Sustainable Nutrient Management

Undergraduate Research – Harnessing Atmospheric Nitrogen

My name is Adeiza Adonuja. Right from when I was young in Nigeria, we played with soil. Little did I know that soil was going to be my career. I gained admission into the Federal University of Technology, Minna, Niger State, Nigeria, to study agricultural science, majoring in soil science and land management. While I was in my final year, I worked on a research project titled Effect of inoculation of legume seeds with elite rhizobia strains on some farmers’ fields.

Nitrogen is one of the macronutrients that plants need, but it is one of the most limited nutrients in the soil because nitrogen is not a constituent of rock minerals. This means nitrogen (nitrate or ammonium) is not present naturally in the soil; it has to be added to the soil through soil amendment, either organic or inorganic. These amendments (fertilizers) are expensive, and local farmers or rural communities cannot afford to buy them, whereas the percentage of nitrogen in the atmosphere is more than 70%. What if there is a way to harness this nitrogen that is abundantly present in the atmosphere into the soil? This is where my undergraduate research comes in. The rhizobia strains are bacteria that have the capacity to go into a symbiotic relationship with legumes (soybean, cowpea, and peanut) and fix the atmospheric nitrogen into the soil.

Master’s Research—Land Use, Nutrient Dynamics, and Carbon Sequestration

Then I got an opportunity to study at Florida A&M University for my master’s in agricultural science, majoring in soil and water sciences, where I worked with a lot of professors in the nutrient management laboratory, the water quality laboratory, and the Center for Water Resources. I sampled soil and water and did an analysis. The problem I tried to solve in my master’s was environmental challenges, with my research topic being the impact of long-term land use on soil nutrient dynamics in Brooksville, Central Florida. These land uses were wetlands, cropland, and forest. The behaviors of nutrients in different land uses differ, and their fate differs too; they may be leached, transported to the water bodies, or absorbed into the soil matrix, which may cause groundwater contamination and eutrophication.

The major focus of this research was on carbon dioxide as a greenhouse gas, which is emitted from agricultural lands. The soil has twice the amount of carbon stored in it than the ocean and the vegetation combined. This makes the soil the way to go when we talk about tackling global warming. I want to show people the value the soil has in solving most of the global problems we face today. First, it was fixing the abundance of nitrogen in the atmosphere to solve the limited nitrogen in the soil. Second is storing carbon in the soil through a process called soil carbon sequestration, which removes carbon dioxide from the atmosphere that is causing global warming and climate change, thereby mitigating global warming.

PhD Research – Nutrient Transport Modeling and Sustainable Amendments

Then I went on to further study for my PhD in Civil and Environmental Engineering at Florida A&M University, still on the quest to use soil to solve problems. Right now, what I am working on or what I want to solve is studying nutrient transport, leaching, and adsorption, and then a model to be able to predict nutrient behavior in soil. The nutrients I am working on right now are nitrate and phosphorus, which are responsible for algal bloom and eutrophication.

Now the amendment is trying to shift from the conventional or synthetic process that was developed through the Haber-Bosch process in 1913, meeting the demand to increase agricultural production due to the increasing human population, which has placed huge pressure on the soil, and it has become depleted of nutrients. This Haber-Bosch process did not take into consideration the impact of this synthetic fertilizer on the environment. Because these fertilizers are synthesized to readily provide nutrients to plants and crops, the plants take up nutrients slowly, and the nutrients are in the available form, so when there is heavy precipitation, these nutrients are washed from the soil through runoff and leaching, and our environments and water bodies get contaminated.

This is where my PhD research comes in to test a newly developed amendment from electrochemically treated biosolid, keeping in mind environmental safety. This research focuses on solving two major problems, which are environmental safety and soil fertility.