Local Govt | National News Video | Parliament Headlines | Politics Headlines | Search

 


Rain a blessing – but watch for nitrate poisoning risks

8 April 2014

Rain a blessing – but watch for nitrate poisoning risks

Rain is high on farmers’ wish list as the run of dry weather in many regions is affecting pasture growth. But nature’s blessing can come with a sting in the tail with the risk of nitrate poisoning in stock increasing when a dry spell is followed by rain or a run of moist, overcast days.

“During a severe drought, lack of moisture stops plant roots from absorbing nitrate. When the rain finally arrives, roots suck up nitrate rapidly, with the pasture accumulating high levels in the stem and leaves,” says Ballance Science Manager Aaron Stafford.

“After a drought-ending rain, it could be two weeks before nitrate levels in pasture stabilise at safe levels, provided environmental conditions are favourable. Hail or light frost can also damage plants, affecting photosynthesis and leading to elevated nitrate levels.

Aaron says plants usually absorb soil nitrogen as nitrate and convert most of it into ammonium and amino acids. But weather conditions in late autumn and winter can sometimes interrupt the conversion process, increasing the risk of nitrate poisoning.

All ruminants can be affected. Cattle are the most susceptible, sheep the least and young stock is more vulnerable than old. Nitrate poisoning sets in rapidly after an animal eats pasture or feed with excessive nitrate levels (0.21% or 2,100 parts per million and above is considered ‘at risk’).

Aaron says rape is known for high nitrate levels, closely followed by other brassicas. Vigorous ryegrass (especially annuals) can create problems, as can cereal green-feeds. Nitrate concentrations are generally higher in new plant growth and decrease with age. Stalks are highest in nitrate content, followed by leaves and then grain. Notably, young pastures (e.g. those re-sown in the last 1-2 years) generally present greater risk to grazing livestock than older pastures.

“Nitrate poisoning progresses quickly and has no ready cure so prevention is important. Testing pasture and feed for nitrate is one option but there are other ways to mitigate the risk.”

Farmers who suspect they have a high nitrate risk can use the following strategies:
• Split nitrogen applications late in the season to distribute nitrogen better. Apply nitrogen after grazing.
• Don’t put hungry stock on high-nitrate feeds. Give them a low-nitrate feed first, preferably one that takes a while to digest (such as straw or hay) so they are less likely to gorge themselves on risky pastures.
• Dilute high-nitrate feeds with low-nitrate feeds. This helps microbes in the rumen adapt to high nitrate feeds. Adjustment can take three to four weeks.
• Pasture nitrate levels are highest overnight and in the morning. Where possible constrain stock access to pasture (particularly in the morning grazing) until animals have been supplemented with low nitrate feed. This could involve in-shed feeding, use of feed pads or laneways, or fencing off areas on pasture to feed out supplementary feed and reduce pasture access.
• Minimise stock intake of pasture in the first 1-2 weeks following drought-breaking rain. This requires adequate supplementary feed to cover this most at-risk period.
• Stock lightly, so animals can selectively graze and avoid hard grazing - the lower part of stems have the highest nitrate content.
• Provide a lot of clean drinking water for stock on high nitrate forage.

ENDS

© Scoop Media

 
 
 
 
 
Parliament Headlines | Politics Headlines | Regional Headlines

Gordon Campbell: On The Mana-Maori Party Deal

If the self-interest involved wasn’t so blatant, the electorate deal between the Maori Party and Hone Harawira would be kind of poignant. It’s a bit like seeing the remaining members of Guns’n’Roses or the Eagles back on the road touring the nostalgia circuit… playing all the old hits of Maori unity and kaupapa Maori politics.

Can the two surviving Maori Party MPs (one electorate, one list) credibly work together with the old firebrand who split up the group years ago, and still hope to rekindle some of that same old magic? More>>

 

Private Provision: First Social Bond To Focus On Mental Health

New Zealand’s first social bond will help around 1700 people with mental illness into work, Finance Minister Steven Joyce and Social Investment Minister Amy Adams say. More>>

ALSO:

Megaupload Case: High Court Rules Dotcom, Co-Accused Eligible For Extradion

Internet entrepreneur Kim Dotcom and his three co-accused are eligible for extradition to the United States, New Zealand's High Court ruled... Justice Murray Gilbert upheld a decision by the District Court that there were grounds for Dotcom, Mathias Ortmann, Bram van der Kolk and Finn Batato to be extradited. More>>

ALSO:

PREVIOUSLY:

Immigration: Short Reprieve For Nine Indian Students

A temporary hold on deportations of nine Indian students is a step in the right direction but the Government urgently needs to implement safeguards to stop further injustices to more international students, the Green Party says. More>>

EARLIER:

Port Hills Fire: Midday Update, Monday 20 February

• 9 homes destroyed
• 2 homes with partial damage. Damage includes things like cracked windows, heat damage.
• 3 properties with damage to other external structures e.g sheds or outbuildings More>>

ALSO:

Welfare: WINZ Breaching Privacy Laws With WINZ Vetting Rules

E tū, the union for security guards, says WINZ may be breaching privacy laws with its new screening process for people visiting WINZ offices. The vetting requires WINZ security guards to check photo ID and whether visitors to WINZ offices have an appointment.More>>

ALSO:

Get More From Scoop

 

LATEST HEADLINES

 
 
 
 
 
 
 
 
Regional
Search Scoop  
 
 
Powered by Vodafone
NZ independent news