Dan Bloomer (LandWISE) and Bruce Searle (Plant & Food Research)

Soil Moisture-Density Gauges are commonly used in construction and roading to monitor soil density. This enables engineers to determine that sufficient compaction has been achieved to ensure foundation stability.

This article summarises results from a Sustainable Farming Fund project co-funded by the Foundation for Arable Research and LandWISE.

LandWISE cropping trials have often found yield limitations where legacy compaction is not removed prior to establishing a new crop. A study was undertaken to see if a soil moisture – density gauge can give a valid measure of soil density in cropping fields, whether soil density is altered by cultivation practices and if it affects yield.

Fig.1 Top view of Troxler Moisture-Density Meter

A Troxler 3440 soil moisture density gauge was used to assess soil at sites in Gisborne, Manawatu and Hawke’s Bay. One key advantage of the gauge is that measurements are completed quickly (a couple of minutes) in the field. Conventional sampling requires large samples to be taken, dried for several days in a lab, and then weighed to determine density and moisture.

Results showed the Troxler can give valid measures of soil density but must be calibrated for each soil type and depth. Some physical cores must be taken and processed to allow this.

The calibration curves for two Hawke’s Bay soils are shown in Figure 2. These show the relationship between gauge soil density ‘estimates’ and soil density measured by removing, drying and weighing soil cores.

Figure 2. Relationship between estimated soil density obtained using individually calibrated Troxler measurements and soil core measured density for Twyford and Mangateretere soils.

Once calibrated, the Troxler offers the advantage of quickly collecting a large number of soil compaction measurements at different depths, without the cost of laborious soil sampling.  A draft protocol was prepared for calibration purposes.

Project details here>

You’ll see that our website offers “Feeds”. A wee search engine checks our site each day for new material and lets you know if it finds any.
The steps below show you how to have Page Bloomer Feeds set as a favourite on your web browser.

Subscribe via RSS

RSS feeds set a favourites link in your web browser. The RSS feed collects our updates for you. When you look at your feeds, it contains items put on our website. You get the information, but you have to remember to look regularly yourself.

How do you subscribe to RSS feeds?

1. Look for this icon  

It tells you the website offers feeds. On the PageBloomer site, you’ll find it on the right, just below the Search the Site box

2. Click on Subscribe via RSS

 • A special PageBloomer page will come up showing all the latest content.

At the top of the page is a box in which you’ll find a link to set up the subscription.

3. Click on Subscribe to this feed

• A pop-up Subscribe to this feed asks if you want to subscribe to LandWISE

4. Click Subscribe and a Feed called PageBloomer will be added to your favorites

5. Check your favorite feed regularly for Page Bloomer Associates updates or to quickly search our postings. You can search here by categories too.

We have just updated our website and are now using postings as well as static pages. We have introduced the ability for readers to post comments and hope you’ll use the site for discussion.  One key hope is that this will help improve the quality of resources we provide here. 

As always, let us know of glitches or other problems.