Acidification of soil is a natural process with major ramifications on plant growth. As soils become more acid, particularly when the pH drops below 4.5, it becomes increasingly difficult to produce food crops. As soil pH declines, the supply of most plant nutrients decreases while aluminum and a few micronutrients become more soluble and toxic to plants. These problems are particularly acute in humid tropical regions that have been highly weathered. According to Sanchez and Logan (1992), for example, one third of the tropics, or 1.7 billion hectares, is acid enough for soluble aluminum to be toxic for most crop plants. We will look at some of the causes of acidification and list some of the expected results of both acidification and the practice of liming for acid neutralization.

What’s Inside:

  • What Causes Soil to Become Acid?
  • Soil pH and Aluminum
  • Effects of Acidification
  • Solution to the Problem
  • What Happens When Soil is Limed
  • Dangers of Over-Liming the Soil

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TN #48 Acid Soils of the Tropics

Robert D. Harter, Ph.D

Acidification of soil is a natural process with major ramifications on plant growth. As soils become more acid, particularly when the pH drops below 4.5, it becomes increasingly difficult to produce food crops. As soil pH declines, the supply of most plant nutrients decreases while aluminum and a few micronutrients become more soluble and toxic to plants. These problems are particularly acute in humid tropical regions that have been highly weathered. According to Sanchez and Logan (1992), for example, one third of the tropics, or 1.7 billion hectares, is acid enough for soluble aluminum to be toxic for most crop plants. We will look at some of the causes of acidification and list some of the expected results of both acidification and the practice of liming for acid neutralization.

What’s Inside:

  • What Causes Soil to Become Acid?
  • Soil pH and Aluminum
  • Effects of Acidification
  • Solution to the Problem
  • What Happens When Soil is Limed
  • Dangers of Over-Liming the Soil

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