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ARS Home » Southeast Area » Raleigh, North Carolina » Soybean and Nitrogen Fixation Research » Research » Publications at this Location » Publication #190927
Title: SOIL NITROGEN MINERALIZATION AND MICROBIAL BIOMASS IN FORAGE PRODUCTION SYSTEMS: INFLUENCES OF NITROGEN FERTILIZATION RATES AND TYPES

Author
item IYYEMPERUMAL, I - NC STATE UNIV
item GREEN, JIM - NC STATE UNIV
item Israel, Daniel
item SHI, WEI - NC STATE UNIV

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/10/2005
Publication Date: 11/1/2005
Citation: Iyyemperumal, I., Green, J., Israel, D.W., Shi, W. 2005. Soil nitrogen mineralization and microbial biomass in forage production systems: Influences of nitrogen fertilization rates and types. Agronomy Abstracts file///E:/techprogram/AM05/P8324.HTM.

Interpretive Summary:

Technical Abstract: Our objective was to determine the effects of swine lagoon effluent (SLE)and ammonium nitrate (AN) on soil N supplying capacity and microbial functional groups of N mineralizers and nitrifiers in a forage production system. We collected soils at 0 – 7.5 cm depth in 2004 from field plots planted with Bermuda and Tall fescue that received AN and SLE from 1999 – 2001 at rates equivalent to 0, 200, 400, and 600 kg available N ha-1 yr-1, respectively. Fertilization significantly (P < 0.05) increased total soil N, amino sugar N (ASN), microbial biomass N (MBN), potential N mineralization and nitrification, indicating that fertilization improved soil N supplying capacity. However, soil microbial biomass C (MBC) was greatest at the lower fertilization rate, i.e. 200 kg N ha-1 yr-1. Microbial biomass C:N ratios also decreased significantly with fertilization rates (P < 0.05), suggesting that fungal biomass declined with increased N fertilization. In comparison with AN, soils receiving SLE had lower total soil N, ASN, MBC, microbial biomass C:N ratios and potential nitrification rates. The different effects between SLE and AN, especially at higher N fertilization rates, on soil and microbial properties are likely due to heavy metal stress associated with SLE application.