Keeping a weather eye on El Niño

1 October 2015

This season there is a high probability El Niño will influence New Zealand weather patterns. The National Institute of Water and Atmospheric Research (NIWA) is predicting a 90 per cent chance of El Niño affecting the upcoming summer season.

This early warning gives farmers the opportunity to adapt their systems and manage El Niño’s impact.

El Niño is a global climatic pattern that is generated by a rise in ocean water temperatures, which is caused by weakening trade winds along the coast of South America and the equator. The Southern Oscillation Index (SOI) – calculated from the pressure difference between Tahiti and Darwin – is used in conjunction with these indicators to predict future weather conditions. When the SOI reaches sustained negative values, as now, El Niño conditions are more likely.

Aaron Stafford, Science Manager at Ballance Agri-Nutrients, has been monitoring the strengthening El Niño trend. “It is forecast to be quite a strong event this summer, the strongest since the 1997-98 season,” says Aaron. “We have seen the indicators for it over winter, with cold south-westerly blasts, and the forecast for spring is predominant west/south-west trade winds. If the trend continues into summer, the result will be higher rainfall in the western parts of the country, and very dry central and eastern areas, with a more extreme drought risk.”

In the areas where conditions look likely to be dry, farmers are urged to develop a plan to maximise their production early on in the season, and review it regularly as the season progresses. Aaron’s advice is to make the most of the rainfall while it lasts. “I would be culling less productive stock promptly, and sowing a greater area in summer forage crops,” says Aaron. “To compensate for the area temporarily taken out of production, I would shift more of my nitrogen fertiliser budget to earlier in the season. The response to nitrogen, and adequate soil moisture, is likely to be greater earlier in the season, so it’s a good opportunity to secure production by bringing it forward.”

If low-producing cows are culled early (taking into account factors such as production worth, somatic cell count, temperament and age), the remainder of the herd, particularly younger cows, can have better access to feed and expensive supplements can be reduced if there are less mouths to feed.

If updated regularly, feed budgets will indicate when nitrogen applications will be most advantageous. Applications earlier in the season are likely to be best. The key to profiting from nitrogen is using the resulting extra feed effectively. It either needs to fill a feed deficit or be turned into high-quality supplement. Using SustaiN will ensure more fertiliser nitrogen ends up in the soil, where it can be used by plants, as opposed to being lost to the atmosphere through volatilisation.

Aaron also has some advice for farmers planting summer crops. “Crops can provide high-quality feed on farm and can be very cost-effective when managed well. Think about the type of summer crops you are using and consider planting more drought-tolerant species, like chicory and plantain, lucerne might be an option in some areas. These plants have deep roots and will grow through a dry summer period. Or, if you are using other crops like turnips, get them planted early so they become well established before the soil gets dry.”

Farmers on the wetter, west side of the country can take advantage of the extra rain. Aaron suggests they may be able to use nitrogen to promote additional growth through the summer, as long as conditions remain suitable.

For more ideas about strategies for coping with El Niño this season, talk to your local Fonterra Farm Source Technical Sales Rep or Ballance Representative.

Article supplied by Ballance Agri-Nutrients