Wednesday, 13 February 2019 10:55

Using fert wisely

Written by  Greg Campbell, Ravensdown chief executive
Greg Campbell. Greg Campbell.

OPINION: We all know that overuse of fertiliser harms the environment, but that shouldn’t mean fertiliser becomes a dirty word.

As one of the farmer cooperatives supplying much of New Zealand’s fertilisers, Ravensdown expects and welcomes scrutiny on how fertiliser is used. But we want to set the record straight about the importance of fertiliser to our food, economy, people and country. 

Some recent claims blame fertiliser entirely for the destruction of waterways and soils and say the nation could farm without it. It makes for a good yarn, or even a simple billboard, but it’s not true. 

Fertiliser is simply food for plants. Plants take nutrients from the soil to grow; fertiliser puts more nutrients back into the soil so more plants can grow again. 

New Zealanders like to think we have great farms partly because of great soil. But in fact much NZ land is geologically new and naturally lacks the nutrients needed by the many plants we eat and use. 

The soil can particularly lack phosphorus, nitrogen, sulphur and potassium. Phosphorus, for example, is used by plants to store and transfer energy. It aids root and flower development and increases growth rates. 

Virtually everything you will buy this summer from a store will have been grown or fed using fertiliser. 

Farmers and growers use fertiliser to create the affordable quality food we eat or export and grow nutritious crops for animals. It powers our beef, sheep and dairy farms and the fast-growing horticulture sectors now taking the world’s chefs by storm. 

Each year, fertiliser used by all these sectors contributes billions of dollars to our economy and helps to employ tens of thousands of Kiwis. 

Fertiliser is simply a tool in a toolbox. Under-use it and you see real impacts on what can be created and consumed. Overuse it and you risk losing nutrients into the waterways or atmosphere. As a tool, fertiliser can be used smartly or not so smartly. 

Unlike a corporate listed company, Ravensdown is a cooperative owned by its farmers; it’s not here to maximise profit but to help with the responsible use of its products. 

Nutrients need to be applied responsibly. As one of the biggest investments in a farm operation they need to be managed and wastage minimised. Too much of the wrong fertiliser in the wrong place at the wrong time can cause environmental problems. 

Whether from city living or fertiliser use, nutrients such as nitrogen and phosphorus can be washed by rain into other parts of the ecosystem, especially waterways. In waterways, nitrogen and phosphorus act as food for waterborne plants, including algae. Those plants can choke waterway habitats and they reduce oxygen available for other water dwellers. Hence the rules in many regions, limiting the amount of nitrogen that can be lost from farms. 

Most of the total nitrogen that fuels NZ’s grass-based farming comes from legumes (clover-like plants) that can capture nitrogen from the air. These little plants are worth billions of dollars to the economy, but they only grow at certain times of the year. 

Plants often need additional support at strategic times and places and that’s why farmers use mineral fertiliser selectively. 

Ravensdown has a range of services and products to help farmers use fertiliser responsibly. 

These include precision testing, mapping and spreading, so farmers know exactly what to use where. We produce products that reduce nitrous oxide emissions. We have the country’s biggest network of farm environmental consultants who help farmers come up with ideas to reduce impacts. 

Whether it’s from too many plants like clover or peas, too much fertiliser or too much extra feed, if the animal or plants can’t use all the nitrogen from those sources, then nitrogen may be lost from the soil. Our certified advisors guide customers on their inputs and outputs so that they can achieve their goals and farm smarter. 

At times this has meant advice resulting in less fertiliser applied. This is fine for us. We don’t incentivise our team based on how much they can sell. Representing a cooperative, they are there to help the customer owner buy the right amount not the highest amount. 

• Greg Campbell is Ravensdown’s chief executive

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