Advancing Soil Physics for Securing Food, Water, Soil and Ecosystem Services

Abstract

Core Ideas Contributions are mainly from the 2017 International Soil Physics Workshop in China. Soils are fundamental in supplying food, energy, water (FEW), and ecosystem services. Interdisciplinary (convergence) approaches are needed to address FEW challenges. Soils are foundational to sustaining the food, energy, and water (FEW) systems and provide many essential ecosystem services. Soil degradation is a major threat to food security in China and elsewhere in the world. It is critical to advance soil science to improve the FEW systems so that FEW supplies can be provided to human populations in a sustainable and resilient manner. To do so, we must understand interactions among soil physical, chemical, and biological processes, as well as the role, function, and contribution of soil physical processes to delivering FEW supplies and ecosystem services. Soil processes and crop production are strongly controlled by physical processes such as soil water flow, aggregate stability, compaction, heat regime, irrigation and drainage, soil aeration, etc. Recognizing the importance of soil physics to the nexus of FEW systems, the collection in this special section mainly includes research presented at the International Workshop of Soil Physics and the Nexus of Food, Energy, and Water held on 3–5 Aug. 2017 at Shenyang, China. This special section covers diverse topics including fundamental soil physical properties and water flow, land use and agricultural management, soil organic carbon management, soil physical modeling, and transport of emerging contaminants. More future research using interdisciplinary (nexus or convergence) approaches should be undertaken to address challenges in many contemporary and emerging FEW issues.

Field observations of soil hydrological flow path evolution over 10 millennia

“…A laboratory test of the water drop penetration time (DeBano, 1981;Doerr et al, 2000) on a soil sample of the upper soil material showed that the organic layer is highly water repellent in dry conditions (air dried for 2 weeks; water drop penetration time > 10 min). An increase in the hydrophobicity index (Tillman et al, 1989) with increasing moraine age was also found by Maier et al (2019). Thus, we conclude that the hydrophobicity of the organic top layer has a big impact on infiltration and the initiation of unstable flow.…”

“…The ability of soil to store and to transport water is essential for its ecosystem services such as nutrient cycling or water and gas balances (Clothier et al, 2008;Amundson et al, 2015;Hatfield et al, 2017;Shang et al, 2018). Thus, the interaction of water and soil is an elementary foundation for the existence and functioning of terrestrial ecosystems.…”

“…Preferential flow in the form of macropore flow occurs mostly in fine-textured soils, whereas finger and funnel flow rather occurs in soils with a coarse texture (Hendrickx and Flury, 2001). General factors which can cause preferential flow paths are surface structure and properties such as vegetation cover, microtopography or hydrophobicity, as well as subsurface soil properties such as soil structure and soil type, subsurface heterogeneities, flow instabilities, and plant root activities (Weiler and Naef, 2003;Clothier et al, 2008;Bachmair et al, 2009;Jarvis, 2007;van Schaik, 2009;Wang et al, 2018). Soil water conditions were also found to have an influence on the preferential flow path characteristics (Gimbel et al, 2016;Hardie et al, 2011;Bogner et al, 2008).…”

Relating soil physical properties to other soil properties and crop yields

“…This was due to reduced BD from long-term continuous cropping systems which increased annualized crop yields in contrast to increased BD from crop-fallow systems which increased BD but lowered annualized crop yields. Many researchers 15 , 17 , 27 reported that BD was negatively related to crop yield. However, Logsdon and Karlen 2 demonstrated that BD had no effect on crop yield.…”

“…Sene et al 14 found that sand concentration and SHC were positively correlated, but soil aggregation was negatively correlated to crop yield. Shang et al 15 reported that soil water content and aggregate stability (AS) were positively related, but BD was negatively related to crop yield. Similarly, several researchers 16 , 17 observed that BD was negatively related to crop yield.…”