**1. Introduction**

Phosphorus (P) is an essential macronutrient for plant growth and development and is also considered as an important nonrenewable global resource for the agricultural production system [1]. It is an important growth-limiting factor in the agricultural production of the world due to its immobility and poor availability to plants in soil [2, 3]. Continuous application of P-fertilizer is crucial for the modern agricultural production system. A large amount of P-fertilizer is derived from the finite and nonrenewable

source of phosphate rock. If this situation continues, it is predicted that the current global rock phosphate reserves could run out within the next 50–100 years [4, 5], or peak phosphorus could occur due to the global demand for agricultural production within a decade [5]. The fertilizer industry is concerned with the already rising cost of phosphate fertilizer associated with agricultural production. Because of this, scientific researchers are paying more attention to the long-term sustainable management of P-fertilizer. It is evident from different research findings that P is involved in several plant physiological and biochemical functions of plants. It is actively involved in growth and reproduction [6], flowering [7], seed formation [8], root development [9], disease resistance [10] and photosynthesis [11]. As a structural component of nucleic acids, lipids, and sugars within the plant cells, it is actively involved in the growth and development of plants both at the cellular and whole plant levels. The deficiency of P in the soil causes a significant decrease in primary root growth. It alters the root architecture (morphology, topology, and root distribution) by lateral root formation and increasing the length and density of root hairs [12]. Reduced root growth also causes a decrease in plant growth and results in significant crop loss. This highlights the importance of P-nutrition in crop production and emphasizes sustainable P-fertilization to enhance plant growth and development.

Phosphorus is a scarce and complicated element because it involves organic and inorganic (35–70% of total P in soil) stocks in soil [13]. P is one of the most important nonrenewable resources, and it has already received global attention due to its low availability in soil (mainly due to slow diffusion and high fixation in soil) [14]. Optimum P-fertilization is necessary to make an economic profit in farming, but the application of P-fertilizer to soils having excess P is not economically beneficial. If P is not applied to soil, plants take up P from soil reserves. In contrast, P applied to the low P soil might be profitable in farming [15]. Soils containing optimal amounts of P need to be properly managed, with appropriate fertilizer applications to maintain (or slightly decrease) their P-status. Adopting sustainable P-fertilizer management to reduce fertilizer costs would also decrease the negative effects of leaching and runoff to the environment.

Therefore, this chapter will focus on different aspects of P-management for sustainable environmental conservation. It will also review the biochemical functions, forms, behavior, and transport of P in soil. The problems associated with P-management strategies and possible action plans for sustainable agricultural and environmental conservation regarding the changing global perspectives are presented.
