Heritage scientist timeline – Thomas William Walker
Thomas William Walker, known to many as ‘Prof’, was a key player in the evolution and development of modern New Zealand soil science. As well as being a leading soil scientist on the world stage, he was without doubt the leading soil scientist of his time in New Zealand.
Thomas William Walker, soil scientist
Thomas William Walker (1916–2010), often also known as Prof, was a leading soil scientist.
Many New Zealanders will remember the Prof from his vegetable gardening segment in the popular national television series (1991–2003) Maggie’s Garden Show. His ability to communicate across the wide spectrum of people interested in soil science, from academics to students, farmers and the general public, elevated him to legendary status
My job was my hobby and I owe so much of my enjoyable life to a very good teacher, the excitement of research in soil science and the fun of communicating with students, farmers and gardeners.
Thomas William Walker
Walker was born in England in 1916 and, at an early age, demonstrated a love of and aptitude for chemistry. In 1937, he obtained a first class honours degree in chemistry and, in 1939, a PhD in agricultural chemistry.
At the outbreak of the Second World War and having just completed his PhD, Walker was exempted from induction into the Armed Forces in order to continue with his work in soil testing and the investigation of soil problems in the field. Wartime conditions meant that Britain needed to become self-sufficient in its food production, and campaigns like ‘Dig for Victory’ required the involvement of soil scientists to communicate best practice to farmers. Given Walker’s articulate, colourful and ‘down to earth’ way of communicating, he was asked to do a lot of talking to farmers.
Just after the war, Walker was appointed Provincial Soil Chemist for the West Midlands, the grassland counties of England. He soon became involved in the debate around the use of manufactured nitrogen fertilisers versus the natural nitrogen fixation in soils achieved by growing leguminous pasture plants like white clover. This drew him to a research focus on the nitrogen economy of legume-based pastures.
In 1951, the Chair of Soil Science at Lincoln University was advertised, and Walker, familiar with the almost complete dependence of New Zealand agriculture on nitrogen fixation, successfully applied. As head of the research team, Walker set about running a series of field experiments across a range of soils, throughout Canterbury, to determine the nutrient requirements for establishing and improving the productivity of grass-clover pastures. The effects of phosphorus, molybdenum and sulfur on biological nitrogen fixation by clovers were thoroughly investigated. In addition to these nutrient studies, Walker also instigated research into the sequences of soils in Canterbury, particularly with respect to the influence of phosphorus content of soil parent materials on the accumulation of carbon, nitrogen, sulfur and organic phosphorus in grassland soils.
After directing 6 years of ground-breaking research at Lincoln, Walker returned to England to accept the Chair of Agriculture at King’s College Newcastle upon Tyne, an outpost of Durham University. During his time at King’s College, he was influenced by Dr Edward Compton, who was a keen follower of the much-respected soil scientist Hans Jenny. However, after a few years, he realised that he missed the challenge of researching New Zealand’s soil formation, structure and fertility and returned in 1960 to his original position of Chair of Soil Science at Lincoln.
Professor Walker fishing
Outside of work, fishing was a great passion Professor Walker enjoyed in the company of colleagues. He often joked that it was really the fishing that had brought him to New Zealand.
In his second stint at Lincoln, Walker’s research interests focused on soil formation processes with special emphasis on phosphorus. Working in collaboration with Keith Syers, a postdoctoral fellow in the Department of Soil Science at Lincoln, a model of changes in soil phosphorus during pedogenesis was proposed. This became known as the Walker and Syers model.
By the 1970s, Walker had established at Lincoln a soil science teaching philosophy that integrated pedology and soil chemistry with soil fertility. It was a novel approach that won much positive comment.
Walker was appointed Emeritus Professor of Soil Science at Lincoln University on his retirement in 1979 after 27 years of service spread over the time periods 1952–1958 and 1960–1979. At the time of his death in 2010, Walker was Lincoln University’s longest-serving Emeritus Professor.
Professor Walker at 90
Professor Walker celebrating his 90th birthday at Lincoln University in 2006.
The timeline below lets you see aspects of Thomas's life and work, and how his findings changed scientific thinking. A full timeline transcript is here.
Thomas William Walker – soil scientist
- Changing scientific ideas
- Advances in science and technology
- Biography
Farming practices in Ancient Rome
500 BCE to 5th century CE. The Ancient Romans know about manure, fallowing, fertilising effects of leguminous plants, crop rotation and soil treatment with marl.
Māori arrive in New Zealand
When Māori arrived in New Zealand they brought crops to cultivate.
Māori and soil
Prior to the arrival of Europeans Māori had already identified at least 30 types of soil. Māori treated soils with ash, gravel or sand. They also practiced fallowing.
Calcareous manures
Edmund Ruffin, an American agriculturalist, presents a paper explaining how, by applying calcareous earth (marl or lime), the acidity of soil can be reduced.
Birth of soil chemistry
During the mid to late 19th century German botanist Philip Carl Sprengel (1787–1859) debunks the ‘humus theory’ of plant nutrition and replaces it with the ‘soluble soil salts’ theory – soil salts serve as plant nutrients not humus.
Nitrogen cycle
From 1836–1876, French chemist Jean Baptiste Boussingault works on tracing the path of nitrogen between living organisms and the physical environment. He demonstrates that plants do not absorb nitrogen from the air but from the soil in the form of nitrate.
Law of the minimum
The law of the minimum principle developed by Carl Sprengel in 1828 is popularised by German chemist Justus von Liebig. It states that plant growth is controlled not by the total amount of resources available but by the one present in the least amount.
Rothamsted Estate
English entrepreneur and scientist John Bennet Lawes, owner of Rothamsted Estate, appoints chemist Joseph Gibert as his scientific collaborator. Together, they lay the foundations of modern scientific agriculture and establish the principles of crop nutrition.
Pedology
German Friedrich Albert Fallou coins the term ‘pedology’. In his book of 1862, Fallou recognises the soil as a natural body that needs to be studied. He introduces the concept of soil profile and establishes a soil classification based on parent rock.
Inception of soil science
Dokuchaev, Public domain
From mid to late 19th century German-American Eugene Hilgard (1833–1916) and Russian Vasily Dokuchaev (1846–1903) are key players in formalising the study of soil for the benefit of both farmers and the consumers of farm products. Dokuchaev sees the soil as “an independent natural-historical body” resulting from the collective influence of subsoils, climate, flora and fauna, geological age and relief of the locality.
Darwin’s earthworm study
Charles Darwin’s book on earthworms is the first scholarly treatment of soil-forming processes.
Dokuchaev and the Russian influence
Dokuchaev’s book on soil formation leads to his elevation as the founder of pedology by Russian soil scientists. Dokuchaev sees the soil as “an independent natural-historical body” resulting from the collective influence of subsoils, climate, flora and fauna, geological age and relief of the locality.
Legumes and nitrogen fixation
Jim Deacon, Institute of Cell and Molecular Biology, The University of Edinburgh
Germans Hermann Hellriegel and Hermann Wilfarth conduct experiments in nitrogen fixation in legumes. They establish that nodules on the legume root and the bacteria contained within allow the conversion of nitrogen from the air into compounds the plant can use.
Influential book on soil science
The ‘father of American soil science’, Eugene Woldemar Hilgard, publishes a book that at the time becomes soil scientists’ standard text – Soils, their formation, properties, composition, and relations to climate and plant growth in the humid and arid regions.
Glinka and pedogenesis
Russian Konstantin Glinka (1867–1927) contributes a great deal to the understanding of the principles of the geographical distribution of soils and soil formation. Glinka’s propagation of the principles of pedogenesis in Russia and abroad has a progressive influence.
Haber-Bosch process
Germans Fritz Haber (1868–1934) and Carl Bosch (1874–1940) manufacture ammonia on an industrial scale. The Haber-Bosch process converts atmospheric nitrogen to ammonia. Nitrogen fertiliser generated from this process currently feeds an estimated one-third of the Earth’s population (2014).
Born in England
Thomas William Walker is born on 2 July 1916 in Shepshed, Leicestershire, England.
Soil classification
During the early 20th century Curtis F Marbut (1863–1935) develops the first formal soil classification scheme for the United States – classification of soils should be based on morphology instead of on theories of soil genesis. In 1911, Marbut publishes some of the first soil maps of the rich agricultural lands of the mid-western states such as Illinois.
Educated at Loughborough Grammar School
Thomas is greatly influenced by his chemistry teacher Freddy Grey. Of the six fellow students in the upper 6th science class taught by Grey, five go on to graduate PhD and two became Fellows of the Royal Society.
New Zealand Soil Bureau’s first pedologists
New Zealand Soil Bureau’s first pedologists, Dr Leslie Grange and Dr Norman Hargraves Taylor appointed. An English translation of Russian Konstantin Glinka’s book was published by American Curtis Marbutt. Marbutt’s translation has a significant impact on the early days of soil science in New Zealand and is the key text available in the 1930’s for the Soil Bureau.
Cobalt deficiencies and sickness
Soil chemist Elsa Kidson and colleagues determine a lack of cobalt in soil is the cause of a serious wasting disease in cattle and sheep. They recommend adding small amounts of cobalt to the soil rather than feeding it to stock.
Royal College of Science London, BSc
Awarded a Royal Scholarship. Graduates in 1937 with a BSc First Class Honours and as an Associate of the Royal College of Science
Alternative forms of phosphate fertiliser
Thomas William Walker, as part of the Second World War effort in the UK, investigates alternative forms of phosphate fertiliser at Rothamsted Experimental Station, one of the oldest agricultural research institutions in the world.
Royal College of Science London, PhD
Awarded the Diploma of Imperial College as well as a PhD in Agricultural Chemistry. The title of Walker’s thesis is The influence of soil type on the growth of plants.
Rothamsted Experimental Station
Jack Hill, Creative Commons 2.0
Receives a Salter’s Scholarship for 2 years to work at Rothamsted Experimental Station. Along with former Loughborough Grammar School classmate George Cook, they are given the task of finding alternative sources of phosphate fertiliser as back-up due to the prospect of the loss of the Pacific resources with the onset of the Second World War.
Soil formation
In the mid to late 19th century, Swiss-American Hans Jenny (1899–1992), an expert on soil formation, devises a generic mathematical relationship that connects the observed properties of soil with the independent factors that determine the process of soil formation: S = f(cl, o, r, p, t, ...), where S is soil properties, cl is regional climate, o is potential biota, r is relief, p is parent material, t is time and any other identifiable variables.
Factors of soil formation
Swiss-American Hans Jenny develops numerical functions to describe soil in terms of five interacting factors. In 1941, his seminal text Factors of soil formation is published. It is from this book that Thomas Walker draws inspiration, and most of his soil sequence studies are based on Jenny’s concepts.
Manchester University
Appointed to the position of Lecturer and Adviser in Agricultural Chemistry. He spends the war years engaged in the British Government’s national food production programme applying his knowledge and research skills to boosting wartime food output – the ‘Dig for Victory’ campaign.
National Agricultural Advisory Service
Joins the NAAS as Provincial Advisory Soil Chemist in the West Midlands – the grassland region of England.
Biological fixation by clovers
Irina Moskalev, licensed via 123RF Ltd
Between 1952 and 1958, Walker’s research group conducts a number of key field trials throughout Canterbury assessing the effects of phosphorus, nitrogen, molybdenum and sulfur on biological nitrogen fixation by clovers. From these studies comes a series of key papers leading to the greater understanding of legume nutrition.
Canterbury Agricultural College, New Zealand
Courtesy of Lincoln University Archives, licensed under Creative Commons 3.0
Arrives in New Zealand with wife Edna and three daughters to take up an appointment as Foundation Professor of Soil Science. Canterbury Agricultural College is later named Lincoln College in 1961 and then Lincoln University in 1990.
Innovative soil fertility research
Courtesy Lincoln University
Begins ground-breaking research in adopting a soil sequence approach in field studies of soil fertility.
King’s College, Newcastle upon Tyne
Returns to England to take up the Chair of Agriculture at King’s College, Newcastle upon Tyne, a college of the University of Durham, England.
Soil sequences
On returning to Lincoln in 1960, Walker embarks on soil sequence studies over the following two decades, based on chronosequences, climosequences and lithosequences in both the South and North Islands, one of the first and most notable being the pedology of the Franz Josef chronosequence. These studies incorporate understanding from soil surveys into soil fertility by employing soil chemistry and mineralogy.
Returns to Lincoln College
Returns to New Zealand to once again take up his original position as Chair of Soil Science at Lincoln College.
Fate of phosphorus during pedogenesis
At Lincoln College (now University), studies of soil sequences continue throughout the 1970s, and many of these studies are incorporated in the 1976 Geoderma paper by Walker and Keith Syers – The fate of phosphorus during pedogenesis. The paper distils data from four New Zealand soil chronosequences to show that soil nutrients follow predictable but fundamentally different patterns during long-term ecosystem development.
Thomas retires
After holding the Chair of Soil Science at Lincoln University for 27 years, Professor Walker retires.
Changes in world fertiliser use
Between 1950 and 1988, world fertiliser use rises from 14 million to 144 million tons. Fertiliser use peaks in the US and some western European countries in the 1980s. Since 1985, there has been a ten-fold increase in nitrogen fertiliser use in New Zealand.
Soils and human impact
During the 1990s there is a growing awareness among the science community that soils and land use play an important role in moderating all of the environmental impacts of human existence – nutrient cycling, biodiversity loss, climate change and water quality among others.
Television career
Professor Walker commences a journey into television, starring as the vegetable gardening ‘Prof’ in the programme Maggie’s Garden Show. Several series of this programme run from 1991 to 2003.
Receives ONZM
© Crown Copyright 2002–2005.
Professor Walker is appointed an Officer of the New Zealand Order of Merit (ONZM).
Digital soil maps
Soil mapping moves online. Landcare Research develops S-map Online, a digital soil map and national soils database. S-map can be applied at any scale from individual back gardens to regions. S-map provides maps on specific soil attributes to help land users fine-tune soil management processes.
Dies in Christchurch
On 8 November, aged 94, Prof Walker dies. Family members say, “He was small in stature but larger than life and passionate about four things – his wife Edna, his work, his fishing and the soil – the soil in his own garden and the soils of New Zealand.”
Soils and climate change
The 4 per 1000 Initiative is launched at the Paris Agreement on climate change. The initiative proposes an annual 0.4% increase in soil carbon sequestration to help offset CO2 emissions. This voluntary action will also help soil fertility and food security.
Thomas William Walker – soil scientist
This timeline lets you see aspects of Thomas's life and work, and how these fit into a wider science picture of soil science. A full transcript is underneath.
Useful link
Get a glimpse of Prof Walker and his enthusiasm for soil science with this short video on the Te Ara website from Maggie’s garden show, in it he talks about the importance of good garden soils.
