|SCUDIERO, ELIA - University Of California - Cooperative Extension Service|
Submitted to: Advances in Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/2019
Publication Date: 10/1/2019
Citation: Corwin, D.L., Scudiero, E. 2019. Review of soil salinity assessment for agriculture across multiple scales using proximal and/or remote sensors. Advances in Agronomy. 158:1-130. https://doi.org/10.1016/bs.agron.2019.07.001.
Interpretive Summary: Assessing or rather mapping and monitoring soil salinity from field (<3 km2) to regional scale (10-106 km2) is valuable because of its effect on crop yield, with an estimated annual global loss of $27.3 billon USD in crop productivity. However, mapping soil salinity is extremely challenging because salinity is a dynamic soil property that can change considerably over space and time. The presented paper comprehensively reviews the assessment of soil salinity from field scale to multi-field or landscape scale to regional scale. It discusses the need and justification for mapping and monitoring salinity, basic concepts of soil salinity and its measurement, past geophysical and remote imagery research critical to salinity assessment, current approaches for mapping salinity at different spatial extents or scales, effect of spatial scale on salinity model accuracy, and future direction of field- to regional-scale salinity assessment. The review is unique from previous reviews in its comprehensiveness and in the presentation of the critical milestones that have occurred in salinity assessment research to bring us to our current level of knowledge and understanding. The information presented is of value and benefit to policy makers, water and land resource managers, producers, agriculture consultants, cooperative extension specialists, Natural Resource Conservation Service field staff, and soil and water researchers.
Technical Abstract: Mapping and monitoring soil spatial variability is particularly problematic for temporally and spatially dynamic properties such as soil salinity. The tools necessary to address this classic problem only reached maturity within the past 2 decades to enable field- to regional-scale salinity assessment of the root zone, including GPS, GIS, geophysical techniques involving proximal and remote sensors, and a greater understanding of apparent soil electrical conductivity (ECa) and multi- and hyperspectral imagery. The concurrent development and application of these tools have made it possible to map soil salinity across multiple scales, which back in the 1980s was prohibitively expensive and impractical even at field scale. The combination of ECa-directed soil sampling and remote imagery has played a key role in mapping and monitoring soil salinity at large spatial extents with accuracy sufficient for applications ranging from field-scale site-specific management to statewide water allocation management to control salinity within irrigation districts. The objective of this paper is: (i) to present a review of the geophysical and remote imagery techniques used to assess soil salinity variability within the root zone from field to regional scales; (ii) to elucidate gaps in our knowledge and understanding of mapping soil salinity; and (iii) to synthesize existing knowledge to give new insight into the direction soil salinity mapping is heading to benefit policy makers, land resource managers, producers, agriculture consultants, extension specialists, and resource conservation field staff. The review covers the need and justification for mapping and monitoring salinity, basic concepts of soil salinity and its measurement, past geophysical and remote imagery research critical to salinity assessment, current approaches for mapping salinity at different scales, milestones in multi-scale salinity assessment, and future direction of field- to regional-scale salinity assessment.