Chapter 3: pH and EC Measurement
Soil pH and electrical conductivity (EC) are fundamental indicators of soil health and fertility. This chapter explores their importance, measurement technologies, and application in precision agriculture.
Soil pH measures the acidity or alkalinity of soil on a scale from 0 to 14, with 7 being neutral. Most agricultural soils range from pH 4.5 to 8.5. pH affects nutrient solubility, microbial activity, and overall soil chemistry.
Glass electrode pH sensors are the standard for soil measurement. A glass membrane sensitive to hydrogen ions generates a voltage proportional to pH. The WIA-AGRI-005 standard requires pH accuracy of ±0.2 units with 0.1 unit resolution.
EC measures the soil's ability to conduct electricity, indicating salt concentration and overall fertility. Measured in deci-Siemens per meter (dS/m), EC values typically range from 0 to 4 dS/m in agricultural soils.
| EC Range | Salinity Level | Impact |
|---|---|---|
| 0-2 dS/m | Low | Suitable for most crops |
| 2-4 dS/m | Medium | Some crop restrictions |
| 4-8 dS/m | High | Limited crop selection |
| >8 dS/m | Very High | Most crops affected |
Combined pH and EC monitoring enables precise soil management. pH adjustments using lime or sulfur optimize nutrient availability. EC monitoring prevents salt buildup and guides irrigation and fertilization strategies.