Soil Metrics... What we tested and why
Zones we grouped results to
Comments about the Zones:
these are broad areas, grouped up to a Zone to simplify communication about their key attributes that affect the success of a potential Soil Carbon Project and the associated constraints to greater plant production that drives it Note, the soil values below are average to Zone, and in most cases include multiple sample sites with a range in values, that can understate the range. See the full results below for actual results per sample site to see the variation within Zone
Topsoil Results Averaged to Zone
Summary Points for Topsoils:
With respect to growing more pasture biomass:
Total Phosphorus levels are good, presumably the result of long term floodplain deposition, but available P is primarily low (circa 5-10ppm except in Front/Jacks) for significant increases in dry matter production, and hence stocking rate or SOC% gains. Increasing P availability, which means doing the least possible to increase soluble Calcium, soil pH and decrease Aluminium looks to be potential for higher value return in terms of intervention AFTER sub-divisions are achieved. Very fine lime at low rates to gauge impact on soil chemistry and grass production is suggested since it is not just grass production but SOC% that will potentially benefit Remember also increased available P, from the total P inherent, will flow through to plant P levels and hence metabolisable energy and animal performance. See that confirm low P levels where soil P is low Sulphur levels are primarily good, reflecting these soils being at the lower end of the floodplain as a site of deposition rather than leaching Bulk density is surprisingly low (good) for the elevated Magnesium & Sodium, which is evident in the SOC% Sodium levels are elevated, again likely from flood water deposition, and any and all attempts to raise available Calcium will improve this constraint to greater biomass and hence SOC% increases Aluminium levels are on the high side for legumes to really punch more nitrogen into the system and allow greater protein levels. The charts below show the relationships between higher pH, higher soluble Calcium and lower available Aluminium Trace elements are a non-concern for biomass production until the existing limiting factors are removed. Detailed recommendations are here in Charts
Relationships on Lockwood between available P, soil pH and Aluminium base saturation%
Below is a broader sample set in Atlas
Priorities Post Project Registration
Summary for Subsoils
Subsoils generally will not see the effects of topsoil inputs at 30cm+ depths, nutrient generally just does not leach/move through the profile that far, with the exception of sulphur and nitrogen, which are mobile and will leach in well drained soils.
So what matters for subsoil results is the extent to which the subsoil chemisty is a constraint to pasture root development.
What the results above tell us about these subsoils:
Sodium levels increase with depth, except in Front block, 30-50cm sodium levels ie approximately double. The implication of this is that greater sodium and the related decrease in Calcium base saturation, tend to constrain plant plant root development in these depths due to them being more prone to hard-setting or waterlogging when too dry or wet respectively. Soils like Front paddock would be expected to increase soil Carbon far more effectively than where sodium is elevated, as result of the better (lower) bulk density and soil structure evident in the soil chemistry results.
FULL RESULT SET 0-30cm Results Per Sample Site
What These Results Tell Us About Grass Production
The Good News:
There is enough total Phosphorous and Sulphur in the system to allow for greater legume production and grass production, unlocking the potential is the challenge at hand The better soils in terms of available Phosphorus and structure, are presently lower Carbon, indicating good upside potential The Bad News:
Subsoil sodium will constrain pasture root development (and hence Carbon) where elevated
Link to download raw lab results:
Lab Batch References: N.../1-x
Soil Analysis
