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Soil acidity and soil salinity arise from different but sometimes overlapping processes:

🧪 Causes of Soil Acidity:

• Leaching of basic cations (Ca²⁺, Mg²⁺, K⁺, Na⁺) due to high rainfall, which leaves behind H⁺ and Al³⁺ ions.
• Use of acid-forming fertilizers, especially ammonium-based (e.g., urea, ammonium sulfate).
• Decomposition of organic matter, releasing organic acids.
• Natural weathering of acidic parent material.
• Continuous cropping without liming, which removes base nutrients through harvest.

🧂 Causes of Soil Salinity:

• Irrigation with saline water or poor drainage, leading to salt accumulation.
• High evaporation rates, which draw salts to the surface.
• Capillary rise from saline groundwater.
• Improper fertilization practices, especially with chloride- or sodium-based compounds.

✅ Prevention and Treatment:

For Acidic Soils:

• Apply agricultural lime (CaCO₃) or dolomite to neutralize acidity.
• Use balanced fertilization, avoiding excessive ammonium fertilizers.
• Implement crop rotation with legumes to improve nutrient cycling.
• Maintain good organic matter levels, but manage residue inputs wisely.

For Saline Soils:

• Improve drainage to flush salts below the root zone.
• Use gypsum (CaSO₄) for sodic soils to replace Na⁺ with Ca²⁺.
• Irrigate with good-quality water and apply leaching fractions.
• Grow salt-tolerant crops during reclamation.
• Avoid over-irrigation and monitor electrical conductivity (EC) of soils.

Tohid Nooralvandi Soil becomes acidic and saline due to various natural and human-induced factors. Acidic soils are mainly caused by the leaching of basic nutrients such as calcium and magnesium, especially in areas with heavy rainfall. The continuous use of acid-forming fertilizers like ammonium sulfate and urea also contributes to soil acidity. Additionally, the decomposition of organic matter produces organic acids, and in some cases, the parent rock material itself is naturally acidic. On the other hand, saline soils develop due to poor drainage and high evaporation, which lead to the accumulation of salts on the soil surface. Irrigating with saline water, excessive use of chemical fertilizers, and the upward movement of groundwater containing dissolved salts also contribute to soil salinity.

To prevent and treat acidic soils, farmers can apply agricultural lime (calcium carbonate) to neutralize the acidity and improve soil pH. Proper nutrient management through balanced fertilization and the addition of organic matter like compost can help stabilize the soil. Acid-tolerant crops may also be planted when liming is not feasible. For saline soils, improving drainage is essential to allow salts to be flushed below the root zone. Using clean, non-saline irrigation water and applying gypsum (calcium sulfate) can help replace harmful sodium ions and improve soil structure. Additionally, adopting crop rotation with salt-tolerant crops and avoiding over-irrigation and fertilizer misuse are effective practices to manage and rehabilitate saline soils.