Contents


**Chapter 7 137** Phosphorus Recovery through Waste Transformation: Implication for an Alternative Fertilizer *by Valentin Nenov, Hyusein Yemendzhiev and Gergana Peeva*

Preface

The burgeoning world population largely depends on plants and/or on plantassociated food resources. Plants need several nutrient elements at optimal levels to maintain their growth, metabolism, and productivity, as well as to sustain under adverse conditions. Phosphorus (P) stands second to nitrogen in terms of its essentiality as a plant macronutrient, as well as due to its involvement in all plant developmental stages, primary and secondary plant metabolisms, maintenance of membrane structures, and in the structural skeleton of biomolecules (including adenosine triphosphate (ATP), nicotinamide adenine dinucleotide phosphate (NADPH), nucleic acids, phospholipids, and sugar phosphates). Interestingly, under an inevitable wide range of abiotic stresses, P supply maintains cell turgidity and cell membrane stability, modulates plant–water relation, improves photosynthetic functions, enhances energy-rich compounds (including ATP, cytidine triphosphate (CTP), guanosine triphosphate (GTP), uridine triphosphate (UTP), and phosphoenolpyruvate (PEP)), and combats oxidative stress-caused consequences via maintaining the major enzy-

matic and non-enzymatic components' antioxidant defense system.

in turn is adding varied toxic elements to the soils.

outcomes for an alternative fertilizer.

Though the concentration of P in soil is 2000-fold higher than that in the plant, most soil-P is unavailable for uptake by plants because most soil-P is fixed in the form of Al/ Fe or Ca/Mg phosphates. Additionally, less than 0.1% of the total P exists in inorganically (Pi) available forms for plant uptake due to low solubility of Pi, slow diffusion, and high soil reactivity. Hence, most plants face the problem of P-deficiency in agricultural fields worldwide. To achieve the aforementioned benefits of P in plants, P-containing fertilizers are being added to agricultural lands to sustain high yields. However, only the least amount of the applied phosphate (20%–30%) is used by most cultivated plants, and the rest is lost, eventually causing water eutrophication. Moreover, mined rock P is the prime source of P used in agriculture worldwide, which

Given the preceding, this book, Phosphorus in Soils and Plants, provides a comprehensive overview of P in soils and plants, P dynamics in the soil–water–sediment environment, the major roles of P in the photosynthetic dark phase-biochemical pathways, major approaches for the sustainable management of P in agriculture to maintain optimum plant/crop growth and safeguard the environment, main mechanisms underlying the role of P in the regulation of plant–microbe interactions in the rhizosphere for optimum plant growth and metabolism, literature on the role of microbial phosphate-solubilization in management of soil and plant nutrients, and insights into P-recovery through waste transformation to implicate the research

We believe that this volume will serve as an important resource for plant biologists involved in teaching or research, as it provides major insights into P in soils and plants.
