If the soil is too acidic or too basic or alkaline then plants can't grow at all. So, soil naturally should be acidic or basic. The pH of soil is also affected by the use of chemical fertilisers in the fields. The pH of acidic soil can reach as low as 4 and that of basic up to 8.3.

**Plants and pH Sensitivity**

Plants, like most living organisms, are sensitive to changes in pH levels. pH is a measure of the acidity or alkalinity of a solution, and it represents the concentration of hydrogen ions (H+) in the solution. The pH scale ranges from 0 to 14, with values below 7 indicating acidity, values above 7 indicating alkalinity, and 7 representing neutrality.

**Effects of Acidic pH on Plants**

1. **Nutrient Availability:** The pH of the soil directly affects nutrient availability to plants. In acidic soils, certain essential nutrients like phosphorus, potassium, and calcium become less available to plants. This can lead to nutrient deficiencies and hamper plant growth and development.

2. **Toxicity:** Acidic pH levels can result in the accumulation of toxic elements such as aluminum and manganese in the soil. These elements can be taken up by plants and cause toxicity symptoms, leading to stunted growth, chlorosis (yellowing), and even plant death.

3. **Microbial Activity:** Acidic pH can inhibit the activity of beneficial soil microorganisms that play a crucial role in nutrient cycling and plant health. This can disrupt the symbiotic relationships between plants and certain beneficial bacteria and fungi, affecting nutrient uptake by the plants.

**Effects of Alkaline pH on Plants**

1. **Nutrient Imbalances:** Alkaline soils can limit the availability of certain essential nutrients, such as iron, manganese, and zinc, leading to nutrient imbalances in plants. This can result in nutrient deficiencies or toxicities, causing various physiological disorders and reduced plant growth.

2. **Ion Imbalances:** Alkaline pH can alter the balance of ions within plant tissues, affecting various physiological processes. For example, it can disrupt the uptake and transport of water, leading to water stress in plants. It can also interfere with the absorption of certain ions, affecting enzymatic activities and metabolic processes.

3. **Soil Structure:** Alkaline soils tend to have a higher clay content and poor soil structure. This can result in poor water drainage, reduced oxygen availability to plant roots, and increased susceptibility to root diseases. These factors can further hinder plant growth and development.

**Plant Adaptations and pH Tolerance**

While plants generally prefer slightly acidic to neutral pH levels, different plant species have varying degrees of tolerance to pH fluctuations. Some plants, known as acid-loving plants (e.g., blueberries and azaleas), thrive in acidic soils, while others, called alkali-loving plants (e.g., cacti and succulents), can tolerate alkaline conditions.

Plants have various adaptations to cope with pH changes, such as:

1. **Ion Exchange:** Plants can modify their root exudates to release hydrogen ions, which can replace other cations like calcium and magnesium bound to soil particles. This ion exchange mechanism helps plants acquire necessary nutrients even in high-pH soils.

2. **Root Morphology:** Plants can develop specialized root structures, such as root hairs, to increase their surface area for nutrient absorption. They can also develop deeper root systems to access nutrients and water in lower soil layers, bypassing the pH-affected surface layers.

3. **Symbiotic Relationships:** Certain plants form beneficial associations with mycorrhizal fungi, which can enhance nutrient uptake, particularly phosphorus, even in acidic or alkaline soils. These fungi help extend the root system and improve nutrient absorption efficiency.