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Title: Impact of biosolids and tillage on soil organic matter fractions: Implications of carbon saturation for conservation management in the Virginia Coastal Plain

Author
item Stewart, Catherine
item Follett, Ronald
item WALLACE, JAMES - Colonial Soil And Water Conservation District (COLONIAL SWCD)
item Pruessner, Elizabeth

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/16/2012
Publication Date: 3/15/2012
Citation: Stewart, C.E., Follett, R.F., Wallace, J., Pruessner, E.G. 2012. Impact of biosolids and tillage on soil organic matter fractions: Implications of carbon saturation for conservation management in the Virginia Coastal Plain. Soil Science Society of America Journal. 76:1257-1267.

Interpretive Summary: In the Virginia Coastal Plain, growers have been practicing rotational no-tillage and continuous no-tillage with and without biosolid application over 20 years to improve soil quality. We sampled forty eight grower’s fields representing the three primary soil series under cultivation and report soil organic carbon (SOC) and soil nitrogen (SN) stocks of whole soils and fractions. Soils with continuous no-tillage and biosolid application had significantly greater SOC stocks than the rotationally no-tilled sites with no biosolid application in two of the three sites. Surprisingly in these sandy soils, the majority of SOC was mineral-associated and showed no effect of tillage or biosolid application. The POM fraction was much greater under NT and biosolid application. Practices that concomitantly decrease soil disturbance and increase C returned to the soil are necessary to increase C storage in these soils, but increased SOC stocks was in a labile fraction that could potentially be lost through subsequent changes in management practice.

Technical Abstract: Long-term soil conservation management decreases soil bulk density, increases water infiltration and water holding capacity. In the Virginia Coastal Plain, growers have been practicing rotational no-tillage and continuous no-tillage with and without biosolid application over 20 years to improve soil quality. We sampled forty eight grower’s fields representing the three primary soil series under cultivation (Altavista, Bojac, and Kempsville/Emporia complex) and report soil organic carbon (SOC) and soil nitrogen (SN) stocks. To examine the effect of these practices on C and N stability, soils were fractioned into particulate organic matter (POM) and mineral-associated fractions. Soils with continuous no-tillage and biosolid application had significantly greater SOC stocks than the rotationally no-tilled sites with no biosolid application in two of the three sites. Surprisingly in these sandy soils, the majority of SOC was mineral-associated and showed no effect of tillage or biosolid application. The POM fraction was much greater under NT and biosolid application. Practices that concomitantly decrease soil disturbance and increase C returned to the soil are necessary to increase C storage in these soils, but increased SOC stocks was in a labile fraction that could potentially be lost through subsequent changes in management practice.