Hood IL-2700 Automatic Soil Infiltration Meter

Overview

The Hood IL-2700 Automatic Soil Infiltration Meter is a field-deployable, pressure-controlled infiltration measurement system engineered for high-reproducibility quantification of saturated and near-saturated hydraulic conductivity (K_sat) in situ. It operates on the principle of constant-head (or variable-head) infiltration under controlled surface pressure conditions, utilizing a Mariotte reservoir to maintain hydrostatic head stability during measurement. Unlike traditional double-ring infiltrometers requiring soil surface sealing or contact-layer preparation, the IL-2700 employs direct-contact ring placement—eliminating edge flow artifacts and minimizing site disturbance. Its design adheres to the theoretical framework of Wooding’s steady-state solution for axisymmetric infiltration into homogeneous, isotropic porous media, enabling robust K_sat derivation without iterative numerical inversion. The instrument is calibrated for use across diverse soil textures—from sandy loams to structured clayey soils—and supports both transient and quasi-steady-state analysis modes.

Key Features

• Direct surface deployment: No soil surface pre-treatment, no sealing compound, and no interfacial layer required—reducing setup time and operator-induced variability.
• Mariotte-type pressure regulation system (5 L capacity) ensures stable, bubble-free water supply with automatic head compensation over extended measurement durations.
• Adjustable surface pressure range from +25 cm to −25 cm H₂O, enabling precise determination of air-entry value and bubble point pressure via integrated U-tube manometer (±1 mm resolution).
• Dual-ring configuration: 16 cm and 24 cm diameter infiltration chambers allow comparative assessment of scale-dependent infiltration behavior and lateral flow correction.
• Onboard data logger records up to 2,000 sequential measurements at user-defined intervals (1–100 s), with real-time display on integrated LCD screen.
• RS232 serial interface enables direct connection to laptop or field tablet for live monitoring, parameter adjustment, and firmware updates.
• Pressure transducer and flow-path architecture conform to ISO 11274:2022 (Soil quality — Determination of saturated hydraulic conductivity) and ASTM D3385–22 (Standard Test Method for Infiltration Rate of Soils in Field Using Double-Ring Infiltrometer).

Sample Compatibility & Compliance

The IL-2700 is validated for use on undisturbed, minimally tilled, or cultivated mineral soils with minimal surface crusting or vegetation interference. It accommodates heterogeneous profiles when combined with complementary methods (e.g., tension infiltrometry or Guelph permeameter). All wetted components are constructed from UV-stabilized polypropylene and stainless steel (AISI 316), ensuring chemical resistance to common field contaminants including humic acids, low-concentration fertilizers, and mildly acidic or alkaline pore waters. The system meets CE marking requirements for electromagnetic compatibility (EN 61326-1) and environmental protection (RoHS Directive 2011/65/EU). Data acquisition protocols support audit-trail generation compliant with GLP principles, and raw timestamped datasets are exportable in CSV format for traceability.

Software & Data Management

The included Windows-based software (v4.2+) provides full control over sampling parameters, real-time visualization of cumulative infiltration vs. time, and automated K_sat calculation using Wooding’s analytical solution. Users may apply linear or non-linear regression to select the steady-state segment, manually exclude outlier points, and overlay multiple runs for comparative analysis. Export options include PNG/SVG graphics, tabular reports with metadata (GPS coordinates, soil description, ambient temperature), and batch-processed summary files compatible with GIS platforms (e.g., QGIS, ArcGIS Pro). The software maintains local encryption of calibration coefficients and supports password-protected user profiles for multi-operator environments.

Applications

• Field-scale assessment of infiltration capacity for irrigation scheduling and drainage design.
• Evaluation of soil structural degradation following tillage, compaction, or fire events.
• Calibration and validation of vadose zone models (e.g., HYDRUS-1D, SWAP) used in watershed hydrology and contaminant transport studies.
• Long-term monitoring of infiltration trends in restored ecosystems, landfill covers, and green infrastructure (bioswales, rain gardens).
• Supporting regulatory submissions under EU Soil Thematic Strategy, US NRCS Technical Note Hydrology-5, and FAO’s World’s Soil Resources Report frameworks.

FAQ

Does the IL-2700 require soil surface leveling or removal of organic litter prior to measurement?

No—its ring base is designed to conform to minor surface irregularities; only large debris or standing water must be cleared.
Can the instrument measure unsaturated hydraulic conductivity?

Not directly; it quantifies near-saturated K_sat. For unsaturated conditions, coupling with tension infiltrometry or evaporation-based methods is recommended.
Is the U-tube manometer factory-calibrated and traceable to national standards?

Yes—each unit ships with a NIST-traceable calibration certificate for the manometer scale and pressure transducer.
What maintenance is required between field deployments?

Rinse all wetted parts with deionized water after use; inspect O-rings for compression set; verify Mariotte tube seal integrity before each campaign.
Is remote data transmission supported (e.g., via GSM or LoRaWAN)?

Not natively—the RS232 interface supports third-party telemetry modules, but wireless capability requires external hardware integration and custom scripting.