Doug has over 30 years experience in soil science and 16 years running his own successful private science consultancy, agKnowledge Ltd. This unique set of skills allows Doug to offer a range of consultancy services: legal work including dispute resolution and expert testimony, planning, implementation and management of scientific projects on behalf of clients, providing clients with independent assessment of research on fertiliser products and related services, media & speaking engagements, and appearance and presentation at scientific conferences.

Doug frequently contributes to agricultural forums and responds to media requests. Doug's innate ability to communicate complicated scientific concepts to the layperson makes him an engaging and thought-provoking public speaker. Doug has appeared widely throughout the agricultural conference market, and the NZ media. You can see a summary of these engagements on the media page.

If you've got a project in mind that you'd like to talk to Doug about, drop us a line here.

Scientific Consulting

Doug's professional views are often sought by companies who have undertaken a body of research and want an independent assessment. Recent projects include ProGibb (Nufarm), EcoN (Ravensdown), LessN (Donaghys), Adveco Diatomatious Clay (Todd Industries), Avail and Nutrisphere (Taurus Agriculture).

In addition, some clients request Doug's experience and expertise to design and manage research programs and experiments to test their products or investigate alternative uses for fertiliser-like materials. Current examples include research on slow-release N and K fertiliser and the potential agronomic uses of coal fly-ash.

Expert Witness & Legal Reporting

Doug's unique combination of practical and academic experience ensures he can provide valuable advice and assessment on complicated soil and agricultural related issues.

Doug is available to provide expert witness testimony for legal proceedings, and has appeared in a large number of cases from 1987 to 2012. Well known throughout the industry for his impartiality and independence, Doug's opinion is often sought to provide robust defence assistance or mediation in complicated legal issues. If you would like to make a confidential enquiry please contact Doug here.

Public Speaking & Conferences

Doug is a seasoned and experienced speaker, who has contributed to dozens of conferences and events nationally. His style can be described as passionate, energetic and humorous. He aims to inform listeners of complicated scientific concepts in simple terms, and provide a unique insight to science and it's role in society.

A selection of his recent speaking appearances is below, and topics include the role of science in society and scientific presentation related to pasture nutrition and soil fertility. If you would like to chat about an event, please contact us here.


  • 1986 Speaking Tour, ANZAC Fellow, throughout Australia on “Soil Acidity and Liming – The NZ Perspective“
  • 1988 Presentation Grasslands Society of Victoria Australia. The Mac Troupe Memorial Lecture “Maxicrop – Science, Farming and the Law“) in Ballarat, Victoria, Australia
  • 1990 Speaker Conference Phillipines. Invited speaker to the conference “Phosphorus Requirements for Sustainable Agriculture in Asia and Oceania“. International Rice Research Institute, Manila, Phillipines
  • 1994-1996 Member International Committee on Soil Acidity and Liming
  • 1996 Paper The Sulpher Institute (Washington DC) USA. Invited to submit paper on “Fertiliser Technologies in NZ” in Washington DC, USA
  • 1997 The Sulphur Institute (Washington DC) India. Invited to submit paper on “Fertiliser Technologies in NZ” in New Delhi, India
  • 1997 Study Tour Federal Republic of Germany. Invited to visit research organisations and fertiliser industry personnel, to discuss and share knowledge and information regarding sulphur deficiency. Funded by the NZ/FRG Science Scheme
  • 2000 Keynote speaker, Third International Conference on Soil Acidity Africa. Invited to be a keynote speaker, Natal, South Africa
  • 2009 Keynote speaker, Department of Agriculture Western Australia industry and farmer conference
  • 2014 Keynote speaker, South African Fertiliser Association Conference, Johannesburg, South Africa. Paper presented: Pseudo Science: A Threat to Agriculture?
  • 2014 Keynote speaker, CropLife National Members Forum, Canberra, Australia. Paper presented: Pseudo Science: A Threat to Agriculture?
  • 2015 Keynote speaker, 14th International Symposium for Soil & Plant Analysis, Hawaii. Paper presented: Do Soil and Plant Testing Laboratories have a Responsibility to Science?
  • 2015 Keynote speaker, Grains Research & Development Corporation Update Conference, Adelaide, Australia. Paper presented: Science Must Be Asserted - The Case for Agricultural Science.
  • 2015 Grains Research & Development Corporation Update Conference, Adelaide, Australia. Workshop: Alternative Products - Questions for the Salesman.

New Zealand Conferences & Field Days

  • 2012 Conference Grasslands 2012 NZ presented “Evaluating the Agronomic Effectiveness of Fertiliser Products“
  • 2012 Seminar NZIPIM Hamilton presented powerpoint “The Importance of White Clover“
  • 2012 Field Day Farm IQ Onewhero “Developing a Farm Fertiliser Plan“
  • 2012 AGM Federated Farmers Southland Soil Fertility and Pasture Nutrition
  • 2012 AGM Federated Farmers Manawatu Managing Water Quality
  • 2013 NZ Grasslands Association Conference, presented " Evaluating the Agronomic Effectiveness of Fertiliser Products"
  • 2014 Harcourts Real Estate Annual Conference, presented " Science Is Important"
  • 2014 Avocado Growers Annual Conference, presented "Pseudo-Science: A Threat to Agriculture?"
  • 2014 NZ Association of Animal Health & Crop Protection, presented "Pseudo-Science: A Threat to Agriculture?"
  • 2014 Biological Farming Conference, presented " The Myth of Biological Farming"
  • Doug is a regular contributor to the Fertiliser and Lime Research Centre annual workshops at Massey University