Tree Fruit Soils and Nutrition















 

 

Physical Properties of Soil


Permeability (the rate at which water moves through the soil) and Water-Holding Capacity (WHC; the ability of a soils micropores to hold water for plant use) are affected by

  • The amount, size and arrangement of pores
  • Macropores control a soil’s permeability and aeration.
  • Micropores are responsible for a soil’s WHC

Porosity is in turn affected by

  • Soil texture
  • Soil structure
  • Compaction
  • Organic matter

soil texture triangleSoil texture (the relative proportions of sand, silt, and clay) is important in determining the water-holding capacity of soil:

  1. Fine-textured soils hold more water than coarse-textured soils but may not be ideal
  2. Medium-textured soils (loam family) are most suitable for plant growth

- Sands are the largest particles and feel gritty
- Silts are medium-sized and feel soft, silky, or floury
- Clays are the smallest sized particles and feel sticky and are hard to squeeze.
- Relative size perspective: Sand (house) > Silt > Clay (penny)

Four main types of soil structure (the arrangement of aggregates in a soil):

  • Platy - common with puddling or ponding of soils
  • Prismatic (columnar) – common in subsoils in arid and semi-arid regions
  • Blocky – common in subsoils especially in humid regions
  • Granular (crumb) – common in surface soils with high organic matter content

Properties of soil particle size

  Sand Silt Clay
Porosity mostly large pores small pores predominate small pores predominate
Permeability rapid low to moderate slow
Water holding capacity limited medium very large
Soil particle surface small medium very large

Soil Compaction destoys the quality of the soil because it restricts rooting depth and decreases pore size. The effects are more water-filled pores less able to absorb water, increasing runoff and erosion, and lower soil temperatures. To reduce compaction:

  • Add organic matter
  • Make fewer trips across area
  • Practice reduced-till or no-till systems
  • Harvest when soils are not wet

Next page: Soils, water, and plant growth

 

 

 

Updated July 15, 2004

 

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