Null creation of air-filled structural pores by soil cracking and shrinkage in silty loamy soils

• Published in: Soil science Vol. 173; no. 2; pp. 130 - 142
• Main Authors: Taboada, M.A, Barbosa, O.A, Cosentino, D.J
• Format: Journal Article
• Language: English
• Published: Baltimore, MD Lippincott Williams & Wilkins 01-02-2008; Lippincott Williams & Wilkins Ovid Technologies
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Clay; clods; crack size distribution; Cracks; Earth sciences; Earth, ocean, space; eroded soils; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; grassland soils; pastures; Physical properties; Porosity; shrinkage; silt loam soils; soil cracks; Soil mechanics; soil pore system; Soil sciences; soil shrinkage; soil water content; Soils; Surficial geology; tillage; Argentina; South America; fissures; physical properties; Silty soil; Air content; porosity; shrinkage indices; Property of soil; Cracking; degradation; air; clay mineralogy; mineral composition; Regeneration; Loamy soil; clod shrinkage; silty loamy soils; Soil cracking; Wetting drying cycle; shrinkage; organic carbon; size distribution; macroporosity
• ISSN: 0038-075X; 1538-9243
• DOI: 10.1097/SS.0b013e31815d8e9d

Information about abiotic regeneration of air-filled porosity in silty soils is scarce. It could be a key mechanism to explain their low physical resilience. In the present work, we aim at evaluating whether changes in intrinsic soil properties (e.g., soil organic carbon, clay content, and clay mineralogy) caused by degradation affected soil volume response to wetting-drying cycles. Volume and size distribution of cracks and clod shrinkage curves were determined in silty loamy soils (Typic Argiudoll) of Argentina under nearby conventionally tilled (CT), eroded CT, and Pasture management. Crack volume increased from 1000 cm3 in CT and Pasture soils to 6000 cm3 in the more clayey and swelling eroded CT soil. Crack size distribution was similar in all studied soils with large cracks (first and second size order) prevailing over small ones (fourth and fifth size order). Clod shrinkage curves had no S-shape, thus showing the lack of structural shrinkage in all studied soil management regimens. Air content in structural pores was as low as 0.03 to 0.10 cm3 g-1 at the air entry point. This little air entry during drying agreed with the lack of small cracks and can be related to the prevalence of plasma (i.e., silt and clay) over sand. Results showed that key intrinsic properties did not drive soil volume changes in the studied silty loamy soils. They change their volume during drying, but the creation of air-filled structural pores is little or null. [PUBLICATION ABSTRACT]