Professor Phil Brookes, 1951-2023

Phil Brookes was a soil biologist whose research was influential globally and greatly contributed to enhancing Rothamsted’s reputation in soil science research over the last 40 years. A major focus of his work concerned the survival and activity of soil micro-organisms and their interactions with soil organic matter.

Phil joined the Chemistry Department at Rothamsted in 1976 and initially worked on aspects of soil phosphate chemistry with ‘Johnny’ Johnson and then Geoff Mattingly. A few years later he and I were thrown together by our respective bosses, Geoff Mattingly and David Jenkinson, and charged with developing a method for measuring the quantity of phosphorus (P) held in the cells of living microorganisms in soil, biomass P. This was successfully achieved, with a method published in 1982, building on Phil’s expertise in soil P chemistry and my previous experience in developing a method to determine the quantity of carbon held in soil microbes (biomass C) based on chloroform fumigation and incubation. Phil became fascinated by ideas developed by David Jenkinson about the value of treating soil microbes as a whole population rather than concentrating on identifying individual species – the “microbial biomass” concept. This approach remained a strong driver of his research throughout his career. A paper he published in 1987 with Eric Vance and David Jenkinson described a new and more convenient way to estimate biomass C using chloroform fumigation but followed by extraction instead of incubation. The method is still widely used and for some years was the most highly cited paper in the journal Soil Biology and Biochemistry, the home for the majority of his publications.

Phil also investigated various pollution issues including, with Steve McGrath, ground-breaking work demonstrating the negative impact on soil microbes of metals from applications of sewage sludge (now more delicately termed biosolids), using an existing field experiment at Woburn Farm. Later he returned to studies on soil P dynamics. A paper published in 1995 (with Goswin Heckrath, a visiting German student, together with Paul Poulton and Keith Goulding) was the first demonstration of phosphate leaching through soil to drainage water, mainly via movement through cracks and channels (by-pass flow). Even small quantities of P entering surface waters can have major impacts on water quality with implications for fisheries. As an enthusiastic fisherman, this was a significant issue for Phil, especially concerning water quality in lochs in Ireland, where he spent much leisure time pursuing his hobby. He was proud to meet Mary Robinson when she was President of Ireland and discuss these issues with her.

Phil worked with numerous Ph.D. students, early career scientists and Visiting Scientists from around the world, becoming a mentor and inspiration to many younger colleagues. After his retirement from Rothamsted in 2011 he took up a prestigious Chinese government Fellowship to work at Zhejiang University where he spent some 6 years. Following his second retirement he enjoyed living in his beloved adopted country of Ireland where he had many friends and enjoyed bee-keeping, vegetable growing and his lifelong passion of fishing. Many older Rothamsted colleagues have memories of searching in freezers for precious samples of soil and finding plastic bags containing Phil’s trout awaiting later culinary use; cooking, especially fish dishes, was another passion.

In addition to being a highly influential soil microbiologist, he was a larger-than-life character. He was always ready for a scientific argument if he thought someone was misinterpreting the evidence or accepting unjustified assumptions. He will be greatly missed by colleagues and former students across the world, by his family and by his many friends in Ireland. At his funeral many of his Irish fishing friends gave him a guard of honour wearing their fishing gear – a fitting tribute.

David Powlson, October 2023