1. NPK Detection: The NPK sensor in the soil measures the levels of nitrogen, phosphorus, and potassium present.

2. Data Conversion: The measured data is initially in milligrams per kilogram (mg/kg). The app converts this data to kilograms per hectare (kg/ha) using the bulk density (mg/kg * bulk density/m³ * depth/m / 1000).

3. Calculating Required Fertilizer: The converted data is then subtracted from the recommended fertilizer amount, which is stored in a database specific to different crops and soil types. This calculation determines the required amount of fertilizer.

4. Final Answer: The app divides the required amount of fertilizer by the concentration of NPK to determine the exact quantity needed. This final answer indicates the amount of fertilizer in kg the farmer should apply to the field.

1. Optimized Fertilizer Usage: The solution ensures that crops receive the appropriate amount of fertilizer, reducing waste and preventing overuse or underuse of nutrients.

2. Cost Efficiency: Farmers can save costs by using fertilizer more efficiently, as they will only apply the required amount instead of excess.

3. Environmental Sustainability: By minimizing fertilizer runoff, the solution helps prevent water pollution and negative impacts on ecosystems.

4. Increased Crop Yield: Providing crops with the correct amount of nutrients promotes healthy growth and can lead to improved yields.

This solution differs because it combines hardware (NPK sensor) and software (mobile app) to provide a best approach to fertilizer monitoring. It considers factors like crop type, soil type, bulk density, and depth to calculate the exact fertilizer requirement. Additionally, the integration with a mobile app makes it user-friendly and accessible to farmers.

1. Technical Challenges: The hardware components, such as the NPK sensor and connectivity devices, may cause technical issues.

2. Data Accuracy: The accuracy of the NPK sensor readings and the inputted data from farmers may affect the accuracy of the fertilizer recommendations. Moreover, the data provided for the amount of fertilizer required may not be accurate, which may result in decrease of yield as well.

1. We should develop the NPK sensor hardware and mobile app software.

2. We should educate farmers about the benefits and usage of the solution, providing training on using the mobile app and inputting accurate data.

3. We should rgularly update the fertilizer database within the mobile app to maintain accuracy.

We should gather feedback form farmers so to improve ourself and by completing their needs. We should maintain its acuracy, affordability and should ensure that it does not affect environment and increase crop yield.