The importance of soil pH in successful agricultural production

The importance of soil pH is one of the most neglected, yet decisive, pillars in modern agriculture.

While fertilizers and cutting-edge technology dominate the discussions, this silent factor determines whether nutrients reach plants or remain trapped in the soil.

An imbalance can turn a promising field into an unproductive one, even with high investments in inputs.

But why do so many producers still underestimate this variable? The answer lies in the lack of technical information and the belief that fertilization alone solves everything.

The reality is harsh: according to Embrapa (2024), 60% of arable land in Brazil has inadequate pH, leading to losses of up to 40% in productivity.

In this article, we will explore how pH influences everything from soil microbiology to fertilizer efficiency.

You'll discover real-life stories of producers who transformed entire crops simply by correcting this factor, advanced management techniques, and why precision agriculture is revolutionizing this control.

What is Soil pH and Why is it So Crucial?

pH is a logarithmic scale that measures the concentration of hydrogen ions in the soil, ranging from 0 (extremely acidic) to 14 (highly alkaline).

A pH between 5.5 and 7.0 is considered ideal for most crops as it allows for maximum nutrient availability.

When the pH is outside this range, a phenomenon called chemical fixation: elements such as phosphorus and potassium form insoluble compounds, becoming inaccessible to the roots.

In acidic soils (pH < 5.5), aluminum and manganese reach toxic levels, while in alkaline soils (pH > 7.5), iron, zinc and copper become unavailable.

A striking example is wheat in Paraná. Producers who applied limestone to raise the pH from 4.8 to 6.2 reduced their need for phosphate fertilizer by 35%.

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Phosphorus, previously retained in the soil, began to be absorbed, resulting in more vigorous plants and heavier grains.

Another case is that of citrus farming in São Paulo. Orchards with a pH below 5.0 exhibited leaf chlorosis (yellowing) due to micronutrient deficiency.

Correction with agricultural gypsum and limestone not only reversed the problem but also increased resistance to pests.

How Does pH Affect Microbial Life and Soil Health?

Soil microbiology is sensitive to pH. Nitrogen-fixing bacteria, such as those of the genus Rhizobium, have maximum activity at pH between 6.0 and 7.0.

In acidic soils, its efficiency drops dramatically, reducing the availability of natural nitrogen for plants.

Beneficial fungi, such as mycorrhizae, also suffer. They help roots absorb water and nutrients, but at pH levels below 5.0, their colonization declines.

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On the other hand, some pathogens, such as Fusarium, thrive in acidic soils, increasing the risk of root diseases.

A study by Esalq/USP showed that soils with adjusted pH presented 20% more microbial activity compared to uncorrected areas.

This means greater decomposition of organic matter, nutrient cycling and, consequently, reduced dependence on synthetic fertilizers.

pH Correction and Sustainable Management Techniques

Liming is the most common method for raising pH, but its efficiency depends on the type of limestone (dolomitic or calcitic) and the depth of incorporation.

In very acidic soils, application must be done in advance, as the reaction takes 3 to 6 months.

For alkaline soils, elemental sulfur or agricultural gypsum are the best options. Sulfur, when oxidized by bacteria, releases hydrogen ions that gradually acidify the soil.

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A recent advance is the use of bioremediators, such as acidifying bacteria (Thiobacillus), which accelerate pH correction without environmental impacts.

In Australia, sugarcane growers reduced alkaline pH by 0.8 units in just 8 weeks using this technique.

Precision Agriculture: The Importance of Soil pH

pH sensors coupled to drones and IoT systems already allow detailed mapping of variations within the same crop.

Companies like Precision Planting They offer equipment that adjusts the application of correctives at a variable rate, avoiding waste.

Read more: The relevance of soil pH for agricultural crops

In Mato Grosso do Sul, a soybean farm integrated this data with satellite imagery, identifying critical zones where the pH was below 5.0.

Localized correction increased productivity by 18% in the following harvest.

The Role of pH in Fertilizer Efficiency and Environmental Impact

A little-discussed but crucial aspect is how pH influences the efficiency of applied fertilizers.

In soils with a pH below 5.5, up to 60% of the applied phosphorus can become insoluble, binding to aluminum and iron.

This not only represents a financial waste, but also increases the risk of aquifer contamination when these nutrients are carried away by erosion.

In alkaline soils, urea undergoes accelerated volatilization, losing up to 30% of its nitrogen to the atmosphere before it can even be used by plants.

A study conducted by the Federal University of Viçosa demonstrated that correcting the pH to 6.0 increased the efficiency of nitrogen use in 22% in corn crops, proving that the chemical balance of the soil enhances all investment in fertilization.

The Relationship Between pH and Resistance to Climate Change

Soils with balanced pH are more resilient to extreme weather conditions.

When well chemically structured, they retain moisture better during droughts and drain more efficiently during periods of heavy rainfall.

This is because optimal microbial activity, favored by adequate pH, produces more glomalin – a protein that improves soil aggregation.

In the Cerrado, properties that maintained pH between 5.8 and 6.2 suffered 40% fewer losses during the record drought of 2024 compared to uncorrected areas.

This characteristic makes pH management a key strategy for adaptive agriculture, especially in increasingly unpredictable climate scenarios.

Correcting soil acidity is therefore not only a productivity factor, but a true insurance policy against climate risks.

Conclusion: pH is the Invisible Foundation of Sustainable Agriculture

Ignore the importance of soil pH It's like building a house without a foundation. No matter how much technology you apply, without this balance, the results will always fall short of their potential.

Producers who invest in regular analysis and accurate corrections reap lasting benefits: lower fertilizer costs, healthier plants, and greater resistance to climatic stresses.

The question remains: Is your soil working for you or against you?

Frequently Asked Questions on the importance of soil pH

1. How often should I test my soil pH?
Testing is recommended every two years for perennial crops and before each harvest for annuals. Very acidic or alkaline soils require more frequent monitoring.

2. Can I correct the pH with just organic matter?
Organic matter helps, but it's no substitute for liming or gypsum in severe imbalances. It acts slowly and has limited effect on severely degraded soils.

3. Can excess limestone be harmful?
Yes. Applying more than necessary can raise the pH too much, blocking micronutrients. Always follow the technical recommendations.

This content has been meticulously developed to provide up-to-date, actionable information, ensuring you make informed decisions. The importance of soil pH It’s not a detail—it’s the difference between a mediocre crop and an exceptional harvest.