What is soil solution?

Soil solution is specifically defined as the water found in the soil that contains dissolved ions, molecules, and gases. This component is crucial for plant growth because it is the primary means through which nutrients are transported from the soil to plant roots. Water in the soil acts as a solvent, allowing various essential nutrients such as nitrogen, phosphorus, and potassium to dissolve and be available for uptake by plants. Additionally, soil solution plays a role in the soil's chemical processes, influencing pH levels and the mobility of pollutants.

The first choice suggests a mixture of soil and water but does not convey the critical aspect that the dissolved substances in the water are what define soil solution. The third option refers to the solid part of the soil, which misses the essential fluid dynamics involved in plant nutrition. The fourth option, relating to pH, indicates a soil property but does not align with the definition of soil solution, which specifically emphasizes the role of dissolved components in the water within the soil. Thus, the best definition of soil solution encompasses the water in soil that carries these dissolved elements vital for plant health.