We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
Published online by Cambridge University Press: 12 January 2024
What Is Soil?
Soil means different things to different people. To a farmer or horticulturalist, it is a medium for plant growth. To an engineer, it is something to build on, or remove, before construction can occur, or it may actually be a type of medium used for road building, house foundations, or septic drain fields. To a hydrologist, soil functions as a source of water purification and supply. To some geologists, it is the post- Pliocene overburden that is covering up the rocks!
We use a slightly modified statement from the one offered by Johnson (1998a) as the best and most widely applicable definition of soil: Soil is organic or lithic material, normally at the surface of planets and similar bodies, that has been altered by biological, chemical, and/or physical agents. This definition and the one proposed by Richter and Markewitz (1995) – “Soil is the biologically excited layer of the Earth's crust” – give equal rank to biological processes and agents, which were ignored by some previous definitions that focused on the physical and chemical processes of soil formation. Pedologists and soil geographers often use a similar definition: A soil is a natural, threedimensional body that has formed at the Earth's surface through the interactions of at least five soil-forming factors (climate, biota, relief or topography, parent materials, and time). This definition emphasizes that soils are “naturally occurring” bodies and introduces the five soil-forming factors into the equation, front and center. All of these definitions have merit and fit with the ways in which soils are discussed in this book.
Soils are composed of clastic particles (mineral matter), organic materials in various stages of decay, living organisms, water (or ice), and gases within pores of various sizes (Fig. 2.1). The absolute amounts of each, and their arrangement into a particular fabric, are the sum of soil morphology. Every soil has a distinct morphology, defined as its structure or form. Soil morphology is all that can be seen and felt about a soil. It includes not only “what is there” but also how it is “put together” – its architecture. To many, the main components of soil morphology include horizonation, texture, color, redoximorphic features, porosity, structure, and consistence, i.e., the look and feel of the soil.
To save this book to your Kindle, first ensure [email protected] is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.
