X-ray computed tomography-measured soil pore parameters as influenced by crop rotations and cover crops

This study examined the effect of crop rotations and winter cover crops (CCs) on near-surface pore characteristics of a silty clay loam soil in a 27-yr no-till field experiment. The crop rotation treatments included a 2-yr corn (Zea mays L.)-soybean [Glycine max L. (Merr.)] (CS) rotation and a 4-yr corn-soybean-oat (Avena sativa L.)-winter wheat (Triticum aestivum L.) (CSOW) rotation. The subplot treatment was CC and no-CC (fallow). Intact soil cores (7.62 by 7.62 cm) were extracted from each treatment in July 2018 from soybean plots and examined for X-ray computed tomography (CT)-measured pore parameters and other soil physical and hydrological properties. Data showed that, compared with fallow, the CC reduced bulk density (rho (b)) by 6% and increased saturated hydraulic conductivity (K-sat) and water infiltration rate (q(s)) by 1.5 times. Soils under CSOW rotation had 16, 14, and 4% higher values of soil organic carbon (SOC), total nitrogen (TN), and wet aggregate stability (WAS) compared with those under CS rotation, respectively. The CSOW rotation significantly (P < .05) increased number of CT-measured pores, number of macropores (>1,000 mu m diameter), coarse mesopores (226-1,000 mu m diameter), macroporosity, and mesoporosity compared with the CS system. The CT-measured total porosity, number of macropores, and macroporosity were 43, 34, and 60%, respectively, higher with CC as compared to the fallow plots. The CT-measured pore parameters were well correlated with soil rho (b), K-sat, q(s), SOC, TN, and WAS. This study emphasizes that cropping systems that include diverse crop rotations (CSOW) and CC has potential to enhance SOC, pore characteristics, and associated physical and hydrological properties.