Cracks and Potholes in Vertisols: Characteristics, Occurrence, and Management

Abstract

Abstract Vertisols constitute one of the unique soil orders, with distinct characteristics including self-mulching, swelling and shrinking, cracking, and pothole formation; and excessive surface runoff and soil erosion during high rainfall. Cracks are among distinct features and are used as defining criteria of Vertisols in Soil Taxonomy. The process of cracking is a significant researchable issue in soil science with regards to the occurrence, formation, management, and modeling. Management of Vertisols is a challenging task because of specific physical constraints such as narrow workable range of soil moisture, peculiar consistency of sticky when wet and very hard when dry, and cracking. The cracking pattern is affected by a variety of factors including clay content, soil moisture, tillage practices, cropping system, and land use. In addition, cracking is also affected by type and amount of clay and the moisture regime. Cracks can have both positive and negative influence on the soil–plant system. Soil cracks provide a passage for quick water entry into the deeper layer of soil profile in the rainy season, in turn reducing risks of soil erosion and enhancing the soil moisture reserves. On the other hand, slumping surface soils through cracks results in formation of potholes which exacerbate risks of ground water pollution. Cracks can aggravate losses by evaporation of irrigation- or rain water from the greater evaporating surface area during the postirrigation/rainy season. Increase in evaporative loss has implications to scheduling of irrigation and the quantity of water application. Cracks are also important to the movement of water down the soil profile following the prolonged/extended dry season, but are also a cause of extrawater losses through evaporation from the cracks’ surfaces. Despite their significance, scientific and practical knowledge about crack management in Vertisols is scanty. Cracking patterns in soil can be modified by tillage practices, organic amendments, and crop residue management. Therefore, suitable land management practices include measures for conserving the ground water such as permanent broad bed and furrow, and ridge-furrow systems used in conjunction with the application of organic manures and amendments and conservation tillage system. Such measures can decrease the formation of wide cracks, reduce loss of water through evaporation in semiarid environment, and improve soil health. This chapter describes occurrence, formation, characterization, and management of cracks and potholes for sustaining soil health and enhancing crop productivity on Vertisols.