Research shows that lowering fertilizer pH can increase solubility and availability of zinc

Researchers from the University of Adelaide, using the Canadian Light Source at the University of Saskatchewan, have developed a method to increase the efficacy of zinc in fertilizers—a critical development as worldwide many soils are deficient in zinc. Despite the widespread use of zinc-enriched fertilizers, deficiencies remain, significantly impacting crop yields and food quality.

The study, published in the Soil Science Society of America Journal, utilized the HXMA beamline to analyze how changes in fertilizer composition affect the solubility of zinc at the molecular level. The team initially hypothesized that the type of zinc compound would determine solubility. However, findings indicated that the pH level of the fertilizer is the crucial factor influencing the availability of zinc to crops.

The research demonstrated that zinc solubility is not influenced by the specific zinc phosphate compounds formed but rather by the acidity of the fertilizer. Zinc added to more alkaline fertilizers, such as diammonium phosphate, showed very low solubility, limiting its effectiveness.

By lowering the pH of the fertilizer through the application of an acid solution, the solubility and availability of zinc were significantly increased. The researchers also developed a barrier coating for fertilizer granules that separates the zinc from phosphate, enhancing the uptake of zinc by plants.

This advancement has led to the patenting of these new technologies by The Mosaic Company, in collaboration with the University of Adelaide’s Fertilizer Technology Research Centre. Mosaic, a leading global producer of concentrated phosphate and potash, aims to refine zinc fertilization practices to boost yields and improve food nutrition.

Dr. Rodrigo da Silva, leading the research, emphasized the importance of these findings for agricultural productivity, stating, “It is crucial to improve zinc fertilization practices, to maximize yields and produce more nutritional food.” This breakthrough could significantly impact the fertilizer industry, offering a way to produce more efficient fertilizers that better meet the nutritional needs of crops.