Brazilian phosphate miner Aguia Resources’ (ASX:AGR) soybeans trial suggests its “natural” fertiliser might be able to replace synthetic version.

The company is one of a handful on the ASX developing fertiliser from rock phosphate, an organic farming-friendly additive which hasn’t been as easily absorbed by plants as the chemical alternatives.

Now tests of direct application natural fertiliser (DANF) from Aguia’s Três Estradas phosphate project suggest the product has “high potential” to replace conventional phosphate fertilisers, the company says.

“These first results on the agronomic efficiency of our DANF are most positive,” said managing director Dr. Fernando Tallarico.

The Três Estradas DANF was tested in the same conditions as other conventional phosphate fertilisers known to have high solubility, and they performed very well.”

Soybeans are a key industry in the Brazilian state of Rio Grande do Sul, which has around 5.7m hectares of soybean crops which yielded 19 million tonnes in the 2018/2019 harvest.

Almost as good as synthetics

Testing of two types of phosphate ore was carried out by Integrar Gestão e Inovação Agropecuária (“Integrar”), an agronomic consulting firm in southern Brazil.

The tests on carbonatite saprolite (CBTSAP) and amphibolite saprolite (AMPSAP). The agronomic performance tests looked at how efficiently phosphorus was delivered into plants.

The soybean test will be followed by ryegrass and rice.

The best results, both in crop yield and phosphorus remaining in the soil, came from a mixture of rock and mono-ammonium phosphate fertilisers.

“The soybean that was treated with the application of our fertilisers, CBTSAP and AMPSAP, returned yields that exceeded expectations for a first production cycle,” the company said.

“The expectation is that in a short time period, the differences in productivity between the conventional phosphate fertilisers, and CBTSAP and AMPSAP, will be further reduced or be negligible.

“This is because of the cumulative effect of the fertiliser in the soil over time, which favours Natural Phosphates as they are slower release products.”

Not a simple switch

Rock phosphate is normally used to ‘supercharge’ inorganic fertilisers like superphosphate and this is what most of the Australian miners are aiming their production for.

Using the ‘organic’ raw form, though, poses a few problems.

Phosphorus, the element, is not easy for plants to extract from soil generally and rock phosphate is one of the least soluble forms. Little rock phosphate is currently used in agriculture because of low availability of phosphorous, high transport costs, and low crop responses.

Another issue is that there isn’t much good quality rock phosphate out there.


In other news:

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Wide Open Agriculture (ASX:WOA) has brought in national researcher CSIRO to help scale up a protein extraction process for lupin.

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