Alkaline soils tend to be rich in calcium, which locks up iron and manganese and makes them unavailable to plants, especially those not adapted for alkaline soils such as camellias or rhododendrons. Symptoms are similar to magnesium deficiency, where the leaf veins remain green and the rest of the leaf turns pale and yellow. The plant may become stunted and will fail to thrive.

Control

Make sure that plants are suitably adapted to the soil type; this may mean growing acid-loving plants in raised beds or containers. Use rainwater rather than tap water to irrigate susceptible plants, and apply good-quality compost and well-rotted manure regularly. To alleviate short-term deficiencies, apply a chelated or fritted form of trace elements and sequestered iron.