Your Fertiliser Is Not Working as Hard as It Could. Soil pH Is Usually the Reason.

Your Fertiliser Is Not Working as Hard as It Could. Soil pH Is Usually the Reason.

The most common reason fertiliser programmes underperform in Malaysian plantations is not product quality or application rate. It is soil pH. A soil with pH below 5.5 does not make fertiliser disappear, but it does make a significant proportion of it inaccessible to plants. The same kilogram of NPK applied to a soil at pH 6.0 delivers more agronomic value than the same kilogram applied to a soil at pH 4.8.

What Happens in Soil Below pH 5.5

Below pH 5.5, aluminium and manganese become increasingly soluble in the soil solution. At concentrations above threshold levels, these elements are directly toxic to root cells, reducing root elongation and branching. A damaged root system cannot take up water and nutrients efficiently, regardless of how much fertiliser is applied.

Simultaneously, phosphorus availability drops sharply below pH 5.5. Phosphorus forms insoluble compounds with aluminium and iron at low pH, binding to soil particles in forms the plant cannot access. In Malaysian lateritic soils, which naturally have high iron and aluminium content, this phosphorus fixation effect is particularly severe. Applying triple superphosphate to a soil at pH 4.8 results in a large proportion of the phosphorus becoming unavailable within days of application.

What Liming Does

Agricultural lime and dolomite neutralise soil acidity by reacting with hydrogen ions in the soil solution. As pH rises above 5.5, aluminium and manganese precipitate back into insoluble forms, removing their toxic effect on roots. Phosphorus that was fixed to aluminium compounds is partially released. The soil microbial population, which is also pH-sensitive, increases in activity, improving nitrogen mineralisation from organic matter.

The result is not just a pH number change on a soil test report. It is a soil that makes more productive use of every kilogram of fertiliser applied. SoilBoost EA, applied alongside liming, provides humic acids that chelate remaining aluminium and improve cation exchange capacity, extending the window of improved nutrient availability between liming events. CSB Organico adds organic matter that buffers pH change and supports the microbial population that becomes active after liming.

Dolomite vs. Agricultural Lime

Agricultural lime is calcium carbonate. Dolomite is calcium magnesium carbonate. Both raise soil pH, but dolomite simultaneously corrects magnesium deficiency, which is common in Malaysian soils derived from granite parent material. If your leaf analysis shows low magnesium alongside low pH, dolomite is the better choice. If magnesium is adequate, standard agricultural lime at a lower cost per tonne of CaCO3 equivalent achieves the same pH correction.

Calculating the Lime Requirement

The lime requirement depends on current pH, target pH, soil texture, and buffer capacity. A general starting point for Malaysian mineral soils in the pH 4.5 to 5.0 range is 2 to 3 tonnes of ground agricultural lime per hectare to reach pH 5.8. For peat soils, the lime requirement is higher per unit of pH change due to the high buffer capacity of organic matter.

Liming and Peat Soils

Peat soils in Malaysia are inherently acidic, with pH typically between 3.5 and 4.5. Liming peat is effective but requires higher rates and more frequent reapplication. The target pH for oil palm on peat is generally 4.0 to 4.5, which is lower than mineral soil targets because peat chemistry is different. Over-liming peat can cause micronutrient deficiencies, particularly copper and zinc. Lime application on peat should be guided by soil test results and applied at the lower end of the recommended range.