Characterizing the phosphorus forms extracted from soil by the Mehlich III soil test

Sugarcane ( Saccharum spp.) in Florida is principally grown on Histosols in the Everglades Agricultural Area. Soil‐test‐based P fertilization recommendations have not been addressed since the 1970s. The objectives of this research were to evaluate the most acceptable soil test P extractant that best correlates to crop yield, and to define soil test P groupings associated with crop response to applied P. Results will be used in the future to recalibrate soil test data to yield and rate of P application. Phosphorus trials were conducted at four sites on organic soils between 1968 and 1972 and additionally at eight sites on organic soils between 1982 and 1990. Phosphorus applications ranging from 0 to 98 kg P ha −1 were broadcast or row‐applied in combination with different cultivars, and/or K, Si, or S rates at 12 sites (multiple experiments used per site per crop). The effectiveness of water, acetic acid, and Mehlich‐1 extractable soil P as yield response predictors was determined. Acetic acid extractable P was more highly correlated to sugar and cane yields ( r = 0.72* and 0.63**, respectively) than water‐extractable P ( r = 0.27** and 0.39**, respectively). Mehlich‐1 extractable P was poorly correlated to sugar ( r = 0.25*) and cane ( r = 0.05 ns ) yields. Acetic acid extractable P was selected as the best‐suited extractant related to crop yield response to P fertilization. Soil test calibration curves (i.e., relative yield as a function of acetic acid extractable P) were determined from the choice of seven types of regression models, in which the reciprocal function was chosen with the highest coefficient of determination ( R 2 ) and minimized residuals. Soil acetic acid extractable P criteria were developed to define soil test level groups associated with yield response conditions: low soil test levels ranged from 0 to 9 mg L −1 , medium from 9 to 39 mg L −1 , and high exceeded 39 mg P L −1 .

Phosphorus (P) loss from urban areas has been identified as a major contributor to declining surface water quality. The objective of this study was to determine the relationship between extractable soil P, depth of soil sampling, and dissolved reactive P (DP) concentration in runoff from turfgrass areas. At each site, runoff was generated on turfgrass and adjoining areas where turfgrass cover was removed. Across all six locations and the wide range of nutrient management schemes, variation of extractable soil P concentration and saturation ratios of 0–2cm samples accounted for 49–59% (r2 = 0.49–0.59, n = 92) of variation of DP concentration in runoff from bare soil and soil with turfgrass cover. Despite a high degree of soil P stratification, changing sampling depth generally did not improve the relationship between soil test P and runoff DP concentrations. Across the narrower range of soil P levels common to lawns in New York (0–50mg kg−1 Morgan extractable soil P), none of the soil tests or P saturation levels (for 0–2cm depth) could accurately predict runoff P concentrations from soil with turfgrass cover (r2 = 0.02 to 0.23, n = 72). For bare soil plots, restricting the analysis to the same range (<50mg kg−1 Morgan extractable P) did not alter the relationship between soil test P and runoff DP concentrations observed for the entire range (0–658mg kg−1) of soil-test P concentrations. These results suggest soil testing will not be an effective tool to predict runoff from turfgrass areas across the range of soil P levels common to New York State.

Phosphorus metabolites occupy a unique place in cellular function as critical intermediates and products of cellular metabolism. Human blood is the most widely used biospecimen in the clinic and in the metabolomics field, and hence an ability to profile phosphorus metabolites in blood, quantitatively, would benefit a wide variety of investigations of cellular functions in health and diseases. Mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy are the two premier analytical platforms used in the metabolomics field. However, detection and quantitation of phosphorus metabolites by MS can be challenging due to their lability, high polarity, structural isomerism, and interaction with chromatographic columns. The conventionally used 1H NMR, on the other hand, suffers from poor resolution of these compounds. As a remedy, 31P NMR promises an important alternative to both MS and 1H NMR. However, numerous challenges including the instability of phosphorus metabolites, their chemical shift sensitivity to solvent composition, pH, salt, and temperature, and the lack of identified metabolites have so far restricted the scope of 31P NMR. In the current study, we describe a method to analyze nearly 25 phosphorus metabolites in blood using a simple one-dimensional (1D) NMR spectrum. Establishment of the identity of unknown metabolites involved a combination of (a) comprehensively analyzing an array of 1D and two-dimensional (2D) 1H/31P homonuclear and heteronuclear NMR spectra of blood; (b) mapping the central carbon metabolic pathway; (c) developing and using 1H and 31P spectral and chemical shift databases; and finally (d) confirming the putative metabolite peaks with spiking using authentic compounds. The resulting simple 1D 31P NMR-based method offers an ability to visualize and quantify the levels of intermediates and products of multiple metabolic pathways, including central carbon metabolism, in one step. Overall, the findings represent a new dimension for blood metabolite analysis and are anticipated to greatly impact the blood metabolomics field.

Summary There is at present little information on the long‐term stability of phosphorus sequestered in wetlands. Phosphorus sequestered during high loading periods may be relatively unstable and easily remobilized following changes in nutrient status or hydrological regime, but the chemical forms of sequestered phosphorus that do remobilize are largely unknown at this time. A lack of suitable analytical techniques has contributed to this dearth of knowledge regarding the stability of soil organic phosphorus. We analysed phosphorus in soils from the ‘head’ of Rescue Strand tree island and an adjacent marsh in the Florida Everglades by 31 P nuclear magnetic resonance (NMR) spectroscopy and high‐resolution mass spectrometry. Tree islands are important areas of biodiversity within the Everglades and offer a unique opportunity to study phosphorus sequestration because they are exposed to large phosphorus loads and appear to be natural nutrient sinks. The 31 P NMR profiling of extracts from surface and sediment samples in the tree island indicates that phosphorus input to Rescue Strand tree island soils is mostly in the form of inorganic ortho‐phosphate and is either refractory when deposited or rapidly recycled by the native vegetation into a stable phosphorus pool largely resistant to re‐utilization by plants or microbes. Mass spectrometry revealed the presence of inositol hexa kis phosphate, a common organic monophosphate ester not previously observed in Everglades’ soils.

Assessing crop residue phosphorus speciation using chemical fractionation and solution 31P nuclear magnetic resonance spectroscopy

A phosphorous/nitrogen-containing diphenylphosphine oxide (DPO) derivative (DPO-SS) was designed and synthesized via a two-step reaction of 4,4′-diaminodiphenylsulfone, 2-hydroxy-benzaldehyde, and DPO. The structure of DPO-SS was confirmed by Fourier transform infrared spectroscopy (FTIR), 1H and 31P nuclear magnetic resonance (NMR) spectroscopy, and mass spectrometry (MS). DPO-SS was used as a flame retardant and curing agent for copolymerizing with diglycidyl ether of bisphenol-A. Thermal and flame-retardant properties of the obtained flame-retardant epoxy resin (F-EP) were investigated by thermogravimetric analysis, dynamic thermomechanical analysis, limited oxygen index (LOI) measurement, vertical burning test (UL-94), and cone calorimeter test. Results indicated that all F-EP samples exhibited excellent thermal stability and flame-retardant property. Especially for F-EP with P content of 0.7 wt% (denoted as EP/P-0.7), it achieved high LOI values (32.4%) and UL-94 V-0 rating. Compared with pure EP, all F-EP samples showed lower heat release rate, total heat release, total smoke produce, and little Tg fluctuation. In order to study the flame-retardant mechanism, the char residues were investigated by FTIR, scanning electron microscopy, and energy-dispersive spectrometer analysis. The results manifested that DPO-SS acted as flame retardant in both gas phase and condensed phase. Water absorption properties of pure EP and F-EP were also compared through immersion experiments. Results showed that EP/P-0.7 sample had apparently lower water absorptivity than pure EP.

ABSTRACTThe reactions of linear polyphenols containing phosphonium fragment with formaldehyde and morpholine (Mannich reaction), as well as with propionic aldehyde, have been studied. As a result, calix[4]resorcinols of novel type have been synthesized, which contain alternating methylphosphonium and ethyl substituents. The structure and composition of the products obtained were confirmed according to 1H and 31P nuclear magnetic resonance, mass spectrometry, and elemental analysis data.

Five New Zealand topsoils, including three sampled under introduced pasture and two in native tussock grasslands, were extracted with 0.5 M NaOH, and the different classes of phosphorus compounds in the extracts distinguished by 31p nuclear magnetic resonance (n.m.r.). Inorganic orthophosphate and orthophosphate monoesters were the major forms of phosphorus in all soil extracts. The tussock‐grassland soil extracts showed the greatest diversity of phosphorus forms, and included compounds with n.m.r. signals ascribed to phosphonates, a previously unreported form of soil phosphorus.

In vivo 31P nuclear magnetic resonance (NMR) spectroscopy provides unique opportunities to study the biochemistry of an organ within the intact animal in a totally non-invasive way. We have used in vivo and in vitro 31P NMR spectroscopy to study steady state changes in the major phosphorus-containing metabolites of the rat liver in control and chronically ethanol-treated rats. Chronic (4 month) ethanol treatment caused a statistically significant increase in the inorganic phosphate and phosphodiester resonances of rat liver in in vivo 31P NMR spectra relative to pair-fed control rats. Phosphomonoester and adenosine 5'-triphosphate resonances, as well as intracellular pH, were not appreciably altered. The effects of chronic ethanol treatment were particularly apparent in the response of the liver to a metabolic challenge of glycerol. Glycerol is phosphorylated almost exclusively in the liver and metabolized predominately via glycolysis and gluconeogenesis. Our in vivo 31P NMR results after administration of glycerol showed a significant increase in the phosphomonoester resonance in the liver of chronic ethanol-treated rats but not for their pair-fed controls. In vitro 31P NMR studies of perchloric acid extracts of liver showed that the increase was due to an accumulation of sn-glycerol 3-phosphate. This effect is due to the NAD(+)-dependent glycerol 3-phosphate dehydrogenase step being inhibited in the chronic ethanol-treated rats. This glycerol test may be useful in assessing the ability of the liver to rapidly regenerate NAD+ in situ and may be a more sensitive indicator of redox imbalance than steady state ratios of redox pairs (e.g., lactate/pyruvate).

Predicting phosphorus availability to spring barley (Hordeum vulgare) in agricultural soils of Scandinavia

Differences in the evaluation of soil phosphorus status by three soil tests (Mehlich 3, extraction with NH&lt;sub&gt;4&lt;/sub&gt;-acetate and water extraction) were tested on 63 agricultural soils with different agrochemical characteristics from the territory of the Czech Republic. Differences between the colorimetric determination of phosphorus and ICP technique were studied. The median of the values of phosphorus supply in soils determined by soil tests was considerably different. Compared to the colorimetric detection of water extraction of soils the median of the NH&lt;sub&gt;4&lt;/sub&gt;-acetate test showed 2.2 times higher values and in Mehlich 3 test the values were 34.8 times higher. The largest difference between the end-point analytical techniques of phosphorus determination, colorimetry and ICP-AES, was observed in the soil test of water extraction. The median of the values determined by ICP-AES was higher by 47%. In NH&lt;sub&gt;4&lt;/sub&gt;-acetate extraction of soils the median of the measured values of phosphorus was higher by 12% and in Mehlich 3 extraction by 7%. Differences in phosphorus concentrations determined by colorimetry and by ICP-AES increased as the phosphorus supply in soils decreased. When the supply of 'available' phosphorus in soil is given, it is always necessary to specify the used soil test including the end-point analytical technique of phosphorus determination to avoid the misleading interpretation of results. The problem of phosphorus in agriculture and in the environment requires thorough revision and methodical standardization.

Lime and/or PK fertilizers were applied as remedial soil treatments to 33 sugar maple (Acer saccharum Marsh.) woodlots established on a broad range of sites in eastern Ontario. All woodlots were actively used for maple syrup production and had suffered varying degrees of crown damage as a result of the 1998 ice storm. Soil and foliar samples were collected one and three growing seasons after treatment to assess changes in soil fertility and nutrition of these stands. Except for Ca from liming, the treatments significantly increased soil supply of added elements (P, K, Ca or Mg) as measured by standard laboratory methods. These effects may be relatively short-lived, as soil nutrient levels on treatment plots had started to decline by the end of the third season after treatment. Liming alleviated acidity on acid soils, but pH of neutral calcareous soils was unaffected, thus allaying initial concerns that liming may be "toxic" on these soils. The liming response was rapid, and persisted into the third growing season. Nutrient responses in soils were reflected in foliar analyses. Leaf P, K, Ca, and Mg were significantly raised when added as soil amendments. The results show that first-season nutrient responses to fertilizer additions are sensitive indicators of treatment effects on soil and foliage of sugar maple in the region. Initial growth assessments suggest a 15–22% basal area increment to P and K applications; however, it is not known if these early treatment effects will translate into long-term tree growth and sap yield responses. Key words: Acer saccharum, phosphorous and potassium fertilization, liming, soil tests, foliar analysis, soil acidity

Fructose-3-phosphate production and polyol pathway metabolism in diabetic rat hearts

Ancient Cultigens or Modern Intrusions?: Evaluating Plant Remains in an Andean Case Study

Anthocyanins are water‐soluble, polyphenolic compounds responsible for coloration in fruits and vegetables, and are known to display antioxidant, anti‐carcinogenic and prebiotic properties in human subjects. This study was conducted to analyze the chemical degradation of anthocyanins in Red Norland potatoes based on colorimetric, spectrophotometric and mass spectrometry analysis. Tuber color and anthocyanin chemistry of fresh and stored (at 4ºC for 90 days) tubers were measured. Anthocyanins were also extracted in acidified methanol from peel tissue and their mean absorbance was measured at 513 nm. Colorimetric analysis of light, chroma and hue angle indicated that tubers darkened over storage time and became less intense in color; storage trends indicate loss of anthocyanins, although not significant due to high variation amongst tubers. Chemical changes in the six most abundant anthocyanins were analyzed between the fresh and stored samples via high performance liquid chromatography ‐ mass spectrometry. The six most abundant anthocyanins varied between a 2‐fold and 8‐fold decrease in concentration in the stored compared to fresh tubers. Based on results, for optimal pro‐health effects of anthocyanins, Red Norland potatoes should be consumed closest to harvest as possible.