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The lab controversy

There is a recent move amongst numerous agricultural consultants to differentiate themselves by using soil labs outside South Africa.   The general thinking is that these labs will identify "other" soil problems and solve the farmer's problems.   Recently Profert invested in an Australian company called Advanced Nutrients and because this company is involved in consultancy work in South Africa and Australia, this same "Lab" debate was raised.   As a result the Profert  team of Ben Krog and Andrew Beckerling decided to collect and send split samples from South Africa to an Australian lab and a South African Lab that had  good reputations.  The soils were both top and sub soils and were collected from all the agents across South Africa.  A total of 54 soil samples were analysed.  The result is the content of this publication.

It is clear from the results that for all elements, except carbon to some extent phosphate, it would not matter where you sent the samples as the results are directly correlated.    Although the actual values differ and therefore the norms differ, the labs procedures would consistently give the same result relative to the norm.  So your consultant might say to you that you need for arguments sake, 600 mg/kg calcium, and not  500mg/kg calcium, if he used a different lab, but actually the results would be the same.   The important aspect is that the norms need to be established for a specific procedure and as crops genetics change we need to continue to improve our norms. 

The lack of good correlations with carbon is disconcerting and needs to be investigated.   If one considers that the whole move is towards biological farming and the carbon content is being used as an indicator of good practice then one needs to be more confident with the result.   This also relates to the development of carbon credits, and although this still needs to be developed with regards to farming systems, the need for a reliable carbon assay that can be used on a commercial scale will become important in the future.

Profert is investigating these outliers but Profert is quite confident that labs that have the correct accreditation in South Africa are not as bad as some consultants would like to indicate and perhaps if more effort was put into testing our norms under South African conditions we would progress further quicker.