An Alternative System of Crop Nutrition
Back in 1894, Julius Hensel wrote Bread From Stones which proposed the idea that all the minerals plants need are present in rocks. He used the annual flooding of farmland beside the River Nile as an example, where the soil’s fertility was maintained for thousands of years by sediment washed down from mountains to the South. Hensel compared this to the soil of many other civilisations which gradually lost its ability to grow crops and so, after a few hundred years, became deserts. He thought that there was no need for animal manure to maintain fertility, and only a light dusting of ground rock dust was needed.
Edward H Faulkner wrote an equally controversial book Plowman’s Folly in 1943, a great read for all No-Tillers. As well as arguing for minimal soil disturbance, he thought that all mineral nutrients originally came from the base material that topsoil is made of. He suggested that it is the same all over the world, whether the underlying base is limestone, granite, sand, clay, chalk or anything else, and that there was no need to apply fertilisers such as Phosphate or Potash.
Even in Faulkner’s time, little was known about soil biology and so he and Hensel had to guess how the minerals were being made available to plants. Hensel thought that the Carbon Dioxide released from plant roots was acidic enough to dissolve rock dust, while Faulkner believed that acids were produced during the process of breaking down organic matter such as dead roots and crop residues. We now know that turning limestone, sand, clay etc into fertile topsoil is a biological process in which many types of bacteria use acidic compounds to break down the base material. This process releases mineral nutrients which are then made available to growing plants.
About twenty years ago someone told me about a simple phenomenon which formed the basis of everything I have done in farming ever since. If you test and measure for available nutrients in both a given area of soil and in a quantity of farm yard manure, (and the manure is then applied to that area), when the soil is tested again after a few weeks, the total nutrients available will be substantially higher than the sum of the two original tests. In other words, the manure stimulates the soil biology to release otherwise unavailable soil nutrients.
I did some total soil mineral nutrient tests using very strong acids which evidenced tons of tied up P, K and Mg, and hundreds of kilograms of B, Mn, Cu and Zn in the top four inches. Some crop roots go down to six feet meaning the amount of existing nutrients in the top four inches can be multiplied 10 or 15 times; therefore, I have an unlimited supply of soil based mineral nutrients in my soil. Not having any manure available, the soil biology needed to be stimulated by other means. Biological Stimulants are widely available nowadays, but back then it was a matter of spraying on molasses. This idea has quickly advanced into more complex mixtures of humic and fulvic acids, soil conditioners and other soil goodies and now forms the basis of my policy of not applying any Phosphate or Potash fertilisers. Due to continuous no-till, my crops now have unheard of levels of mycorrhizal root colonisation, at 80% on wheat rather than the typical value of 30%, which increases each plant’s root rhizosphere by a thousand times. The plants full nutrient requirements are being met by these fungi, (and in the correct ratios), rather than having to accept what ever is in solution in the water they take up.
As always with these things, it is worth referring to what can happen in non-farmed environments. Although a lawn is not natural, keeping the grass short the only human interference; however, I don’t think anyone has ever claimed that removing cuttings makes any difference to how much it grows compared to mulching them down. If it rains, the lawn needs cutting, and there is nothing you can do about it, whether the nutrients are recycled or not. Trees are another great example, in many gardens and parks, fallen leaves are picked up, year in year out. This means that the nutrients are not being recycled as they would in a forest, so every Spring the trees must work with soil biology to extract fresh minerals from the ground to grow new leaves. In the extreme, there are thousands and thousands of perfectly healthy trees growing out of pavements in towns and cities. How can they keep on growing for hundreds of years without recycling nutrients in their leaves when their roots don’t have much access to air or rainfall?
It seems to me that all higher successional plants growing in the absence of recycled nutrients or fertilisers are perfectly capable of extracting all they need from the infinite store underground. I am sure this all seems impossible to mainstream farmers and advisers who test for soluble nutrients and convert percentages into “indices” which are then assumed to represent a level of stored nutrients. Fertiliser is then applied to make up for what has been removed by their harvested crops. In my opinion this system is wrong and I have now come to the conclusion that I do not want my indices above 1; I want all my nutrients tied up in the organic matter or clay where they can’t leach away but are easily available to the crops.
It is quite normal to question yourself when doing something different, and I too have gone through periods when I have wondered if a little phosphate fertiliser, even as a starter, might help. However, when combining wheat crops a few weeks ago which were yielding over 10 tonnes/hectare, I did allow myself a little congratulatory smile because I really was proving that the soil can provide all a crop needs.