regions of the lower North Island just before Christmas.

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