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Soil Property and Landscape Position Effects on Seasonal Nitrogen Mineralization of Composted Dairy Manure

Watts, Dexter B.; Torbert, H. Allen; Prior, Stephen A.

doi: 10.1097/SS.0b013e3181ca38ff
Technical Article

To develop better management practices that optimize the N derived from manure, additional research is needed regarding the mineralization and dynamics of N under field conditions. Thus, an in situ field study using three different soil types located in an agricultural field was conducted to evaluate N mineralization patterns during the summer and winter months. The three Coastal Plain soils (Ultisols) investigated were Bama (sandy loam), Lynchburg (loam), and Goldsboro (loam), representing the landscape position of a summit, drainageway, and sideslope, respectively. Composted dairy manure was incorporated into in situ soil cores, at a rate of 350 kg N ha−1, to evaluate mineralization rates of the soils and their landscape position during the summer and winter months. Addition of composted dairy manure on N mineralization was impacted by season and soil type. This was most evident during summer months (N mineralization was 24%), suggesting that seasonal timing of application will influence mineralization. The seasonal patterns of N mineralization were affected mostly by temperature; N mineralization was minimal during winter (N mineralization was 2%) when temperature was low (∼10 °C) but was greater during summer with higher temperatures (25 °C-30 °C). Landscape and soil texture played an additional role in mineralization. The soil type with the greatest percentage of sand and located in a low-lying area, although N mineralization was low during the winter months, significantly lost more of the added N from dairy compost (80%-90% more) compared with the other soils. During the summer, the loam soil with the greatest water-holding capacity mineralized the most N, significantly mineralizing 9% to 10% more than the other soils. These results show that soil variability, temperature, and landscapes need to be considered when applying manure to agricultural fields.

USDA-ARS, National Soil Dynamics Laboratory, 411 S. Donahue Dr., Auburn, AL 36832. Dr. Dexter B. Watts is corresponding author. E-mail: dexter.watts@ars.usda.gov

Received April 19, 2009, and in revised form November 4, 2009.

Accepted for publication November 9, 2009.

© 2010 Lippincott Williams & Wilkins, Inc.