Polysulphate potential to improve alfalfa production

13 June 2018

Evidence from the Brazilian Agricultural Research Corporation (EMBRAPA) published by the International Potash Institute could have major implications for large scale efficient use of polyhalite, marketed as Polysulphate, on alfalfa in Brazil to adequately supply this important forage crop for livestock with potassium and other nutrients. 

Wanting better fertilizer response in Brazil

Brazil is the fourth largest fertilizer user in the world. A quarter of what is applied is potassium fertilizers, demand for which is driven by the fact that poor acidic soils hinder availability of potassium to crops. However, despite increasing use of potassium fertilizers, mainly potassium chloride, agronomic efficiency is poor. Farmers want better nutrition for their crops, especially alfalfa which is a pillar of Brazilian livestock production.

Comparing sources of potassium

An experiment to compare polyhalite with alternative sources of potassium has demonstrated clear benefits of using this natural, multi-nutrient fertilizer over using potassium chloride or gypsum. At EMBRAPA’s south eastern regional research center, in pots of local soil, alfalfa plants were fertilized with a range of treatments. Four different potassium dosages with seven fertilizer combinations were applied.

Polysulphate - much more than a potassium fertilizer

In the experiment, Polysulphate application, alone or in combination with potassium chloride, gave rise to significantly higher biomass yields than potassium chloride, with or without gypsum. Polysulphate significantly enhanced K, S, Ca, and Mg uptake, particularly when applied alone at the highest dose.

The next phase is large scale field experiments to confirm the findings, but for now an important step has been taken in understanding the role of Polysulphate in feeding the alfalfa crop in Brazil efficiently and effectively.

This summary is extracted from the full research paper available from the International Potash Institute.

Photo: Courtesy of the IPI, International Potash Institute