Abstract
Soil was amended with 14C-labelled unripe straw only (C:N ratio ca. 20), with 14C-labelled unripe straw plus unlabelled ripe straw (C:N ratio ca. 100) or with 14C-labelled unripe straw plus glucose. Half the samples with 14C-labelled straw and half the samples with 14C-labelled plus unlabelled straw were cropped with rape plants. A decreased rate of mineralization of the 14C-labelled straw was found in the planted soil compared with the unplanted soil. The reduction was most profound in the soil amended with both labelled and unlabelled straw, indicating that at least part of the reduction was due to competition between plants and microorganisms for mineral N. No other explanations for the decrease in mineralization in the presence of plants were found. The soil amended with glucose which simulated the effect of root exudates showed an increased rate of mineralization. Therefore, the reduction in the presence of plants was probably not due to microbial use of the rhizodeposition in favour of the labelled straw. Only a minor part of the reduction was apparently due to uptake of labelled C by the plant, as only small amounts were found in the roots and shoots at harvest. The difference in 14C mineralization between treatments was not reflected in the number of bacteria in the soil at harvest. The number of bacteria, which was determined by plate counts and direct microscopy, was the same in all the soils, rhizosphere soils as well as bulk soils.
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BrookesPC, LandmanA, PrudenG, JenkinsonDS (1985) Chloroform fumigation and the release of soil nitrogen: A rapid direct extraction method to measure microbial biomass nitrogen in soil. Soil Biol Biochem 17:837–842
FührF, SauerbeckD (1968) Decomposition of wheat straw in the field as influenced by cropping and rotation. In: Isotopes and radiation in soil organic matter studies. Proc Symp Int Atomic Energy Agency, Food and Agric Org, and Int Soil Sci Soc in Vienna, July 15–19, 1968. Int Atomic Energy Agency, Vienna, pp 241–250
HelalHM, SauerbeckD (1986) Effect of plant roots on carbon metabolism of soil microbial biomass. Z Pflanzenernähr Bodenkd 149:181–188
HobbieJE, DaleyRJ, JaspenS (1977) Use of nucleopopore filters for counting bacteria by fluorescence microscopy. Appl Environ Microbiol 13:1225–1229
MartinJK (1987) Effect of plants on the decomposition of 14C-labelled soil organic matter. Soil Biol Biochem 19:473–474
NewmanEI (1985) The rhizosphere: Carbon sources and microbial populations. In: FitterAM, AtkinsonD, ReadDJ, UsherMB (eds) Ecological interactions in soil-plants, microbes and animals. Spec Publ 4, Br Ecol Soc, Blackwell, Oxford, pp 107–121
ReidJB, GossMJ (1982) Suppression of decomposition of 14C-labelled plant roots in the presence of living roots of maize and perennial ryegrass. J Soil Sci 33:387–395
SallihZ, BottnerP (1988) Effect of wheat (Triticum aestivum) roots on mineralization rates of soil organic matter. Biol Fertil Soils 7:67–70
SAS Institute Inc (1989) SAS/STAT user's guide, version 6, 4th edn, vol 2. SAS Institute, Cary, NC
ShieldsJA, PaulEA (1973) Decomposition of 14C-labelled plant material under field conditions. Can J Soil Sci 53:297–306
SparlingGP, CheshireMV, MundieCM (1982) Effect of barley plants on the decomposition of 14C-labelled soil organic matter. J Soil Sci 33:89–100
SparlingGP, WestAW (1988) A direct extraction method to estimate soil microbial C: Calibration in situ using microbial respiration and 14C-labelled cells. Soil Biol Biochem 20:337–343
TaborPS, NeihofRA (1982) Improved method for determination of respiring individual microorganisms in natural waters. Appl Environ Microbiol 43:1249–1255
WangJ, BakkenLR (1989) Nitrogen mineralization in rhizosphere and non-rhizosphere soil: Effect of the spatial distribution of Nrich and N-poor plant residues. In: HansenJA, HenriksenH (eds) Nitrogen in organic wastes applied to soils. Academic Press, London, pp 81–97
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Bek, S. Mineralization of 14C-labelled unripe straw in soil with and without rape (Brassica napus L.). Biol Fert Soils 17, 21–26 (1994). https://doi.org/10.1007/BF00418667
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DOI: https://doi.org/10.1007/BF00418667