Overview
ISO 7256-2:1984 - "Sowing equipment - Test methods - Part 2: Seed drills for sowing in lines" defines a standardized laboratory and field-compatible test method for evaluating seed drills that sow in lines. The primary objective is reproducibility and comparability of performance results for a given model of equipment when tests are performed in geographically remote locations or under different climatic conditions. The standard limits mandatory field testing to preserve reproducibility, provides a program of mandatory tests (Annex A), optional supplementary tests (Annex B), and an example test report format (Annex C).
Key topics and technical requirements
- Scope and goal: Produce comparable numerical and graphical performance data that account for seed type, hopper level, application rate settings, forward speed, ground slope and surface irregularities (bumps).
- Test categories:
- Static tests (machine stationary; drive wheel rotated to simulate forward speed)
- Mobile tests (machine driven at constant ground speed over uniform surface)
- Mandatory test focus:
- Evenness of flow rate (static collection under each feed mechanism)
- Accuracy of metering (distribution longitudinally and transversely; mobile adhesive strip or visual/acoustic recording)
- Effects of seed level in hopper, flow rate, slope and bumps
- Test parameters and procedures:
- Seed selection by type (regular, small round, light bearded, irregular) and recording of physical characteristics (germination, bulk density, 1 000-seed mass, moisture, purity)
- Typical forward speeds used in tests include 1.50 m/s and 2.50 m/s and the manufacturer’s maximum admissible speed
- Flow tests: seeds collected and weighed (example: five 30 s runs)
- Metering tests: seeds counted in 100 mm sections on adhesive strips; statistical metrics (mean, standard deviation, coefficient of variation) are calculated for performance assessment
- Documentation: Manufacturer instructions and technical specifications must be checked and noted in the test report; Annex C provides an example report format.
Applications and users
Who uses ISO 7256-2:
- Test laboratories and certification bodies seeking reproducible test protocols for seed drills
- Manufacturers and R&D teams for product development, quality control and validation of seed metering systems
- Procurement and specification authors who need objective performance data for purchasing decisions
- Agricultural engineers and researchers analyzing seed distribution, calibration and machine performance
Practical benefits:
- Ensures consistent evaluation of seed drills for sowing in lines
- Enables comparison between models and across testing locations
- Supports troubleshooting of metering, hopper design and field performance effects (slope, bumps)
Related standards
Keywords: ISO 7256-2, seed drills test methods, sowing equipment standard, seed drill testing, metering tests, flow rate, agricultural machinery standards.
