Why remineralise soil?
I have always thought that growing organic vegetables produced healthy food from healthy soil. Traditionally this means taking care of the soil; the aim is to feed the soil and not the plant. I thought that was it, and I was doing all I could, but maybe there was something missing.
The idea of soil lacking something important was brought home by a recent report that showed the level of minerals in fresh fruit and vegetables has decreased by 70% over the last 50 years. Minerals have disappeared from the soil thereby reducing the minerals in our diet.
To understand more about soil it is important to know about how it is made. After the last ice age around 10,000 years ago there were vast quantities of ground up rock produced by glaciers. When living things died they rotted down to make humus. This produced rich soils and plant life flourished. We are now at the end of an interglacial period and the rock dust in most soils has been used up. Some argue that modern farming techniques have hastened the depletion of minerals while others say it is an entirely natural process. The reason why rock dust has gone is not as important as how we can get minerals back into soil to correct the deficiencies.
There is also another characteristic of remineralisation that could have profound effects. When the minerals are broken down into a form that they can be used by plants, atmospheric carbon dioxide is locked up. Large scale remineralisation has the potential to reduce CO
2by significant amounts. For more information follow some of the links below.
The Mineral content of food
As mentioned above a recent report shows that the mineral level in food has decreased by up to 70% over the last 50 years. The full report can be found at: www.organicgarden.org.uk/files/min_dep_report.pdf
The source of the information used to compile this report is data published by the edical Research Council (1940)(2,3,4) and M.A.F.F.(5,6) . These books provide statistics on the chemical composition of foods available to us as a nation between the period 1940 to 1991. Part of the analysis includes the mineral content – in mg per 100gm portion of that food. The analysis provided information on the amounts of Calcium, Magnesium, Potassium, Phosphorous, Iron, Copper and Sodium . It was found that only certain foods within the categories of Vegetables, Fruits and cuts of Meat could be readily traced over this 51 year period. The result of comparing data available in 1940 with that in 1991 demonstrates that in every sub group of foods investigated there has been a substantial loss in their mineral content.
In 1926 Dr. R. A. McCance undertook- with a grant from the Medical Research Council – to analyse raw and cooked fruits and vegetables for their total ?available carbohydrate?.
So began a programme of analysis which resulted, in 1940, with the publication of the Medical Research Council’s, Special Report No: 235, entitled “The Chemical Composition of Foods.” This report represented the culmination of a comprehensive research programme on the chemical composition of foods available to the British public. 1 ounce and 100 grams of different Vegetables, Fruits, Cereals, Meats, Seafoods, Beverages, Beers, Sugars, Preserves, Sweetmeats, Condiments, and Dairy Products were analysed for their organic and mineral content as well as portions of traditional British food recipes including Cakes, Pastries and Puddings.
This, then, was the first determined effort by a number of dedicated Doctors and Food Scientists headed by McCance and Widdowson to establish definitives by which to quantitatively compare and contrast individual dietary intakes. This 1st Edition was subsequently updated by the Medical Research Council in 1946 and 1960 as new foods became available, analytical procedures improved and new information regarding constituents of food (e.g. vitamins/amino acids etc.) were considered as being needed.
Over the next 30 years the need to continually update information resulted in the 4th and 5th Editions which were published in 1978 and 1991 respectively under the title of ?The Composition of Foods?, this time under the auspices of the Ministry of Agriculture Fisheries and Food in conjunction with the Royal Society of Chemistry.
On comparing and contrasting the 1940 figures with the 1991 figures quite a number of variables exist; enough in some instances such as cereals, to make comparisons meaningless. Equally there is a wealth of data available which provides very real insights to the change in food values over the 51 years between 1940 and 1991. The 1940 data often incorporates work published in 1929, 1933 and 1936, similarly the 5th Edition published in 1991 contains data that originates in 1987. For consistency I have used the published dates.
Practical remineralisation (the 2004 trial)
As the soil on the plot is very heavy clay which has not been worked for some years it was decided to make a new top soil. This was achieved by mixing compost with rock dust (more details here.)
There were 10 raised beds, each 4ft (1.2m) wide and 15ft (4.6m) long. Various soils and treatments were used as follows:
1 bed with fresh top soil topped with 1 inch (2.54cms) of compost
1 bed with 4 inches (10cms) of compost
1 bed with compost and sharp sand
7 beds with compost and rock dust (with various treatments)
The filling depth ranged from 4-7 inches (10-18cms.) The same trial crops were grown in each bed, in a small test area, to see if there was a difference in growth rates and plant health.
Initial results were encouraging with crops grown on remineralised soil showing slightly improved levels of minerals compared to those grown in the control beds. However, rock dust can take a while to work and crops needed to be tested over a number of years. The cost of such analysis is prohibitive for an individual so I was unable to proceed with the trial.
Recently I found that the use of a simple BRIX meter can give a reliable indication of overall nutrient density. This means that it is possible to test crops as soon as they are harvested enabling direct comparisons to be made between different types of soil treatments. This is the basis of the 2008 trial (more details here)
Sources of Rock dust and sea minerals
Ocean Grown UK Ltd – suppliers of ‘OceanSolution’ – liquid sea minerals. A concentrated liquid comprising the 90+ elements and aerobic bacteria necessary for all plants to develop strong and healthy tissue.
SeaAgri Inc. – suppliers of ‘SEA-90’ OMRI Listed? for use in Organic Production. Unrefined mined sea minerals – a 100% natural, water soluble, balanced blend of sea nutrients including trace elements.
The Seer Ccentre – rock dust in 25kg bags can be obtained from the SEER Centre and from other outlets listed on their site.
Pinetum Products – sell volcanic rock dust and other minerals.
Links to other remineralisation sites
www.seercentre.org.uk – The SEER Centre in Scotland
www.remineralize.org – Remineralize the Earth (US)
www.menofthetrees.com.au/RockDust.pdf – “Rock Dust Puts Out More Than You Think”