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.

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 sulphur 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, sulphur 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.

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.

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.

Useful link

Get a glimpse of Prof Walker and his enthusiasm for soil science with this short video from the New Zealand Society of Soil Science.


    Published 10 June 2015, Updated 16 June 2015