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United States Department of Agriculture

Agricultural Research Service

Title: Measuring the Specific Surface Area of Soil Using Nitrogen: Variation Due to the Addition of Organic Matter

item Sikora, Lawrence
item Rawls, Walter
item Pachepsky, Yakov

Submitted to: Argentina Soil Science Society Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 15, 2002
Publication Date: January 7, 2003

Interpretive Summary: Amending soils with composts or manures improves the tilth and fertilizer value of soils. Physical properties such as water holding capacity is also improved with amendments. The surface area of soils is related to the capacity of soils to hold water, fertilizer and chemicals needed for production. Greater surface area is generally beneficial. Few studies have evaluated the effects of organic by-products such as manures or composts on surface area changes. Using nitrogen gas adsorption technique, the surface area of soils amended with manures and composts were compared to soil amended with fertilizer. Soils amended with manures or composts had significantly greater surface area than fertilized soil. This result may help explain the benefits obtained when soils are amended with organic by-products which lead to higher soil quality and crop production.

Technical Abstract: Beneficial effects of amending soils with organic by-products includes improvement of chemical and physical factors. Very few studies have studied changes in soil specific surface area (SSA), measured by nitrogen adsorption after amendments of manures and composts. Soil samples were taken from plots before and after a four year application of manures, composts or nitrogen fertilizer. A corn-soybean rotation was grown. Soil samples were tested for changes in soil surface area using nitrogen gas adsorption in 78K. Organic amendments increased SSA by an amount varying from 0.63 m2 g-1 to 0.91 m2 g-1 of soil C increase. Fertilizer increased SSA 0.47 m2 g-1 of soil C increase. The SSA growth has been attributed to the addition of organic matter and the values measured are in agreement with other related experiments using the same technique.

Last Modified: 4/22/2015
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