Chemical fertilizers are synthesized industrially out of estimated proportions of elements like nitrogen, phosphorus, and potassium[1], which provide necessary nutrients for plants to flourish vigorously. Due to intensive cultivation and the insufficient replenishment of nutrients, fertilizers mitigate precipitously declining soil fertility. In combination with organic fertilizers, chemical fertilizers can even revitalize arable lands. Although chemical fertilizers are indispensable to sustain soil fertility and avoid food shortages considering the current human population, they can also be noxious without painstaking attention to soil test reports. Since chemical fertilizers directly affect soil integrity and permeate through water bodies, they can contaminate the groundwater and the environment while contributing a remarkable gain in crop production. Also, chemical fertilizers infiltrate the soil and make plants vulnerable to various pathogens by hampering their roots[1].

When chemical fertilizers disperse throughout water bodies, they increase macronutrients in the environment, such as nitrogen, potassium, and phosphorus, resulting in contamination and eutrophication (nutrient pollution). These macronutrients can cause serious health problems due to overexposure. For instance, nitrogen can remain in water bodies for several years and cause nitrite (and nitrate) to accumulate exponentially. As a result of the high nitrite accumulation, nitrite-contaminated water can cause a blood disorder called methemoglobinemia (MetHb), also known as Blue Baby Syndrome. Furthermore, chemical reactions between nitrites heavily used in synthetic fertilizers instigate DNA damage, lipid peroxidation, and oxidative stress, which can all result in increased cellular degeneration. As a major health issue caused by the excessive use of chemical (synthetic) fertilizers, cellular degeneration can increase the risk of developing cancer. Forebodingly, a 2009 study by researchers at Rhode Island Hospital has found a substantial link between increased levels of nitrates in our environment and food with increased deaths from diseases, including Alzheimer's, diabetes mellitus, and Parkinson's[2].

According to earlier estimations, fertilizers provided approximately 70% of plant nutrients in 2020 at a global level[3]. Therefore, at this point, we cannot obviate the need for organic and chemical fertilizers to achieve sustainable crop production. Nevertheless, applying organic fertilizers in conjunction with chemical fertilizers can engender unexpected results and exacerbates the detrimental effects of chemical (synthetic) fertilizers. Since organic fertilizers behave differently depending on their manufacturing conditions, they change the degree of soil permeability of different soil types, such as loamy, peaty, silty, chalky, etc., not only unpredictably but also structurally. Hence, applying chemical fertilizers to the soil structurally altered by organic fertilizers may intensify the mentioned hazardous effects and lead to serious health conditions.

After scrutinizing the recent research papers on the effects of chemical and organic fertilizers, I noticed there are nearly no appliances focusing on detecting the excessive use of chemical fertilizers in the presence of organic fertilizers and providing real-time detection results for further inspection. Therefore, I decided to build a budget-friendly and easy-to-use proof-of-concept device to detect chemical fertilizer contamination levels with object recognition and inform the user of the model detection results simultaneously in the hope of averting the detrimental effects of fertilizer overuse by prewarning farmers.

To detect chemical fertilizer contamination levels accurately in relation to organic fertilizers, I needed to collect data from a controlled environment manifesting different soil conditions so as to train my object detection model with notable validity. Since utilizing manure as organic...