Soil Management - Putting It All Together

Table of Contents

1. Is your soil healthy?
2. Soil Structure
3. Addressing Soil Structural Problems
4. Available in Published Version of Soil Management

Soils are complex - their health is affected by many factors, and symptoms of problems can be misleading. You must consider all aspects of what's going on in your fields before concluding what the problem is.

Is your soil healthy?

Ask yourself these questions. Do your soils:

• drain and warm quickly in spring?
• stay open and friable after planting, i.e. aren't prone to crusting?
• have little runoff, even after heavy rains?
• store moisture well for crop use during dry periods?
• resist erosion and compaction?
• have a varied crop rotation?
• produce high yielding, high quality, consistent crops (without excessive nutrient or pesticide applications)?

Did you answer yes each time? Give yourself a pat on the back. A few no's? Read on for information on common soil management problems that can have an impact on soil health. We'll look at several challenges in soil management:

• soil structure
• erosion
• droughty soils
• subsidence
• wet fields.

Figure 1. It all comes down to productivity and sustainability; if you take good care of the soil, it will take care of you.

Soil Structure

If your soil has structural problems, chances are it is weather-sensitive or stress-prone due to difficulties in root development and soil exploitation. Well-managed soils are productive, even under difficult growing conditions.

To maintain yields, short-term solutions are often used (such as extra fertilizer, better hybrids, and irrigation), even though poor soil structure is the main problem.

There are four main types of soil structure problems that occur across a range of soil types in Ontario:

• crusting
• compaction
• under-consolidation
• setting-up.

We'll be considering the first two in greater detail. They are more common and more complicated than the others.

Figure 2. Soils farmed with modern agriculture rarely appear like the ideal soil. The processes of tilage, crop seeding, and harvesting tend to destroy aggregates and create a platy or compacted layer. Note how the bulk density increases in the compacted areas, and the impact on crop rooting.

Addressing Soil Structural Problems

Soil Crusting

Following the rapid wetting and drying of an overworked seedbed, a solid sheet forms (0.2 to 5 centimetres thick) that is tight enough to prevent crop emergence. This is known as soil crusting.

Field Symptoms

• following an intensive rain, the soil in top 1 to 2 centimetres flows together to form one solid sheet
• water ponds on the surface
• soil structure below crust still intact.

Crop Symptoms

• crop emergence is sporadic and delayed
• crops leaf out under the soil surface
• growth is slow and stunted.

Figure 2. Beans are particularly vulnerable to crusting, due to the cotyledons emerging. In soils prone to crusting, consider planting beans in rows rather than broadcast, in order to get more concentrated upward movement.

Best Management Practices

• reduce secondary tillage; don't overwork the soil
• use reduced tillage, no-till, or ridge tillage systems to leave crop residue on the soil surface
• use a good crop rotation - include grasses and legumes where possible
• use cover crops
• use manure management to build soil organic matter
• use timely tillage
• work ground at suitable moisture level to prevent bringing up clods - more clods require more tillage
• if a crust has formed before the crop emerges, rotary hoe to break up the crust - this will help the crop emerge, although this perpetuates soil structural problems
• check plant populations
• replant as a last resort
• a light rain will help soften the crust.

Soil Compaction

Compaction is the process of increasing soil density by packing soil particles closer together. It can occur anywhere in the soil profile, but tends to be seen near the surface or at plow depth. Good management can lessen the impact of compaction on soil structure.

Figure 4. Compaction can develop in any soil type. Sandy soils will exhibit an area of tightly packed soil particles. Finer-textured soils often have a gradually increasing density and resistance. The depth of the compaction depends on the type of compacting equipment. Disk pans develop at the bottom of the disked area. Plow pans tend to develop slightly deeper at plowing depth.

Field Symptoms

• water is ponding on soil surface
• erosion is occurring
• pond sizes are getting larger.

Crop Symptoms

• crop growth can be slow, stunted, and variable, particularly under stressful weather conditions
• root tips are flattened and/or swollen
• roots below compacted layer grow normally
• root growth is concentrated along face of soil clods
• crop may exhibit various nutrient deficiencies
• roots tend to grow sideways or down large- sized holes/cracks
• roots aren't penetrating evenly into the soil.

Best Management Practices

• timely tillage and field operations - stay off wet fields; soil should be at proper moisture conditions at tillage depth
• good drainage - tile drainage should be installed in fields with variable drainage
• longer crop rotations that include forages/cereals
• forage crops - leave in for longer than 1 year
• tillage equipment - ensure it lifts and shatters soil (coulter chisel, cultivator) as opposed to pulverizing and grinding (disk)
• alternate tillage depth so that tillage pans aren't created
• limit the amount of traffic, including tillage, across a field
• restrict compaction - create a long, narrow "footprint" with tire arrangement, e.g. radials, large tires, tracks
• limit axle loads to less than 5 tonnes/axle.

Available in Published Version of Soil Management

• Soil Crusting
  • Soil Types Most Affected
  • Past Management that Contributes to the Problem
  • What's Happening in the Soil
  • Other Similar Problems
• Soil Compaction
• Soil Types Most Affected
• Past Management That Contributes to the Problem
• What's Happening in the Soil
• Variations - Wheel Track Compaction
• Detecting Compaction
• Tillage Considerations
• Seedbed Preparation - Chart
• The Chisel Plow
• No-till - What's Really Happening in the Soil

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