Oral history of British science

Jenkinson, David (Part 5 of 7). An Oral History of British Science.

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  • Subjects

    Climate Change Science

  • Recording date


  • Recording locations

    Interviewee’s home, Hertfordshire

  • Interviewees

    Jenkinson, David, 1928-2011 (speaker, male)

  • Interviewers

    Merchant, Paul (speaker, male)

  • Abstract

    Part 5: Comments on recognition in soil samples of effects of ‘pulse’ of labelled carbon dioxide produced by thermonuclear tests [TT] in the 1950s and 1960s; surprise at age of carbon in topsoil and subsoil measured by radio carbon dating [RCD]; use of labelled ‘pulse’ of carbon dioxide to study yearly entry of plant material into soil. Mentions link with later ROTH C carbon turnover model [ROTHC]. Description of method of following radioactive carbon into soil. Mentions names of TTs; ban on atmospheric testing; newspaper article read morning of interview concerning discovery of mislabelled wine through presence of labelled carbon; similar age checking regarding whiskey. [04:28] Mentions ROTH C. Comments on sending soil samples to NERC RCD laboratory, East Kilbride, Scotland; method of determining age at this laboratory. Description of storage of soil samples at RES; packaging of soils for transit to RCD laboratory, including avoidance of contamination, labelling of samples. [08:29] Mentions working alone with assistant; other RCD laboratories used; lack of difficulties in matching results to samples, lack of contamination. Comments on speed with which carbon from TT enters plants; expectation that TT would allow the annual input of carbon to soil to be calculated. [10:42] Description of work in fractionating organic matter derived from labelled plant material to find locations of labelled carbon; findings. Comments on introduction to work of HF Birch by Australian visiting scientist NJ Barrow [NJB]; repetition of Birch’s experiments involving sterilisation of soil with chloroform; finding ‘flush’ of carbon dioxide from decomposition after sterilisation more heavily labelled than soil fractions; questions raised; presence of labelled carbon in organisms, some dormant, killed by chloroform; use of size of ‘flush’ to measure ‘microbial biomass’ of a soil sample; mentions published paper, 1966; developments of method with David S. Powlson [DP]. Detailed comments on new method for measuring microbial biomass developed with American visiting scientist Eric D Vance [EV], including successful published paper. [15:47] Comments on size and behaviour of soil microbe populations derived from sterilisation work, including capacity for long term ‘resting’ state. Discussion of location of soil carbon in microbial biomass, decomposing plant material, HS, resistant forms, including soil minerals. Description of technique of fractionating HS using alkali, acid, filtration. [18:50] Comments on working relations with DP. Description of method of measuring ‘flush’ of carbon dioxide in fumigation incubation method. Comments on location of work with DP; relations with EV. Mentions collaboration with Phil C Brookes [PB]. [24:10] Detailed comments on work concerning accumulation of carbon in soils of Rothamsted Broadbalk ‘Wilderness’ plots, allowed to revert to woodland, using measurements made in 1902, 1965 by DJ and 1999 by DJ and colleagues. [25:30] Mentions significance of results for recent interest in woodland as carbon stores, reducing greenhouse effect; other substances measured accumulating under woodland. Detailed description of fieldwork in ‘Wilderness’ in 1965, including role of assistant, later a police forensic scientist. Mentions fieldwork in 1999 using modern methods for soil sampling. Continued description of 1965 fieldwork; method of movement from field to laboratory; laboratory work. Discussion of labelling of samples by depth and plot number. [29:10] Comments on findings of carbon and nitrogen accumulation work; significance of findings in relation to greenhouse effect; reasons for carrying out work in 1970s, mainly through interest in passage of nitrogen into soils, rather than carbon; relationship between this work and wider Rothamsted concern in the 1960s with nitrogen fixation by clovers, soy beans, legumes. Mentions work with NJB on biological nitrogen fixation, inspired by work of Danish scientist H L Jensen and JB. [33:51] Comments on freedom to follow scientific interests at Rothamsted; interest in nitrogen fixation in the 1960s related to agriculture before nitrogen fertilisers applied widely; Agricultural Research Council unit, University of Sussex on nitrogen fixation; industrialisation of agriculture, involving fertiliser use; lack of awareness in 1960s of discussion of global warming [GW]; awareness of ‘greenhouse effect’; greater concern in 1970s with acid rain [AR] than GW. [36:56] Mentions simultaneous timing of various research interests, including ROTH C and fertiliser nitrogen fate; year in Adelaide, Australia, 1976. Detailed comments on work from 1977 with DP, Johnny Johnson using mass spectrometer [MS] to follow labelled nitrogen in soil. Story of Head of Department, Bernard Tinker [BT] not wanted DJ’s team to order their own MS but to send samples to Letcombe Laboratory; sidestepping this obstacle by asking ARC directly for MS; MicroMass 602 Isotope Ratio MS arriving 1979. Mentions recently reduced cost of nitrogen 15 [N15]. Comments on aims of research on take up of labelled nitrogen fertiliser by plants, form and fate of residue in soil; fieldwork; key findings in contrast to contemporary view that use of nitrogen fertiliser in spring necessarily led to significant ‘leaching’ of inorganic nitrogen; significance; checking of finding on various crops. [42:19] Detailed description of process of analysing labelled samples from field plots; invention of apparatus and method to convert nitrogen in sample to nitrogen gas; action on the gas of the MS; output of MS. Comments on own use of MS, later use of MS by analytical chemist Gordon Pruden. Discussion of MS output: N14 nitrogen 15 [N15] ratio. [46:36] Description of funding of research in the 1960s, 1970s through applications through Head of Department to Directors; change in funding arrangements in 1980s involving formal application for grants. Comments on appeals to significance in terms of nitrate pollution of N15 work in attracting European Community grant; relative freedom after grant awarded. Story of effects on Rothamsted of Thatcher government’s cuts in funding of applied research, involving halving of staff, Director’s strategy of removing whole departments: microbiology, soil physics, pedology. Mentions attempt to sell Rothamsted, prevented by ownership by a trust. [51:06] Detailed comments on concerns in 1980s regarding nitrate pollution, newspaper headline regarding groundwater including ‘Nitrate Time Bomb’, Blue Baby Syndrome. Comments on effect of nitrate ‘issue’ on survival of DJ’s research group.

  • Description

    Life story interview with Professor David Jenkinson, soil scientist

  • Related transcripts

    David Jenkinson interviewed by Paul Merchant: full transcript of the interview

  • Related links

    Visit this interviewee's page on the 'Voices of Science' web resource

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