Simple Soil Health Measurements
Is my soil healthy? That is a question many growers ask. It is not always an easy question to answer. Some will say a soil is healthy if it produces a good crop, has good drainage, readily breaks down crop residues, has higher organic matter levels and holds water for the crop. Others want specific measures or tests to have a number to indicate the health of their soil.
The three components of soil health are physical, chemical and biological. Researchers use very detailed techniques in the lab and in the field, often to measure a single soil health indicator. These measures are not practical or cost effective for the field. Some labs in Ontario and neighbouring states offer soil health tests. The cost for these is low for simple tests and significantly more for a more complex suite of tests. Many of these tests are hard to interpret as more research in Ontario is needed to relate them to our soils.
You may already be taking some samples from your field that can provide a measure of soil health. Soil fertility tests can indicate the health of a soil for the chemical component. If nutrient levels and pH are adequate for the crops grown in the field then the chemical indicators are good. Soil organic matter level, often included in a soil fertility test, is a reasonable soil biological indicator. Adequate organic matter levels for the soil texture can indicate good soil biological activity. See the organic matter level rating of different textures table in to the Managing for Health Soils chapter of the OMAFRA Agronomy Guide - Publication 811.
There are a number of simple low cost tests that can be done in the field to give an indication of soil health.
1. Earthworm Counts
- Dig up a shovelful of soil and count the number of earthworms, if there are 10 earthworms that is a good number
- Count the number of earthworm middens in a quarter metre square (50 cm x 50 cm) area, if there are 10 to 15 middens/m2 that is a considered good
2. Water Infiltration
- Insert a ring (i.e. coffee can with both ends cut out) into the ground far enough so water cannot seep out from underneath the sides of the ring, avoid tire tracks
- Lay a piece of plastic down in the ring covering the soil so it will contain the water
- Pour 800 ml of water in the ring on top of the plastic, this represents about one inch of water
- Remove the sheet of plastic and start timing the amount of time it takes for all the water to drain, repeat a second time and use that time as it is more representative
- If the water is slow to drain, the amount of water left after 30 minutes can be measured with a ruler and recorded along with the time
- Repeat in several areas of the field
- An infiltration rate of 3 to 10 minutes per inch is considered rapid, 30 to 100 is considered moderate and 300 to 1000 minutes per inch is considered slow.
3. Soil Compaction
- Choose a time when the soil is moist but not wet ( a few days after a rain)
- Insert a tile probe or penetrometer into the soil at a constant pressure down to approximately 50 cm
- When using a tile probe feel where there is more resistance and note the depth. If using a penetrometer note where the readings exceed 350 psi and record the depth
- Repeat in several areas of the field
- An alternate method, if there is a growing crop, is to dig up some plants and examine the roots, look for flattened roots or stub ended roots, also look at the rooting pattern
- For more detailed information refer to the Managing for Health Soils chapter of the Agronomy Guide
4. Bury Underwear
- Burying cotton underwear is an easy do it yourself way to assess soil microbial activity.
- Visit the Innovative Farmers Association of Ontario website www. Ifao.com for detailed instructions
- The underwear have to be buried for 2 months so it is best to bury them in the first half of the growing season
Another good indicator of a healthy soil is the yield of a corn crop without nitrogen. The healthier the soil the higher the yield will be. Leave a short strip of corn without nitrogen and do a yield check.
For more information on soil health see the Managing for Health Soils chapter of the Agronomy Guide.
New Publications to Increase Soil Health!
The Ministry of Agriculture, Food and Rural Affairs' (OMAFRA) has developed new soil health publications. The publications provide best management practices to help farmers preserve and conserve soil while improving soil health and crop production. Visit the OMAFRA Soil Health in Ontario web page to learn more about the first twelve titles:
- Adding Organic Amendments
- Erosion Control Structures
- Cropland Retirement
- Soil Health in Ontario
- Field Windbreaks
- Soil Erosion by Water
- Winter Cover Crops
- Wind Strips
- Subsurface Drainage
- Rotation of Agronomic Field Crops
- Buffer Strips
- No-Till for Soil Health
These are just the beginning. OMAFRA is rolling out a total of 21 new publications over the coming year, so check the Soil Health in Ontario web page regularly for new releases.
For more information:
Toll Free: 1-877-424-1300
|Author:||Adam Hayes, Soil Management Specialist/OMAFRA|
|Creation Date:||01 September 2017|
|Last Reviewed:||01 September 2017|