caa a22 4500 477111564 CHVBK 20180405111610.0 cr unu---uuuuu 170330e19960301xx s 000 0 eng 10.1007/BF00015410 doi (NATIONALLICENCE)springer-10.1007/BF00015410 Thompson R. Department of Vegetable Crops, University of California-Davis, c/-USDA-ARS, 1636 East Alisal St., 93905, Salinas, CA, USA aut Pulse-labelling a cover crop with 13C to follow its decomposition in soil under field conditions [Elektronische Daten] [R. Thompson] A preliminary study was conducted using the stable isotope 13C to pulse label the cover crop phacelia (Phacelia tanacetifolia) to examine its decomposition in soil, under field conditions. Plants were grown, in pots, in the greenhouse and after four weeks of growth were labelled with 13CO2 six times, at 1-2 week intervals. A single chamber was placed over the pots, and 13CO2 was generated, inside the chamber, by injecting lactic acid into sodium carbonate (99 atom % 13C). For calculating the quantity of Na2CO3 required, a target enrichment of 5 atom% 13C within the shoots of plants, assuming no respiration losses, was used. When harvested, at flowering, the mean enrichment of the shoot material was 3.0466 atom% 13C, or 1.9654 atom% excess 13C. To assess uniformity of labelling within plants, the shoot of a single plant was divided into leaves and stem from three sections of equal length. Ninety-three percent of this plant's dry matter had a 13C enrichment within 20 % of the weighted mean. At a field site with sandy soil, 13C labelled shoot and root material were combined and mixed with soil (0-15 cm). The soil was sampled 16 and 179 days later to determine the recovery of the added excess 13C in soil total C. The recoveries in soil (0-30 cm) were, respectively, 78 and 40 % at 16 and 179 days; there was appreciable variation associated with the recovery data from day 16, much less so at day 179. Methodological procedures for (i) enhancing the uniformity of labelling with 13C within plants, and (ii) minimising variability in the recovery of 13C from soil are suggested. ei]R Merckx Kluwer Academic Publishers, 1996 cover crop nationallicence 13C nationallicence carbon labelling nationallicence decomposition nationallicence residue nationallicence Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl 180/1(1996-03-01), 49-55 0032-079X 180:1<49 1996 180 11104 https://doi.org/10.1007/BF00015410 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00015410 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Thompson R. Department of Vegetable Crops, University of California-Davis, c/-USDA-ARS, 1636 East Alisal St., 93905, Salinas, CA, USA aut NATIONALLICENCE 773 0- Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl/ 180/1(1996-03-01), 49-55 0032-079X 180:1<49 1996 180 11104 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer