An in situ method for quantifying tillage effects on soil structure using multistripe laser triangulation

Abstract

Soil structure is an important physical property that can be degraded by soil tillage, but methods for quantifying soil structure are both few and time consuming. We developed a method for multistripe laser triangulation (MLT) scanning to quantify soil structure that can be accomplished quickly (15 min of scanning per A horizon exposure) in the field. We scanned three soil pits to a depth of 30 cm in three fields under conventional tillage (CT), three under no-till (NT) and three under perennial grass (PG). For both 0- to 10- and 0- to 30-cm pit depths, we calculated the Dirichlet tessellation area variability (DTAV) for each pit. We found the DTAV from 0- to 10-cm depths was sensitive to tillage type (p = 0.09) and clay percentage (p = 0.06), while the 0- to 30-cm depths were sensitive to neither. Specifically, CT fields had significantly higher 0- to 10-cm DTAVs than NT (p = 0.06) and PG (p = 0.07) fields, while NT and PG were not different from one another (p = 0.99). The information carried by the DTAV may be thought of as the regularity of the Dirichlet tessellation feature areas, which is driven by the regularity of observable soil structural units in the field. The DTAV was not significantly related to soil structure type, grade, or class size described in the field. The DTAV provides an alternative or complement to field soil descriptions that is quick, repeatable, objective, and sensitive to changes in soil structure in response to tillage practice.