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Incorporation of Nitrogen-15-Labeled Amendments into Physically Separated Soil Organic Matter Fractions

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Bosshard, C.; Frossard, E.; Dubois, D.; Mäder, P.; Manolov, I. and Oberson, A. (2008) Incorporation of Nitrogen-15-Labeled Amendments into Physically Separated Soil Organic Matter Fractions. Soil Science Society of America Journal, 72 (4), pp. 949-959.

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Online at: https://www.soils.org/publications/sssaj/abstracts/72/4/949

Summary

Physically separated soil organic matter (SOM) fractions may take different functions in soil N dynamics. We studied the effect of long-term organic matter (OM) management and different soil biological activity on the incorporation of N added with organic and mineral amendments into aggregate fractions and size density fractions. We applied 15N-labeled sheep feces, urine, and mineral fertilizer to microplots installed in plots of conventional (CONMIN) and bio-organic (BIOORG) cropping systems. Soil sampled 112 d after amendment was separated into macro-, microaggregates, and microstructures. Aggregates were then fractionated into free light fraction (LF), intra-aggregate particulate organic matter (iPOM),and the mineral-associated organic matter fraction (MF). Of total soil N, 67% was contained in macroaggregates. Size density fractionation of aggregates revealed that about 60% of soil N was stored in MF while LF and iPOM contained together <3% of soil N. Despite longterm OM input and higher soil biological activity in BIOORG than CONMIN the two soils did not differ in the distribution and content of N in aggregate and size density fractions. Recovery of 15N in nonfractionated soil ranged from 20% (SlurryF) to 25% (SlurryU) of originally applied 15N. The small macroaggregates were for each amendment the major sink (7–12% of applied 15N). In all aggregates and for all amendments, MF was the most important 15N sink, totally containing between 6.6% (SlurryF) to 11.6% (SlurryU) of applied 15N. Less than 1% of applied 15N was recovered in LF, and even less (<0.5%) in iPOM. The proportion of amendment-derived N in aggregate fractions and in several size density fractions (LF, fi ne iPOM, MF) was higher for urine than for feces and mineral fertilizer. Recovery of urine-derived 15N was greater in aggregate fractions of BIOORG than CONMIN soil. During dispersion of aggregates to obtain iPOM and MF, about 27% of total soil N and between 37 and 55% of 15N contained in non-fractionated soil was lost, showing the importance of aggregation to protect N.


EPrint Type:Journal paper
Keywords:Soil sciences, Bodenwissenschaften, Systemvergleich, Dünger, Stickstoff
Agrovoc keywords:
LanguageValueURI
Englishsoil organic matterhttp://aims.fao.org/aos/agrovoc/c_35657
Englishsoil biological activityUNSPECIFIED
Subjects: Soil
Research affiliation: Switzerland > FiBL - Research Institute of Organic Agriculture Switzerland > Soil Sciences
Bulgaria > Agricultural University, Plovdiv
Switzerland > Agroscope > ART - Reckenholz location
Switzerland > ETHZ - Agrarwissenschaften
DOI:10.2136/sssaj2006.0376
Deposited By: Mäder, Paul
ID Code:26387
Deposited On:17 Jun 2014 19:31
Last Modified:17 Jun 2014 19:31
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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