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Effect of nitrogen fertilisation on below‐ground carbon allocation in lettuce
Author(s) -
Kuzyakov Y,
Siniakina S V,
Ruehlmann J,
Domanski G,
Stahr K
Publication year - 2002
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.1202
Subject(s) - rhizosphere , respiration , shoot , soil respiration , nitrogen , chemistry , agronomy , biomass (ecology) , horticulture , botany , zoology , biology , bacteria , genetics , organic chemistry
The aims of this study were to investigate the effect of nitrogen (N) fertilisation on the below‐ground carbon (C) translocation by lettuce and the CO 2 efflux from its rhizosphere. Two N fertilisation levels (80 and 160 kg N ha −1 ) and two growth stages (43 and 60 days) were tested. 14 C pulse labelling of shoots followed by 14 C monitoring in the soil, roots, microbial biomass and CO 2 efflux from the soil was used to distinguish between root‐derived and soil organic matter‐derived C. The 14 C allocation in the below‐ground plant parts was 1.5–4.6 times lower than in the leaves. The total quantity of C translocated into the soil was much lower than in the case of cereals and grasses, amounting to 120 and 160 kg C ha −1 for low and high N respectively. N fertilisation diminished the proportion of assimilated C translocated below ground. About 5–8% of the assimilated C was respired into the rhizosphere. Root‐derived CO 2 (the sum of root respiration and rhizomicrobial respiration) represented about 15–60% of the total CO 2 efflux from the planted soil. Two peaks were measured in the 14 CO 2 efflux: the first peak (4–5 h after labelling) was attributed to root respiration, whilst the second peak (12 h after labelling) was attributed to microbial respiration of exudates. Twelve days after labelling, 0.15–0.25% of the assimilated C was found in the microbial biomass. The higher microbial activity in the lettuce rhizosphere doubled the soil organic matter decomposition rate compared with unplanted soil. © 2002 Society of Chemical Industry