In a well-composted garden soil, mineral deficiencies are unlikely to occur. However, deficiencies in trace elements can occur in soils that are ancient. To help combat this, incorporate a range of organic fertilisers, such as seaweed, plus compost into the soil to provide high levels of plant nutrition and adequate trace elements. Many diseases, especially viruses, cause symptoms that can easily be mistaken for nutritional problems, which are often difficult to diagnose. Temperature extremes and irregular watering also cause symptoms that may appear to be nutritional. Excessive liming of soil or markedly acidic soils can cause mineral elements in the soil to be unavailable to plants. Always check your soil pH first. Select crops best suited to your soil and climate. Also, crop rotation helps to ensure that excessive nutrients are not withdrawn by particular crops.