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Hello all,

I am Tolulope Ayeyemi, ESR (Early Stage Researcher) 8 of P-TRAP and I am hosted by the University of Seville, Seville, Spain. I am specifically working with the “Soil Fertility group” of the Agronomy research group in the Department of Agroforestry Sciences. My research group studies by means of laboratory and field experiments; and has a wealth of knowledge and experience on nutrient dynamics and availability in soils; and particularly focused on phosphorus and iron. Since the beginning of February 2020, I have been working in Seville on the effectiveness of vivianite as a sustainable phosphorus and iron fertilizer for agricultural crops. I am registered as a doctoral student within the Interuniversity Doctorate program in Agrarian, Food, Forestry and Sustainable Rural Development Engineering. I am supervised by Prof. Dr. Antonio Delgado of the University of Seville and Prof. Dr. María del Carmen del Campillo García of the University of Cordoba as my PhD is a joint program between the two Universities. Within the P-TRAP project, I am co-supervised by Prof. Dr. Jonathan Lloyd of the University of Manchester, UK.

Growth experiment using cucumber seeds on different vivianite products.

My research is focused on studying the efficiency of vivianite as a phosphorus and iron fertilizer. Vivianite, an iron phosphate mineral with chemical formula (Fe₃(PO₄)₂∙ 8H₂O) is found in predominantly reducing environments as well as in terrestrial systems and can also be obtained from the precipitation of P from wastewaters. However, the use of vivianite as a fertilizer product has not been fully explored. Although there have been some studies on the use of vivianite to correct iron chlorosis in certain crops. A few studies have also suggested that the concentration of P in vivianite is high enough to make it suitable as a P fertilizer provided that P can be released in soils in a form that can be easily taken up by plants. However, there is little or no information on its use and behavior as P fertilizer in different types of soils and crops. In addition to vivianite, I will also be studying other P rich Fe-oxides as a fertilizer. Vivianite contains an average of 32% Fe and 10% P and may potentially act as a slow-release fertilizer for agricultural crops. I will be studying by the means of pot, laboratory and field experiments and will test different vivianite products from different companies who are involved in the P-TRAP project (Aquaminerals, Fertiberia, Wetsus). I will also test microbially transformed Fe-P products in collaboration with Lordina (ESR5) from the University of Manchester. I am also looking at the effect of organic matter on the release of P and Fe from vivianite. My research will compare the effect of applying vivianite and other Fe-P oxides with conventional P fertilizers with respect to bioavailability, yield and crop quality. This will be carried out in close collaboration with Rochelle (ESR2, KULeuven) and Rouven (ESR10, UNIVIE). It is hypothesized that the use of vivianite as a fertilizer could help close the phosphorus cycle in agriculture. This could reduce leaching of P from soils, and hence reduced eutrophication of surface waters which is a global challenge.

My secondments will be at the University of Vienna, KU Leuven and GEOTEAM. At the University of Vienna, I will be investigating the effect of plant exudates and organic ligands on P and Fe release from vivianite while at KU Leuven, I will focus on measuring bioavailability of Fe and P in soils from field trials. GEOTEAM is a consultancy firm specialized in water and soil management, and agriculture. Here, I will be testing new fertilizer products developed during the course of my research with farmers. The goal is to introduce new types of vivianite based P and Fe fertilizers into agricultural practice.

About myself, I am a Nigerian with a Bachelor of Agriculture degree in Soil Science and Land Resources Management from Obafemi Awolowo University. After my BSc, I worked with the International Fertilizer Development Centre, Abuja, Nigeria, as an Agronomist and Master Trainer. A major part of my job was conducting research trials on soil and crop-specific fertilizers based on new fertilizer recommendations. I obtained my master’s degree in Agricultural Science and Resource Management in the Tropics and Subtropics (ARTS) with specialization in soil fertility and phosphorus recycling from the University of Bonn, Germany. I became interested in researching on alternative sources aside phosphate rock for phosphorus fertilizers during my MSc program due to the decline of phosphate rock deposits across the world which is a global challenge for future food security. My MSc thesis was on examining the suitability of compost from human excreta (humanure) and other organic waste materials as a fertilizer. I researched forms of phosphorus found in humanure and biochar and the change of phosphorus extractability during composting of humanure. This experience sparked in me a continual interest in exploring more options about phosphorus recycling from alternative sources. I found the P-TRAP project as a perfect opportunity to explore my interest considering its holistic approach to the global phosphorus challenge and I hope to make the best out of the research and come up with exciting results.

In my free time, I enjoy singing and listening to music, cooking, counselling and discussing topical issues with people of like minds. I have also started to learn Spanish by myself recently since I will be living in Spain for the next 3 years. I look forward to taking Spanish classes at the language Institute of the University of Seville and hope to achieve a professional working proficiency level in the language during the course of my PhD in Spain.