1 / 16

How does net N mineralization vary across ecosystems in central Florida?

How does net N mineralization vary across ecosystems in central Florida? Can % moisture and/or %C and %N be used to predict net n-mineralization rates? How do different methods in measuring n-mineralization compare?. What is N Mineralization?.

boone
Download Presentation

How does net N mineralization vary across ecosystems in central Florida?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. How does net N mineralization vary across ecosystems in central Florida? • Can % moisture and/or %C and %N be used to predict net n-mineralization rates? • How do different methods in measuring n-mineralization compare?

  2. What is N Mineralization? • N mineralization is the conversion of organic N in soil to inorganic N (NH4+, NO3-) • Plants assimilate most of their N from these inorganic-N pools • Measuring N mineralization provides a general index of the capacity of a soil to make N available to plants via soil solution

  3. Why is it important to measure? • N most limiting nutrient to terrestrial plants • Differences in rates of N mineralization can have significant effects on primary production • Measuring N mineralization can give us a better understanding of soil fertility and ecosystem type and function

  4. 3 Sites • Xeric Hammock • Pine Flat • Cypress 2 Methods • Field Incubations-closed top tubes (Harte et al 1994, Raison et al 1985) • Lab Incubations-Aerobic incubations (Hart & Binkley, 1985)

  5. Hypotheses • H1: N-mineralization rates will differ between sites and these differences will be correlated with soil moisture, and soil C and N. Sites with high moisture and high % of C and N will have higher rates of mineralization. • H2: N-mineralization rates from lab incubations will be less variable due to less variation in temperature and moisture.

  6. Field Incubations 3.75cm IER Bag-Top 12 cm Soil Soil IER Bag-Bottom “Initial” “Final”

  7. Lab Incubations Soil Soil “Initial” T0 “Final” T1

  8. p=0.00 a p=0.06 a b b

  9. Results • CN, % moisture, net-min, net-nitrification greatest in Cypress stand and lowest in Xeric Hammock • Positive correlation between n-min and %moisture and CN • Net-min, net-nitrification and %N mineralized was greater for field incubation soils than lab incubated soils

  10. Conclusions • N-min can vary significantly between different ecosystem types. • Strong correlation between n-min and % soil moisture and CN suggesting that these are good indicators for estimating n-min • Found differences in n-min, net nitrification and % min between field and lab incub suggesting that using just one method may not give as accurate results

  11. References • Harte, SC, JM Starke, EA Davidson and MK Firestone. 1994. Nitrogen mineralization, immobilization and nitrification. Pages 985-1018 in RW Weaver, JS Angle, PJ Bottomley, DF Bezdicek, MS Smith, MA Tabatabai and AG Wollum, editors, Methods of Soil Analysis. Part 2, Microbiological and Biochemical Properties. Soil Science Society of America, Madison, Wisconsin, USA. • Hart SC, and D Binkley. 1985. Correlations among indices of forest soil nutrient availability in fertilized and unfertilized loblolly pine plantation. Plant Soil 85:11-21. • Raison, R, M Connell and P Khanna. 1987. Methodology for studying fluxes of soil mineral-N in situ. Soil Biol Biochem 19:521-530. • Mack, MC and CM D’Antonio. 2003. Exotic grasses alter controls over soil nitrogen dynamics in a Hawaiian woodland. Ecological Applications 13:154-166.

More Related