Effects of tillage and liming on macropore networks derived from X‐ray tomography images of a silty clay soil

Abstract

Soil structure influences water infiltration, aeration and root growth and, thereby, also the conditions for sustainable crop production. Our objective was to quantify the effects of different soil management methods and land uses on the topsoil structure of a silty clay soil. We sampled 32 intact soil columns (18 cm high, 12.7 cm diameter) from an experimental silty clay field with four treatments: conventional tillage (CT), conventional tillage followed by liming (CTL), reduced tillage (RT) and unfertilized fallow (UF). The columns were analysed using 3‐D X‐ray tomography. The samples were taken in autumn after harvest, 7 yr after quick lime was applied to the CTL plots. Despite a relatively large number of replicates per treatment (8, 8, 8 and 6 (two UF samples were excluded), respectively), there were no significant differences between any of the investigated macropore network properties related to tilled treatments. The UF treatment, in contrast, exhibited more vertically oriented macropores, which were also better connected compared to the other treatments. This confirms previous findings that tillage may disrupt the vertical continuity of macropore clusters. The impact of liming on soil pore network properties may have been limited to pores smaller than the resolution in our X‐ray images. It is also possible that the effects of lime on soil structure were limited to a few years which means that any effect would have diminished by the time of this study. These matters should be further investigated in follow‐up studies to understand better the potential of lime amendments to clay soil.

Nutrient leaching driven by rainfall on a vermiculite clay soil under altered management and monitored with high-frequency time resolution

“…This, and the significantly lower CNO 3 N-Q slope than in the three other cropping systems, confirmed findings in adjacent experimental plots of significantly low NO 3 N leaching from fallow (Svanbäck et al 2014). At the same time, there was relatively high PP transport from the experimental plots under fallow, possibly because there were more vertically oriented macropores in fallow soil than in ploughed soil and the macropores were also better connected (Hellner et al 2018). In general, high variability in turbidity relative to Q for fallow (CV T /CT Q ) was observed in the present study.…”

Quantification of the relationship between root parameters and soil macropore parameters under different land use systems in Retisol

“…The six columns of soil from different land uses (forest, grassland and arable land) and soil depths (3-8 and 15-20 cm) are presented in Figs 1 and 2 in the form of 3D visualiza-tions of macropores in the soil. According to literature, the formation of smaller macropores is influenced by freezing and thawing, or the wetting and drying processes occurring in the soil (Hellner et al, 2018;Luo et al, 2010).…”

Estimating the Permeability of Naturally Structured Soil From Percolation Theory and Pore Space Characteristics Imaged by X‐Ray

“…Subsequently, we calculated the joint histogram for all 95 calibrated 3‐D images (see Figure ) and a joint‐threshold grayscale value of 10,171 was determined by the minimum method (Tsai, ). As was also done by Hellner et al (), we applied this threshold value to all gray‐scale‐calibrated images to obtain binary images depicting the X‐ray resolvable pores. Beckers et al () found that a similar global segmentation method performed as well as local approaches that are more demanding in terms of time and computational resources.…”