Question

Draw a simple sketch of cation exchange, showing a root hair, a soil particle with anions, and a hydrogen ion displacing a mineral cation.

Short answer

The common soil cations are calcium ion, magnesium ion, sodium ion, aluminum ion, and ammonium ion. These cations carry a positive charge and can attribute to the holding of the soil onto these cations, known as the cation exchange capacity.

The soil particles are mostly negatively charged and have anions. Cation exchange capacity is responsible for chemical treatment in soil’s suitability. The number of charge of negative ions or anions is based on the soil texture and directly depends on the soil particle’s surface area.

Step-by-step solution

Cation exchange

The common soil cations are calcium ion, magnesium ion, sodium ion, aluminum ion, and ammonium ion. These cations carry a positive charge and can attribute to the holding of the soil onto these cations, known as the cation exchange capacity.

The soil particles are mostly negatively charged and have anions. Cation exchange capacity is responsible for chemical treatment in soil’s suitability. The number of charge of negative ions or anions is based on the soil texture and directly depends on the soil particle’s surface area.

Acidification of soil by roots

The roots help in soil acidification by releasing carbon dioxide from respiration and pumping protons and organic acids for the chemical weathering of soil minerals.

The other factor may be the dead and decaying remains of plants and animals in soil that can produce organic matter for acidification. The pH of the soil is an essential factor for the availability of soil minerals that depends on cation exchange.

Displacement of H+

The cations of minerals penetrate the soil through the cation exchange method, where displacement of cations occurs by other cations such as hydrogen ions.

Plants favor the acidic soil due to the high concentration of protons such as hydrogen ionsthat attribute displacement of a particular mineral binding too tightly to clay particles that plants cannot retain or absorb.

When the displacement of positively charged minerals from soil particles occurs by hydrogen ions, the soil will make plants more available for absorption.