What practice is recommended to correct manganese toxicity in tobacco fields?

Correcting soil pH is crucial when dealing with manganese toxicity in tobacco fields because manganese availability in soil is highly dependent on pH levels. When the soil is too acidic (lower pH), it can lead to an increased solubility of manganese, making it more readily absorbed by plants, which can result in toxicity. Adjusting the soil pH to a more neutral level can help reduce the solubility of manganese, thereby alleviating toxicity symptoms in the plants.

In contrast, the other practices listed may not have a direct impact on correcting manganese toxicity. Disking under the plants could disturb the soil structure but will not effectively address the underlying chemical imbalance. Applying potassium fertilizer does not address the manganese levels and could potentially exacerbate the problem if high levels of potassium further influence nutrient balance. Adding more nitrogen does not contribute to resolving manganese toxicity and might even worsen the nutrient competition among plants. Therefore, adjusting soil pH stands out as the best approach to manage manganese toxicity effectively.