Estimating Earthworm‐Influenced Soil Structure by Morphometric Image Analysis

Abstract

Earthworms have a profound influence on soil processes. However, there is generally a lack of adequate means by which to assess the influence of earthworms on soil structure. Not until quantitative methods on undisturbed soil samples are developed will there be any adequate measure of the influence of earthworms on soil structure. This paper describes an extension of an image‐analysis method developed for the quantitative determination of the influence of earthworms on soil structural properties. Mammillated vughs are most likely developed by the burrowing of soil macrofauna, in particular earthworms. A learning set of mammillated vughs was compiled with pores taken from a soil developed solely through the channeling and casting of earthworms. This learning set was used to classify soil blocks taken from a no‐till and conventionally tilled treated soil. The results indicated that the no‐till soils had more than twice the number of mammillated vughs >1000 μm in diameter. This was attributed to the larger earthworm population in the no‐till soils, coupled with the change in morphology or destruction of some of the mammillated vugh features caused by disturbance in the conventionally tilled soil. This method should allow for a more effective means to evaluate the influence of earthworms on soil properties within any given soil profile.