ISO 7256-2:1984

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

• ISO 7256-1 (precision/single seed drills) - related part of the ISO 7256 series
• ISO 3339 (classification and terminology for sowing equipment)
• ISO 3534 (statistics vocabulary)
• ISO 5698, ISO 5699, ISO 7424 (related agricultural equipment and hopper/test dimensions)

Keywords: ISO 7256-2, seed drills test methods, sowing equipment standard, seed drill testing, metering tests, flow rate, agricultural machinery standards.