Farmer Guide to Soil Sampling Post Natural Disaster || Gerhard Grasser

Farmer guide notes for soil sampling post natural disaster

Gerhard Grasser, AgriSolutions P/L for ORICoop

As an organic, biodynamic or regenerative farmer, you will not need to be told a healthy and functioning soil is the real bottom line to your farm business. To underpin the importance of this primary asset, the following guideline has been compiled by ORICoop consultants as a way of methodical diagnosis of soil and plant health, following any type of natural disaster. While most agronomists and land managers see soil primarily as a nutrient pool, we view soil (and plant root interactions) as a combination of nutrients, physical conditions and key biology each requiring equal attention and treatment. This is especially so when recovery from trauma such as drought, fire or flood are being managed. Before venturing out to perform your soil and plant condition benchmark, consider the prevailing conditions just prior to the trauma of fire, floods or drought. This is important for future repeatability of follow up testing to accommodate seasonal shifts. For example, note whether a particular tree or plant is flowering, budding or setting seed and repeat the testing the following season when this indicator is evident. Using the calendar alone can cause differentiation of seasonal conditions for up to 3-4 weeks to what is actually taking place in the soil. As part of your soil recovery and restoration, we encourage you to take a Visual Soil Assessment, as well as soil nutrient & biology tests with this holistic framework in mind. The more detailed and diligently the tests are taken, the better outcomes that you will achieve in your recovery process. This soil nutrient and biological testing is funded to approved disaster affected organic farmers as part of the Organic Farmers Bushfire Appeal or Organic Farmer Flood Appeal. Any questions around the Appeal, contact Carolyn Suggate.

Physical Condition

• Visual Soil Assessment (VSA) is most important. No amount of data can describe all soil physical attributes as can the eyes, nose and touch on a plug of soil dug up and pulled apart out in the field.

• If unfamiliar or a bit rusty on the VSA format, click here for the original 8 step PDF version or for the printed revised 2nd edition not available on-line but can be bought here with all the updates.

• To prepare for the VSA, read through the preamble and instructions. Print or copy scorecard of PDF version Page 13. A basic tool kit will need to be assembled before venturing out armed with your camera – and allow ¾ hour to perform this detailed assessment until you become more proficient. **Note: Edition 1 has an 8 step scorecard while Edition 2 is 10 steps but don’t let this stop you!

• While VSA is a methodical way to read and record soil conditions in the field, the use of a soil penetrometer will further enhance the experience and information gathering. Three other observations should be added to the VSA –

1. Soil temperature at 10cm,

2. Soil smell at the top compared with soil smell from the bottom of the 30cm hole.

3. Soil adhesion on the plant roots indicating microbial activity in response to root exudates (sugars) from plant photosynthesis.

• While an experienced farmer might use an unmetered probe or piece of wire to gauge for soil compaction, a soil penetrometer with a fitted gauge provides hard data for those less experienced or wanting to record figures for future reference.

You can refer here for details on how and why a soil penetrometer could be used to help understand what is happening in the ground below.

Nutrients

• Soil sampling and analyses is practically mandated measuring available, exchangeable and total nutrient pool levels to quantify inputs and actions. (Particularly important when the land has experienced trauma such as drought, flood, fire, over harvesting/ grazing, cultivation/fallowing, chemical applications/ residues).

• We recommend EAL’s RA-Pack-003 which includes heavy metals potentially affecting growth and presenting possible toxicity after fire events (refer to the Chromium 3 to Chromium 6 effect due to high temperatures). Where heavy metal testing is not required, use EAL’s RA-Pack-002.

• The process of soil sampling in itself presents the greatest error in obtaining accurate data. Refer to EAL here and read/print instructions and soil testing summary here. Be mindful that a stainless steel or plastic soil corer should be used (ideal thickness 2040mm diameter).

• Print and fill in the Soil Submission Form customised for ORICoop by EAL here, and securely pack the composite soil sample in a lunch ziplock bag and EXPRESS POST with form enclosed addressed to:

EAL, PO Box 157, LISMORE NSW 2480

• Don’t forget to sign the postage declaration on front of the satchel! Results should be received by email the following week.

In consultation with your biological consultant, advice can then be provided on a likely action plan towards soil & plant recovery

Key Biology

• Some soil fundamentals such as fungal:bacterial ratio to suit specific crops and earthworm counts are essential indicators of an active and healthy Soil Foodweb. Maintaining the correct F:B in the root zone to meet plant requirements is as important as having the correct soil pH. (Bacteria support weeds and lower order annual plants, whereas fungi are needed to successfully grow woody and higher order perennial plants).

• As part of the VSA, smelling the soil and compost for its ‘earthiness’ and fungal overtones can provide an approximation of its suitability while earthworm activity, numbers and diversity together will represent the general health and well being of the compost, soil and the rhizosphere.

• Soil structure and porosity in the VSA also indicate the probable microbial populations and species but this can only be confirmed by Soil Foodweb microbial analyses for active and total bacteria and fungi, protozoa, nematodes and mycorrhizal colonisation.

• Hosting a diversity of microbes and higher order soil biology will offer pest and disease resistance, optimum plant growth and soil function under a wide range of conditions. A full Soil Foodweb Assay by a qualified laboratory is desirable to quantify the various soil organisms and calculate nutrient cycling potential. Refer to AGPATH or SoilFoodWeb for more details on testing. (The lab used is dependent on your location).

• Look beyond the soil food web and record any other insects such as dung beetle activity, cockchafers, army beetles, clover fleas, aphids, grubs, etc as soil and plant health indicators. Disease indicators should also be noted and monitored pre and post recovery. Don’t forget to use the camera! You can also participate in this biodiversity climate science program here.

While managing these 3 parameters (Physical condition, Nutrients and Key Biology) as the essential cornerstones to a healthy and functioning soil, it is the overarching management that can just as quickly undo the work being done at soil level. Rules such as 100% cover 100% of the time, increasing diversity (of plants, animals and microbes), retaining adequate solar receptors (leaf area) to supply microbial populations, building soil organic carbon to aid in soil water holding capacity and provide for the soil foodweb will determine the growing system resilience and ability to recover from trauma.

ORICoop has a team of leading biological consultants working with our farmers in natural disaster recovery. We are excited that some of the best soil experts have volunteered to help farmers bring their soils back to life and growth. It is also an opportunity to learn more about soil biology and the nature zoo under our feet while reassessing the organic business post what is a long journey to recovery. We are cheering for all of you!