Question

Describe the effect of low pH and high soil density on root growth and function

Answer 1

The pH of the soil has an enormous influence on soil biogeochemical processes. Soil pH is, therefore, described as the “master soil variable” that influences myriads of soil biological, chemical, and physical properties and processes that affect plant growth and biomass yield.

Soil pH is a measure of the acidity or basicity (alkalinity) of a soil. pH is defined as the negative logarithm (base 10) of the activity of hydronium ions in a solution.Soil pH is considered a master variable in soils as it affects many chemical processes. It specifically affects plant nutrient availability by controlling the chemical forms of the different nutrients and influencing the chemical reactions they undergo.

The pH of an alkaline soil can be reduced by adding acidifying agents or acidic organic materials

Soil strength and matric potential effects on root growth were independently significant for most crop and soil combinations. Under high soil conditions, the effect of soil water on root growth was evident only in its effect on soil strength. Bulk density had a significant effect on root growth independent of soil strength and matric potential in three cases.

High bulk density is an indicator of low soil porosity and soil compaction. It may cause restrictions to root growth, and poor movement of air and water through the soil. Compaction can result in shallow plant rooting and poor plant growth, influencing crop yield and reducing vegetative cover available to protect soil from erosion. By reducing water infiltration into the soil, compaction can lead to increased runoff and erosion from sloping land or waterlogged soils in flatter areas. In general, some soil compaction to restrict water movement through the soil profile is beneficial under arid conditions, but under humid conditions compaction decreases yields.

The following practices can lead to poor bulk density:

• Consistently plowing or disking to the same depth,
• Allowing equipment traffic, especially on wet soil,
• Using a limited crop rotation without variability in root structure or rooting depth,
• Incorporating, burning, or removing crop residues,
• Overgrazing forage plants, and allowing development of livestock loafing areas and trails, and
• Using heavy equipment for building site preparation or land smoothing and leveling.