Chapter 1 Summary: Soil Formation and Properties PDF

Chapter 1 summary Soil is the thin layer of material covering the earth’s *.surface and is formed from the weathering of rocks Soil is made up mainly of mineral particles, organic * materials, air, water and living organisms—all of which.interact slowly yet constantly...

Chapter 1 summary Soil is the thin layer of material covering the earth’s *.surface and is formed from the weathering of rocks Soil is made up mainly of mineral particles, organic * materials, air, water and living organisms—all of which.interact slowly yet constantly :Scientists attribute soil formation to * Parent material.1 Climate.2 Biota (organisms).3 Topography.4 Time.5 Soil is the main source of food for plants, that produce * is for humans, animals and birds. Therefore, most living.things on land depend on soil for their existence Soil is a valuable resource that needs to be carefully *.managed as it is easily damaged, washed or blown away Soil is one of the essential building blocks of our environment and our food *.security Soil formation is the consequence of a combination of biological, physical, and *.chemical processes Horizons and layers ** Soil horizon: Is a horizontal layer of the soil, whose physical features, composition* and age are distinct from those above and beneath.The naming of a horizon is based on the type of material of which it is composed* ,(‫ )تناسق‬Horizon described in terms of its color, size, texture, structure, consistency * root quantity, pH, voids, boundary characteristics and presence of nodules or.(‫ )الخرسانة‬concretions Upper soil horizons may be lacking in truncated soils following wind or water * ablation The growth of trees is another source of disturbance, creating a micro-scale *.heterogeneity which is still visible in soil horizons once trees have died By passing from a horizon to another, from the top to the bottom of the soil profile,* one goes back in time, with past events registered in soil horizons like.(‫ ) الطبقات الرسوبية‬in sediment layers Sampling pollen, testate amoebae and plant remains in soil horizons may help to *.reveal environmental changes which occurred in the course of soil formation Soil horizons can be dated by several methods as radiocarbon, using pieces of * ‫ )دودة‬charcoal provided they are of enough size to escape pedoturbation by earthworm.activity and other mechanical disturbances‫رض‬1‫)ا‬  from paleosols can be found within sedimentary ‫حفوري‬1‫ ))ا‬Fossil soil horizons *.rock sequences, allowing the study of past environments The exposure of parent material to favorable conditions produces mineral soils that *.are marginally suitable for plant growth, as is the case in eroded soils results in the production of organic ( ‫ ) الغطاء النباتي‬The growth of vegetation * residues which fall on the ground as litter for plant aerial parts (leaf litter) or