What is the primary factor that determines soil fertility?

The primary factor that determines soil fertility is the ability to provide essential nutrients to plants. Soil fertility is fundamentally linked to the availability of essential nutrients such as nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. These nutrients are critical for plant growth, development, and overall health, influencing everything from seed germination to flowering and fruiting.

While water retention capacity, soil texture and structure, and microbial activity are all important aspects of soil health, they primarily serve to support the nutritional aspects of soil fertility. For instance, good soil texture and structure can affect how well nutrients are held in the soil, while water retention capacity influences nutrient availability to some extent. Microbial activity can enhance nutrient cycling and availability, but without the inherent ability of the soil to provide essential nutrients, the soil's fertility would be compromised. Thus, the core aspect of soil fertility is ultimately its capacity to supply the necessary nutrients that plants need for growth.