Issue 14 2017
The benefits of prolonged nutrient availability
Fabio Vale presenting the polyhalite poster at the Soil Science Society of America meeting in Florida.
Pressure is a part of modern life. People feel it. Our planet feels it. And so do the crops and farmers that we aim to serve with our products and professional advice. In our work we may feel pressure of time too, and a well put together poster can be a powerful way to present key facts about Polysulphate in a just a few minutes.

Poster pulls out the powerful information

The key results from research to evaluate the residual effect of polyhalite fertilizer on maize grown after soybean on sandy soils in Brazil were pulled together into a poster by Dr. Fabio Vale, IPI Coordinator for Latin America.

The poster pulled in a lot of interest at the recent 2017 Annual Meeting of the Soil Science Society of America ‘Managing Global Resources for a Secure Future’ in Tampa, Florida in the United States.

Polysulphate helps crops to perform under pressure

On Brazil’s sandy soils, soybean is often followed by maize. It is a priority to get greater sustainability in yields of both crops; the characteristic of polyhalite to give prolonged release of nutrients over a long period means that it has the potential to benefit crops in succession.

The trial was conducted in a light textured soil of the Brazilian Cerrado, in Luiz Eduardo Magalhaes, Bahia state, Brazil. The soil has low natural fertility and are poor in phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulphur (S) and micronutrients.

Normally the soybean and maize fertilizations are made to supply only P and K, besides nitrogen (N) for corn. Use of fertilizers containing these other nutrients (S, Mg and Ca) is important to the management of crops in order to get greater sustainability of the yields. The aim of the research was to evaluate the residual effect of the Polysulphate applied in the previous soybean crop on the maize yield.

Five treatments were applied to soybean crop: (1) Control, (2) MAP (104 kg ha-1 P2O5), (3) MAP + KCl (104 kg ha-1 P2O5 + 60 kg ha-1 K2O) , (4) MAP + KCl + polyhalite (104 kg ha-1 P2O5 + 60 kg ha-1 K2O + 20 S), (5) MAP + KCl + polyhalite (104 kg ha-1 P2O5 + 60 kg ha-1 K2O+ 40 S). MAP was applied along the furrow, and KCl and polyhalite in broadcast before sowing. In the following crop, maize, all treatments received same fertilization: 150 kg ha-1 N as urea, 100 kg ha-1 P2O5 as MAP and 60 kg ha-1 K2O as KCl, in order to evaluate residual effect of polyhalite applied on previous soybean fertilization.

Revealing the residual benefits of Polysulphate

The trial plots in the study were strongly affected by the El Nino phenomenon of 2015-16 which caused prolonged drought, and then late rains with low rainfall. Nevertheless K fertilization had a high influence on soybean yield. Polyhalite further increased yields by 10.5% (20 S) and by 19.9% (40 S) as compared to KCl treatment.
Soybean yield as affected by the different treatments. The averages (4 replicates) followed by same letters do not differ statistically by Tukey test 5% of probability.
Potassium deficiency symptoms were observed in the soybean plot treated only with MAP fertilizer.
In addition the residual effect of polyhalite increased maize yields by 6% in comparison with conventional KCI fertilizer use showing the importance of the S, Ca and Mg in Polysulphate fertilizer.
Maize yield as affected by the different treatments, polyhalite was applied only to previous crop. The averages (4 replicates) followed by same letters do not differ statistically by Tukey test 5% of probability.
You can see more about this research at the poster on the IPI website.
Maize plots at the experiment at Alvorada farm, Luiz Eduardo Magalhaes, Bahia state, Brazil.
Mined in the UK, ICL is the first – and only - producer in the world to mine polyhalite, marketed as Polysulphate