Phosphorus fractions of a climosequence of soils in New zealand tussock grassland

The different forms of phosphorus in alkaline extracts of eight New Zealand topsoils, which are members of a climosequence, were characterized by ³¹P-nuclear magnetic resonance (NMR). A further two topsoils were used in an experiment to demonstrate that the NMR technique detected all of the P in the extracts. This direct method of estimating organic P in soil extracts enabled the different types and the relative amounts of P compounds to be estimated.Inorganic orthophosphate and orthophosphate monoesters were the major P components of the extracts from all soils, while all but the two driest soils also contained orthophosphate diesters. Only the high country and alpine soils, developed in a moist cool environment, contained phosphonates, a recently-discovered form of soil P of probable microbial origin.Across the climosequence of soils, the amount of orthophosphate diesters in the extracts was strongly and positively correlated with annual precipitation. This organic P fraction, together with phosphonates, could provide through mineralization a ready supply of “available” P in these mainly undisturbed tussock grassland ecosystems.     

Phosphorus Composition and Phosphatase Activities in Soils Affected by Long-Term Application of Pig Manure and Inorganic Fertilizers

The long-term (25 years) effect of using chemical fertilizers and animal manure on soil phosphorus (P) composition and phosphatase activities was investigated in this study. Results showed that pig manure applications significantly increased soil total P, Olsen P, and phosphatase activities, whereas chemical fertilizers had no significant effects on soil chemical properties and phosphatase activities. Manure applications doubled or tripled the orthophosphate concentrations as compared to chemical fertilizers. Analysis of solution ³¹P nuclear magnetic resonance (NMR) spectroscopy showed that P composition in sodium hydroxide (NaOH)–ethylenediamenetetraacetic acid (EDTA) extracts was dominated by orthophosphate (59–84%), followed by phosphomonoesters (15–40%). More organic P (P_o), especially myo-inositol hexakisphosphate, was observed in soil treated with manure as compared with soil treated with chemical fertilizer.     

Phosphorus compounds in subarctic Fennoscandian soils at the mountain birch (Betula pubescens)—tundra ecotone

Nutrient availability will partly regulate the response of high latitude ecosystems to climate warming, but phosphorus biogeochemistry is poorly understood in Arctic soils. We used NaOH-EDTA extraction and solution ³¹P nuclear magnetic resonance (NMR) spectroscopy to determine phosphorus compounds in subarctic soils from three locations in the Fennoscandian mountains contrasting in latitude and continentality. Soils were taken from open tundra and mountain birch (Betula pubescens Ehrh.) forest at each location. Between 87 and 95% of the total phosphorus was extracted from the surface 2 cm of the organic soil horizons. Most of the extracted phosphorus was orthophosphate monoesters (44-55%), with smaller concentrations of inorganic orthophosphate (15-24%), orthophosphate diesters (12-16%), pyrophosphate (3-18%), inorganic polyphosphate (0-15%) and phosphonates (0-4%). The orthophosphate diesters were further subclassified into DNA (9-13% extracted phosphorus) and phospholipids (1-6% extracted phosphorus), although strong signals in the orthophosphate monoester region of the spectra, consistent with the degradation of phosphatidyl choline in alkaline solution, suggested that phospholipid concentrations were substantially underestimated. The phosphorus composition was broadly similar among soils from the three locations, although no phosphonates were detected in tundra soils from the most southerly site. Deeper organic horizons tended to contain a greater proportion of orthophosphate monoesters than at the surface. The abundance of phosphorus compounds that would be considered readily degradable in temperate environments probably reflects the slow organic matter decomposition in these cold, acidic soils, and suggests that phosphorus availability is unlikely to limit ecosystem productivity on mesic soils at the birch-tundra ecotone during changes induced by climate warming.     

Assessing the bioavailability of dissolved organic phosphorus in pasture and cultivated soils treated with different rates of nitrogen fertiliser

A proportion of dissolved organic phosphorus (DOP) in soil leachates is readily available for uptake by aquatic organisms and, therefore, can represent a hazard to surface water quality. A study was conducted to characterise DOP in water extracts and soil P fractions of lysimeter soils (pasture before and after, and cultivated soil after leaching to simulate a wet winter-autumn) from a field trial. Data on DOP in drainage waters from the field trial were also generated. In water extracts, used as a surrogate for soil solution and drainage water, 70-90% of the total dissolved P (TDP) concentration was made up of DOP, of which 40% was hydrolysable by phosphatase enzymes. Proportions of hydrolysable DOP to TDP in drainage waters of the field trial were less than in water extracts due to enhanced DRP loss via dung inputs, but still large at 35% of DOP. Analysis of lysimeter soils by sequential fractionation indicated that several organic P fractions changed with land use and due to leaching. Further investigation using NaOH-EDTA extracts and ³¹P nuclear magnetic resonance spectroscopy indicated that the greatest changes were a decrease in the concentrations of orthophosphate diester P and an increase in orthophosphate monoester P. This was attributed to mineralization by cultivation and plant roots and also to the leaching of mobile diester P. This study suggests that in such soils with a dynamic soil organic P pool, the concentration of readily bioavailable P in soil solution and drainage waters and the potential to impair surface water quality cannot be determined from the DRP concentration alone.     

31Phosphorus‐Nuclear magnetic resonance analysis in extracts of a phosphorus‐enriched volcanic soil of Chile

Abstract

The nature of organic and inorganic phosphorus (P) in fertilized and unfertilized samples of Vilcun soil, a Chilean medial mesic typic Dystrandept which was studied through ³¹phosphorus‐nuclear magnetic resonance (³¹P‐NMR) analysis carried out on a single alkaline extraction. The total P contents ranged from 1,506 mg P kg^‐1 (B horizon, unfertilized soil) to 7,541 mg P kg^‐1 (A horizon, fertilized soil). The magnitude of the P signal (SEM‐EDAX results) appears to be related to that of the iron (Fe) signal. Signals of ³¹P‐NMR spectra are attributable to inorganic orthophosphate, and orthophosphate monoesters and diesters. No important differences between horizons were observed. Apparently in this soil, P are mainly associated with iron oxides and organic matter. The organic P forms were not readily subjected to mineralization.     

Saprotrophic fungi transform organic phosphorus from spruce needle litter

Fungal decomposition of and phosphorus transformation from spruce litter needles (Picea abies) were simulated in systems containing litter needles inoculated with individual saprotrophic fungal strains and their mixtures. Fungal strains of Setulipes androsaceus (L.) Antonín, Chalara longipes (Preus) Cooke, Ceuthospora pinastri (Fr.) Höhn., Mollisia minutella (Sacc.) Rehm, Scleroconidioma sphagnicola Tsuneda, Currah & Thormann and an unknown strain NK11 were used as representatives of autochthonous mycoflora. Systems were incubated for 5.5 months in laboratory conditions. Fungal colonization in systems and competition among strains were assessed using the reisolation of fungi from individual needles. After incubation, needles were extracted with NaOH and extracts were analysed using ³¹P nuclear magnetic resonance spectroscopy (NMR). Needle decomposition was determined based on the decrease in C:N ratio. Systems inoculated with the basidiomycete S. androsaceus revealed substantial decrease in C:N ratio (from 25.8 to 11.3) while the effect of ascomycetes on the C:N ratio was negligible. We suppose that tested strains of saprotrophic ascomycetes did not participate substantially in litter decomposition, but were directly involved in phosphorus transformation and together with S. androsaceus could transform orthophosphate monoesters and diesters from spruce litter needles into diphosphates, polyphosphates and phosphonates. These transformations seem to be typical for saprotrophic fungi involved in litter needle decomposition, although the proportion of individual phosphorus forms differed among studied fungal strains. Phosphonate presence in needles after fungal inoculation is of special interest because no previous investigation recorded phosphonate synthesis and accumulation by fungi. Our results confirmed that the ³¹P NMR spectroscopy is an excellent instrumental method for studying transformations of soil organic phosphorus during plant litter decomposition. We suggest that polyphosphate production by S. androsaceus may contribute to the phosphorus cycle in forest ecosystems because this fungus is a frequent litter colonizer that substantially participates in decomposition.     

Improving Sensitivity of Solution 31P NMR Analysis in Australian Xeralfs

Phosphorus-31 nuclear magnetic resonance (³¹P NMR) spectroscopy is widely used to identify and quantify phosphorus (P) forms in soil. This study aimed to determine whether narrowing the soil to extractant sodium hydroxide–ethylenediaminetetraacetic acid (NaOH-EDTA) ratio from 1:20 to values as low as 1:4 would improve sensitivity of solution ³¹P NMR spectroscopy without degrading resolution or quantitation. Four Australian soils were tested using four ratios. The narrowest ratio of 1:4 gave the best quality NMR spectra in terms of signal-to-noise ratio. Peak resolution was not degraded on narrowing the ratio. There was no clear effect of narrowing the extraction ratio on extraction efficiency or the distribution of signal among chemical shift regions (orthophosphate, monoester P, diester P, and pyrophosphate). We conclude that a ratio of 1:4 improved NMR analysis for these particular soils and should be considered for other soils, particularly low-P soils, where NMR sensitivity is limiting.     

Influence of conifers on the forms of phosphorus in selected New Zealand grassland soils

We examined the effects of conifers on the forms of P in low-fertility tussock grassland soils using ³¹P nuclear magnetic resonance (NMR) and soil P fractionation. Results from field and glasshouse experiments clearly demonstrated that conifers enhanced the mineralization of labile (and to a lesser extent more resistant) forms of soil organic P which, in turn, increased amounts of labile inorganic P in the soil. These findings have important implications for P availability and long-term sustainable management of grassland soils in New Zealand.     

A 31P nuclear magnetic resonance study of the phosphorus species in alkali extracts of soils from long-term field experiments

The different forms of phosphorus (P) in 0.5 m sodium hydroxide extracts of soils from long-term field experiments at Rothamsted were characterized by ³¹P-nuclear magnetic resonance spectroscopy (NMR). The extract from an old grassland soil (pH 4.6) from a plot of the Park Grass Continuous Hay Experiment that had received no fertilizer or lime for at least 125 years contained the following forms of P: inorganic orthophosphate (22% of the extracted P), orthophosphate monoesters (49%), orthophosphate diesters (14%), phosphonates (3%), pyrophosphate (4%) and two unidentified forms of P (7%). The soil extract from a Park Grass plot given inorganic phosphate fertilizer (35 kg P ha^?1) annually for 121 years contained the same forms of P and, in addition, a small amount of polyphosphate. There was also evidence of an increase in the orthophosphate monoester fraction. Another old grassland soil, of pH 6.1, contained more total and organic P than Park Grass but the extract contained fewer forms of P: inorganic orthophosphate (14% of the extracted P), orthophosphate monoesters (39%), orthophosphate diesters (34%) and an unidentified form (13%). An area of this grassland that had been ploughed up 20 years previously, and kept bare since, contained less organic P. The extract contained less of the phosphate diesters but the more stable monoesters remained relatively unchanged.     

Identification of soil organic phosphorus by 31P nuclear magnetic resonance spectroscopy

Abstract

Soil samples from different land use systems were collected before cropping (in spring) and after harvest (in fall) for organic phosphorus (P) extractions by 0.4M sodium hydroxide (NaOH) and characterization by ³¹P nuclear magnetic resonance spectroscopy. To prevent hydrolysis of organic P compounds prior to sample concentration, NaOH was removed from the NaOH soil extracts using a G‐25 Sephadex column. The ³¹P NMR spectra in the NaOH soil extracts showed the presence of glucose‐6 phosphate (up to 64%), glycerophosphate (up to 45%), nucleoside monophosphates (up to 91%), and polynucleotides (up to 58%) as the major forms of organic P in soils. The relative concentration of nucleoside monophosphates and polynucleotides decreased in some of the soils after harvest. The ³¹P NMR spectra of the extracts also revealed the presence of phosphoenolpyruvates, a previously unreported form of soil organic P.     

Phosphorus Availability in Soils Amended with Different Phosphate Fertilizers

Abstract

Accurate measurement and characterization of phosphate rock dissolution are important for a better understanding of phosphorus (P) availability in soils. An incubation study was carried out on two New Zealand topsoils (0–15 cm; high P buffering capacity Craigieburn and low P buffering capacity Templeton) amended with North Carolina phosphate rock (NCPR) and water‐soluble phosphate (WSP) at 218 mg P kg^?1 (equivalent to 60 kg P ha^?1). Isotopic exchange kinetics was carried out after 12 h and 28 days of incubation to characterize P availability. This study showed that sensitivity of capacity factors (r₁/R, n) to explain changes in E_1min values was affected by the P buffering capacity of the soils. The recovery of applied P in the E pool (Rec_inE%) with extended incubation time was similar from the NCPR and WSP treatments (3.1–3.3%) in the Craigieburn soil compared with the Templeton soil in which Rec_inE% values were greater in WSP (9%) than NCPR (1.3%) treatment. The higher values of P derived from the applied P fertilizers in the E pool (Pdff_inE%>80%) suggested that the NCPR application in both soils would be efficient for increasing P availability to plants.     

Technique of soil sample pretreatment for analysis of 15N:14N isotope ratio

Abstract

The technique of simultaneous quantitative determination of mineral N soil forms (nitrates, exchangeable and non‐exchangeable ammonium, and total amount of these compounds) and sample pretreatment for the analysis of ¹⁵N:¹⁴N ratio is suggested. The technique is based on the selective association of NH₄ ⁺‐ions into indophenol complex and subsequent ethyl‐acetate extraction of this complex from solution. The mineralization of indophenol is carried out in alkaline medium with simultaneous NH₃ distillation into H₂SO₄ titrant. The application of given technique allows us to shorten significantly the time required for analysis and to increase the accuracy of analytical determination.     

A study of soil and fertilizer phosphorus intake by Barley plants,using Radioactive tracer technique

Introduction

Phosphorus applied on a phosphate deficient soil, by increasing the root development of the plant, or by stimulating the soil microflora especially in the rhizosphere, may increase the amount of phosphorus which the plant takes up from the soil. This present paper is a report on a pot culture investigation of such an effect of added phosphorus.     

Interference by magnesium in the determination of nitrate in 2 M KCl extracts of soil by steam distillation

Abstract

Steam distillation of 2 M KCl extracts of soil showed low recovery of NO₃‐N when compared with an automated method for NO₃‐N determination. The low recoveries were more pronounced in extracts where a soil:solution ratio of 1:2.5 had been used. In extracts where the Mg²⁺ content was in excess of 0.02 M Mg, recoveries of added NO₃‐N could be as low as 25%. Increasing the amount of Devarda's alloy or using a 1:10 soil:solution extraction ratio overcame the problem of low NO₃‐N recovery. Calcium salts did not interfere in the recovery of added NO₃‐N.     

The comparative plant availability of 32P myo‐inositol hexaphospha.te and KH2 32PO4 added to soils

Abstract

The comparative availability to Lolivm perenne of ³²P myo‐inositol hexaphosphate (IH³²P) and KH₂ ³²PO. added to soil could be determined unequivocally from the ³²P count of leaf material even when dry matter yields and total P content were not significantly different from the control.

IH³²P was equivalent to KH₂ ³²PO₄. in a soil with a low P retention at 200 p.p.m. P but not at 20 p.p.m. P. IH ³²P was totally unavailable in two soils with high P retention at 200 p.p.m. and 20 p.p.m. P, whereas uptake of KH₂ ³²PO₄. was observed in each instance.     

Polyphosphate Speciation for Soil and Fertilizer Analysis

Abstract

Ammonium polyphosphate fertilizers provide an analytical challenge because they contain mixed phosphorus (P) species in solution as orthophosphate, pyrophosphate, and tripolyphosphate species. The conventional technique for the determination of polyphosphate concentration in solution is measuring the difference between total digested P and initial orthophosphate with colorimetry. Online colorimetry was compared with ion chromatography as a method for the speciation and quantification of the chemical species of P supplied in polyphosphate fertilizers.

Ion chromatography was able to speciate all of the P species supplied in polyphosphate fertilizer, whereas colorimetry detected only P in solution as orthophosphate and, by the difference between the measurement of digested and undigested samples, total condensed P species. Ion chromatography had a detection limit of 0.02 mg P L^?1 for orthophosphate, 0.03 mg P L^?1 for pyrophosphate, and 0.05 mg P L^?1 for tripolyphosphate. The detection limit for orthophosphate measured by colorimetry was the same as that measured by chromatography, but the working range of concentrations was considerably greater for chromatography—from 0.02 to 200 mg P L^?1 compared with 0.02 to 2 mg P L^?1.     

Prediction of phosphorus requirements of Desmodium intortum cv. greenleaf using a phosphorus sorption index and extractable phosphorus

Abstract

The rates of applied phosphorus required for 90% maximum yield of Desmodiim intortum cv. Greenleaf were calculated from pot experiments using 24 fertilized and unfertilized soils from the Atherton Tableland, Queensland, Australia.

Phosphorus required was highly correlated (r² = 0.94) with the phosphorus sorbed (P sorbed) by the soils at a supernatant solution P concentration of 0.08 ppm. P sorbed was found to be a function of phosphorus buffer capacity at 0.08 ppm ("PBC") and phosphorus extractable by acid (0.005 M H₂S0₄) or bicarbonate (0.5 M NaHCO₃). PBC was highly correlated (r² = O.84) with a phosphorus sorption index ("PSI") derived from one addition of 500 μg P g^‐1 soil.

Combining PSI with acid or bicarbonate extractable P in a multiple regression equation allowed the estimation of phosphorus required with multiple correlation coefficients of R² = 0.80 and R² = 0.83 respectively.     

Phosphorus speciation and colloidal phosphorus responses to short-term cessation of fertilization in a lime concretion black soil

Long-term excessive application of mineral fertilizer has led to soil acidification and phosphorus(P) accumulation, increasing the risk of P loss and environmental pollution, and cessation of fertilization is widely considered as a cost-effective management strategy to relieve this situation; however, how such cessation influences P speciation and concentrations in a bulk soil and colloidal fractions and whether decreasing P concentration might maintain soil fertility remain unclear. In this stu...     

Fractionation of soil cadmium from some new zealand soils

Abstract

The concentrations and forms of soil cadmium (Cd) in 12 different New Zealand topsoils were investigated using a sequential fractionation procedure. Total soil Cd concentrations were low and ranged between 0.03 μg g^‐1 to 1.34 μg g^‐1 and were highly correlated with total soil phosphorus (r²=0.85, P<0.01). Results indicated that there was a wide range in the concentrations of Cd associated with individual soil fractions and large variations between soils. On average for all soils, the smallest proportion of Cd was in exchangeable forms, i.e., 3%, with 12% in the crystalline oxide fraction, 13% in the amorphous oxide fraction and the greatest proportion of Cd associated with the organic 34% and residual 38% fractions. There was evidence to show that a soil extractant which is commonly used to predict plant uptake of Cd from soils, i.e., 0.04 M ethylene diamine terra acetic acid (EDTA), extracts Cd from both exchangeable and organic forms of soil Cd.     

The determination of ‘L’ values by discrete and integrated sampling procedures

Abstract

A discrete and an integrated sampling procedure were used to determine ‘ L ‘ values for maize plants grown in a soil. In the discrete procedure a plant was grown in a sand culture labelled with ³³P solution and then transferred in a soil which was labelled with ³²P. In the integrated sampling procedure plants were grown entirely in a P label led soil.

The discrete procedure permits point of time observation so that changes in the equilibrium between solution and surface P and mineralization rates can be monitored.