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

 

PARLIAMENT TODAY:

Harmful Digital Communication Bill Passes: Focus Must Be On Education

InternetNZ acknowledges the passage of the Harmful Digital Communications Bill into law this afternoon, and says that the sooner the education efforts at the heart of the legislation start, the better... More>>

ALSO:

3-Year Transport Plan: No Plans On Six Northland-Election Bridges

The Transport Authority’s decision to fund only four of the 10 bridges promised in National’s shameless Northland by-election bribe is a huge embarrassment for Transport Minister Simon Bridges, Labour’s Transport spokesperson Phil Twyford says. More>>

ALSO:

Gaza Blockade: Māori TV Crew Returning Safely From Israel

A Māori Television crew will be flown back from Israel after their boat was detained by the Israeli Navy while attempting to break the Gaza blockade. More>>

ALSO:

Family Violence: Increasing Reporting But Fewer Resolutions

“We are aware the Police have embarked on a significant programme of change in how they respond to family violence. The data suggests that adequate resourcing including investing in staff training, support and culture change will be required for this to be effective.” More>>

ALSO:

Health: NZ Children Still Suffer Rickets From Lack Of Vitamin D

Vitamin D deficiency continues to cause rickets in young New Zealanders, new University of Otago research has found. The researchers say that their finding suggests that at-risk mothers and children should be better targeted for Vitamin D supplementation. More>>

Also GPs, Housing, Milk: PM Press Conference On The UN Security Council

In a press conference today the Prime Minister discussed the upcoming appointment of New Zealand to chair the UN Security Council. He said they would put pressure Asad in Syria and attempt to “jump start” negotiations between Israel and Palestine. More>>

ALSO:

Housing: State Houses Could Sell To Overseas Groups

Bill English’s admission that he would sell hundreds of New Zealand’s state houses to the Australians is the latest lurch in the Government’s stumbling, half-baked housing policy, Labour’s housing spokesperson Phil Twyford says. More>>

ALSO:

AND:

Get More From Scoop

 

LATEST HEADLINES

 
 
 
 
 
 
 
 
 
Regional
Search Scoop  
 
 
Powered by Vodafone
NZ independent news