1、A meta

Hyperspectral and multispectral remote sensing provide effective, non-invasive tools for estimating crop leaf nitrogen, phosphorus, and potassium content (LNC, LPC, and LKC). Therefore, a comprehensive evaluation of these technologies is needed.

2、(PDF) Colorimetric detection of nitrogen, phosphorus, and potassium

In order to precisely provide nitrogen, potassium, and phosphorus via irrigation, this study designed a method for their field detection based on photoelectric colorimetry.

3、Real

In this review, several technologies, and methods for analyzing Nitrogen, Phosphorus, and Potassium (NPK) levels are reported and discussed highlighting their advantages and limitations.

4、Optical Sensing of Nitrogen, Phosphorus and Potassium: A

The feasibility of a compact, modular sensing system able to quantify the presence of nitrogen, phosphorus and potassium (NPK) in nutrient-containing fertilizer water was investigated.

5、Methods for Determining Nitrogen, Phosphorus, and Potassium (NPK

Nutrient Content NPK is macronutrient content that important for the growth of a plant. The measurement of NPK conducted periodically, but the measurement using.

Determination of Nitrogen, Phosphorus, and Potassium in Water

A modification of an inductively coupled plasma (ICP) emission spectrometer is described that enables the simultaneous determination of nitrogen, phosphorus, and potassium in water-soluble fertilizers.

Application of Visible/Near Infrared Spectrometers to Quickly Detect

In this study, a small visible spectrometer and a small near-infrared spectrometer were used to collect spectrum information of 33 different common chemical fertilizers including compound fertilizers, blended fertilizers and controlled-release fertilizers.

(PDF) Determination of soil nutrients (NPK) using optical methods: a

It also explains briefly the working of each method and mentions the most recent advancements made in the given testing method.

Detection of nitrogen, phosphorus, and potassium (NPK) nutrients of

Detection of nitrogen, phosphorus, and potassium (NPK) nutrients of soil using optical transducer Published in: 2017 IEEE 4th International Conference on Smart Instrumentation, Measurement and Application (ICSIMA)

Methods for Determining Nitrogen, Phosphorus, and Potassium (NPK

This Research is conducted to determine the nutrient content of the soil, consisted of nitrogen, phosphor, and calcium (NPK) using digital image processing based on Features from Accelerated Segment Test (FAST) and backpropagation artificial neural network.

Nitrogen (N), phosphorus (P), and potassium (K) are the three major nutrient elements essential for plant growth. These nutrients play crucial roles in agricultural production, making their identification methods particularly important. The following categories outline methods for distinguishing nitrogen, phosphorus, and potassium fertilizers:

1. Physical Methods

• Color Observation: Nitrogen fertilizers are typically white or light gray, phosphorus fertilizers are dark gray or black, and potassium fertilizers appear yellowish or brown.
• Shape Inspection: Nitrogen fertilizers often come in granular form, phosphorus fertilizers are usually powdery, and potassium fertilizers may be flaky or block-shaped.
• Texture Touch: Nitrogen fertilizers are loose and easy to crush; phosphorus fertilizers are hard and resistant to crushing; potassium fertilizers are relatively soft but less fragile than nitrogen fertilizers.
• Weight Comparison: Nitrogen fertilizers are generally heavier than other fertilizers of the same volume due to larger nitrogen molecules, while phosphorus and potassium fertilizers are lighter.

2. Chemical Methods

• Solubility Test: Observe dissolution in water. Nitrogen fertilizers dissolve quickly, phosphorus fertilizers slowly, and potassium fertilizers are insoluble.
• pH Testing: Use titration to measure acidity/basicity. Nitrogen fertilizers are typically acidic, while phosphorus and potassium fertilizers have higher pH levels.
• Ion Detection: Employ instruments like atomic absorption spectrometers to detect N, P, and K content.
• Combustion Method: Heat the sample and analyze combustion products. Nitrogen fertilizers produce blue flames, phosphorus fertilizers release white smoke, and potassium fertilizers yield purple flames.

3. Biological Methods

• Biological Assay: Use specific microorganisms (e.g., nitrogen-fixing bacteria) to detect nitrogen content.
• Enzyme Activity Determination: Assess soil enzyme activity (e.g., urease activity) to estimate nitrogen, phosphorus, or potassium levels.

4. Instrumental Analysis Methods

• X-ray Fluorescence Spectrometry (XRF): Measure elemental X-ray absorption rates to quantify N, P, and K.
• Infrared Spectroscopy (IR): Analyze organic/inorganic compound absorption patterns to identify fertilizer components.
• Nuclear Magnetic Resonance Spectroscopy (NMR): Detect hydrogen nuclear signals to determine nutrient content.
• Mass Spectrometry: Identify elements based on mass-to-charge ratios.

5. Empirical Methods

• Visual Inspection: Judge fertilizer type by color, shape, texture, and other physical traits.
• Label Reference: Check packaging labels for stated N, P, and K concentrations.
• Expert Consultation: Seek input from experienced farmers or agronomists.

Diverse methods exist for identifying nitrogen, phosphorus, and potassium fertilizers. For accuracy, combining multiple approaches is recommended. In agricultural practice, tailoring the identification strategy to specific contexts ensures reliable results.