What does the term "sequester P" refer to in terms of phosphorus management?

The term "sequester P" refers to the process of locking up phosphorus in insoluble forms. This means that phosphorus, which plants need for growth, becomes chemically bound in a way that makes it unavailable for plant uptake. Sequestration often occurs in soils with high levels of certain minerals that bind phosphorus tightly, which can lead to deficiencies in phosphorus for crops despite adequate total phosphorus levels in the soil. This is a critical concept in phosphorus management, especially in agricultural systems, where understanding the dynamics of phosphorus availability is essential for optimizing crop nutrition and reducing the risk of environmental impacts from phosphorus runoff.

In contrast, the other choices focus on different aspects of phosphorus management. Enhancing phosphorus availability would involve practices aimed at ensuring that phosphorus is present in forms that plants can easily absorb, which is contrary to sequestering it. Reducing phosphorus input in fertilizers is related to limiting the amount of phosphorus applied to soil, but it doesn't address the chemical binding of phosphorus. Measuring soil phosphorus levels deals with assessing how much phosphorus is present in the soil rather than how it is chemically altered or made unavailable. Thus, the correct understanding aligns with the concept of isolating phosphorus in forms that are not readily available for plant use.