Jon Williams provides a fascinating insight into the development of chemical farming, the super-importance of calcium and magnesium, and the limitations of using PH as a guide to fertilising. He ends with a useful soil sampling suggestion
At the end of the second World War there was rationing in the UK and the Government edict to agriculture was to expand food production and farmers quite rightly responded to that call as they always do and particularly in times of crisis. This has been recently highlighted with the Covid Virus raging the country and the shut-down of most industries but agriculture remained resolute and carried on producing food for the nation.
However there is a major difference between agriculture and other industries and food production from our soils needs to be re-classified as “The Practice of Agriculture”.
Why is this so?
Firstly it is important to understand that companies such as ICI were very powerful at the end of the war as they had produced all the raw materials used for bomb making such as TNT (Nitrogen) and Potassium from their mined resource at Cleveland. The call for increased food production resulted in these bomb making ingredients being used for food production. The drive for more and cheaper food is the ethos we have followed ever since and has resulted in a more industrial approach to agriculture involving inputs and outputs and the margin of cost between these two regarded as success or failure of the farming methodology principals followed.
This approach to agriculture has resulted in ever tighter margins of production as the costs of the inputs have risen, and the yields have stagnated. This has been made worse as the hidden cost of the depletion of the natural assets of the soil such as Organic matter have not been accounted for. The result of this is soils used for cropping only, being depleted of organic matter to the extent that 70% of all arable land in the UK has now less than 3% organic matter remaining. This situation obviously cannot continue and if the UK was taken as one large farm it is out of balance with the intensive livestock areas having too much organic matter averaging 9.5% (the results of over 900 soil samples in Wales).
For good soil structure, nutrient holding capacity and good water retention the ideal levels need to be between 5 % and 7% and farmers are increasingly becoming aware that they need to rebuild this organic matter with the introduction of cover crops and re-introducing grassland as part of a rotation with livestock, as well as reduced tillage.
This rebuilding of soil organic matter levels includes the sequestration of carbon as it contains 55% Carbon and moisture retention levels improve, up-to 170,000 of extra water per hectare being held within the soil per 1% increase.
With the emphasis on public good along with food production this can be termed as “Regenerative agriculture” as we develop systems to rebuild soil as well as produce food it is likely farmers who have this intention will receive financial benefits alongside building a more resilient business.
The increasing supply of fertiliser was encouraged by ICI when they set up a company still operating today to carry-out basic soil analysis which was a guide for farmers as to which fertiliser to purchase and a PH reading for liming requirements to ensure a better response to that chosen applied fertiliser. Today it is important to understand that this was a tool to be used to purchase fertiliser only and it is now time to consider a more detailed look into soil analysis for building resilience in the food production process.
With the increasing awareness of impending climate change with rising temperatures and more unpredictable weather patterns it is imperative that we transform our agricultural practices quickly.
To achieve this transition as quickly as possible we need to follow the Albrecht Philosophy of soil analysis which is the result of 36 years of research into soil chemistry and along with soil texture can be used to amend the soil to improve soil structure and the aerobic nature of soil. This method of soil analysis results in a picture being formed of the effect of past management on the soil and can be used as a management tool to take the farm forward for improved crop performance and at the same time sequester carbon.
Having carried out nearly a 1000 of these tests there are several issues which are being highlighted and the first and possibly most important is the realisation that every field can be different according to its past cropping policy and this is why we need to consider agriculture as a practice and not an industry.
The realisation that the soil sampling method is holding back the development of this approach to food production is key to building a more resilient business and that the two nutrients required in greatest volume in soil – Calcium and Magnesium – need to be raised up to 80% on the clay colloid with the balance between the two dependent on soil texture. This incidentally raises the PH and so it is not PH that is the key indicator for successful crop performance but the level of these two major nutrients that governs the response of other elements and enhances crop performance.
pH can be at optimum for ever!
The choice of liming material can be done when a detailed soil sample is carried out and I suggest that all purchases of lime from a quarry need to come with a full analysis as the soil amendment needed may be for Calcium limestone or Dolomitic limestone depending on the existing levels with no more than two tonne being applied at any one time. For major shifts in the levels of Calcium and Magnesium the liming always need to be done in volume, however for small adjustments the liming can be achieved using the granular products now available such as Calci-fert or Mag-fert. The introduction of these relatively new products means that we need never allow the PH of soils to drop below the optimum for ever and the potential for improved crop performance is ensured.
Calcium is “KING” in the soil as it can be considered the trucker that takes most other elements into the plant and the other major nutrient Magnesium has a key role to play in “Nitrogen Use Efficiency” within the plant and so correcting both these nutrients and raising the levels to near to 80% on the clay colloid is a priority and not PH as such, which is essentially a measure of Hydrogen Ions.
More nutrient dense quality food
The adoption of this method of assessing soil quality is key to future proofing the resilience of the practice of agriculture and switches the emphasis away from the industrialisation of farming towards a more holistic approach to food production with the added benefit of producing more nutrient dense quality food. This is highlighted by the fact that 50% of the UK population is short of Magnesium and we ignore this method of analysis to the detriment of our soils, our crop performance and the health of the people we supply with our produce.
Maintaining these two major nutrients ensures that the locked-up Phosphorus in the soil and applied soluble fertiliser Phosphorus is made more available to the plant. The positively charged Calcium will attract the negatively charged Phosphorus reducing the potential for run-off and severe lock up when more Aluminium is present as a result of low Calcium levels.
Farmers need to be rewarded when they produce such quality food and ensuring a fair price is essential for the shift towards the practice of agriculture and away from the more industrialised approach.
Monitoring soil with detailed soil analysis as a management tool.
I suggest farms are split into four areas for the purpose of soil analysis with a quarter of the farm being analysed every year and in year five the process is repeated. This needs to be the base from which to go forward before digital nutrient mapping and variable fertiliser rates can be employed successfully.
To ensure Min-Till is successful a good open structured soil needs to be established via this soil analysis method which when used to balance the major nutrients will produce and maintain a crumbly soil structure which is ideal for slotting in new seeds. So the need for traditional cultivation methods is eliminated and The Rodale Institute of America has been developing systems and machinery to introduce these methods for successful crop establishment on a wide scale including in organic agriculture systems. (therodaleinstitute .org)