Grounded (old)

Making sense of agriculture and the environment

Nutrient loss measurement and modelling

Do you have a farming system that you believe is efficient environmentally, and should have low nutrient losses, yet according to OVERSEER your losses are still comparable to other farms? There are many farmers trying a wide range of different practices to improve profitability and the environment, but often what they do cannot be fully reflected in OVERSEER, potentially resulting in farmers being unfairly penalised by regional councils.

I am a soil & farm systems scientist specialising in nutrient loss from New Zealand farms. I can conduct on-farm research into factors that influence nutrient loss, install equipment to directly measure nutrient losses, and model nutrient loss using OVERSEER. I have a good understanding of the strengths and limitations of OVERSEER, and can clearly relate it to the real situation on-farm. I regularly conduct work for major agricultural industry organisations to inform submissions on regional council rules, particularly in Canterbury. I also conduct on-farm research for individual farmers, particularly into how their farming practices may influence nutrient loss and how to have any improvements recognised by regulatory bodies.

I am currently working on potentially revolutionary approaches to make on-farm measurement of nutrient loss more practical and affordable than it has ever been to date. This is essential to reduce the farming industry's reliance on models. If you would like the nutrient loss from your farm directly measured using an experimental approach, contact me.


On-farm Research

  • On-farm measurement of soil, pasture, and animal factors that influence nutrient loss, to determine whether farm practices may reduce N & P loss.
  • Direct measurement of nutrient losses.
  • OVERSEER modelling of nutrient loss, clearly related to the real farm situation.
  • Understand, investigate & communicate implications for the entire farm system.

Different urine making machines


Speaking & Consulting

  • Clearly explain nutrient loss in layman's terms to any audience (what it is, why it matters, whole-farm implications, how it is measured & modelled, benefits & limitations of different approaches, relevance to regulations...)
  • Advise regulators on designing effective regulations that may actually help the environment without unnecessarily harming farm businesses.
  • Advise affected parties on regulations, provide scientific supporting evidence for submissions, represent parties in hearings and caucusing.

Samuel speaking at LUDF (Image: NZ Dairy Exporter)

Pasture Yield Mapping

  • Find low production areas within paddocks, investigate reasons & how to fix
  • Map gross margin - find areas earning money vs costing money
  • Assess investments (e.g. does a new irrigator improve yield?)
  • Research: cost-effective pasture production measurement on large field plots

Customised pasture meter for yield mapping

Why choose Grounded?

I have broad experience and a down-to-earth approach. I worked as a research scientist at AgResearch prior to starting Grounded, and have also worked on both sheep & beef and dairy farms. There are plenty of scientists in the country, and plenty of people with farming experience, but it can be hard to find someone who is both qualified and understands real NZ farming systems.
I can also understand the bigger picture - why an issue matters, and what the future implications are.
I am committed to scientific truth, regardless of what ideas may be currently popular. If I think something is scientifically questionable, I'll say so. I work for myself so have the freedom to speak the plain truth as I see it.
I can explain scientific issues to any audience, from schools to courtrooms.

  Lincoln University
        PhD in Soil Science (studying nutrient leaching losses).
  Massey University
        Intermediate and Advanced Sustainable Nutrient Management certificates.

Professional memberships:
New Zealand Grasslands Association
New Zealand Society of Soil Science

Research publications:

Click here to view my publications on