A growing interest in soil health and conservation agriculture, as well as criticism of unsustainable farming practices, have increased the need for soil testing techniques that provide a more holistic assessment of soil health.There is a movement towards regenerative agriculture in order to increase resilience and long term sustainability of farming practices. Farmers are fertilizing more efficiently, decreasing their dependency on chemical fertilisers and increasing biological diversity in their soils.  A list of companies and their service offerings can be found in the table below:

Name of company
Service offering / product
Brookside Laboratories (USA) Brookside offers complete agricultural/turf, environmental, accredited (ISO 17025) geotechnical testing and soil health testing services.
Intertek Intertek is a leading testing services provider to industries worldwide and been awarded the ISO 17025 accreditation for its Precision Agriculture Laboratory based in Johannesburg, South Africa. The accreditation comprises chemical and microbiological analyses to ISO/IEC 1725:2005. 
Nemlab  Nemlab is a diagnostic laboratory that identifies which nematodes occur in your soil and roots and whether they can be harmful to your current or future crops. 
Nvirotek Labs NviroTek Laboratories is an independent national, world class analytical facility for Agriculture in Southern Africa.
Radicle Soil Health Laboratory and Consulting Service  They provide analytic services that measure the health status of soil. The laboratory follows recognized methods of analyses and is ISO 17025:2005 accredited.
SGS Offices & Labs  SGS helps you accurately assess and precisely manage soil fertility, reducing both the cost and negative environmental impact of fertilizers yet still improving your crop yields. 
Soil Health Solutions They offer an analytical service that will establish how far soils have been degraded, as well as, how good soils have been managed on a “Conservation Agriculture” production system.
Woods End Laboratories (US) Solvita test kit. The test measures the rate of carbon dioxide (CO2) respiration and the presence of organically bound nitrogen in soil. These are both key indicators of soil fertility. The kit replaces traditional CO2 tests, can be completed within 24 hours, and is more cost-effective for South African farmers at a cost of about R200 per test. Read more at this link.
Zylem  Consultants and Laboratory testing & analysis (Brookside Laboratory Incorporated (BHI) registered consultant).

 

Hear various experts (audio files) speak at South Africa's first soil health conference (Stellenbosch 2016):

Here are a few links to better understand soil health & soil health testing: