Authors: R GarciaRuiz E M Baggs
Publish Date: 2007/09/21
Volume: 299, Issue: 1-2, Pages: 263-274
Abstract
Emissions of N2O and CO2 were measured following combined applications of 15Nlabelled fertiliser 100 μg N g−1 10 atom excess 15N and organic olive crop weed residues Avena sativa Ononis viscosa Ridolfia segetum and Olea europea 100 μg N g−1 to a silt loam soil under controlled environment conditions The objective was to determine the effect of varying combinations of inorganic fertiliser and plant residues on these emissions and soil mineral N dynamics Emissions were generally increased following application of residues alone with 23 ng N2O–N g−1 soil 2 ng N2O–N g−1 soil mg−1 biomass and 389 μg CO2–C g−1 soil 39 μg CO2–C g−1 soil mg−1 biomass emitted over 28 days after addition of the Ridolfia residues in the absence of fertiliserN N2O emissions from these residueonly treatments were strongly negatively correlated with residue lignin content r = −091 P 005 total carbon content r = −090 P 005 and lignin + polyphenoltoN ratio r = −070 P 01 However changes in the net input of these compounds through application of 2575 5050 and 7525 proportional mixtures of Avena and Ononis residues had no effect on emissions compared to their single 0100 or 1000 applications Addition of fertiliserN increased emissions by up to 30 ng N2O–N g−1 28 days−1 123 particularly from the low residueN treatments Avena and Ridolfia where a greater quantity of biomass was applied resulting in emissions above that of the sum from the unfertilised residue and fertilised control treatments In contrast fertiliser application had no impact on emissions from the Olea treatment with the highest polyphenol 2 and lignin 11 contents due to strong immobilisation of soil N and the 15N–N2O data indicated that residue quality had no effect on the denitrification of applied fertiliserN Such apparent inconsistencies mean that before the potential for manipulating N input organic + inorganic to lower gaseous N losses can be realised first the nature and extent of interactions between the different N sources and any interactions with other compounds released from the residues need to be better understoodThis research was funded by the Ministry of Education Culture and Sport of Spain Mobility of academic staff programme Experimental work was undertaken at Imperial College London Wye Campus and we wish to thank Mr Jon Fear and Dr Nicole Wrage for their assistance with the 15N analysis there We also thank Dr JA Carreira and Dr Benjamín Viñegla for early discussions of the manuscript
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