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United States Department of Agriculture

Agricultural Research Service

Research Project: NUTRIENT CYCLING AND UTILIZATION ON ORGANIC DAIRY FARMS

Location: New England Plant, Soil and Water Research Laboratory

Title: Phosphatase Activity of Ultisols and Relationship to Soil Fertility Indices

Authors
item Senwo, Z - ALABAMA A&M UNIV
item Ranatunga, D - ALABAMA A&M UNIV
item Tazisong, I - ALABAMA A&M UNIV
item Taylor, R - ALABAMA A&M UNIV
item He, Zhongqi

Submitted to: Journal of Food Agriculture and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 14, 2006
Publication Date: January 15, 2007
Citation: Senwo, Z.N., Ranatunga, D., Tazisong, I.T., Taylor, R.W., He, Z. 2007. Phosphatase Activity of Ultisols and Relationship to Soil Fertility Indices. Journal of Food Agriculture and Environment.5:262-266.

Interpretive Summary: Particular enzymes in soil influence phosphorus (P) availability for plant growth. Information is limited on the composition of these P-releasing enzymes and how soil properties affect their distribution. We measured the activities of three P enzymes (acid phosphatase, alkaline phosphatase, and phosphodiesterase) in six highly weathered soils from Alabama and examined those activities in relation to various soil properties. In each soil the activity of acid phosphatase > alkaline phosphatase > phosphodiesterase, although the specific activity in each soil was different. Stepwise regression analysis revealed cation exchange capacity (CEC), soil organic matter, iron, manganese, and sand contents were the main soil properties influencing acid phosphatase distribution whereas pH, iron, and CEC significantly influenced alkaline phosphatase distribution. Organic matter and pH significantly influenced phosphodiesterase distribution. These results indicate which soil properties influence P availability through their effect on P-releasing enzymes.

Technical Abstract: Phosphorus availability is influenced by soil P-releasing enzymes. Information is limited on the composition of these P-releasing enzymes in and how soil properties affect their distribution. In Ultisols of Alabama, low levels of labile inorganic P (Mehlich-III P) and higher amounts of bicarbonate- and NaOH-EDTA-extractable organic P suggest the ecological significance of phosphatases for mineralizing organic P to inorganic P for plant uptake. In this case study, we chemically assayed and evaluated soil phosphatase composition and attempted to identify a combination of soil factors significant in predicting their distribution. The common feature in the six soils tested was the activity of acid phosphatase > alkaline phosphatase > phosphodiesterase, although the specific activity in each soil was different. Stepwise regression analysis revealed cation exchange capacity (CEC), soil organic matter, Fe, Mn, and sand contents were the main significant soil properties influencing acid phosphatase distribution, cumulatively accounting for 26.9, 37.7, 52.4, 59.5, and 67.8% of the total variability, respectively, whereas pH, Fe, and CEC significantly influenced alkaline phosphatase distribution, cumulatively accounting for 37.0, 54.8, 59.4% of the total variability, respectively. Organic matter and pH significantly influenced phosphodiesterase distribution, cumulatively accounting for 58.4 and 67.3%, respectively, of the total variability. The low alkaline phosphatase and phosphodiesterase activities may signify the nature and origins of diester phosphate in these soils.

Last Modified: 4/18/2014
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