“We know more about the movement of celestial bodies than about the soil underfoot.” - Leonardo Da Vinci, circa 1500’s
The Cornell University team, including my host Robert Schindelbeck, has for some time focused on soil health as a means of addressing major soil fertility, erosion and leaching problems in the North East. They have developed a Comprehensive Assessment of Soil Health (CASH) protocol which encompasses biological, physical and chemical measurements, rigorously selecting appropriate indicators and evaluating the indicators and setting targets by drawing on wide-ranging, replicated research trials. It is very reassuring to have the research to support the service offered.
The CASH service includes:
Physical: Available Water Capacity
Surface Hardness
Subsurface Hardness
Aggregate Stability
Biological Organic Matter
Soil Protein
Soil Respiration
Active Carbon
Chemical pH, P, K, Mg
Trace elements: Mg, Fe, Mn, and Zn
The Soil Health CASH test is aimed at taking a long-term view of the soil, and it is not expected to be used for short-term fertiliser application, although it could be used for that if wished as the chemical analysis uses standard extraction methods. It is backed up by an excellent manual
https://soilhealth.cals.cornell.edu/training-manual
which explains in detail how each indicator effects soil functioning, and health and what can be done to improve it. There are additional analyses that can be undertaken including salinity, which could be useful for some situations.
The Solvita respiration test, which is also used by NRM in their Soil Health test
http://www.nrm.uk.com/services.php?service=soil-health
, gives an indication of biological activity but at Cornell is supported by the potassium permanganate active carbon test. This is more indicative of the carbon available as a substrate for biological activity.
The soil protein is total protein; it may not be all available as a substrate or for crop growth but it is indicative of potential nitrogen supply.
This analysis is in no way equivalent to the Albrecht/ Base Cation Saturation Ration type of analysis that I have seen elsewhere; there is no analysis of phosphate reserves or of sulphur, both of which Albrecht advocates consider to be critically important. There is general agreement that as atmospheric sulphur levels decline it should be given much greater priority and perhaps considered one of the major elements along with nitrogen, calcium, phosphorus, potassium and magnesium.
All soil analysis is only a snap-shot in time, very imprecise but non-the-less essential to better understanding and getting the most out of the soil and minimising environmental problems.
We are certainly in agreement that long term trends as indicated by annual analysis of representative fields are critically important and that comparative analysis of good and poor parts of a field is one of the most informative uses of soil analysis. It really does reveal what may be limiting productivity. Plant tissue analysis is an important further means of monitoring any deficiencies in the plant and doing comparative analysis of good and bad areas to identity field problems.
The approach taken by Cornell is practical and user friendly, it is backed by good science and ensures that soil structure and biological activity is properly taken into account when considering the need for any fertiliser inputs.