How to assess a profile pit

The crop is looking good now – an ideal time to dig a profile pit. A profile pit gives you a unique insight into the soil: how healthy is it? By doing this at least once a year, you can anticipate potential problems in time and see whether soil improvement measures have been effective.

Where and when do you make a profile pit?

• Pay attention to crop growth in the plot, find a representative spot, homogeneous or unusual.
• Dig the hole at least 20 meters from the edges of the plot.
• Be alert for driving ruts, as the soil below is extra compacted.
• Make a profile pit preferably in a well-developed crop in reasonable moisture conditions.

How do you make a profile pit?

1. Select two locations in the plot that you would like to compare.
2. Dig a profile pit of 50 by 50 cm and at least 40 cm deep at both locations.
3. Cut out a spade-sized block of soil from the side: first from the top 20–25 cm, then from the bottom 20–25 cm.

How do you assess the soil?

Pay attention to these four aspects:

1. Rooting: Pay attention to the depth and thickness of the roots, taking into account the typical rooting depth and thickness of the crop in question. Check that the roots are evenly distributed. If the entire profile has many visible roots, we speak of intensive rooting. Thickened roots can indicate soil resistance caused by soil compaction.
2. Structure: The crumbliness of the soil. Is it rounded and crumbly, or sharply lumpy with hard, blocky clods? A good structure has at least 25% crumb and no sharply lumpy elements.
3. Disruptive layers: Disruptive layers can be recognized by a transition from loose soil to firmer soil, over which roots sometimes grow horizontally. A disruptive layer is often found at ploughing depth.
4. Soil life: Soil life can be difficult to see, especially under dry conditions. Look for pores, structure, and the decomposition of organic matter, which indicate the presence of life.

_{Sources
A thorough look at your soil: how to assess a profile pit - Better Soil Management
#FarmSoil - Green Knowledge Network
Soil Assessment - Green Knowledge Network}

More information:
Soil Compaction File
Professional information for arable farmers