Gypsum Effects On Carbon Sequestration and Soil Quality.

Gypsum is an important chemical conditioner to improve soil quality and enhance carbon (C) sequestration. To evaluate the impact of gypsum on soil quality and C sequestration potential of heavy clay soil for economic crop production, a randomized complete block experiment was conducted at Defiance County research and demonstration field, northern Ohio from 2004 to 2009. The treatments were 0 (control), 1 and 2 Mg gypsum/ha, respectively. Composite soil samples at 0-15 cm depth were randomly collected, processed, and analyzed for microbial biomass (SMB), pH, electrical conductivity (Ec), total C (TC) and N (TN), particulate C (POC) and N (PON), active (AC) and passive C (PC), bulk density (rb), porosity (ft), and macro- (MA) and microaggregate (MIA) distribution. The data were normalized to calculate a soil quality index using addtive method. Results show that SMB, TC and TN, AC, POC, PON, and MA significantly increased over time in 2 Mg gypsum ha^-1 treatment compared with control. Soil quality, as a measure of overall soil condition, was increased significabntly by gypsum application, and the impact was more pronounced in 2 Mg gypsum/ha treatment. However, crop yield did not increase significantly by gypsum application.