The Role of Lime in Soil pH Adjustment and Nutrient Management
Most soils, due to the excessive use of synthetic fertilizers and acidic salts, become acidic over time. This acidity can negatively impact plant growth and the availability of essential micro and macro nutrients. To address this issue, it is crucial to improve soil pH. In this article, we will discuss the function of lime in adjusting soil pH and its role in nutrient management.
What is Lime and How Does it Affect Soil pH?
Lime, primarily calcium hydroxide (Ca(OH)?), is a basic compound that is readily available and easily applied to soils. When added to acidic soils, lime can enhance the pH levels, making them more favorable for optimal plant growth. The effectiveness of lime in raising soil pH is well-documented in agricultural practices.
Calcium Hydroxide and Soil pH Control
Lime is effective in controlling the growth of harmful microorganisms and balancing soil pH. However, the impact of lime on soil pH can vary based on the soil's initial nutrient levels. For instance, in soils with high sodium and/or potassium levels, the addition of lime can lead to a decrease in pH, contrary to the expected outcome.
Understanding Nutrient Influences on Soil pH
The efficiency of lime in altering soil pH is determined by the nutrient levels already present in the soil. A scale assigns values to various nutrients, with calcium and magnesium receiving a score of 1, while potassium and sodium receive scores of 2 and 4, respectively. This scale helps in predicting the pH changes when different nutrients are added to the soil. However, pH is not the primary reason to add a specific nutrient but can be the result of the nutrients added.
Case Study: Lime Application and pH Adjustment in Imperial Valley
To illustrate the effectiveness of lime in adjusting soil pH and nutrient levels, we can look at a case study from Bo Shropshire, an expert in soil fertility who operates in Imperial Valley, California. According to Shropshire, an extensive soil sample taken in 1999 from a 18-acre field that had been farmed for over 40 years showed a pH of 8.1 and a sodium content of 17.14 percent. After applying 8000 pounds of 30% calcium lime, the pH dropped to 7.9 with a sodium level of 6.6, indicating a significant change in both pH and secondary element levels.
Shropshire emphasizes the importance of base saturation percentages, specifically the calcium and magnesium levels. In his area, the target base saturation percentage for calcium and magnesium is now 80:10, compared to the initial 69:11, which offsets the high magnesium content and effectively reduces the sodium load. This adjustment not only improves soil structure but also enhances water management, as the high total exchange capacity (TEC) soils do not easily leach sodium out.
Sodium Management and Water Quality
The irrigation water in the Imperial Valley has a pH ranging from 7.7 to 8.3 and a sodium level of 1800-2200 pounds per acre-foot. High sodium levels can significantly affect crop growth and soil structure. By maintaining adequate calcium levels, the sodium content is kept in check, leading to better crop yields and improved soil quality.
Conclusion
In conclusion, the use of lime is a critical aspect of soil pH adjustment and nutrient management. The effectiveness of lime is dependent on the existing nutrient levels in the soil, and understanding these levels is crucial for achieving the desired soil pH and optimal crop growth. By implementing the strategies outlined in this article, farmers and gardeners can improve their soil health and enhance the overall productivity of their land.
References
Shropshire, Bo. Personal communication, 2023.
Kinsey Agricultural Services. Personal communication, 2023.
Perry Agricultural Laboratories. Personal communication, 2023.