Rapid soil compaction assessment

 Project Title

L07-033 Rapid assessment of soil compaction contributions to losses in field crops

Project Funding

  • MAF Sustainable Farming Fund
  • Foundation for Arable Research
  • Hawke's Bay Regional Council

Project Status

Completed 2009


The study was conducted to evaluate:
  • Whether a Troxler Soil Moisture-Density Gauge can give a valid measure of soil density in cropping fields.
  • Whether soil density is altered by cultivation practices and if it affects yield


Gauge validation The Troxler gauge was calibrated on several different cropping soils.  Densometer and moisture readings were made to 150 mm and 300mm soil depth. The probe was removed and physical soil density cores extracted, dried and density calculated.  Effect of density on yield The Troxler was used to determine soil density and soil moisture in three strip-tilled maize paddocks with different soil types; clay loam, silt loam and sand. Two separate plant growth zones were identified within each paddock. On the clay loam and sand, areas with small plants and large plants (at growth stage V6) were each sampled for density and moisture. In the silt loam paddock, half had been deep ripped to alleviate compaction and the other half not. Final yields were measured and correlations with soil density and moisture at early growth determined.

Main Findings

The Troxler nuclear densometer can give reliable soil density readings. The machine derived density values were not reliable unless calibrated for each soil. However, if machine counts were used, a strong, soil dependent correlation between the machine derived density and physically measured core density was found.  It is far quicker to take many readings using the Troxler than to take, transport and process numerous physical core samples. But some samples are required for calibration. We did not find a strong correlation between soil density sampled at maize growth stage V6 and final yield. On the sand, half the small plants were in wet, and half in dry, locations. Half the small plants had higher soil density and half lower. The deep ripped paddock showed some differences in soil density, but not in yield.

Download Project Reports

Report summary Assessing compaction contributions to crop losses using a soil moisture gauge 294 kB pdf Full project science report Rapid Assessment of Soil Compaction using a soil moisture density gauge 838kB pdf Draft protocol for Calibration of Troxler 75kB

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