Phosphorus (P) limitation is expected to increase due to nitrogen (N)‐induced terrestrial eutrophication, although most soils contain large P pools immobilized in minerals (Pi) and organic matter ...(Po). Here we assessed whether transformations of these P pools could increase plant available pools alleviating P limitation under enhanced N availability. The mechanisms underlying these possible transformations were explored by combining results from a 10‐year field N addition experiment and a 3700‐km transect covering wide ranges in soil pH, soil N, aridity, leaching, and weathering that could affect soil P status in grasslands. Nitrogen addition promoted the dissolution of immobile Pi (mainly Ca‐bound recalcitrant P) to more available forms of Pi (including Al‐ and Fe‐bound P fractions and Olsen P) by decreasing soil pH from 7.6 to 4.7, but did not affect Po. Soil total P declined by 10% from 385 ± 6.8 to 346 ± 9.5 mg kg−1, whereas available P increased by 546% from 3.5 ± 0.3 to 22.6 ± 2.4 mg kg−1 after the 10‐year N addition, associated with an increase in Pi mobilization, plant uptake, and leaching. Similar to the N addition experiment, the drop in soil pH from 7.5 to 5.6 and increase in soil N concentration along the grassland transect were associated with an increased ratio between relatively mobile Pi and immobile Pi. Our results provide a new mechanistic understanding of the important role of soil Pi mobilization in maintaining plant P supply and accelerating biogeochemical P cycles under anthropogenic N enrichment. This mobilization process temporarily buffers ecosystem P limitation or even causes P eutrophication, but will extensively deplete soil P pools in the long run.
Limitation of grain crop productivity by phosphorus (P) is widespread and will probably increase in the future. Enhanced P efficiency can be achieved by improved uptake of phosphate from soil ...(P-acquisition efficiency) and by improved productivity per unit P taken up (P-use efficiency). This review focuses on improved (P-use efficiency, which can be achieved by plants that have overall lower P concentrations, and by optimal distribution and redistribution of P in the plant allowing maximum growth and biomass allocation to harvestable plant parts. Significant decreases in plant P pools may be possible, for example, through reductions of superfluous ribosomal RNA and replacement of phospholipids by sulfolipids and galactolipids. Improvements in P distribution within the plant may be possible by increased remobilization from tissues that no longer need it (e.g. senescing leaves) and reduced partitioning of P to developing grains. Such changes would prolong and enhance the productive use of P in photosynthesis and have nutritional and environmental benefits. Research considering physiological, metabolic, molecular biological, genetic and phylogenetic aspects of P-use efficiency is urgently needed to allow significant progress to be made in our understanding of this complex trait.
The effects of long-term excessive phosphorus (P) fertilization on the P fraction changes and P loss risk in orchard soils remain unclear. This study aimed to assess the concentrations of and ...relationships among the soil total P (TP), Olsen-P and P fractions in pomelo orchard (PO) soil during different fertilization periods. The PO soils were in a severe P overapplication state (905.4 kg P2O5 ha-1 yr-1), with a high P surplus (773.5 kg P2O5 ha-1 yr-1) and low P use efficiency (PUE, 14.7%). Such long-term excessive fertilizer P input significantly increased the TP, Olsen-P, and P fraction concentrations and significantly reduced the proportions of Org-P and reduction-P (Red-P) in both the surface (0–20 cm) and subsurface (20–40 cm) soils but increased the proportions of easily soluble P (Sol-P), aluminum-P (Al–P) and iron-P (Fe–P) rather than calcium-P (Ca–P). Furthermore, the P fractions exhibited a corresponding increasing trend and a significant linear (or two-stage linear) relationship with the soil P surplus. There is a serious risk of P loss when the P surplus in the surface soil exceeds 4128 kg P ha-1. Al–P had the highest correlation with Olsen-P (R = 0.984, p < 0.01), followed by Sol-P, Fe-P, Ca-P, Org-P and Red-P (R = 0.973, 0.908, 0.8783, 0.820 and 0.697, respectively, p < 0.01). However, only Sol-P and Al–P had a major direct impact on Olsen-P. In general, long-term excessive P application exerted a remarkable and differentiated impact on the soil P fractions. An increase in the Sol-P and Al-P fractions could lead to enhanced P bioavailability and environmental risk in acidic red soils. Therefore, P management in the PO production system needs to control the P fertilizer input and monitor the soil P fractions, which merits further investigation.
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•Excessive P fertilizer accumulates in surface and subsurface layers of pomelo soils.•Iron-bound P and aluminum-bound P are impacted the most by P overfertilization.•Easily solution P and aluminum-bound P show high correlation with Olsen-P.•Soil P surplus exceed 4128 kg P ha-1 will steeply increase soil P loss risks.•The depletion of accumulated P in highly intensive orchard soil is worthy of study.
Phosphorus (P) is an essential nutrient for marine phytoplankton and indeed all life forms. Current data show that P availability is growth‐limiting in certain marine systems and can impact algal ...species composition. Available P occurs in marine waters as dissolved inorganic phosphate (primarily orthophosphate Pi) or as a myriad of dissolved organic phosphorus (DOP) compounds. Despite numerous studies on P physiology and ecology and increasing research on genomics in marine phytoplankton, there have been few attempts to synthesize information from these different disciplines. This paper is aimed to integrate the physiological and molecular information on the acquisition, utilization, and storage of P in marine phytoplankton and the strategies used by these organisms to acclimate and adapt to variations in P availability. Where applicable, we attempt to identify gaps in our current knowledge that warrant further research and examine possible metabolic pathways that might occur in phytoplankton from well‐studied bacterial models. Physical and chemical limitations governing cellular P uptake are explored along with physiological and molecular mechanisms to adapt and acclimate to temporally and spatially varying P nutrient regimes. Topics covered include cellular Pi uptake and feedback regulation of uptake systems, enzymatic utilization of DOP, P acquisition by phagotrophy, P‐limitation of phytoplankton growth in oceanic and coastal waters, and the role of P‐limitation in regulating cell size and toxin levels in phytoplankton. Finally, we examine the role of P and other nutrients in the transition of phytoplankton communities from early succession species (diatoms) to late succession ones (e.g., dinoflagellates and haptophytes).
Phosphorus is an important nutrient for crop productivity. More than 60% of the total phosphorus in cereal crops is finally allocated into the grains and is therefore removed at harvest. This removal ...accounts for 85% of the phosphorus fertilizers applied to the field each year. However, because humans and non-ruminants such as poultry, swine and fish cannot digest phytate, the major form of phosphorus in the grains, the excreted phosphorus causes eutrophication of waterways. A reduction in phosphorus accumulation in the grain would contribute to sustainable and environmentally friendly agriculture. Here we describe a rice transporter, SULTR-like phosphorus distribution transporter (SPDT), that controls the allocation of phosphorus to the grain. SPDT is expressed in the xylem region of both enlarged- and diffuse-vascular bundles of the nodes, and encodes a plasma-membrane-localized transporter for phosphorus. Knockout of this gene in rice (Oryza sativa) altered the distribution of phosphorus, with decreased phosphorus in the grains but increased levels in the leaves. Total phosphorus and phytate in the brown de-husked rice were 20-30% lower in the knockout lines, whereas yield, seed germination and seedling vigour were not affected. These results indicate that SPDT functions in the rice node as a switch to allocate phosphorus preferentially to the grains. This finding provides a potential strategy to reduce the removal of phosphorus from the field and lower the risk of eutrophication of waterways.
Phosphorus (P) is an essential element for all life, is essential for global food security, and is a limited, nonrenewable global resource, making its efficient use vitally important. There is a ...commonly held belief that P fertilizer is very inefficient because P recovery by crops in the year it is applied is often only 10-15%. The residual fertilizer P not recovered by the crop is believed to be permanently tied-up or “fixed” in the soil in forms not available to plants. However, field experiments do not support that view. The behavior of inorganic P in fertilizer when applied to the soil can be explained as contained in four pools of varying availability to plants based on its accessibility to plant roots and its extractability by soil test reagents. Phosphorus use efficiency can be assessed in several ways, but the “balance” method (i.e. partial nutrient balance) calculated as a P removal-to-input ratio and expressed as a percent best reflects the behavior of fertilizer P in soils and supports the concept of P transfer and availability within the four pools discussed. When determined by the balance method, P recovery is often in the range of 50-70% or even higher. Improving fertilizer P use and effectiveness is achievable through the implementation of fertilizer best management practices within the context of 4Rs—application of the right nutrient source, applied at the right rate, right time, and in the right place.
• Many Proteaceae are highly phosphorus (P)-sensitive and occur exclusively on old nutrient-impoverished acidic soils (calcifuge), whilst a few also occur on young calcareous soils (soil-indifferent) ...that are higher in available calcium (Ca) and P. Calcium increases the severity of P-toxicity symptoms, but its underlying mechanisms are unknown. We propose that Ca-enhanced P toxicity explains the calcifuge habit of most Proteaceae.
• Four calcifuge and four soil-indifferent Proteaceae from South-Western Australia were grown in hydroponics, at a range of P and Ca concentrations.
• Calcium increased the severity of P-toxicity symptoms in all species. Calcifuge Proteaceae were more sensitive to Ca-enhanced P toxicity than soil-indifferent ones. Calcifuges shared these traits: low leaf zinc concentration (Zn), low Zn allocation to leaves, low leaf Zn:P, low root : shoot ratio, and high seed P content, compared with soil-indifferent species.
• This is the first demonstration of Ca-enhanced P toxicity across multiple species. Calcium-enhanced P toxicity provides an explanation for the calcifuge habit of most Proteaceae and is critical for the management of this iconic Australian family. This study represents a major advance towards an understanding of the physiological mechanisms of P toxicity and its role in the distribution of Proteaceae.
Optimal phosphorus (P) managements can improve the crop yield without reducing soil P supply capacity over the long term. In this study, the rapeseed–rice rotation experiments were conducted to ...evaluate the effect of five optimal P fertilizer managements, including the addition of RA (rooting agents), PSB (phosphate solubilizing bacteria), CMP (calcium and magnesium phosphate fertilizer), DP1 (starter P) and DP2 (foliar fertilizer) with the reduction of 40% (in the 1st rapeseed season) and 75% (in the 2nd rapeseed season) P fertilizers of farmers’ fertilizer practice (FFP) on crop productivity and soil P fertility in low and high P fertility soils. Seed yield, P partial factor productivity, and P recovery efficiency of both cultivars, Shengguang168 (SG168) and Zhongshuang 11 (ZS11), were significantly improved under optimal P managements, and the increase of them in low P fertility soil was more than that in high P fertility soil. Total P surplus was lower under optimal P managements than under FFP in both P fertility soils. The increasing amount of crop yields under optimal P managements for both cultivars was equivalent to that of 16.0–38.3 kg P2O5 hm−2 of P fertilizer application, and the order of the optimal P managements was as follows: RA > PSB > CMP > DP1 > DP2. In addition, the grain yield of rotated rice cultivar Longliangyou1212 (LLY1212) without P supply was not reduced in both fertility soils. Compared with low P fertility soil, yields of SG168, ZS11 and LLY1212 in high P fertility soil increased by 28.1%–71.7%, 28.3%–78.9% and 26.2%–47.2% at the same treatment, respectively. In summary, optimal P managements in the rapeseed season could stabilize the crop yield, promote P use efficiency and the capacity of soil P supply in the rapeseed–rice rotation, especially in low P fertility soil.
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•Yield and P use efficiency of rapeseed were improved under optimal P managements.•Optimal P managements are the equivalent of 16.0–38.3 kg P2O5 hm−2 of P fertilizer.•High P fertility soil has sustainable productivity in the rapeseed–rice rotation.
•Organic P (OP) availability is strongly driven by OP forms and mineral types.•Ryegrass was able to take up about 3–18% of OP adsorbed to soil minerals.•Adsorbed glycerophosphate was more available ...than the other OP forms.•Montmorillonite-OP showed the highest P uptake and kaolinite-OP the lowest one.•The binding strength of OPs to the mineral surface did not explain P availability.
Organic phosphorus (OP) represents a significant fraction of the total P pool in soils. With the increasing use of organic resources to substitute mineral P fertilizers and the need to recover P from the soil, it is pivotal to gain insight into the interactions between various OP forms and soil minerals and their consequences on P availability. Here, we aim at elucidating the extent to which OP compounds adsorbed onto major soil minerals may be available to plants. Ryegrass (Lolium multiflorum) plants were grown in RHIZOtest devices in the presence of OP including myo-inositol hexakisphosphate (IHP), glycerophosphate (GLY), and glucose-6-phosphate (G6P) and inorganic P (IP) compounds that were previously adsorbed onto Fe and Al oxyhydroxides (goethite and gibbsite, respectively) and clay minerals (montmorillonite and kaolinite). Phosphorus availability and P uptake were then determined through rhizosphere and plant characterization. Irrespective of the type of mineral, ryegrass was able to take up about 3–18 % of adsorbed OP compounds. The magnitude of availability and uptake depended on the OP compounds and the type of soil minerals. The potential availability of OP adsorbed by different minerals was strongly mediated by mineral-OP interaction types and properties. The P uptake increased in the following order: kaolinite-OP ≪ gibbsite-OP ≤ goethite OP ≪ montmorillonite-OP. Phosphorus uptake from adsorbed OP compounds showed contrasting patterns compared to adsorbed IP and depended more on available P concentration in the rhizosphere rather than on the binding strength of OPs to the mineral surface.
Low soil fertility and high fertilizer costs are constraints to wheat production, which may be resolved with integrating fertilizer phosphorus (P) and farm-yard manure (FYM). Study objectives were to ...evaluate P source impacts on soil, P efficiency, and wheat growth in a calcareous soil.
Treatments included P fertilizer (0, 17, 26, or 39 kg P ha-1) and/or FYM (0 or 10 T ha-1) in a: 1) incubation experiment and 2) wheat (Triticum aestivum spp.) field experiment.
Soil organic matter increased (30-72%) linearly for both fertilizer and FYM, whereas pH decreased (0.1-0.3 units) with fertilizer only. Addition of fertilizer and FYM increased plant available P (AB-DTPA extractable soil P) an average of 0.5 mg P kg-1 soil week-1 with incubation. The initial increase was 1-9 mg P kg-1, with further increase after 84 d of ~3-17 mg P kg-1. There was also a significant increase of available P in the soil supporting plants in the field study, although the magnitude of the increase was only 2 mg kg-1 at most for the highest fertilizer rate + FYM. Grain (66 to 119%) and straw (25-65%) yield increased significantly, peaking at 26 kg P ha-1 + FYM. The P Absorption Efficiency (PAE), P Balance (PB), and P Uptake (PU) increased linearly with P rate, with the highest levels at the highest P rate. The P Use Efficiency (PUE) was highest at the lowest rates of P, with general decreases with increasing P, although not consistently. Principal component analysis revealed that 94.34 % of the total variance was accounted for with PC1 (84.04 %) and PC2 (10.33 %), with grain straw yield significantly correlated to SOM, PU, and PAE. Regression analysis showed highly significant correlation of PB with P-input (R2= 0.99), plant available P (R2= 0.85), and PU (R2= 0.80). The combination of FYM at the rate of 10 T ha-1 and fertilizer P at 26 kg P ha-1 was found as the optimum dose that significantly increased yield. It is concluded that FYM concoction with fertilizer-P not only improved SOM and residual soil P, but also enhanced wheat yields with reasonable P efficiency.
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