Cover crop effects on μCT‐measured geometrical pore characteristics

Abstract

Cover crops (CC) could improve soil physical, chemical, and biological properties; however, the micrometer scale quantification of geometric pore characteristics in CC soil is limited in the literature. The objective of this study was to differentiate geometrical pore characteristics between CC and no CC (NCC) by computed tomography (CT). The study design consisted of winter CC and summer corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation with no‐till management. The sample cores were collected after 7 yr of mixed species CC establishment. Six 0‐to‐65‐mm‐long soil cores (28‐mm diam.) were imaged at 29‐μm resolution, and three‐dimensional volumes were analyzed using Fiji‐ImageJ2 software. Slice thickness was 29 μm, and the minimum achievable voxel size was 90 nm. Images within the top and bottom 7.25 mm were removed, and two depths within a core were analyzed for soil pore parameters. The total pore volume was significantly greater (P < .05) in CC compared with NCC, with 8.4 and 2.5 times greater values in CC at 7.25–27.25 and 37.25–57.25 mm, respectively. The total (individual + branched) and the individual pore count were significantly greater (P < .05) in CC compared with NCC for both depths. The porosity of CC soil at 7.25‐to‐27.25‐mm depth was 10 times greater than that of NCC. The branched pore count was not significantly different between two treatments. Overall, the micrometer scale determination of geometrical pore network characteristics showed added benefits of CC use compared with NCC; thus, the use of CC can be beneficial in improving soil pore networks.