NaHCO3-extractable Phosphorus Research Articles

Comparative Analysis of Soil Phosphorus Determination Methods and Their Correlation with Plant Phosphorus in Standing Wheat Crops

This study compared the accuracy of various soil phosphorus assessment methods to measure the soil's ability to supply plants with phosphorus over a brief period in the field. Twenty individual soil samples were collected from a standing wheat (Triticum aestivum L) crop at depths ranging from zero to twenty centimeters. An equivalent plant spike sample was also procured from the soil sampling fields. In comparison to the wet acid digestion method used to detect phosphorus in plants, several methods were utilized to assess phosphorus in the soil, including resin extractable phosphorus, AB-DTPA extractable phosphorus, NaHCO3 extractable phosphorus, water-soluble phosphorus in suspension, and paste. The levels of variation and deficiency of phosphorus, which were found by different methods followed different patterns as shown by the fact that, AB-DTPA method finds phosphorus deficiency in 20% of samples while on the other hand, Olsen method finds phosphorus deficiency in 80% of samples. Even with such a small sampling area, none of the procedures showed a significant correlation with any other method that might account for uneven variation among the samples when determined by distinct procedures. However, corrections were observed to a certain degree between ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA) extractable and resin, as well as between other procedures and the plant P scale. Both resin and ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA) had a strong relationship with plant phosphorus, with the former showing a significant correlation of 0.48 and 0.21, respectively. Hence Resin and AB-DTPA methods are recommended for the determination of phosphorus under certain soil and plant conditions.

Effect of magnetic iron-zirconium modified zeolite on the different phosphorus forms in river sediment under aerobic and anoxic conditions

Abstract In this study, a magnetic iron-zirconium modified zeolite (FeZrMZ) was synthesized. Through sediment culture experiments, the influence of the addition of modified materials on the migration and transformation of phosphorus in river sediments was investigated. The results showed that the modified zeolite could not only effectively reduce the phosphorus concentration in the overlying water, but also significantly reduce the phosphorus concentration in the pore water of sediments. The addition of modified zeolite makes the unstable weakly adsorbed phosphorus (NH4Cl-P) and redox phosphorus (BD-P) transform into the more stable metal oxide-bound phosphorus (NaOH-P) and very stable residual phosphorus (Res-P). The four types of bioavailable phosphorus (BAP), including water-soluble phosphorus (WSP), readily desorbable phosphorus (RDP), algae-available phosphorus (AAP), and NaHCO3 extractable phosphorus (Olsen-P). Under anoxic conditions, they were reduced by 53.5%, 14.1%, 23.8%, and 49.9% respectively. Under aerobic conditions, they were reduced by 23.2%, 16.6%, 32.1%, and 50.0%. The addition of magnetic iron-zirconium modified zeolite could clearly reduce the release potential of phosphorus in sediment, and it could be recovered through the action of an external magnetic field, so it could be used as an effective sediment modifier to control the sediment release of phosphorus.

Transformation of internal sedimentary phosphorus fractions by point injection of CaO2

The transformation of sedimentary phosphorus (P) fractions by point injection of CaO2 was investigated in this study. The results showed that the addition of CaO2 increased the dissolved oxygen (DO) in the overlying water as well as its pH. Simultaneously, the concentrations of total organic carbon (TOC), ammonia nitrogen (NH4+-N), total phosphorus (TP) and dissolved inorganic P (DIP) in the overlying water were sharply reduced by the point injection of CaO2, indicating that this accelerated the mineralisation rate of organic matter. It also favoured the formation and maintenance of the micro-oxidation environment in the deep sediments. NH4Cl-P, Fe/Al-P and Ca-P increased significantly, while the Res-P decreased sharply, especially close to the injection point of CaO2, accelerating the transformation of P. These results can all be attributed to the oxidation of organic P and the adsorption of dissolved P from the overlying water. Additionally, the NaHCO3-extractable phosphorus (Olsen-P) and algal available phosphorus (AAP) were reduced, and their percentages in Ca-P and Fe/Al-P also decreased, especially close to the injection point of CaO2. The bioavailable P decreased from 25.6% (the initial) to 17.2% (the mean for the different distances) after the point injection of CaO2, when the sum of the Olsen-P and AAP was used to calculate the bioavailable P. This indicates that point injection of CaO2 favours not only the transformation of P species but also inhibition of the bioavailable P. This is attributable to acceleration of the transformation from bioavailable to inert P.

Landscape-scale soil phosphorus variability in the McMurdo Dry Valleys

AbstractThe predicted increase in liquid water availability in the McMurdo Dry Valleys (MDV), Antarctica, may have profound consequences for nutrient cycling in soil and aquatic ecosystems. Our ability to predict future changes relies on our understanding of current nutrient cycling processes. Multiple hypotheses exist to explain the variability in soil phosphorus content and availability found throughout the MDV region. We analysed 146 surface soil samples from the MDV to determine the relative importance of parent material, landscape age, soil chemistry and texture, and topography on two biologically relevant phosphorus pools, HCl- and NaHCO3-extractable phosphorus. While HCl-extractable phosphorus is highly predicted by parent material, NaHCO3-extractable phosphorus is unrelated to parent material but is significantly correlated with soil conductivity, soil texture and topography. Neither measure of soil phosphorus was related to landscape age across a gradient of ~20 000 to 1 500 000 years. Glacial history has played an important role in the availability of soil phosphorus by shaping patterns of soil texture and parent material. With a predicted increase in water availability, the rate of mineral weathering may increase, releasing more HCl-extractable phosphorus into soil and aquatic ecosystems.

Evaluation of phosphorus distribution and bioavailability in sediments of a subtropical wetland reserve in southeast China

The phosphorus (P) fractions and bioavailable P in the sediments from the Quanzhou Bay Estuarine Wetland Nature Reserve were investigated using chemical extraction methods for the first time to study the distribution and bioavailability of P in the reserve sediments. A hypothesis was presented suggesting that the bioavailable P in the sediments could be evaluated using the P fractions. The total phosphorus (TP), inorganic phosphorus (IP), organic phosphorus (OP), non-apatite phosphorus (NAIP), and apatite phosphorus (AP) contents in the sediments were in the ranges of 303.87–761.59mgkg−1, 201.22–577.66mgkg−1, 75.83–179.16mgkg−1, 28.86–277.90mgkg−1, and 127.36–289.94mgkg−1, respectively. The water soluble phosphorus (WSP), readily desorbable phosphorus (RDP), algal available phosphorus (AAP), and NaHCO3 extractable phosphorus (Olsen-P) contents in the sediments were in the ranges of 0.58–357.17mgkg−1, 80.77–586.75mgkg−1, 1.09–24.12mgkg−1, and 54.96–676.82mgkg−1, respectively. The correlation analysis results showed that the NAIP was the major component of the bioavailable P and that the impact of the AP on the bioavailable phosphorus may be minimal. Due to the low TP content in the sediments of the Quanzhou Bay Estuarine Wetland Nature Reserve, the potential pollution risks of P in the sediments may not be very high. The results also show that the bioavailable P concentrations in the sediments of the Quanzhou Bay Estuarine Wetland Nature Reserve could not be evaluated by measuring the P fractions and that the hypothesis was untenable.

Bioavailability of phosphorus in Abu Qir Bay and Lake Edku sediments, Mediterranean Sea, Egypt

The aim of this study is to investigate the distribution of phosphorus bioavailability (total phosphorus, organic, and inorganic phosphorus) in the sediments from two areas (Abu Qir Bay and Lake Edku) located east of Alexandria City. Abu Qir Bay is a very important productive area of the Mediterranean Sea off Egypt, since it receives nutrient-rich brackish water from Lake Edku as well as El-Tabia pump station. The release of phosphorus from the sediment is generally important for eutrophication, which influences the sea-water quality of the study area. Sediment samples from 10 sites of Abu Qir Bay and eight sites of Lake Edku were subjected to a seven-step extraction procedure to determine organic, inorganic, and total phosphorus as well as phosphorus bioavailability: water-soluble phosphorus (WSP), readily desorbable phosphorus (RDP), algal available phosphorus (AAP), and NaHCO3-extractable phosphorus. Our results indicate low recovery of available phosphorus extracted by CaCl2 for the sediments of the lake and the bay. The sediments of Lake Edku were richer in organic and inorganic phosphorus. The range and mean concentration (μg g−1) of the organic P were 17–260 (129) for Abu Qir Bay, and 84–930 (349 μg g−1) for Lake Edku. The accumulation of fresh macrophyte debris in Lake Edku sediments plays an important role in organic-matter enrichment (average 9%) and phosphorus bioavailability. The inorganic P was higher than the organic P for the study area, and its content (μg g−1) ranged from 127 to 446 (mean; 252) and from 515 to 947 (mean; 682) for Abu Qir Bay and Lake Edku sediments, respectively. The distribution of both total P and organic P content in the lake sediments revealed a decreasing level from the eastern to the western region, towards the opening of Boughaz El-Maadia, while the inorganic phosphorus increased from 598 μg g−1 in the eastern side to 875 μg g−1 in the western region of the lake. In general, the rank order of extraction efficiency was the same in the two regions, and the amount extracted was in the sequence AAP>Olsen-P>WSP > RDP.

Organic carbon and plant nutrient dynamics under three land uses in the highlands of West Cameroon

Assessing land use-induced changes in soil systems is essential for addressing the problem of agroecosystem transformation and sustained land productivity. We compared organic carbon (OC) characteristics and plant nutrient levels in surface horizons (0–10 cm) of semi-permanent, mixed food crop fields (CF), Eucalyptus grandis plantations (EP) and tea (Camellia sinensis) plantations (TP) from an andic Palehumult in the highlands of West Cameroon. For more insight in organic matter transformations, OC, total nitrogen (TN) and NaHCO3 extractable phosphorus (NaHCO3–P) were analyzed on whole soils and size fractions (SF). Structural composition of soil organic matter (SOM) was assessed by solution 13C NMR spectroscopy. Land use conversion from CF to EP and ET increased OC stocks in surface horizons by a factor of 2.14 and 1.95 for EP and TP respectively after 15 years. In all land uses, O-alkyl C, aromatic C and carboxylic C were the dominant OC species, accounting for between 75.6 and 76.1% of total soil OC. The organic NaHCO3–P fraction was significantly higher (79.4±7.2 μg g−1) under TP and lowest under EP (58.8±4.3 μg g−1) as a result of phosphorus fertilization. The EP system recycled and accumulated substantial amounts of Ca and Mg in surface soil horizons. The inorganic NaHCO3–P fraction and K were significantly lower (P<0.05) under EP suggesting an immobilization in litter and standing biomass. TP had the lowest Mg level due probably to export through shoot harvest. Sites under EP and TP have significantly (P<0.001) higher proportion of silt and correlatively a lower proportion of clay. Soil size fractions exhibited distinct properties with respect to organic nutrient concentration, mineralization status and stability with silt and clay-sized fractions being enriched in OC and TN compared to whole soils. The highest quantitative changes after 15 years was recorded in the silt-sized fraction which accounted for 58–66% of total soil carbon.

Soil Variables for Predicting Potential Phosphorus Release in Swedish Noncalcareous Soils

The accumulation of P in agricultural soils due to fertilization has increased the risk of P losses from agricultural fields to surface waters. In risk assessment systems for P losses, both P release from soil to solution and transport mechanisms need to be considered. In this study, the overall objective was to identify soil variables for prediction of potential P release from soil to solution. Soils from nine sites of the Swedish long-term fertility experiment were used, each with four soil P levels. Phosphorus extractable with CaCl2 was used as an estimate of potential P release from soil to solution. Ammonium lactate–extractable phosphorus (P-AL) or NaHCO3–extractable phosphorus (Olsen P) could not be used alone for prediction of potential P release since soils with high phosphorus sorption capacity (PSC) released less P than soils with low PSC at the same soil test phosphorus (STP) level. Degree of phosphorus saturation (DPS) was calculated as Olsen P or P-AL as a percentage of PSC derived from P sorption isotherms or from Fe and Al extractable in ammonium oxalate. The CaCl2–extractable total phosphorus (CaCl2–TP) was exponentially related to these DPS values (r2 ≥ 0.79). The CaCl2–TP was also linearly related to ratios between Olsen P or P-AL and a single-point phosphorus sorption index (PSI; r2 ≥ 0.86). These ratios, which are easily determined and gave good correlations with CaCl2–TP, seemed to be the most useful estimates of potential P release for risk assessment systems.

Soil variables for predicting potential phosphorus release in Swedish noncalcareous soils.

The accumulation of P in agricultural soils due to fertilization has increased the risk of P losses from agricultural fields to surface waters. In risk assessment systems for P losses, both P release from soil to solution and transport mechanisms need to be considered. In this study, the overall objective was to identify soil variables for prediction of potential P release from soil to solution. Soils from nine sites of the Swedish long-term fertility experiment were used, each with four soil P levels. Phosphorus extractable with CaCl2 was used as an estimate of potential P release from soil to solution. Ammonium lactate-extractable phosphorus (P-AL) or NaHCO3-extractable phosphorus (Olsen P) could not be used alone for prediction of potential P release since soils with high phosphorus sorption capacity (PSC) released less P than soils with low PSC at the same soil test phosphorus (STP) level. Degree of phosphorus saturation (DPS) was calculated as Olsen P or P-AL as a percentage of PSC derived from P sorption isotherms or from Fe and Al extractable in ammonium oxalate. The CaCl2-extractable total phosphorus (CaCl2-TP) was exponentially related to these DPS values (r2 > or = 0.79). The CaCl2-TP was also linearly related to ratios between Olsen P or P-AL and a single-point phosphorus sorption index (PSI; r2 > or = 0.86). These ratios, which are easily determined and gave good correlations with CaCl2-TP, seemed to be the most useful estimates of potential P release for risk assessment systems.

Physical and chemical characterisation of the agricultural lands of the Soan - Sakesar Valley, Salt Range, Pakistan

Soil samples (depth, 0–20 cm) from the Soan–Sakesar Valley were analysed for a variety of parameters: pH, electrical conductivity (ECe), alkalinity, Na, K, Ca, Mg, Cl, SO4, Li, B, and NO3 in saturation extracts; organic carbon (C), NaHCO3-extractable phosphorus (P), and total P in whole soil; and mineralogical investigations in whole-soil and separated clay fractions. A Principal Component Analysis was carried out on the correlation matrix (i.e. on standardised attributes) and soil samples were subdivided into salinity groups. The mean ECe levels of Groups 1–4 were 1.27, 2.75, 2.07, and 5.67 dS/m, respectively; the corresponding sodium adsorption ratios were 5.36, 7.9, 15.7, and 29.6 mmol0.5, respectively. In these soil groups, suitable crops were suggested on the basis of their salt tolerance and the salinity of the irrigation water. The low availability of P from phosphatic fertilisers and farmyard manure as a result of fixation by calcite, which is present in these soils to the extent of 7.8–15.2%, resulted in a lower yield of grain crops (wheat and maize). On the other hand, higher application rate of nitrogen (N) fertilisers together with farmyard manure to irrigated crops and vegetables resulted in N leaching from the crop rooting zone into groundwater. The soils investigated had mixed clay mineralogy with a dominance of chlorite, illite, and kaolinite, whereas major non-clay minerals are predominantly albite, calcite, and quartz.

Quantification of mycelial development of arbuscular mycorrhizal fungi using image analysis

Quantitative and reproducible information concerning the development of the extraradical mycelium of arbuscular mycorrhizal fungi (AMF) is lacking due to the difficulties in extracting, identifying and estimating hyphal lengths. In this study, using a rhizobox growth system, the lengths of hyphae of AMF estimated using an image analysis system were not significantly different from data obtained by a trained observer using a modified grid-line intersect method. The assessment of lengths of hyphae on membrane filters or slides was, however, much quicker using image analysis, and allowed the complete sample to be quantified, unlike the grid-line method where a limited number of fields of view are assessed. The image analysis procedure is objective, observer-independent and less laborious than the manual method of assessment. Of the four different methods of sample preparation compared, membrane filter methods were found to be the most appropriate for quantitative sampling from three non-soil substrates. Glomus monosporum (UKC M3) produced twice as much extraradical mycelium and hyphal length per centimetre of colonised root than G. geosporum (BEG 11) on both leek and linseed in a durite sand at final harvest (63 days). Both AMF also produced more hyphal length per centimetre of colonised root on linseed than on leek. The spatial distribution of both AMF, however, was similar in durite sand and no correlation with levels of NaHCO3-extractable phosphorus was noted. In a third experiment, with G. manihotis (UKC INDO-1) colonising a tropical forage legume, Pueraria phaseoloides, in two other growth substrates, a different pattern of development of the extra-radical mycelium was observed. Because of a higher content of particulate matter, which collected on the membrane filters, the extraction technique had to be modified to give optimal performance of the image analysis system.

PHOSPHATE-SOLUBILIZING BACTERIA AND FUNGI IN VARIOUS CULTIVATED AND VIRGIN ALBERTA SOILS

Seventeen sites throughout southern Alberta were sampled in the spring of 1981. Total and NaHCO3-extractable phosphorus and soil texture were determined for each soil sampled. Phosphate-solubilizing and total bacterial and fungal populations were determined by serial dilution and plate counting. Available P constituted an average of 1% of the total P present in the soils. Phosphate-solubilizing bacteria and fungi made up 0.5 and 0.1%, respectively, of the total bacterial and fungal populations. A highly significant correlation was found between the numbers of total and phosphate-solubilizing fungi and the levels of total P in the soil. As a group, the fungi were superior to bacteria in solubilizing both freshly precipitated calcium phosphate and Idaho rock phosphate. Fungi also retained this ability over many subculturing transfers. A high percentage of the bacterial isolates lost their solubilizing ability when subcultured. A significant correlation was found between an organism’s ability to solubilize freshly precipitated calcium phosphate in agar plates and Idaho rock phosphate in solution culture. Key words: Fungi imperfecti, Penicillium sp., phosphate-solubilizing microorganisms

RESIDUAL EFFECTS OF PHOSPHORUS FERTILIZER. II. FOR WHEAT AND FLAX GROWN ON CHERNOZEMIC SOILS IN MANITOBA

Broadcast applications of 0, 100, 200 and 400 kg P/ha were made on two Chernozemic soils in 1965. The soils were cropped for 8 yr in a continuous wheat-flax rotation. In each year, crops grown on the phosphorus treatments yielded more and had higher phosphorus content than crops grown without added phosphorus. Over 8 yr of cropping, 100 kg P/ha was the most efficient treatment in increasing yield. Yield increases beyond 100 kg P/ha were either not significant or only marginally significant. Wheat used twice as much phosphorus as did flax. Together the two crops used approximately 30, 22 and 14% of the 100, 200 and 400 kg P/ha applied. The NaHCO3-extractable phosphorus level of the 100 kg P/ha treatment after 8 yr of cropping was reduced to about 8 kg P/ha which is considered to be inadequate for crop production. Soils treated with 200 and 400 kg P/ha contained high levels of NaHCO3-extractable P (20–54 kg P/ha) and little response in yield to additional P would be expected in the near future. Annual variation in yield and phosphorus uptake by the crops were affected by water supply. In years of high water supply, yield and phosphorus uptake were generally higher than in years of low water supply.

The Distribution and Abundance of Vesicular Arbuscular Endophytes in Some Western Australian Soils

The distribution and abundance of large-spored vesicular arbuscular (VA) endophytes was examined at three localities in Western Australia. Within each locality, soil samples were collected from sites with a range of soil properties and superphosphate histories. Vesicular arbuscular endophytes were widespread. Spores were found in all but five of 104 samples. In two of the samples where spores were not found, plants grown in the soils formed VA mycorrhizas. Root infection by a fine endophyte resembling Rhizophagus tenuis was also frequently observed. Five spore types were found. Honey-coloured sessile spores were present in 85% of the samples. The yellow vacuolate spore type was the second most common endophyte, but its distribution was mostly limited to cultivated and fertilized soils. Endophytes other than the yellow vacuolate spore type occurred on both virgin and agricultural soils. The distribution of honey-coloured sessile and yellow vacuolate spores in cultivated soils appeared to be associated with variation in soil pH. The total numbers of spores collected on a 106 μm sieve were not correlated with soil pH, NaHCO3-extractable phosphorus or superphosphate history.

Suppression of superphosphate-phosphorus fixation by farmyard manure II. Some studies on the mechanisms

Abstract Studies were conducted on a calcareous loam soil to find out the effect of premixing superphosphate (SUP) with farmyard manure (FYM) at a 1 to 4 ratlo on the NaHCO3 extractable phosphorus, lime, and phosphate potentials, and the conversion of SUP to various phosphatic forms. SUP was applied at rates of 98, 245, 490, and 2453 kg P/ba. The soil was incubated for various time intervals from 0 to 96 days. At all the time intervals, NaHCO3 extractable phosphorus remained at a higher level in the premixed treatments than that found in the unmixed or SUP treatment only. The soil solution in the premixed treatments contained Ca phosphates of higher solubility than those in the unmixed treatment. The content of Al, Fe-P, and NH4Cl extractable-P (soluble-P) in the soils of premixed treatments were found to be greater, occurring at the expense of Ca-P. Octocalcium phosphate appeared to be a fairly stable form in all these soils. The implications of these studies on the availability of phosphorus to plants have been discussed.

PRODUCTIVITY INDICATORS FOR A BROWN SOLONETZ AND ASSOCIATED SOILS UNDER IRRIGATION

The pH, electrical conductivity, sodium-adsorption ratio, saturation percent, hydraulic conductivity, NO3 content, and NaHCO3-extractable phosphorus were determined on an irrigated Solonetzic soil complex. The soils were sampled to the 142-cm depth at 20 locations on a small, levelled field. Yields of barley were obtained in the field and in the greenhouse on soil cores. Stepwise multiple regression analyses indicated that hydraulic conductivity and available phosphorus in the 0- to 15-cm depth were the most important factors explaining yield variation in the field. In the greenhouse, available phosphorus was more important and hydraulic conductivity was of secondary and minor importance.