Fert Options with Robin Boom Agronomic Advisory Services

In recent years some smaller fertiliser importers have been bringing in high analysis phosphatic fertilisers such as triple super, pure dicalcium phosphate, RPR and DAP and selling them considerably cheaper than what the two big fertiliser co-ops have been selling them for.

There’s also been serious question marks regarding the efficacy of some of the RPR fertiliser blends the two co-ops have been selling to farmers, and through my columns in this newspaper I seem to be the only whistle-blower out there rising the alarm on these.

However, I’m pleased to say Ravensdown is now mixing in Algerian rock with their Sechura RPR, which is considerably better than their Sechura/Moroccan BG4 blend or straight BG4 it was selling as ‘Direct Application Phosphate Rock’ a couple of years ago which really was only suitable for pine trees.

Ballance has also upped its game and is now offering a serpentine super/Sechura blend, and I will be suggesting this option to many of my hill country farming clients as at 11 per cent P and $310/tonne it certainly stacks up.

No comparative trials

Since the old Te Kuiti Research Station trials, which finished 25 years ago, there have been no comparative phosphate fertiliser trials that I’m aware of. However, I was approached by a couple of Australians, who run a company across the Tasman called Fert Direct and who’ve been marketing a sulphur-infused triple superphosphate product called Triple Plus, to run a trial comparing their product against a whole lot of commercially available phosphate products sold here.

So in June I laid down a four replicate trial comparing Ravensdown superphosphate, Ballance Triple Super/Sulphur blend, Triple Plus from Fert Direct, Replenish Dicalcium Phosphate from Terracare, Dicalcium Phosphate from Fertilisers Direct, Sechura RPR from Kiwifert, Algerian RPR from Quinfert and granulated Egyptian RPR from Dickie Direct.

All plots received the equivalent of 45kg/ha of P plus 30kg/ha sulphur on a site with low pH, phosphorus and sulphur levels.

The photograph shows the trial site where trim cuts were performed and cages placed from which pasture cuts will be harvested and dry matter growth determined intermittently during a 12-month period.

Although the Australian company will be funding it the first year, as they are confident their product will outperform the local products, thereafter a local RPR importer has offered to fund the trial (assuming he’s happy with the performance of his product).

As this will be the first comparative phosphate trialling of so many commercially-available products for more than 25 years, the results will be of interest to all farmers and their consultants – and through this column I hope to keep you updated with results. What needs to be factored in obviously is the economics, as the cost per unit of P from the various products is quite variable, particularly when cartage and spreading costs are included.

More expensive

Also it was interesting to learn from the Australians that fertiliser prices are more expensive here than in Australia. One product, which gets hardly a mention here is MAP – or Mono Ammonium Phosphate – which is the highest P fertiliser with 11 per cent N and 23 per cent P and is listed on the Ravensdown price list for close to $900/tonne. But these gentlemen believe they could sell it for under $700/tonne and still make a profit. Sales of their Triple Plus product in Australia have gone from 5000 tonnes five years ago to 30,000 tonnes last year, so it’ll be interesting to see how they get on when they make a foray into the NZ market in the next few months. Don’t, however, expect your fertiliser reps to inform you of these options, as they are only interested in promoting their particular products.

Robin Boom, CPAg, member of the Institute of Professional Soil Scientists. Ph: 0274448764.