Discrimination of soil aggregates using micro-focus X-ray computed tomography in a five-year-old no-till natural fallow and conventional tillage in South Africa

Soil use and management effect on soil microstructure was quantified. Soil aggregates ∼10 mm diameter were collected from two fields: a five-year-old No-till natural fallow management (NTNF) and continuous cultivation (CC). The aggregate microstructure was determined with X-ray micro-focus computed tomography (X-ray μCT) and image analysis was done using VGstudio MAX 3.0. Aggregate stability was higher in NTNF by ≈ 5.7%. Micro-aggregates constituted ≥80% of the aggregates in both treatments. Total porosity, microstructural pore properties (pore distribution, pore shape proportion) and visualization were similar in NTNF and CC. Despite the similarities, aggregates under NTNF had higher total number of pores. Therefore, managing soil through NTNF improve porosity even when the effect on the overall soil aggregation is not obvious. The study showed that aggregate stability is significantly linked to aggregate microstructure.