Wednesday, November 7, 2007
293-12

Alpha- and Beta-glucosidase Activities of an Ultisol: Effect of Tillage, Residue Management, and Various Nitrogen Fertilizations.

Priscilla M. Mfombep, Zachary N. Senwo, Robert W. Taylor, and Elica M. Moss. Natural Resources & Environmental Sciences, Alabama A&M University, 4900 Meridian St, Normal, AL 35762

Soil is important in agriculture and maintenance of global environmental quality because minor alterations in the soil-stored-elements such as carbon significantly influence global processes. Agricultural practices that require soil tillage, residue management, and various nitrogen fertilizations result in soil changes which need to be monitored. Glycosidases such as α- and β-glucosidases, degrade low molecular weight carbohydrates to release sugars for soil microbial function and are sensitive to soil changes. When assessed alongside other soil properties, α- and β-glucosidases can be useful indices of soil changes. The objective of this study was to determine the effect of various tillage, residue management, and nitrogen fertilization practices on soil α- and β-glucosidase activity of a Decatur silt loam soil.

The treatments included various combinations of tillage systems (conventional till, mulch till, and no-till), cropping systems and management practices [cotton in summer and rye (Secale cereale L.) cover crop in winter], and nitrogen fertilization [ammonium nitrate (0 and 100 kg N ha-1) and poultry litter (0, 100, and 200 kg N ha-1)].  Soil properties measured included pH, moisture, bulk density (BD), soil organic carbon (SOC), particular organic carbon (POC), microbial biomass carbon (MBC), potential carbon mineralization (PCM), total nitrogen (TN), particular organic nitrogen (PON), and microbial biomass nitrogen (MBN).

The results showed that both α- and β-glucosidase activities were significantly inter-correlated and were significantly correlated with SOC, MBC, POC, PCM, and TN. The highest SOC were recorded in the fertilized rye treatments regardless of whether it was conventionally tilled, no-tilled, poultry litter or ammonium nitrate fertilized. Treatments that received higher N fertilization showed higher α- and β-glucosidase activities, SOC, and MBN, but less PCM.


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