Failure of an iterative curve-fitting procedure to successfully estimate two organic N pools

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• 作者：L. Dendooven ; R. Merckx ; L.M.J. Verstraeten and K. Vlassak
• 关键词：aerobic incubation ; C and N mineralization ; crop residues ; soil organic matter pools ; Stanford and Smith
• 刊名：Plant and Soil
• 出版年：1997
• 出版时间：1997
• 年：1997
• 卷：195
• 期：1
• 页码：121-128
• 全文大小：109 KB

文摘

Fitting a double negative exponential function to N mineralization data can be used to characterize two organic nitrogen pools; an easily decomposable (N_dpm) and a resistant one (N_rpm). The relevance of those two calculated N mineralization pools was investigated by adding easily decomposable organic material to soils. Soil amended with crop residues of sugar-beet or bean was mixed with an equal amount of coarse sand, incubated at 35 °C and leached at specific time-intervals. Upon leaching, NH₄+ and NO₃- were measured in the extracts. A double negative exponential function was fitted to the data and two organic N pools were defined. Fitting a double negative exponential function to N mineralization data to characterize an active and resistant organic N pool was sometimes impossible; the N mineralization data did not always resemble a negative exponential function. Additionally, the size of the two pools calculated were not constant with time and were often meaningless; the N_rpm pool was greater than the soil organic N content, the size of the N_rpm pool was smaller than the N_dpm pool or one of the N pools was negative. Relevant values for both N_rpm and N_dpm which were consistent with incubation time were only obtained when excessive amounts of organic material, normally not dealt with in the field, were applied.