Calcium Oxide

The strong alkalinity (pH > 12) generated when CaO reacts with soil moisture creates extremely unfavourable conditions for soil-borne pathogens including fungi, bacteria, and nematodes. This sanitising effect is used as a pre-plant soil treatment in high-value crops and areas with history of soil disease problems.

The lime requirement is determined by soil testing — measuring soil pH and buffer pH to calculate the amount of lime needed to raise pH to the target level. CaO dosage is calculated based on its neutralising value (typically 150–180 vs CaCO₃ base of 100), applying lower rates than agricultural lime to achieve the same pH correction.

Calcium oxide requires careful handling as it is caustic and reacts exothermically with water. PPE (gloves, eye protection, dust mask) should be used. It should not be applied to growing crops directly and must be incorporated into soil or diluted before plant contact.

Calcium oxide is the fastest-acting of all liming materials. Soil pH correction can begin within days of application, whereas calcium carbonate may take several months. This makes CaO particularly useful before planting when rapid pH correction is needed.

Yes. Calcium oxide's pathogen-controlling alkalinity is valuable for preventing soil-borne diseases like club root in brassicas and fusarium in cereals. It should not be used in soils already at neutral to alkaline pH as it may raise pH to levels harmful to most crops.