Variations in Natural Nitrogen-15 Abundance as an Aid in Manure-nitrogen Studies1
- F. Selles and
- R. E. Karamanos2
The fate of manure N in the soil-plant system was studied in a growth chamber experiment with soil columns (Typic Haploborolls) using three rates of manure (equivalent to 0, 60, and 90 Mg ha−1) and two water regimes. Estimates of manure N contribution to various compartments of the system were derived using the changes in natural 15N abundance of the N sources in the system. These sources included manure-derived inorganic N from manure amendments to the soil, inorganic N initially present in the soil and soil-derived inorganic N. Calculations of the contribution of each source to soil, plant, and leachate were based on the principle of isotopic dilution. Complete recovery of manure and manure-derived N in the systems studied were obtained and N balances were drawn for both uncropped and cropped treatments through a series of calculations. This was not possible in all cases when the contribution was calculated from the difference between manure amended and nonamended treatments. Although large propagated errors may be incorporated in the calculations based on the isotopic dilution principle, the proposed technique appears to be sensitive enough to semiquantitatively describe the fate of manure N in the soil-plant system.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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