Nitrogen‐15 Recovery in Soil Incubated with Potassium Nitrate and Clover Residues

In the southeastern USA, legumes are used as green manure to meet crop N requirements of a following crop, but recovery is usually lower than from conventional fertilizers. We conducted a laboratory study for 26 wk under aerobic conditions to monitor recovery of 15N‐labeled KNO3 (fertilizer) and cri...

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Bibliographic Details
Published in:Soil Science Society of America journal 2001-09, Vol.65 (5), p.1430-1436
Main Authors: Muriuki, Anne W., King, Larry D., Volk, Richard J.
Format: Article
Language:English
Subjects:
Agronomy. Soil science and plant productions
Biological and medical sciences
Environment
Experiments
Fertilizers
Fundamental and applied biological sciences. Psychology
General agronomy. Plant production
Nitrogen
Nitrogen fertilization
Nitrogen, phosphorus, potassium fertilizations
Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries
Soil-plant relationships. Soil fertility. Fertilization. Amendments
Soils
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Summary:In the southeastern USA, legumes are used as green manure to meet crop N requirements of a following crop, but recovery is usually lower than from conventional fertilizers. We conducted a laboratory study for 26 wk under aerobic conditions to monitor recovery of 15N‐labeled KNO3 (fertilizer) and crimson clover (Trifolium incarnatum L.) residues (clover) in organic, inorganic, and microbial biomass N pools. Volatilization of NH3 from decomposing clover residues was monitored for 12 wk. Three hundred–gram samples of a Typic Kanhapludult soil were amended with N (0.051 mg N kg−1 dry soil in fertilizer and 0.049 mg N kg−1 dry soil in clover). A control with no N was also included. Although inorganic N (NH4, NO2, and NO3) accumulated throughout (fertilizer > clover > control), the rate of accumulation did not differ among treatments. Organic and microbial biomass N concentration did not differ among treatments, but applied N recovery in microbial biomass was greater in clover than fertilizer (P < 0.05) throughout. Ammonia volatilized was negligible. After 26 wk, applied N recovered in soil inorganic N was 66% for fertilizer and 40% for clover; in soil organic N, 18% for fertilizer and 50% for clover; and in microbial biomass N, 0.75% for fertilizer and 1.5% for clover. Applied N presumed denitrified was 16% in fertilizer and 10% in clover. We concluded that clover green manure can meet the N requirements of a following crop from the time of emergence in the southeastern USA.
ISSN:0361-5995
1435-0661
DOI:10.2136/sssaj2001.6551430x