Description
A 3-in-1 Soil NPK Sensor is a soil testing device that measures the levels of nitrogen (N), phosphorus (P), and potassium (K) in the soil within a range of 0–1999 mg/kg, allowing quick assessment of soil fertility. It is widely used in smart agriculture, greenhouse cultivation, and precision farming to help users optimize fertilization, improve crop growth conditions, and increase yield efficiency. ATO soil NPK sensor supports RS485 and analog output for easy integration with data loggers, controllers, and IoT systems for real-time monitoring and remote data management.
Technical Specifications
| Specification | Details |
| Model | ATO-OHR-MT50 |
| Measurement Range | 0–1999 mg/kg (N, P, K) |
| Resolution | 1mg/kg (N, P, K) |
| Accuracy | ±2% F.S. (N, P, K) |
| Response Time | ＜1 s (Real-time feedback) |
| Power Supply | DC 10–30 V (Wide voltage support) |
| Power Consumption | ≤0.15 W (@12 V DC, 25°C) |
| Operating Temperature | 0–55°C |
| Output Types (Optional) | RS485 (Modbus RTU) / 4–20mA / 0–5V / 0–10V |
| Protection Rating | IP68 Waterproof |
| Probe Material | High-grade 316 Stainless Steel |
| Sealing Material | Black flame-retardant epoxy resin |
| Load Resistor | Current Output RL ≤ 500 Ω; Voltage Output RL ≥ 250 kΩ |
| Installation | Direct insertion |
| Cable Length | 2 m (customizable) |
| Dimensions | 45 × 12 × 128 mm |
| Weight | 500g |
| Certification | CE |
| Warranty | 12 months |
Features & Benefits
- Precision Nutrient Analysis: Measures Nitrogen (N), Phosphorus (P), and Potassium (K) with a full measurement range of 0–1999 mg/kg and a resolution of 1 mg/kg.
- Industrial Durability: Equipped with 316 stainless steel probes, specifically designed for corrosion resistance and to withstand electrolysis in saline or heavily fertilized soils.
- IP68 Military-Grade Sealing: Unlike standard sensors, our vacuum-sealed black flame-retardant epoxy resin ensures the unit is 100% waterproof and structurally stable for multi-year underground deployment.
- Multi-Protocol Output: Whether you need an RS-485 soil NPK Sensor for Modbus RTU networks or a 4-20mA soil nutrient transmitter for PLC integration, ATO offers full compatibility.
- Ultra-Low Power for IoT: Consuming ≤0.15 W, it is the ideal low-power soil sensor for IoT gateways, solar-powered weather stations, and remote data loggers.
- Rapid Response: Get real-time feedback in <1s, enabling high-frequency data collection for automated greenhouse fertilization.
Size (unit: mm)
Wiring
Wiring for Transmitter Output
| Wire Color | Description |
| Red | Power + |
| Black | Power – / Transmitter Output – |
| Brown | Transmitter Output + |
Wiring for RS485 Output
| Wire Color | Description |
| Red | Power + |
| Black | Power – |
| Yellow | RS485 A |
| Green | RS485 B |
Note: Actual wiring colors may differ; always follow the manual or label provided with the sensor.
Typical Applications
- Precision Agriculture & Fertigation: Integrate into a real-time soil nutrient monitoring system to reduce fertilizer waste and improve crop yield through “on-demand” nutrient delivery.
- Smart Greenhouse Management: Use as an automated greenhouse fertilization sensor to maintain optimal NPK ratios for high-value hydroponic or soil-based crops.
- Soil Research & Geology: Provides researchers with high-frequency data for in-situ soil NPK measurement in forest ecology or land reclamation studies.
- Commercial Horticulture: Ideal for golf courses and urban landscaping to ensure turf health while monitoring the environmental impact of runoff.
- Digital Farming IoT Networks: A cost-effective node for wholesale soil sensor deployments across large-scale “Smart Farm” initiatives.
Note: While highly versatile, this soil sensor is designed for soil and solid substrates. It is not recommended for pure liquid hydroponics or highly rocky terrain, where the probes might be physically bent during insertion.
| NPK Sensor for Smart Greenhouses | NPK Sensor for Forestry & Orchards | NPK Sensor for Soil Research |
Selection Guide: Choosing Your Soil NPK Sensor
When selecting a 3-in-1 industrial-grade soil NPK sensor, consider your integration architecture:
| Factor | Recommendation | Why it matters |
| System Type | RS485 (Modbus RTU) | Best for digital soil NPK analyzers connecting multiple nodes to a single BUS (up to 1200m). |
| Industrial Control | 4-20mA / 0-10V | Standard for legacy PLC systems; 4-20mA offers the best noise immunity for long cables. |
| Developer Use | 0-5V Output | Preferred soil NPK sensor for Arduino/Raspberry Pi projects and rapid prototyping. |
| Environment | IP68 / 316 Steel | Essential for long-term buried applications where soil acidity would degrade plastic probes. |
FAQ
Q1: How do I calibrate the ATO soil NPK sensor?
The soil sensor comes factory-calibrated. For field recalibration, compare readings with lab soil test data and adjust your system baseline accordingly.
Q2: Which communication interface should I use for IoT integration?
RS485 with Modbus RTU is recommended for long-distance and networked systems because of its strong anti-interference capability.
Q3: How does it compare to a lab test?
Lab tests are for one-time audits; the ATO NPK sensor is for real-time management. It captures the “when” and “where” of nutrient changes that periodic lab tests miss.
Q4: Can this NPK sensor be left in the soil during winter?
Yes. With an IP68 rating and flame-retardant epoxy sealing, the ATO-OHR-MT50 sensor is designed for long-term burial. It operates safely between 0–55°C.
Q5: How to protect the cable from livestock or field damage?
Use IP66 waterproof junction boxes and bury cables in PVC conduits for maximum durability.
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