Regulation of Plant-Microbe Interactions in the Rhizosphere for Plant Growth and Metabolism: Role of Soil Phosphorus

Abstract

Soil phosphorus (P) plays a crucial role in regulating plant-microbe interactions in the rhizosphere. This chapter provides an in-depth analysis of the role of P in plant physiology, growth, and its availability in soil. Phosphorus acquisition and uptake, its impact on plant metabolism, and its influence on plant growth and development are reviewed in this chapter. The mechanisms by which plants acquire P from the soil, including the production of phosphatase enzymes, secretion of organic acids, mycorrhizal symbiosis, changes in root morphology, phosphorus use efficiency, and mobilization and transporters, are also reviewed. The chapter also explores the impact of P on microbial communities in the rhizosphere and its role in plant-microbe interactions. Finally, the implications of P availability in the rhizosphere for sustainable agriculture and crop production are discussed, highlighting the potential for improving P availability in the soil to enhance agricultural productivity and environmental sustainability.

1. Introduction

The rhizosphere, the region of soil surrounding plant roots, is a dynamic environment where various interactions between plants and microorganisms occur [1]. Among these interactions, the exchange of nutrients is crucial for plant growth and development. Phosphorus (P) is one of the essential macronutrients for plants known to play a vital role in several physiological processes, including photosynthesis, energy transfer, and nucleic acid synthesis [2]. However, P-availability in the soil is often limited since it is highly reactive and readily forms insoluble compounds unavailable to plants [3]. Plants have evolved various strategies to acquire P from soil to overcome this limitation. These mechanisms involve the secretion of organic acids, enzymes, and other compounds that can solubilize and mineralize P [4] through associations with beneficial microorganisms such as mycorrhizal fungi and rhizobacteria [5].

The interactions between plants and microorganisms in the rhizosphere play a crucial role in regulating P-availability [3]. Microorganisms can contribute to the solubilization and mineralization of P and make it available to plants [6]. Conversely, some microorganisms can immobilize or compete for P and reduce its plant availability [7]. Therefore, understanding the dynamics of plant-microbe interactions in the rhizosphere is essential for improving P-acquisition and enhancing plant growth and yield [8]. Moreover, sustainable agriculture and crop production practices require minimizing chemical fertilizers and enhancing the natural processes of nutrient cycling in soil [9]. Harnessing plant-microbe interactions to optimize P-uptake can reduce the environmental impact of agriculture while improving soil health and crop productivity [10]. Therefore, studying the role of P in plant-microbe interactions in the rhizosphere is critical for developing efficient and sustainable agricultural systems.

This chapter aims to: (i) provide an in-depth analysis of the role of P in plant physiology, growth, and its availability in soil; (ii) discusses P-acquisition and -uptake, its impact on plant metabolism and its influence on plant growth and development; (iii) examines the mechanisms underlying the soil-P acquisition in plants, and the production of phosphatase enzymes, secretion of organic acids, mycorrhizal symbiosis, changes in root morphology, P-use-efficiency, and mobilization and transporters; (iv) explores the impact of P on microbial communities in the rhizosphere and the role it plays in plant-microbe interactions; and (v) highlights the significant implications of P-availability in the rhizosphere for sustainable agriculture and crop production.

2. The role of phosphorus in plant physiology and growth

Among the most critical essential macronutrients, P is required by plants for their proper growth and development. It plays a crucial role in plants’ physiological and biochemical processes, including photosynthesis, energy transfer, cell division, nucleic acid synthesis, and membrane transport. Therefore, understanding the role of P in plant physiology and growth is crucial for plant scientists, agronomists, and farmers to optimize crop production and improve the sustainability of agricultural systems.

2.1 Phosphorus acquisition and uptake

Phosphorus is an essential nutrient for plant growth and development, playing a crucial role in various metabolic processes such as ATP synthesis and nucleic acid formation [2]. Plants require large amounts of P, which is often the limiting factor in its growth [10]. Plants take it up as phosphate ions (H₂PO₄ and HPO₄²⁻) found in the soil [11]. The availability of phosphate ions in the soil is affected by soil pH, temperature, moisture, and microbial activity [3]. However, P is often present in limited amounts in soil, mainly in insoluble phosphates [12]. Therefore, plants have developed various mechanisms to acquire and uptake P from the soil [13]. One of the strategies plants use to obtain P is through production of phosphatase enzymes (Figure 1). These enzymes can hydrolyze organic phosphates in the soil, releasing inorganic phosphate ions that the plant can take up. Several studies have shown that plants can increase the production of phosphatase enzymes in response to low soil-P levels [4, 14]. Plants can also secrete organic acids, such as citrate and malate, to solubilize insoluble P compounds in the soil. These organic acids can chelate with metal ions, reducing their ability to bind with phosphates and making them more available for plant uptake [15].

Figure 1.

Representation of the major processes involved in phosphorus-aquision by plants involving organic acid secretion.

Furthermore, many plants form symbiotic associations with mycorrhizal fungi, which can enhance P-uptake and -translocation in the plant. Mycorrhizal fungi can extend their hyphae into the soil, increasing the surface area for P-uptake. They can also release phosphatase enzymes and organic acids, increasing P-availability [16].

2.2 Phosphorus and plant metabolism

Phosphorus is vital in plant metabolism as an essential macronutrient for growth and development. According to Rao and Pessarakli [17], P is absorbed by plant roots as phosphate ions and then transported to various plant tissues and organs (Figure 2). Once inside the plant, P is involved in numerous metabolic pathways, including photosynthesis and respiration. In photosynthesis, P is a fundamental component of ATP, the primary energy source for plant cells. ATP is synthesized in the thylakoid membranes of chloroplasts through the phosphorylation of ADP (adenosine diphosphate) using energy from light [10]. P also regulates photosynthetic carbon metabolism by activating specific enzymes and proteins involved in the process. P is also crucial to nucleic acids, such as DNA and RNA. Nucleic acids are involved in gene expression and protein synthesis, essential for plant growth and development. In addition, P is involved in forming phospholipids, crucial components of cell membranes [18]. Phospholipids serve as precursors for synthesizing signaling molecules, such as inositol phosphates, which are involved in various cellular signaling pathways [19]. P also plays a crucial role in regulating various metabolic processes in plants. P regulates the synthesis and activity of various carbohydrate, lipid, and protein metabolism enzymes [20].

Figure 2.

Representation of the major modes of phosphorus uptake in plants.

Understanding the role of P in plant metabolism is crucial for optimizing its availability in the soil and improving agricultural productivity and sustainability. Research into P and its plant functions can help develop strategies to enhance soil P levels, leading to healthier and more productive crops.

2.3 Phosphorus and plant growth development

Phosphorus is essential for plant growth and development [21]. It is required for cell division and elongation, which are critical processes in plant growth [2]. P deficiency can lead to stunted growth, reduced seed production, and poor fruit quality in plants [11]. P also plays a vital role in root development, crucial for nutrient and water uptake from the soil [22]. In addition, P can improve plant resistance to environmental stresses, such as drought, heat, and cold, by regulating the expression of stress-related genes and enhancing the production of stress-related proteins [23] (Figure 3). Table 1 lists the major phosphate-solubilizing microorganisms reported beneficial for plant growth.

Figure 3.

Representation of the major roles of phosphororus in plant growth, development and yield.

Microorganism	Test plant	Benefit(s) to plants	References
Aspergillus niger	Munbean	Improved P and N uptake, heat tolerance	[24]
Aspergillus niger	Wheat	increased the growth and phosphate uptake	[25]
Aspergillus niger	Rice	Rock phosphate solubilization, and improved growth	[26]
Azospirillum brasilense	Wheat	Increased yield	[27]
Azotobacter chroococcum	Wheat	Enhanced phosphorus uptake, symbiotic growth	[28, 29]
Achromobacter piechaudii	Rice	Enhanced phosphorus uptake, yield	[30]
Bacillus subtilis	Munbean	Improved P and N uptake, heat tolerance	[24]
Bacillus circulans	Munbean	Improved P and N uptake, heat tolerance	[24]
B. subtilis	Tomato	Improved yield	[31]
Bacillus megaterium	Wheat	Enhanced phosphorus uptake, increased growth	[6, 32, 33]
Burkholderia cepacia	Chickpea	Alleviated glyphosate induced toxicity	[34]
Enterobacter ludwigii	Rice	Improved biomass and chloropohyll content	[35]
Glomus sp. (mycorrhizal fungi)	Sorghum	Increased phosphorus uptake and biomass	[36]
Penicillium bilaii	Barley	Improved phosphorus uptake and yield	[37]
Pantoea agglomerans	Maize	Improved phosphorus availability and yield	[38, 39]
Pseudomonas fluorescens	Wheat	Increased growth and P levels	[40]
P. fluorescens	Tomato	plant growth and increased total root length, surface area and volume	[41]
P. fluorescens	Maize	Improved phosphorus availability, yield	[42]
Serratia marcescens	Maize	Improved biomass and yield	[43]
Pseudomonas sp.	Maize	Improved biomass and yield	[43]
S. marcescens	Wheat	Enhanced phosphorus uptake, increased growth	[44]
Streptomyces sp.	Rice	Improved plant growth by antagonizing phytopathogens	[45]
Trichoderma viride	Cucumber	Improved growth	[46]
Trichoderma viride	Soybean	Improved phosphorus uptake	[47]

Table 1.

Major phosphate solubilizing microorganisms reported beneficial for plant growth.

3. Phosphorus availability in soil and mechanisms underlying its acquisition in plants

3.1 Production of phosphatase enzymes

Plants have developed a sophisticated network of mechanisms to cope with various environmental stresses, such as nutrient deficiency, drought, and high salinity. One crucial strategy plants employ is through the production of phosphatase enzymes, which play a crucial role in mobilizing P from various organic and inorganic sources in the soil [4]. The secretion of phosphatase enzymes by plant roots into the rhizosphere enables the breakdown of a wide range of organic P-based compounds, making inorganic P readily available for plant uptake [48, 49]. Under low P-conditions, plants induce the expression of genes encoding phosphatases, increasing enzyme activity in various tissues [50]. This upregulation of phosphatase activity helps plants to efficiently scavenge phosphate from the soil and maintain their growth and development. Moreover, mycorrhizal fungi can stimulate phosphatase activity, enhancing P uptake and translocation in plants [4].

The major phosphatases identified in plants include acid phosphatases, alkaline phosphatases, and purple acid phosphatases [4]. These enzymes are involved in the hydrolysis of different types of P-compounds, such as nucleotides, phospholipids, and phytate. Phosphatase enzymes have been shown to have multiple functions in plants, such as regulating iron homeostasis and improving the availability of minerals like iron, zinc, and calcium for plant uptake [4, 14].

3.2 Secretion of organic acids

Plants also secrete organic acids, such as citrate and malate, into the rhizosphere to solubilize inorganic P-compounds such as iron and aluminum phosphates [51]. These acids chelate metal ions bound to P, releasing P into the soil solution and making it available for plant uptake [52]. Through this mechanism plants cope with P deficiency and low availability in the soil [51]. The secretion of organic acids by plant roots facilitate the solubilization and uptake of essential nutrients, including P, iron, and aluminum [53]. Organic acids are low-molecular-weight compounds that chelate cations and dissolve insoluble mineral compounds, making them more available for plant uptake [51].

Plant roots, including citrate, malate, and oxalate, secrete several organic acids [15]. Citrate is the most commonly secreted organic acid, and is involved in the solubilization and uptake of various nutrients, such as iron, aluminum, and P [54]. On the other hand, malate is involved in the uptake of aluminum, while oxalate helps in the uptake of calcium and aluminum [15]. These organic acids are secreted into the rhizosphere by specialized cells in the root, known as root border cells, and root hairs [53].

Various factors, including nutrient deficiency, pH, and root exudates, regulate the secretion of organic acids in plants [55]. Under nutrient-deficient conditions, plants induce the expression of genes encoding enzymes involved in organic acid synthesis and transport, increasing their secretion [51]. Additionally, the pH of the rhizosphere can also influence organic acid secretion, with lower pH values generally leading to increased secretion [55].

Releasing organic acids by plant roots may also substantially affect the soil microbial ecology. Organic acids can act as a carbon source for soil microorganisms, promoting their growth and activity [56]. Additionally, the solubilization of nutrients by organic acids can also increase microbial activity and diversity in the rhizosphere. Several studies have reported on the secretion of organic acids by different plant species. For instance, a study by Palomo, Claassen [57] showed that maize plants secrete high citrate levels under P-deficient conditions, enhancing their P uptake. In another similar study soybean plants were reported to secrete malate and oxalate under aluminum stress conditions, which was argued to increase aluminum tolerance [58].

3.3 Mycorrhizal symbiosis

P, an essential nutrient for plant growth and development. However, it is often limited in soil due to low availability and solubility. The mycorrhizal symbiosis enables plants to overcome P-limitation by accessing P from a larger soil volume and increasing P-uptake efficiency by forming highly branched arbuscules. Mycorrhizal symbiosis is a mutually beneficial relationship between plants and fungi, where the plant provides the fungus with carbohydrates in exchange for nutrients, including P. The arbuscules provide a large surface area for P uptake and translocation from the soil to the plant.

Mycorrhizal fungi can also release enzymes and organic acids that help to solubilize P-compounds in soil, making them available for plant uptake. The release of organic acids by mycorrhizal fungi, such as citrate, malate, and oxalate, can increase the solubility of insoluble P compounds, such as calcium phosphates, by forming complexes with metal ions that bind to P, thus freeing it for plant uptake [59]. Additionally, mycorrhizal fungi can release enzymes such as acid phosphatase, which can hydrolyze organic P-compounds, such as phytate, and release inorganic P for plant take up [4].

3.4 Change in root morphology

One common strategy plants employ for increasing P-uptake is the production of longer and more branched roots, which can increase the surface area of the root system and improve the plant’s ability to explore the soil for nutrients. For example, several studies have shown that plants grown under low P-conditions produce longer and more branched roots than those grown under high P-conditions [60, 61].

In addition to changes in root length and branching, plants can also alter the distribution of root hairs, which are small projections from the root surface that increase the surface area of the root system. Under low P-conditions, some plant species produce more root hairs per unit length of root than under high P conditions [62]. Plants can also alter the morphology of their root tips to improve P-uptake. For example, some plants produce cluster roots, which are highly branched structures that form at the tips of roots and increase the surface area of the root system. These structures are prevalent in plants that grow in soils with low P-availability, such as Proteaceae and Casuarinaceae species [63]. Another strategy that plants use to increase P-uptake is the production of exudates, which are organic compounds released by plant roots that can increase P-availability in soil. For example, some plants release organic acids that can solubilize mineral-bound P and make it available for uptake [4]. In addition to these morphological changes, some plant species have also evolved symbiotic relationships with mycorrhizal fungi, which can improve P-uptake by extending the root system and increasing the surface area of the root system [5].

3.5 Phosphorus use-efficiency

Plants can increase their P use-efficiency by adopting various strategies to optimize P-metabolism in the soil. One of the primary strategies is to enhance the uptake of P from the soil, which is achieved by developing an extensive root system that allows plants to explore a larger volume of soil, and the secretion of organic acids and enzymes that solubilize and release bound P in the soil [64]. Plants can increase their P use-efficiency by recycling and reusing internal P reserves. For example, plants can remobilize P from old leaves to new growth areas during leaf senescence, improving their ability to acquire P from the soil [65]. This way the plants recycles and reuses their own internal reserves of P. Plants can remobilize P from old leaves, stems, and other tissues to support new growth, reducing their reliance on external sources of P [66]. This process is especially important under low P availability conditions, where efficiently reallocating P from senescent tissues to new growth can improve plant fitness and productivity [67].

3.6 Phosphorus mobilization and transporters

Plants can mobilize and transport P within their tissues to improve their ability to acquire P from the soil. P can be mobilized within plant tissues by phosphatase enzymes, which break down organic P-compounds into inorganic forms that are more readily available for plant uptake. Plants also have specific transporters that can uptake inorganic P from the soil and transport it into their tissues [68].

Membrane proteins are called P-transporters to facilitate P transport across plants’ plasma membranes and other intracellular membranes [69]. Several P-transporters exist in plants including the PHT1, PHT2, PHT3, PHO1 transporters [70]. The PHT1 transporter family is the most extensively studied and is involved in inorganic phosphate uptake from the soil [71]. This transporter family comprises 9 to 13 members in different plant species and is expressed in the root epidermis and cortex, where they play a crucial role in the uptake of inorganic phosphate from the soil [71]. They have been shown to have a high affinity for inorganic phosphate and can transport it against a concentration gradient [72]. PHT2 transporters are expressed in the plasma membrane of root hairs and are involved in phosphate uptake and translocation [54].

PHT3 transporters are localized in the chloroplast and are involved in phosphate transport from the cytoplasm to the chloroplast, which is required for photosynthesis [73]. PHO1 transporters translocate inorganic phosphate from the root to the shoot in plants [74, 75]. They are localized in the plasma membrane of the root endodermis and are responsible for loading inorganic phosphate into the xylem for transport to the shoot [74]. PHO1 transporters have also been shown to play a role in the secretion of phosphate-containing compounds into the rhizosphere, which can increase the availability of P in the soil [69]. The regulation of P transporters is critical for maintaining P-homeostasis in plants [2]. Several factors can influence the expression and activity of P-transporters, including P availability, plant age, and environmental stresses [76]. Under low P-conditions, plants can upregulate the expression of PHT1 transporters, leading to an increase in phosphate uptake [76]. Similarly, under drought stress, the expression of PHT1 transporters can be downregulated, leading to a decrease in phosphate uptake [76]. Table 2 lists the major transport proteins and highlights their important functions.

Protein name	Function	References
PHT1 Transporters	Facilitate the uptake of inorganic phosphate (Pi) from the soil into root cells	[71, 77]
PHO1 Transporter	Transports Pi from root cells to the xylem for long-distance transport to the shoots	[69]
SPX Proteins	Regulate Pi homeostasis by inhibiting the activity of PHT1 transporters and promoting PHO1 transporter expression	[78, 79]
PHR1 Transcription Factor	Regulates the expression of genes involved in Pi uptake and remobilization in response to Pi deficiency	[80, 81]
miR399	Represses the expression of PHO2, a negative regulator of Pi uptake, under Pi-deficient conditions	[82, 83]
IPS1	Encodes a non-coding RNA that regulates Pi homeostasis by repressing the expression of PHO2 and promoting Pi uptake	[82, 84]
Purple Acid Phosphatases (PAPs)	Involved in the hydrolysis of organic phosphates in the soil, releasing Pi for plant uptake	[7, 85]
NRT1.1 Transporter	Involved in the uptake of nitrate and can also transport Pi under Pi-deficient conditions	[79, 86]
NLA E3 Ubiquitin Ligase	Regulates the trafficking and degradation of PHT1 transporters in response to Pi availability	[87, 88]
RbohD NADPH Oxidase	Involved in Pi sensing and signaling by producing reactive oxygen species (ROS)	[89]

Table 2.

Major plant transport proteins involved in phosphorus uptake.

3.7 Organic phosphorus mineralization

According to Sharpley [90], organic P-compounds comprise a significant proportion of total P in many soils. However, these organic P-compounds are often not readily available to plants. Microorganisms play a crucial role in the mineralization of organic P, which is the process by which organic P-compounds are converted into inorganic P-forms. Several factors influence the rate of organic P-mineralization, including soil pH, moisture content, temperature, and the availability of nutrients such as nitrogen and P. For example, studies have shown that organic P-mineralization rates increase with increasing soil pH [91, 92]. Plants can also play a role in organic P-mineralization by releasing organic acids or other compounds that can stimulate microbial activity and increase the availability of inorganic P. For instance, in one experiment the release of root exudates by maize plants increased the mineralization of organic P in the soil [93].

Overall, organic P-mineralization is a crucial process in P-cycling in soils and is essential to plant nutrition. Understanding the factors influencing this process can help optimize fertilizer management strategies and improve crop productivity.

4. Phosphorus and microbial communities in the rhizosphere

The availability of P in the soil can significantly affect the composition and function of microbial communities in the rhizosphere. In P-limited soils, microbial communities can be dominated by species adapted to low P-conditions, such as phosphate-solubilizing bacteria and fungi. These microorganisms can produce organic acids and enzymes that can solubilize P-compounds in soil, making them available for plant uptake. On the other hand, high P levels in soil can harm microbial communities in the rhizosphere. Excessive P can lead to the eutrophication of soil and stimulate the growth of opportunistic microorganisms that are not beneficial for plant growth. Moreover, high levels of P can decrease the diversity of microbial communities in soil, as certain species may become dominant due to their ability to tolerate high P-levels.

In addition to the direct impact of P on microbial communities, the composition of microbial communities in the rhizosphere can also affect P-cycling in soil. For example, mycorrhizal fungi in the rhizosphere can enhance P-uptake and translocation in plants, as these fungi can form symbiotic associations with plant roots and improve nutrient uptake.

The availability of P in the soil can strongly influence microbial community composition in the rhizosphere. For example, high P-levels in soil can decrease the abundance of arbuscular mycorrhizal fungi (AMF) [77]. AMF play a crucial role in plant P acquisition, and their reduction can harm plant growth. In contrast, low P levels can increase the abundance of bacteria that can solubilize P [94]. These bacteria can release P from organic compounds and make them available to plants.

Moreover, the form of P in the soil can also affect microbial community composition. Inorganic P, such as phosphate, is soil’s most common form of P. However, organic P, such as phytate, is also present in the soil, and its availability is generally low [95]. Some microorganisms, such as phosphate solubilizing bacteria (PSB) and fungi, can convert organic P into inorganic P, making it available to plants. The activity of these microorganisms can be influenced by the plant species and the management practices used in the field [96]. Figure 4 describes impact of P on microbial communities and plant.

Figure 4.

Representation of the major role of plant-microbe interaction in improving phosphorus availability to plants.

5. Plant-microbe interactions and phosphorus-availability in the rhizosphere

One of the most well-known plant-microbe interactions is the mycorrhizal association between plants and fungi (Figure 5). Mycorrhizal fungi form a symbiotic relationship with plant roots, where the fungi colonize the roots and extend their hyphae into the soil, increasing the surface area for nutrient uptake. In return, the fungi receive carbohydrates from the plant. Mycorrhizal fungi are particularly effective at accessing and mobilizing P in the soil, often found in low concentrations and insoluble forms. The fungi can release enzymes that break down organic forms of P and make them available for plant uptake [5].

Figure 5.

Schematic representation of the major impacts of mycorrhizal assoctiations on phosphorus uptake on plant.

Another type of microbes that can impact P availability in the rhizosphere are PSB. These bacteria convert insoluble forms of P into soluble forms, which plants can take up. PSB can release organic acids, chelating agents, and enzymes that solubilize P, making it available to the plant [97]. In addition to solubilizing P, PSB can enhance root growth and plant biomass by producing phytohormones [98].

Plant-microbe interactions in the rhizosphere can also affect the distribution of P in the soil. For example, some plant species can exude organic compounds that attract specific microbes, influencing the spatial distribution of P in the soil [99]. The presence of microbes in the rhizosphere can also alter the chemical properties of the soil, making it more favorable for plant growth and P uptake [100]. Research has also shown that PSB can interact synergistically with other soil microorganisms, such as mycorrhizal fungi, to further enhance plant growth and nutrient uptake. By promoting a diverse and healthy microbial community in the rhizosphere, PSB can help to create a more resilient and sustainable agricultural system.

6. Improved phosphorus-availability in soil: implications for sustainable agriculture and crop production

The PSB are known to solubilize P from organic and inorganic sources and make P more available for plant uptake [6]. When introduced into the rhizosphere, PSB can improve the availability of P in soil and enhance plant growth and development [101]. One potential implication of using PSB in sustainable agriculture is the reduced need for synthetic fertilizers. Synthetic fertilizers are commonly used to supplement soil P levels but can have negative environmental impacts such as eutrophication and groundwater pollution [102]. Using PSB, farmers can reduce their reliance on synthetic fertilizers and promote more sustainable agricultural practices. Another implication of using PSB is the potential for improved crop yields and food security. The availability of P in soil is a limiting factor for crop production. PSB can increase the amount of available P and enhance crop growth and development [103], leading to higher crop yields, improved food security, and increased farmer income.

The P resources are finite, and the increasing global demand for food has pressured this vital nutrient’s availability [104]. PSMs are group of microorganisms such as bacteria, fungi, and actinomycetes, that solubilize insoluble phosphate compounds [6]. PSMs as biofertilizers have been found to improve crop yields and P use-efficiency [32]. In addition, incorporating organic materials, such as compost and manure, can enhance soil P availability by increasing microbial activity and soil organic matter content [105]. Organic amendments can also help buffer soil pH, increasing P-availability [106]. Also, breeding plants with improved P-uptake and -utilization capabilities can produce more efficient P-use and higher yields [107]. This approach requires genetic resources and a deeper understanding of the mechanisms underlying plant P-uptake and -utilization [108]. Nevertheless, through precision agriculture and soil testing, farmers can better understand the P-status of their soil and tailor fertilizer applications accordingly [109]. Precision agriculture technologies, such as variable-rate fertilizer applicators, can help ensure P is applied efficiently and effectively.

Improving P-availability in soil has significant implications for sustainable agriculture and crop production. Enhanced P-availability can increase crop yields and reduce dependence on synthetic fertilizers, which can have negative environmental impacts [110]. Additionally, by optimizing P-use, the agricultural sector can better manage the depletion of finite P resources [104].