News & Advice

In many industries, trends come and go with the seasons. But on farms across New Zealand, one thing never goes out of style - superphosphate.  It remains a consistently reliable essential for maintaining healthy pastures and productive farming across the length of the country.  

Few agricultural tools have stood the test of time as well as superphosphate. It works, it’s price competitive, and it’s flexible in how farmers can use it.

New Zealand-made superphosphate delivers sulphur as sulphate — the form plants absorb directly and use immediately for energy and growth. It’s like the carbohydrate humans need for an energy fix before heading off on a long run. In our pasture-based systems, particularly in year-round grazing - that matters enormously. We farm with mixed swards dominated by ryegrass and an abundance of clover. Clover is the nitrogen engine of our paddocks, fixing atmospheric nitrogen into the soil. But to thrive, clover needs phosphorus and sulphur.

Modern alternatives like DAP or Triple Super have little sulphur, or elemental sulphur is added. Elemental sulphur must first be converted in the soil before plants can use it. Apply superphosphate in spring, and you’ll see the results in that season’s growth and grazing.

Research shows that applying phosphorus and sulphate together delivers more than the sum of its parts. Pasture growth responses are higher when both are applied in tandem, compared to each nutrient applied separately.

Global market conditions work in our favour. The ingredients for superphosphate can be sourced competitively, and today it’s still cheaper to import the raw materials and manufacture here than to bring in finished products. Local manufacture also improves supply chain resilience in these uncertain global times.  

The result is more bang for the buck than alternatives. Not only is superphosphate accurately tuned to New Zealand pasture, it is a consistently cheaper source of phosphorus than DAP when valuing all nutrient components. Over the last 10 years in New Zealand, phosphorus derived from superphosphate manufactured by Ravensdown was around 11% cheaper than phosphorous derived from DAP. Further to that, superphosphate prices have been a lot less volatile, swinging a maximum of 37% above the 10-year average price, while DAP has swung up to 74% above the 10-year average price.

New Zealand soil fertility has been built up over decades, so most farmers now use superphosphate mainly to replace the nutrients removed in growing and grazing. That makes it a maintenance fertiliser — one that keeps the whole pasture system ticking over without waste. 

The exception is during years of lean income, like those recently experienced by sheep and beef farmers. Fertiliser maintenance is usually reduced in these times. There is an argument right now for catch-up applications to lift soil fertility that would have suffered.   

Superphosphate is not going out of fashion — because plants haven’t changed. What has changed is our understanding of how to use it. Decades of New Zealand research has given farmers confidence about timing, rates, and responses. We now have a balanced, efficient system: locally manufactured superphosphate tailored for our soils, precision application tools, and farmers who know how to use them. 
Superphosphate has been amazingly adaptable with its abilities to include trace elements and compatible nitrogen products, and to enable modern precision practices and technology. Farmers can target exactly where and when they need it. Soil testing, GPS-guided spreading, and years of field research mean farmers know how to match application rates to stocking pressures, soil types, and seasons. 

Our use of it may be more sophisticated, but locally made superphosphate is as relevant to modern New Zealand farming as it was to our farming grandparents. It’s ingredients are the nutrient bedrock of all farming. Some products disappear with age. Superphosphate has appeared even better.