Fert Options with Robin Boom Agronomic Advisory Services

This month I celebrate 30 years of running my own business doing soil testing and providing independent fertiliser advice to farmers. Back in April 1989 liquid fertilisers were commonly used. Products such as Maxicrop, Reaction, Response Black Label, Plant Plasma, Premium Black Gold, Moana Fish Fertiliser and Nitrosol had become popular alternative options when fertiliser subsidies on superphosphate-based products were removed in 1983.

Some dairy farmers who had experienced animal metabolic problems such as bloat and milk fever from excesses of P and K, found after changing to these liquid products the animal health problems went away. However, these were never going to be a long term solution because these liquid products could never economically maintain soil fertility. Following the prolonged Maxicrop court case where the judge went in favour of the Ministry of Agriculture and Fisheries scientists, their popularity started to wane.

Spraying 20 litres/ha of an 8:5:5 NPK was only giving 1.6kg/ha N, and 1kg/ha each of P and K, so inevitably nutrient reserves were mined and pasture productivity would fall. For a dairy farmer producing 800kg/ha MS, maintenance P is 32kg/ha and K is 60kg/ha, so using a liquid fertiliser meant only a tiny fraction of maintenance was being provided. Such products were commonly sold for around $600/200 litre drum, which at 20 litres/ha worked out to be $60/ha.

Back then urea was hardly used at all, but cost around $400/tonne, superphosphate $160/tonne and potassium chloride around $350/tonne. Today urea is about 50 per cent more expensive and superphosphate and potash about double these prices. So for the liquid fertiliser with a NPK rating of 8:5:5, when applied at 20 litres/ha, gave about $5 of nutrients compared to solid fertilisers – so were about 10 times more expensive as a nutrient source, hence the criticism by MAF soil scientist Doug Edmeades on ‘Fair Go’ in 1985 which sparked the Maxicrop court case.

RPR fertilisers

In the Waikato and Bay of Plenty, the main fertiliser supplier was BOP Fertilisers, whereas in the King Country, Farmers Fert, based out of New Plymouth, competed with BOP Fertilisers.

Reactive Phosphate Rock fertilisers were also coming onto the scene and there was a flurry of research investigating their efficacy at that time. The first RPR on the market was Duraphos, sold by Wrightons for a couple of years in the late-1980s, which was Arad rock from Israel.

Then about 14 farmers, mainly from the King Country and Gisborne region, got together and formed Norphos, which imported Sechura RPR from Peru, which was the top performing RPR from MAF trial work. The superphosphate companies imported the black North Carolina rock, which they also used to make up Longlife super, but as a RPR it was also a good performing rock. Due to its high cadmium content it was taken off the market in the late-1990s. RPR fertilisers sold for around $180/tonne back then, so as a form of P they were about 30 per cent cheaper on the ground. In 1990 Bert Quin started importing RPR from Egypt under the brand Quinphos.

There were a couple of Hamilton-based fertiliser companies active in the 1980s too. JD Wrights, which later morphed into Agricorp, was based in Te Rapa and made organic blends of RPR, Rotokawa sulphur, serpentine, lime and biosolid material. A second company was Natumix, which worked out of Matangi making a blend of burned lime from the cement works and Sechura RPR.

Lime Ash

Another byproduct available in 1989 was Lime Ash from the Te Awamutu dairy factory, which used the high sulphur containing coal from Pirongia. Lime was put into the chimney stack screens to absorb the sulphur, which was a cause for acid rain. This product was a very quick-acting lime, but also contained about four per cent sulphur and one per cent boron, and at $6/tonne was very good value. Foremost Fertilisers then started up and took over marketing this product, calling it Foremost Green and the price went to $15 and got up to $39/tonne at one stage. In all it had about $45 worth of lime, sulphur and boron. Foremost Fertilisers used it to make dicalcium phosphate products, but when the dairy factory stopped using the coal from Pirongia in the late-1990s they had to go to other lime sources.

This was the fertiliser industry I entered into 30 years ago, and controversy and confusion over fertilisers back then was no different to what it is today – except that the products and companies have changed. Being independent I was able to sort out the wheat from the chaff, and guide clients into what their land and livestock really needed based on their soil and herbage test data. I have a number of loyal clients for whom I’ve been part of their business success for well over quarter of a century – and I still enjoy the challenge of getting them best value for money from whatever products are in the marketplace.

Robin Boom, CPAg, member of the Institute of Professional Soil Scientists. Ph: 0274448764. Email: agronomics@xtra.co.nz