Soil is composed of minerals, soil organic material (SOM), water, and air, according to the Montana State University’s soil scientists, Ann McCauley. The actual composition of these various components within soil has a big influence on the porosity; i.e., the composition affects the movement of water into and through the soil (McCauley, 2005), and the movement of water into and through soil is absolutely necessary for productive crops, and healthy ecosystems. The binding together of soil particles is called “aggregation” and when water passed into the soil aggregation, if it is healthy, will keep the porosity and water movement slow and productive, which “improves fertility and carbon sequestration in the soil” (avoiding erosion at the same time) (McCauley).
McCauley explains that the pores in the soil have a number of important functions. Soil that is coarse will have many pores and fine-textured soils; because they are “more tightly arranged” have smaller pores. When the soil has been cultivated over the long term, the soil’s porosity decreases because of a decrease in soil organic material, McCauley continues. When there is a lot of crusting on the surface of the soil, and compaction, it decreases porosity and “inhibits water entry into the soil” (McCauley). And when there is crusting, and the water cannot penetrate the soil, erosion and rapid runoff of water is in evidence. On the other hand, in Montana when the soil has good porosity, water then can get through the topsoil and fill the pores until they are saturated. Some of that water will “drain freely from the soil via gravity” and some will be held in “micropores” (called capillary forces), to be removed by the roots of plants drawing it up (“uptake”) or by evaporati...
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...teract in ways that sustain both the soil and the crops or other vegetation, no matter where on the planet this interaction might occur. In Montana, understanding the importance of soil porosity can help keep farmers from over-cultivating; and in Brazil, where tree canopy ecosystems are being burned in favor of grassy savannah, understanding those dynamics helps agricultural professionals and farmers in their efforts to maintain balanced, productive soils.
Works Cited
McCauley, Ann, and Jacobsen, Jeff. Basic Soil Properties. Retrieved June 10, 2011,
From http://landresources.montana.edu/swm/PDF/Final_proof_SW1.pdf. (2005).
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Vahey, C. D., Aiken, H. L., Sloane, M. D., Clarke, P. S., and Vargas, D. (2010 Jan. 15).
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