Recovery of 15N-labeled Ammonium by Barley and Maize Grown on the Soils with Long-Term Application of Chemical and Organic Fertilizers

The fate of applied nitrogen (N) fertilizer in a barley-maize-barley crop sequence on an alluvial soil with for different histories of soil fertilization (main plots) was examined at Kyoto, Japan. The four main plots were not fertilized (NF), or fertilized with only chemical fertilizer (CF), only barnyard manure (MF) and chemical fertilizer + barnyard manure (GM) for nine years, and then two open-bottom boxes (mini-plot) were embedded in the middle of each main plot. 15N-labeled ammonium sulfate was applied to the mini-plots only before planting the first crop barley in group I, and before planting the first and the second crops in group 2. The highest biomass yield and Nuptake were observed in the GM main plot throughout the barley-maize-barley crop sequence, and in the MF main plot in the last two crops. In the mini-plots, recovery of 15N by the first barley ranged from 4%in MF to Il%in NF. After the third crop harvest, 11 to 23% of the labeled N remained in the soil in group I. The rate of remaining 15N was notably higher in MF and CM than in CF and NF. Labeled N applied before planting the second crop maize in group 2 also remained in the soil at a higher rate and recovered less by the plants in MF than in the other mini-plots.Recovery of applied N by the second crop maize in group 1, was less than 2%in all mini-plots. The contribution of the applied N to the total N uptake in the first crops was higher in NF and CF (24-48%) than in MF and CM (7-15%), and that to the subsequent crop was negligible in all mini-plots. In the soils previously fertilized with manure for nine years, the applied N was held in the soil more abundantly, but was less utilized by the plants grown in the above crop sequence than in the soil not fertilized with manure previously.

Abstract licence: CC BY-NC

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