Who has never complained about the absence of flavour in supermarket tomatoes, particularly when out of season? Almost without exception we laud the merits of homegrown produce as being much more flavourful, even more so if crops have been grown from heritage varieties. Very hipster these days. Many people believe that the flavour has been sacrificed in commercial crops in the quest for high production.

Things are never that black and white. For some years, we have been pondering the triggers for flavour. I cite my experience with tomatoes in Southern Italy. A taste treat beyond compare, so full of flavour were they. But it was only the first week of June so it wasn’t a hot, dry summer that determined the quality of the taste. Nor, indeed, was it the variety. In recent years there has been an explosion of heirloom or heritage seed varieties becoming available in this country. We have tried growing a fair number of different ones and, to be ruthlessly honest, while better than the wishy washy supermarket ones, they all fall well short of those I ate in Italy. That leaves the soil as the key variable.

The answer may indeed lie in the soil. Unfortunately the solution is not as simple as scattering fertiliser with added trace elements, which is the usual recommended treatment. We have taken good care of our soils here and believed that we made good, balanced compost to nourish them. I use the past tense – believed. Summer reading here is “The Intelligent Gardener” by Steve Soloman. That is to say, Mark is reading it and sharing the highlights as he goes. While some of the book drives him nuts, the underlying premises make a lot of sense. Our soils are almost certainly nowhere near as good as we thought.

The subtitle of the book is “Growing Nutrient-Dense Food”. Nutrient density has been hovering on the periphery of our lives ever since Kay Baxter started writing about it. It is the principle that you can have two apparently similar crops but one has a much higher nutritional value than the other. Kay Baxter is the leading light of the Koanga Institute and a true pioneer of organics and the preservation of heirloom and heritage varieties in this country. She advocates the use of Brix measures to determine nutrient density. Brix are commonly used in the wine industry to measure sugar content.

It may be something of a leap to link flavour to nutrient density, but it seems logical that there may well be such a link and certainly both go back to the nature of the soil.

As a country, New Zealand has some widely recognised soil deficiencies. Insufficient naturally-occurring iodine is why we have iodised salt in this country. Prior to that, goitre was very common in humans and indeed in animals. “Bush sickness” is a widely recognised problem attributable to cobalt deficiencies on pumice soils. Selenium is deficient. At the risk of treading on sensitive ground in the Waikato, I understand that the trace element fluorine is deficient in NZ which is a major contributor to why New Zealanders have long been renowned for poor teeth. According to my father, who was a medico in the British army in WW2, they could pick the NZ soldiers at time of autopsy because most had false teeth. Correspondingly, pre-dental bleaching, all those beaming white toothy smiles of many Americans were apparently attributable to higher levels of naturally occurring fluorine.

If you are really keen on running a closed system of food production with no external inputs, it matters a great deal that you understand the exact composition of your soils in considerable detail. Even then, it is not as simple as topping up a certain element because there are reactions and inhibitors which can affect the ability of soils to incorporate additions. But most of us get our food from a variety of sources, which means deficiencies don’t usually have dire effects on human health because there is a degree of balancing out which occurs.

Mark is planning to delve further into the exact compositions of our soils. We are interested to see whether better balanced soils will give us better flavoured food. We will be watching to see if the link between flavour and nutrient density is proven. Certainly, it is disconcerting to have our existing notions about the quality of our soil and compost turned upside down. But this is not a once over lightly project which will appeal to all gardeners.

If you want to know more, the Koanga website is: http://koanga.org.nz/ The book referred to is “The Intelligent Gardener” by Steve Soloman. (New Society Publishers; ISBN:978 0 86571 718 3). Elder daughter purchased it for her father from the bookshop of Canberra Botanic Gardens. In this country, you may need to order it, in which case the ISBN number is important.

First published in the Waikato Times and reprinted here with their permission.