Author: Shane Ylang Major: Environmental, Soil, and Water Sciences 

The recycling of phosphorus (P) from P-containing wastewaters into fertilizers is a necessary area of research for the sustainability of water resources, the environment, and global food production. Phosphorus recycling could reduce our dependence on rock phosphate (RP), reduce eutrophication in surface waters from the cleaner wastewaters that would be put back into the environment, and reduce the need for the excess application of fertilizers that are mostly lost in runoff. A specific example of a wastewater recycled P fertilizer is the mineral struvite (MgNH4PO4 · 6H2O). 

In order to study the possible benefits of struvite, I have conducted a 79-day greenhouse potted-plant experiment. My objective of my experiment has been to help provide further information on possible benefits of the use of struvite within an agriculture setting. I am researching the response of corn and soybean to P fertilization of two struvite sources, Crystal Green (a chemically precipitated struvite) and an experimental (electrochemically precipitated) struvite source made here at the university, alongside four others, commonly used, commercially available P fertilizers in a silt-loam soil. Treatments included two controls and six P sources; 1) unamended control (No P/-N), 2) N control (No P/+N), 3) triple superphosphate (TSP), 4) monoammonium phosphate (MAP), 5) diammonium phosphate (DAP), 6) RP, 7) Crystal Green (CG), and 8) electrochemically precipitated struvite (ECST). All eight treatments were replicated three times for both soybean and corn, totaling 48 pots. 

I recently just finished the growing period of my research. On 7/15/2019, I took the final plant height measurements and each pot was destructively sampled. Each pot had four samples taken for chemical analysis: soil, below- and aboveground plant material, and beans or cobs. All of the plant material was oven-dried, and eventually ground to 2-mm and the soil samples were also oven dried and ground and sieved. A sub-sample of all of the ground samples was then taken, packaged, and sent to the soil testing lab at the Arkansas Agricultural Research & Extension Center in Fayetteville, AR. 

During the data collection of my research, everything went pretty well. However, during the growing stage, there was two insect infestations that required a total of four pesticide applications. Besides the knowledge I gained about the research process, this topic has shown me that there are even more environmental issues facing the world right now. In addition to topics like climate change, pollution and deforestation, the general public does not know what P is used for, how it supports our world, and current and potential future problems that surround the concentrations of P that are around the world.    

Phosphorus is considered a non-renewable resource that is a crucial nutrient for life and worldwide food production. Phosphorus is obtained by mining phosphate-containing rock, RP, a sedimentary rock formed by marine deposits. These RP deposits could be depleted in the next one to two centuries and the depletion of these reserves has the potential to cause severe effects on the world’s food supply and the world’s economic, political, and social relations.  

My mentor, Dr. Kris Brye, has guided me in advice and methodology on how to perform and conduct my research. During my experiment and the deconstruction process, many graduate students helped me along the way by not only providing help physically intensive portions of data collection, but also through advice of their research experience. I also attended the first day of the 2019 Arkansas Water Resource Conference where I present that data I have obtained so far with the other graduate and doctoral students also on the university’s struvite project. The day I attended the conference, speakers gave talks over nutrient recovery and waste water management.  

I am currently working on conducting statistical analysis of the data I have so far, waiting on the chemical analysis of my samples and writing my thesis with the hope of being published.