Agriculture Reference
In-Depth Information
Soil Types & Properties
Aggregate Formation
Microbes decomposing organic matter create compounds that glue soil particles together.
Like getting sticky fingers from eating cotton candy, sugars that are excreted from plant
roots cause clumping. Humus, which refers to stable organic matter that has been fully
broken down, also binds soil particles together.
Fungal hyphae
,
collectively called
mycelium also have a role in stabilizing aggregates. Soils are further enhanced through the
activities of insects, earthworms and other larger organisms when they burrow through the
soil. These organisms also deposit fecal matter which becomes stable soil aggregates, over
time.Whenplantsandanimalsdecomposeonthesurface,theresultingresidueandorganic
matter improves soil structure by becoming food for fungi and bacteria that in turn help
keep the process going indefinitely.
In addition to the biological activities that support the formation of soil structure, physical
and chemical processes present are also important. Physical actions such as freezing and
thawing cycles affect soil structure just as much as wetting and drying, compaction by
animalsormachinery,orthemovementofrootspushingandextendingthemselvesthrough
the soil. Chemically, electrostatic charges help to bind minerals to larger particles together,
creating different forms of minerals, clays and so on.
Next, remember that the ground is not simply made up of a uniform field of soil particles.
In real life it is composed of a great range of textures that vary depending upon
geographical region, how the land has been treated, and based on the presence of other
forms of life (e.g. bacteria, worms, moles, and others). Take for example rocky soils from
a mountainous region. In this case you can expect the topsoil to be filled with a mix of
clays,sands,gravels,organicmatterandacertainamountoflargerrocksorboulders.Other
