Soil Management: Other Soil Management Problems

Putting It All Together: Other Soil Management Problems

While compaction and erosion are the two most common areas of difficulty in soil management, there are others.

Droughty Soils

Droughty soils have a low water-holding capacity due to the large number of large pores. Large pores drain quickly, while smaller pores hold plant available water. The large pores are filled with air, which increases oxidation or loss of organic matter, further reducing the potential to store water.

Through irrigation, soils prone to droughtiness can be very productive. High-value vegetable crops grow well on many of these soils. However, the low return of plant material from vegetable production doesn't improve the water-holding capacity of these soils.

When checking the site for droughtiness, ensure that the moisture stress symptoms are not due to other factors, such as a restricted root system.

Field Symptoms

• the soil is usually dry, and after a rain, water filters through quickly.

Crop Symptoms

• crops are stressed and wilted, leaves are curled or cupped
• plants are yellow, looks like a nitrogen deficiency
• crops are stunted.

Droughty soils tend to have low organic matter levels, low nutrient-holding capacity, and a high potential for nutrient leaching. Manure application can help build organic matter levels and supply nutrients. A word of caution: apply manure at reasonable rates, just before planting, to reduce the potential for leaching.

Best Management Practices

• use reduced tillage systems and residue management to create a layer of residue to conserve and retain moisture
• use cover crops
• include forages in the crop rotation
• apply manure (manure management) or other organic materials to build soil organic matter levels and improve water-holding ability
• irrigate high-value crops using an irrigation scheduling system to conserve water
• use good irrigation practices such as irrigating in late afternoon or at night to reduce evaporation.

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Subsidence

Subsidence is a gradual lowering of the surface elevation of an organic muck soil, or a reduction in the thickness of organic matter.

Over hundreds of years, organic soils have developed from the layers of plants laid down in low, wet areas. The high water table creates anaerobic conditions that slow the breakdown of organic materials. However, drainage is essential to make production of high-value vegetable crops practical.

Once the original muck soil is drained and tilled, the process of subsidence begins. The organic matter is lost or broken down in a number of ways:

• wind erosion
• water erosion
• biological oxidation
  • drainage and tillage add air to the soil, speeding the degradation of organic materials by aerobic bacteria.

Biological oxidation is the most significant.

Subsidence can account for large losses of soil. For example, at the Bradford Muck Research Station the following losses have been measured:

1945-1957: 1.08 cm/yr
1957-1967: 4.8 cm/yr
1967-1975: 1.08 cm/yr
1975-1983: 0.47 cm/yr

for a total of 73.4 cm over 38 years.

Field Symptoms

• topsoil depth decreasing
• foundations or previously buried objects may be exposed/li>
• subsoil often exposed by plow.

Crop Symptoms

• nutrient deficiencies may occur
• crop may be less consistent in quality and yield
• pesticide interactions may occur due to changes in pH and soil organic matter.

Best Management Practices

• manage water table levels to reduce aeration, thereby minimizing the oxidation rate of organic matter
  • in non-crop situations, keep the water table as close to the soil surface as possible
  • during the cropping season, maintain the water table at the optimum level for the crop grown
• apply copper to soil to slow the rate of decomposition or loss of organic matter
  • copper inactivates certain soil enzymes that degrade organic matter
• plant cover crops to keep the soil covered and to return organic matter to the soil
• reduce wind and water erosion to stop soil loss.

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Wet Fields (or Naturally Poorly Drained)

Wet areas are often symptoms of other problems - compaction, for example. However, there are some soil types which, because of their position in the landscape or their texture and subsoil, are naturally poorly drained.

Without proper attention and management, these poorly drained soils can develop other problems:

• wet soils are more prone to soil structural damage from tillage, planting, and harvest operations
• wet soils are colder, and the slow warming of these soils can result in reduced yields.

Field Symptoms

• water is lying on the fields
• sidehill seepage is evident
• field is soggy in spring after fall plowing
• field is rutted after harvest (there may be a thick layer of residue that was buried by plowing)
• field is slow to dry in spring.

Crop Symptoms

• crops are yellow or dead in areas of a field
• deep-rooted crops that overwinter are heaved
• plants are stressed and more insect and disease damage is evident
• root growth is concentrated at a shallow depth.

Best Management Practices

• install drainage and/or surface drains
• use crop rotations
  • include deep-rooted crops such as alfalfa, clover, etc.
• grow crops suited to wetter soil conditions or crops that are planted later in the growing season i.e. soybeans, winter wheat (winter survival may be variable).
• use seed treatment
• use disease-resistant/tolerant crop varieties
• use a reduced tillage system such as ridge tillage, which will create a zone of drier soil for plant growth
• use tillage carefully to expose soil to the air for evaporation and soil warming
• encourage earthworm populations for macropore development, by leaving residue on the soil surface
• use timely tillage and field operations
  • minimize tillage passes to reduce compaction
• consider planting the area to pasture or trees.

Wet soils are often in a vicious cycle. The wet soil conditions lead to compaction during tillage and harvest. This in turn reduces water movement. The poor soil structure leads to wet soil conditions, and so on.

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Available in Published Version of Soil Management

• Droughty Soils
  • Soil Types
  • Past Management
  • What's Happening in the Soil
• Subsidence
• Soil Types
• Past Management
• Wet Fields
  • Soil Types
  • Past Management
  • What's Happening in the Soil
    

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