• Water moves easily through a well structured soil.
• A well-structured soil is very porous (lots of air space).
• Roots can penetrate soils with good soil structure more easily.
• Poorly structured topsoil will crust, which can reduce crop emergence and water movement into the soil.
  

• With a shovel, cut a square of soil about the width of the shovel and about 15 cm (6 in.) deep.
• Lift it up with the shovel.
• Pick the soil up and drop it from waist height.
• Compare how the soil breaks apart to the photos below.
• Also compare the aggregates to the diagrams and photos in Table 8-2, Types of Soil Structure.
  

• Restricts air and water movement through the soil
• Restricts root growth, limiting the plants' ability to take up water and nutrients.
• Reduces the size of soil pores.
  

• Identify the areas that have potential compaction problems.
• Choose a time when the soil is moist.
• Using a tile probe or flexible rod, probe the affected area to a depth of 50 cm (20 in.) and compare to a fencerow or unaffected area.
• Insert the probe into the ground at a slow, steady speed.
• Your arms should be slightly bent, acting as the pressure gauge, measuring the force required to push the tip of the probe through the soil.
• Note the depths at which the tip of the probe requires more force to push it through the ground. These areas may be where roots cannot penetrate.
• Use a shovel to dig up the plants in the affected area and examine the roots. Compare the roots to healthy plants from an unaffected area. The compacted area will have plants with malformed/-restricted roots. Roots may be concentrated in the top 10-20 cm (4-8 in.) of the soil.

Note: When using a probe to compare compaction in different parts of fields, the areas measured must have similar moisture content for the results to be comparable.

• Soil organic matter plays a key role in soil structure, nutrient cycling and water-holding capacity, which can have significant impacts on crop growth.

• Soil samples taken for nutrient analysis to a depth of 15 cm (6 in.) can also be analyzed for organic matter.
• Take samples as per the guidelines described in Soil Sampling,or from areas of concern within a field.
• Soil from a fencerow or woodlot can be analyzed for comparison.
• See Organic Matter, and Adding Organic Material (Residues), for more information.

• The colour of the surface soil (at the same moisture level) across a field is a visual indicator of soil organic matter levels.
• Lighter coloured soil on the side of a knoll in a field can be an indicator of the loss of topsoil due to tillage erosion.
• Tilling below the topsoil layer will mix in lower organic matter subsoil, causing those areas to appear lighter.
  

• Check whether the soil colour across the field is fairly uniform.
• Generally, the darker the soil, the higher the organic matter level, if soil moisture levels are equal.
• Areas of the field that were old wetlands will usually be darker in colour, as they would have accumulated higher levels of organic matter prior to being drained.
  

• Drives organic matter breakdown and nutrient cycling
• Plays a role in water movement through the soil
• Has an impact on soil structure
• A lifeless soil will not be a productive soil
  

• Count the number of large earthworm holes (middens, as shown in the photo on the far left) in a square metre: 10 or more per square metre is a good population.
• Small earthworm populations can be assessed by digging up a shovelful of soil and breaking it apart to see how many are found.
• The smell of a soil can also be an indicator of a healthy soil life population. A sweet, forest smell is good; a swampy smell indicates a less than ideal situation.
• See Soil Life, for more information
  

Can affect:

• Timeliness of field operations
• Soil erosion
• Root growth
• Amount of air in a soil
  

• Observe the field to see if moisture drains away quickly and the soil is warm and ready for field operations in the spring
• Observe the crop to see if excess moisture is reducing yield, except in wet years
  

• Moisture available for crop growth
• Reduces moisture stress during dry periods
  

• Observe the field to see if the soil stores moisture well.
• Observe the crop to see if it suffers during moderate dry spells.
  

• Poor crop growth if not caused by insects, diseases, weeds, the weather or some other circumstance, could indicate a soil problem.

• Observe the crop in the field, especially prior to reproduction; look for differences in growth and in colour of the crop.
• The crop should be a dark green colour, and growth should be rapid and relatively uniform.
• Yield maps are also a good indicator of differences in crop growth in the field.

• Poor root growth, if not caused by insects or disease, is likely due to a soil factor.
• A plant root explores a large volume of soil for uptake of nutrients and water essential for plant growth.
  

• Carefully dig up the plant root.
• Generally, there should be a uniform distribution of the roots.
• White roots indicate live roots.
• Roots will grow down in the soil and on an angle out from the base of the plant, in roughly a straight line.
• Roots that take a sudden turn likely encountered a compacted area.
• Soil compaction will also restrict roots and result in a shallow or restricted root system.
  

• The correct nutrient and pH levels in a soil are essential for good crop growth.
• Testing the levels is critical to being able to correct deficiencies.
  

• See Chapter 9, Soil Fertility and Nutrient Use, for information on soil and tissue sampling and how to correct deficiencies.