Assessment of the responses of soil pore properties to combined soil structure amendments using X-ray computed tomography

Abstract

Soil amendments, such as straw mulch, organic fertilizers and superabsorbent polymer (SAP), are extensively applied to improve soil structure and porosity, and we reported the functional consequences of the individual application of these amendments in our previous study. However, whether combined amendments are more effective than their individual applications for improving soil pore structure is unknown. Here, we conducted X-ray computed tomography (CT) scanning on undisturbed soil columns to investigate the efficiency of two-amendment application, including straw mulch and organic manure, SAP and organic manure, or SAP and straw mulch, for improving soil pore properties and pore distribution. The X-ray CT technique allows us to accurately determine the number, morphology, and location of macropores (>1 mm in diameter) and smaller pores (0.13–1.0 mm). Compared to the control treatment, which showed the lowest increase in soil porosity, all the combined treatments led to an increase in the numbers of both macropores and smaller soil pores, causing a significant improvement in soil structure and porosity. Among these treatments, the application of both straw mulch and organic manure was the most effective for improving soil porosity and soil physical structure.

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

“…In general, soil pore characteristics measured using the CT approach and the traditional method using SWR (data not shown) and other hydrologic properties reflect a similar trend between managements. Soil ρ b has a strong negative correlation with all sizes of soil pores (porosity, macroporosity, and coarse mesoporosity) and pore numbers (total number of pores, number of macropores, number of coarse mesopores), which is consistent with other studies (e.g., Udawatta, Anderson, Gantzer, & Garrett, 2006;Yang et al, 2018) (Table 5). Water transport properties such as K sat and q s were positively correlated with each of the CTmeasured pore parameters.…”

“…Soil porosity is a critical parameter that can affect the movement and storage of water, nutrients, aeration, erosion, and microfauna in the soil (Amezketa, 1999;Whalley, Dumitru, & Dexter, 1995). Soil pore morphology, including circularity, size distribution, and connectivity, affect the transmission and storage of soil water (Eynard, Schumacher, Lindstrom, & Malo, 2004;Yang et al, 2018). For instance, pores that are circular and connected and have a diameter of >300 μm (i.e., macropores) promote rapid movement of air and water within the soil profile (Jarvis, Larsbo, Roulier, Lindahl, & Persson, 2007).…”

The Characteristics of Absorbency Under Load (AUL) for Superabsorbent and Soil Mixtures

“…Water absorption by SAPs in soil depends on several factors, including soil structure, saline content, temperature, pH, moisture content, and presence of microorganisms, as well as soil wetting and drying cycles 23 . On the other hand, in terms of surface performance characteristics, the amendment type does have a significant effect on certain soil parameters, e.g., shear strength, soil structure and total soil porosity 24–28 .…”

Recent Achievements and New Research Opportunities for Optimizing Macronutrient Availability, Acquisition, and Distribution for Perennial Fruit Crops

“…Soil amendments like manures, composts, surface mulches, cover crops, and biochar can affect the size distribution and stability of soil aggregates [52]. In turn, these changes will affect soil porosity, soil pore size distribution and bulk density and cause consequent changes in soil hydraulic properties [53,54] that are inextricably linked to nutrient retention and availability in soils. Although increasing soil organic matter is often suggested as a strategy to improve soil moisture retention in the root zone, reported results have been mixed.…”