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a Dep. of Plants, Soils, and Biometeorology
b Dep. of Biology
c Dep. of Agricultural Systems Technology and Education, Utah State Univ., Logan, UT 84322
* Corresponding author (jennyn{at}cc.usu.edu)
Measurements of gross N transformation rates are important to properly understand N cycling processes in agricultural soils where both productive and consumptive processes occur. The objective of the study was to determine the effect of repeated application of dairy-waste compost (DC), liquid dairy-waste (LW), and ammonium sulfate (AS) on gross N mineralization and nitrification rates and N supplying potential of an agricultural soil. Our goal was to examine both production and consumption of inorganic N for their effects on the balance between N supply from treated dairy-wastes and plant N demand. Treatments were applied at rates approximately equivalent to 100 and 200 kg available N ha1 for 6 yr annually. Field-based N15 pool dilution techniques and laboratory incubation experiments were employed to measure gross rates and mineralization potential of the soil. Both levels of DC raised the labile organic N pool significantly but only the high level DC significantly increased the decomposition rate constant (k). The mean gross N mineralization rates for 1999 to 2002 for the high levels of DC, LW, and AS were 5.72, 2.89, and 1.27 mg N kg1 d1, whereas gross nitrification rates were 10.24, 1.57, and 0.74 mg N kg1 d1, respectively. Net mineralization rates were <35% of gross rates while nitrate consumption was not significant under any treatment. Variability in gross rates was high in the soils receiving DC, which could be due to presence of hotspots of labile organic matter. Elevated gross N transformation rates in plots receiving DC indicate the dynamic nature of this agricultural soil after repeated applications of dairy-waste.
Abbreviations: AS, ammonium sulfate DC, dairy waste compost LW, liquid dairy waste
This article has been cited by other articles:
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M. Y. Habteselassie, B. E. Miller, S. G. Thacker, J. M. Stark, and J. M. Norton Soil Nitrogen and Nutrient Dynamics after Repeated Application of Treated Dairy-Waste Soil Sci. Soc. Am. J., June 21, 2006; 70(4): 1328 - 1337. [Abstract] [Full Text] [PDF] |
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