Phosphorus, one of the major three nutrients for plants, is required for plant growth, and it serves as an indicator for global environmental sustainability. It is important to understand the variations of phosphate in soils and soil-water systems in order to address a number of global challenges such as food production and regulating fertilizer applications for crops grown in various soil conditions and climate regimes. The goal of this research project is to use the latest graphene-based technology to develop a low-cost sensor capable of real-time monitoring of the phosphorus content in soil. This collaborative project between researchers at the U.S. institutions of Kansas State University and the University of Alabama at Huntsville, and the U.K. institution of the University of Sheffield, will be conducted by an interdisciplinary team with expertise in soil and water science, geology, electrical engineering, and the fundamental chemistry and physics of soil-graphene interactions. Development of such sensors will enable farmers to choose the right amount of fertilizer to apply to the fields. This research project aims to develop an additively-manufactured graphene sensor array and a portable wireless system for continuous in-field monitoring of electrochemical signals. Such a system would be applied to the mapping of soil phosphates in diverse agricultural landscapes in the US Midwest (Kansas) and the UK East Midlands (Derbyshire Dales and Peak District). Structurally and chemically tailored graphene materials will be used to print graphene sensors with quasi-three-dimensional and porous graphene morphologies. The materials will be designed to achieve high electrical conductivity as well as reversible and high electron charge-transfer characteristics when exposed to soil phosphates. A fundamental understanding of phosphate ion binding with various graphene morphologies will be gained using state-of-the-art ultrafast laser spectroscopy and high-end computational modeling. A Bluetooth communication module with an Arduino platform will be constructed and interfaced with the sensor arrays for sensor data acquisition. Controlled environmental testing of spatial and temporal variations of phosphate ions over other interfering ions will be carried out at specific sites in Kansas and at Europe's largest controlled environment P3-facility housed at the University of Sheffield. The fundamental sensing characteristics and drift optimization with temperature, humidity, salinity, and soil pH will be identified and optimized for reliable data collection. Soils ranging from coarse calcareous to loamy montmorillonitic and silicate-rich soils in two countries will be utilized as testbeds to measure the sensing capabilities of the printed arrays. Furthermore, the project will explore the detection of phosphates over other interfering ions in soils, such as nitrates, silicates, and heavy metals, by using chemically-functionalized graphene sensors. This research will help to strengthen the national and economic security of both the U.S. and the U.K. and will strengthen the future workforce by bridging the gaps between science, technology, agriculture, and environmental disciplines through the training of graduate students, undergraduate students, and postdoctoral scientists.