1、Understanding phosphorus mobilization mechanisms in acidic soil amended

Calcium-silicon-magnesium-potassium fertilizer (CSMP) is usually used as an amendment to counteract soil acidification caused by historical excessive nitrogen (N) applications. However, the impact of CSMP addition on phosphorus (P) mobilization in acidic soils and the related mechanisms are not fully understood.

2、Fertilizers and Soil Acidity

Monoammonium phosphate (MAP), single superphosphate (SSP) and triple superphosphate (TSP) all add P to soil in the form of the H₂PO₄⁻ ion, which can acidify soil with a pH greater than 7.2 but has no effect on soil pH in acidic soils.

3、Choosing the Right Fertilizer for Acidic Soils

This article delves into the characteristics of acidic soils, their effects on plants, and offers detailed guidance on choosing fertilizers that best suit such conditions.

4、The Effect of Phosphorus Fertilizer Sources and Lime on Acidic Soil

Application of PARP phosphate sources significantly improves soil exchangeable acidity and present acid saturation by 42% and 41%, respectively, over the commonly used NPSB standard sources of phosphorus fertilizer.

5、Understanding phosphorus mobilization mechanisms in acidic soil amended

Calcium-silicon-magnesium-potassium fertilizer (CSMP) is usually used as an amendment to counteract soil acidification caused by historical excessive nitrogen (N) applications.

Which Fertilizers Produce Acidity in Soil? A Scientific Approach with

If your goal is to lower soil pH, use acidifying fertilizers like Olitar P44 Urea Phosphate, Olitar Sulfotar SC 800, or Oligro Sonacid. However, if your soil is already acidic, you may need neutral fertilizers like Olitar Potas 3-0-30 or calcium-based fertilizers to maintain pH balance.

Technical Bulletin: Fertilizers and Soil Acidity

The form of P fertilizer added to soil can affect soil acidity, principally through the release or gain of H+ ions by the phosphate molecule depending on soil pH

Blended soil amendments: A viable strategy to reduce soluble phosphorus

Typically, aluminum (Al)- and iron (Fe)-rich soil amendments have been evaluated for acidic soils, whereas calcium (Ca)-based amendments have been evaluated for alkaline soils (Kleinman, 2017).

Sources and Solubilization of Phosphatic Fertilizers

Rock phosphate is a natural and cheap, and suits acid soils. In alkaline conditions, phosphorus is commonly unsoluble, unless amendments such as sulfur, organic matter, or phosphorus solubilizing bacteria are added to improve phosphorus bioavailability.

Organic amendments promote soil phosphorus related functional genes and

Organic amendments, such as straw, biochar, and manure, provide sustainable alternatives to chemical P fertilizer (Xu et al., 2025). These amendments enhance soil bioavailable P and promote P mobilization by soil microorganisms (Sun et al., 2015).

Acidic soils, defined as those with a pH below 6.0, often lack phosphorus, a critical macronutrient essential for plant growth. In agricultural production, the rational application of phosphate fertilizer amendments can significantly enhance soil fertility and crop yields. Below are detailed recommendations for improving acidic soils using phosphate fertilizer amendments:

I. Understand Soil Type and Nutrient Status

1. Soil Composition: Acidic soils may contain components like limestone or shale, whose minerals release carbonate ions, contributing to soil acidity.
2. Nutrient Assessment: Conduct soil tests to determine pH, nitrogen (N), phosphorus (P), potassium (K), and other nutrient levels.
3. Microbial Activity: Analyze soil microbial communities and their roles in nutrient decomposition and transformation.

II. Select Appropriate Phosphate Amendments

1. Organic Fertilizers: Compost, green manure, and animal manure improve soil structure and organic matter content.
2. Chemical Phosphate Fertilizers:
   • Ordinary Superphosphate (Ca(H₂PO₄)₂)
   • Triple Superphosphate (Ca(H₂PO₄)₂·2H₂O)
   • Calcium Magnesium Phosphate (Ca₃(PO₄)₂·Mg₃(PO₄)₂) These provide direct phosphorus uptake for plants.
3. Trace Element Phosphate Fertilizers: Examples include ammonium ferric phosphate (NH₄Fe(H₂PO₄)₂O₇), which supplements specific phosphorus needs.

III. Application Methods

1. Base Application: Evenly distribute phosphate fertilizers into the plow layer (~30 cm deep).
2. Topdressing: Apply additional fertilizers during critical crop growth stages based on soil and crop needs.
3. Mixed Application: Combine phosphate fertilizers with nitrogen (N) or potassium (K) fertilizers to improve nutrient use efficiency.

IV. Key Considerations

1. Avoid Over-Fertilization: Excessive phosphorus may worsen soil acidity and reduce other nutrient availabilities.
2. Regular Soil Testing: Adjust fertilization strategies annually based on crop requirements and soil conditions.
3. Environmental Impact: Prioritize sustainable sources and proper handling of phosphate fertilizers to minimize ecological harm.

V. Case Studies

1. Case 1: A farm applied compost annually during spring plowing. Over several years, soil pH normalized to neutral, and crop yield/quality improved significantly.
2. Case 2: A fruit grower used compound phosphate fertilizers, resolving soil acidity while enhancing fruit quality and productivity.

For acidic soils, selecting suitable phosphate amendments and scientific fertilization practices is crucial. Proper management boosts soil health, crop productivity, and agricultural sustainability.