Soil pH
Soil pH
This Soil pH indicator and all other indicators in the Land Manager’s Monitoring Guide series are provided in PDF format to allow you to either read it on the screen, or from a version that you print, that can be used in the field as a reference to guide your monitoring activities.
Content for the Soil pH indicator follows the heading structure below:
- What is it?
- Why monitor this indicator?
- Planning monitor this indicator
- How do I measure it?
- Level 1 monitoring
- Level 2 monitoring
- How to record your results
- What does your data mean?
- What are some management options?
- Other information sources
- Glossary
- References
- Acknowledgments
To decide if you want to download the Soil pH indicator, read the following introductory information that describes what it is and why you would use it.
What is it?
Soil pH indicates the concentration of acidity or alkalinity within a soil profile. The pH scale is the means by which the degree of acidity is measured. Scientifically it is a measure of the hydrogen ion activity. It is represented in a logarithmic scale ranging from less than zero (strongly acidic) to 14 (strongly alkaline).
Soils can be naturally acidic, neutral or alkaline and this can be measured by testing the pH value of the soil. The pH value can differ within and across a paddock or the property and vertically though the soil’s profile and can change over time at the same location and depth. The pH of the soil in a paddock can change as a result of the use of the paddock, management practices and natural processes. The pH level within the soil influences soil conditions and plant growth. Change in soil pH refers to regular monitoring of any variation over time in soil pH.
It is very important to note in coastal areas that the presence of acid sulfate soils can make for very high acidity readings.
Why measure soil this indicator?
Understanding the pH of your soils is essential to determine how suitable your soils are for long-term productive agriculture. Gaining an understanding of the variation in soil pH throughout your soil and across your property can help in making decisions about how you use the land.
The pH of all soils change over time; some agricultural practices accelerate this change. To understand the baseline pH level, the rate of change and what this means for management, is the reason behind monitoring pH over time. The pH of soils may also fluctuate during the year depending on moisture levels. Monitoring soil pH will indicate whether your land use and management practices are changing this key parameter of soil health.
Soils most at risk are lighter-textured sands and loams with low organic matter levels, and the naturally acidic red clay loam soils. Soils least at risk are the neutral to alkaline clay soils.
Growing plants lower the alkalinity in the soil. When harvested products are removed, the soil becomes more acidic. The impact is greatest where a large quantity of material is removed, as in the production of silage, hay and sugarcane. Research has shown that some agricultural practices, for example fertilising with ammonium-based nitrogen or deep ripping, significantly alter soil pH over time by influencing soil conditions, affecting plant growth, reducing nutrient availability and ultimately resulting in land degradation. Factors that accelerate acidification include:
- The application of ammonium-based nitrogen fertilisers to naturally acid soils at rates in excess of plant requirements
- Leaching of nitrate nitrogen, originally applied as ammonium-based fertilisers, out of the root zone
- Continued removal of alkaline plant and animal produce and waste products from the paddock
Conducting a baseline assessment and monitoring for change in soil pH will provide important information to assist your management action decision-making. As with all monitoring activities, you will need to clearly identify why you want to monitor soil pH and how monitoring this indicator may support your property or business planning objectives.
Downloads
- The print-friendly version of this indicator (PDF, 318K)* (PDF, 206 kB*) that contains a copy of all the pages from the soil pH section of the Land Manager's Monitoring Guide.
- Datasheets for levels 1 and 2 monitoring of the soil pH indicator have been provided below as portable document format (PDF), zipped files (ZIP) and executable Excel files (EXE). These datasheets will help you to record and analyse your monitoring data and include metadata sheets, field recording sheets, spreadsheets and example data and charts.
- Datasheets for level 1 and 2 monitoring (PDF, 144K)* (PDF, 23 kB*)(ZIP, 10 kB)(EXE, 78 kB).
- Acidity monitoring tools (PDF, 171K)* (PDF, 171 kB*)
If you experience any difficulty downloading or accessing the materials within the Land Manager's Monitoring Guide please contact the LMMG Team.
* Requires Acrobat Reader
Last updated: 04 November 2008