4.1.10 Testing and Monitoring 

Key Knowledge: indicators and techniques for testing and monitoring environmental health.

Soil Health

Soil health is the foundation of any terrestrial food or fibre system. Monitoring soil health allows producers to spot degradation before it causes widespread crop or pasture failure.

Techniques for Testing:

• Soil pH Chemical Assays: Using a field testing kit (with indicator powder and liquid) or a digital pH probe to measure the acidity or alkalinity of the soil water solution. Testing tells managers if they need to apply lime to correct acidity.

• Electrical Conductivity (EC) Meters: Mixing a precise ratio of soil and distilled water to test the solution with an EC meter. High EC indicates a buildup of dissolved salts (salinity), which restricts a plant's ability to absorb water.

• Soil Organic Carbon (SOC) Lab Analysis: Sending core samples to a laboratory to measure the percentage of organic carbon. High SOC indicates excellent biological activity, soil structure, and moisture retention.

• Bulk Density Core Sampling: Driving a metal cylinder of a known volume into the soil, drying the sample in an oven, and weighing it. High bulk density values mean the soil is tightly packed and suffers from compaction, which restricts root growth.

Water Health

Water health monitoring tracks the environmental impact of the farm on the surrounding catchment and ensures that irrigation water is safe for crops and livestock.

Techniques for Testing:

• Macroinvertebrate Sampling (Water Bug Surveys): Scooping water and sediment from a farm creek using a kick-net to count the types of small bugs present. Sensitive species like mayfly and caddisfly nymphs only survive in clean water. If only pollution-tolerant species like bloodworms are found, water health is poor.

• Dissolved Oxygen (DO) Meters: Using an electronic DO probe to measure the concentration of oxygen ($mg/L$) in the water column. Low DO is a key indicator of organic pollution or recent algal blooms.

• Turbidity Tubes: Pouring a water sample into a long, clear tube with a black-and-white symbol (a Secchi disk pattern) at the bottom. The user looks down the tube and records the point at which the symbol disappears. High turbidity means excessive soil erosion is washing into the waterway.

PRACTICE

Skill Check

You are an agricultural consultant called to a mixed-farming property in the Western District of Victoria. The producer provides you with three puzzling symptoms:

1. The creek at the boundary has become cloudy and murky.

2. A nearby paddock of clover has stunted root development and yellowing leaves.

3. A low-lying grazing area is showing bare patches of ground where nothing will grow.

The Task: In your workbook, match each symptom to the correct testing technique you would use to diagnose the exact issue, and name the environmental indicator you are tracking.

PRACTICE

Exam-Style Questions

Question 1 (2 Marks)

Explain how a water bug survey (macro-invertebrate sampling) can be used to monitor the long-term health of a waterway passing through a cattle property.

Question 2 (4 Marks)

A broadacre grain grower notices that their crop yields are declining despite applying the same volume of fertiliser each year. Analyse how using both NDVI drone mapping and bulk density core sampling could help diagnose the underlying issue.

Exam Tip

When describing testing techniques in an exam, including the correct scientific terms could help with marks on the big questions. (Add the units of measurement if you know them). 

• Do not just say test the salt. Say: Measure the Electrical Conductivity (EC) using an electronic meter, (recorded in microsiemens per centimeter (muS/cm)). 

• Do not just say check the mud. Say: Measure the turbidity of the water column using a calibrated turbidity tube.

SAC Tip

If you are asked to design a monitoring protocol for a SAC task or exam question, always emphasise the need for baseline data and a control site.

• The Logic: You cannot claim that a farm upgrade (such as fencing off a riverbank) has improved environmental health unless you know what the metrics were before the project began.

• The Structure: Your response should state that you will test water health parameters (like turbidity and DO) upstream before it enters the production zone (the control) and compare those numbers to tests taken downstream over a twelve-month period to evaluate the true impact of the management change.