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.     

Influence of aggregate size on phosphorus changes in a soil cultivated intermittently: analysis by <Superscript>31</Superscript>P nuclear magnetic resonance

A pot trial using wet-sieved soil aggregates (>4, 4–2, 2–1, 1–0.5, 0.5–25, and remaining soil <0.25 mm) from a soil that had been cultivated out of permanent pasture and used for winter forage crops for 2 years examined changes in P forms before and after 35 weeks when resown with perennial ryegrass. Soil analyses showed that P was depleted after 35 weeks growth. Changes in P forms were analyzed by ³¹P nuclear magnetic resonance of soil NaOH-EDTA extracts, which removed 98–96% of total P (about 1,080 mg kg⁻¹ in unsieved soil before pasture growth). This indicated that aggregate size influenced the concentrations and forms of P probably via a combination of physical protection and moisture status: orthophosphate, monoesters, diesters and pyrophosphate increased with decreasing size, while phosphonates and polyphosphates were unaffected. The increase in pyrophosphate was attributed to fungal growth, while decreases in orthophosphate and labile organic P (diesters) decreased due to either leaching or mineralisation and plant uptake. The largest decrease was associated with orthophosphate, which could be replenished by fertiliser. However, given the soil’s high potential for P loss, this should only be done to meet conditions for optimal plant growth as any excess would increase the risk of loss. To further minimise P loss without affecting pasture yield, management should maintain or improve soil structure.     

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.     

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.     

Temperature field of complex soilscapes (by the example of the Vladimir opolie region)

Problems of the assessment of soil temperature regime at the polypedon level have yet to be solved. An approach suggested by the authors consists of three stages: (1) the characterization and prediction of the soil water regime as a factor influencing the soil temperature regime, (2) the obtaining of thermophysical functions for the particular elements of complex soilscapes, and (3) the calculation and assessment of the temperature regime of complex soilscapes in the form of the functional fields of soil temperature isopleths. This approach has been applied to predict the soil temperature regime of an arable field in the Vladimir opolie region. The complex soilscape of the field consists of medium loamy agrogray soils, agrogray soils with the second humus horizon, and podzolized agrogray soils. At the beginning of the growing season, minimum temperatures are observed in the areas of agrogray soils with the second humus horizon; the difference in soil temperatures at a depth of 20 cm reaches 1°C, and the difference in the sum of active soil temperatures reaches 20°C. Then, this difference changes considerably, so that the agrogray soils with the second humus horizon become warmer than the agrogray soils. In general, the functional field of soil temperatures within the complex soilscape is highly dynamic and diverse, which is specified by the variability in the water-physical and thermophysical properties of particular soils.     

31P-NMR-spectroscopic investigations of NaOH-extracts from soils with different land use in Yucatan (Mexico)

In aqueous NaOH-extracts of top-soils (0-10 cm) from typic chromuderts, phosphorus was determined by NMR-spectroscopy. In addition to inorganic orthophosphate, orthophosphate monoesters and diesters were detected. Pyrophosphate was only found in traces after clear-cutting and burning of the forests. The result of clear-cutting and agricultural land use is an increase of inorganic P from 19% (forest) to 33% (maize field). Compost gardens and mature tree gardens contain only 9-13% inorganic P in the NaOH-extract. The organic P-fraction consists mainly of orthophosphate monoesters (57-72%). The orthophosphate diester content is only 10–21%. It could be shown, that the increase of inorganic P in the course of clear-cutting and ploughing is correlated with a decrease of orthophosphate mono- and diesters.     

Organic phosphorus species in humic acids of mountain soils along a toposequence in the Northern Caucasus

Organic P was investigated in humic acids extracted from mountain soils developed in the subalpine, upper subalpine and alpine zones of the Northern Caucasus. P contents of humic acids varied between 3.4 and 14.2 g P kg^?1, depending on P contents of the parent vegetation and on site conditions. Organic P was accumulated at sites where microbial activity is restrained due to soil acidity, low soil temperature and hydromorphy.³¹ P NMR spectroscopy revealed that orthophosphate monoesters were the dominent P species (72–85% of extract- able P), orthophosphate diesters amounted to 12–21%, and phospho- nates ranged between 0 and 9%. Humic acids of soils under cold and wet climatic conditions showed highest concentrations in phospho- nates and orthophosphate diesters. Hence, the accumulation of organo-P in the Caucasian mountain soils was partly due to increasing proportions of potentially available organic P species.     

Organic phosphorus speciation and pedogenesis: analysis by solution 31P nuclear magnetic resonance spectroscopy

Changes in phosphorus (P) during soil development are central to the understanding of labile P for plant productivity and soil P management. We used NaOH‐EDTA extraction with ³¹P nuclear magnetic resonance spectroscopy (³¹P NMR), sequential P fractionation, and general soil chemical characterization to better our understanding of P dynamics within two chronosequences (Manawatu and Reefton) and one Basalt maturity sequence under original native vegetation. With time, orthophosphate and orthophosphate monoesters tended to increase with organic C to a maximum of about two‐thirds of NaOH‐EDTA‐extractable P in young soils (16 000 years in the Reefton chronosequence), but gradually declined thereafter to about one‐third of NaOH‐EDTA‐extractable P in the oldest soils (130 000 years old). This coincided with a depletion of P from primary minerals (e.g. apatite) and readily available P for plant production. This depletion of inorganic P resulted in a greater reliance on organic P cycling via mineralization, hence the depletion of the normally recalcitrant monoester‐P pool. Concomitantly, the build‐up of labile P species (diesters and pyrophosphate) and scyllo‐ over myo‐inositol hexakisphosphate occurred as soils developed, and might be attributed to microbial activity, including scavenging for P. This work highlights the importance of organic P cycling during pedogenesis.     

Characterization of phosphorus in sub-alpine forest and adjacent grassland soils by chemical extraction and phosphorus-31 nuclear magnetic resonance spectroscopy

We used chemical extraction methods and ³¹P-nuclear magnetic resonance (NMR) to investigate the effects of vegetation on the amount and structural composition of phosphorous (P) in the sub-alpine soils of central Taiwan. Chemical extraction methods were used to measure inorganic P (Pi) and organic P (Po) in main soil horizons. The soil P composition was assessed by ³¹P-NMR spectroscopy on alkaline EDTA–NaOH extracts. According to the results of chemical extractions, the forest soil had a higher amount of Pi than the grassland soil, which might be a result of the mineralization of Po. ³¹P-NMR spectra showed inorganic orthophosphate (up to 67%) and orthophosphate monoesters (up to 75%) as the major forms of P extracted in forest and grassland soils, respectively. Smaller proportions of orthophosphate diesters and trace amounts of phosphonates and pyrophosphate were found. With possible hydrolysis of P compounds during chemical extraction and slight systemic error in the processes of extraction with NMR, the results from NMR analysis are, in general, consistent with those of chemical extraction.     

The phosphorus composition of contrasting soils in pastoral,native and forest management in Otago,New Zealand: Sequential extraction and 31P NMR

The distribution and form of P in soil is central to the sustainability of agricultural practice. This study used sequential fractionation and ³¹P nuclear magnetic resonance spectroscopy (³¹P NMR) of NaOH–EDTA extracts to examine the influence of pastoral, native (undisturbed) and forest land use on soil P forms in 5 contrasting soils ranging from a Regosol to a Rendzina in Otago, New Zealand. Climatic factors likely to influence soil P distribution were negated by careful site selection. Together with a decrease in soil organic C (31%), total P decreased in forested soils (mean=674 mg kg⁻¹) compared to native soils (mean=784 mg kg⁻¹). In contrast, the ratio of inorganic to organic P increased (10%) probably due to mineralization of organic P in forest soils, while for pasture soils, accumulation of P in inorganic forms due to P inputs via fertilisers and animal dung was to blame. Investigation of the organic P forms in NaOH–EDTA extracts of each land use by ³¹P NMR indicated that diesters were greatest in the native soil (4–12% of total P in spectra), and declined as a proportion of total P in pasture soils and more so in forest soils. This was reflected in a decline of the diester to monoester ratio. However, the ratio was generally greater in forest than pasture soils and attributed to the labile nature of diesters, mineralization of monoesters in forest soils, and an increase in monoesters in pasture soils from inositol phosphates in plant debris. This effect was pronounced in the Regosol due to sandy texture and the preferential accumulation of plant debris in coarse particle size fractions. Due to the depletion of soil P reserves, forest soils in the area should be followed by pasture and well managed fertiliser additions before replanting.     

Phosphorus Sorption Capacity of Gray Forest Soil as Dependent on Fertilization System

In this paper, the results of the study of changes in the phosphorus sorption capacity of gray forest soils of Vladimir opolie under the impact of different fertilization systems are discussed. The quantitative parameters of the potential buffer capacity of soils for phosphorus (PBC^P) and Langmuir sorption isotherms have been calculated. It is shown that the application of organic fertilizers results in a stronger decrease in PBC^P than the application of mineral fertilizers. The portion of phosphorus of mineral compounds considerably increases, and the high content of available phosphates is maintained. In the variants with application of mineral phosphorus in combination with manure, the portions of organic and mineral phosphorus are at the level typical of unfertilized soils. The energy of phosphate bonds with the soil is minimal upon the application of a double rate of mineral phosphorus at the maximum capacity in relation to phosphate ions.     

Preferential phosphorus leaching from an irrigated grassland soil

Intact lysimeters (50 cm diameter, 70 cm deep) of silt loam soil under permanent grassland were used to investigate preferential transport of phosphorus (P) by leaching immediately after application of dairy effluent. Four treatments that received mineral P fertilizer alone (superphosphate at 45 kg P ha^?1 year^?1) or in combination with effluent (at ～ 40–80 kg P ha^?1 year^?1) over 2 years were monitored. Losses of total P from the combined P fertilizer and effluent treatments were 1.6–2.3 kg ha^?1 (60% of overall loss) during eight drainage events following effluent application. The rest of the P lost (40% of overall loss) occurred during 43 drainage events following a significant rainfall or irrigation compared with 0.30 kg ha^?1 from mineral P fertilizer alone. Reactive forms of P (mainly dissolved reactive P: 38–76%) were the dominant fractions in effluent compared with unreactive P forms (mainly particulate unreactive P: 15–56%). In contrast, in leachate following effluent application, particulate unreactive P was the major fraction (71–79%) compared with dissolved reactive P (1–7%). The results were corroborated by ³¹P nuclear magnetic resonance analysis, which showed that inorganic orthophosphate was the predominant P fraction present in the effluent (86%), while orthophosphate monoesters and diesters together comprised up to 88% of P in leachate. This shows that unreactive P forms were selectively transported through soil because of their greater mobility as monoesters (labile monoester P and inositol hexakisphosphate) and diesters. The short‐term strategies for reducing loss of P after application of dairy effluent application should involve increasing the residence time of applied effluent in the soil profile. This can be achieved by applying effluent frequently in small amounts.     

Sorption of heavy metals by iron-manganic nodules in soils of Primorskii region

The accumulation and deactivation (detoxification) of heavy metals in soils and in soil iron-manganic nodules have been studied. Data on the relative distribution of the total and mobile compounds of heavy metals in soils and nodules upon different rates of technogenic loads are obtained. It is shown that iron-manganic nodules play the role of specific depositors in the soil system, affect the redistribution of heavy metals in the soil cover, and control their migration in the soil profiles.     

Interaction between soils and gas pipelines

The interaction between pipelines and soils manifests itself in the soil disturbance in the course of the pipe installation, in the transformation of the water and temperature regimes in the trenches, and in the appearance of corrosion and cracks on the pipe walls. The more contrasting the soil water regime in the pipe-adjacent sections of the trench, the greater the amount of the pipe damage. The damage of the pipe insulation activates the pipe corrosion. The emission of gases (H₂S, CH₄, CO₂, CO, and H₂) and the activity of sulfate-reducing bacteria are the main causes of the pipes’ destruction. The humus content and the redox potential decrease, and the soil density and concentrations of ferrous compounds increase in the soils of the trench zone. Accidents along pipelines occur most often in the area of serozems and chestnut soils, and this is related to the salinization in the lower soil horizons and to the contrasting soil water regime near the pipe. The number of accidents along the pipelines installed into soddy-podzolic soils is lower.     

Biochemistry of lignin in soils of periodic excessive moistening (from the Example of Agrogray Soils in Opolie Landscapes of the Russian Plain)

Tissues of Angiospermae (deciduous arborous and herbaceous plants) were found to take part in the formation of humus in the agrogray soils. The proportions of lignic phenol contents between the soils did not change neither upon their plowing, no their drainage. Within the catenas studied, the maximal accumulation of phenol compounds takes place in the soils of the mesodepressions with long-term reduction conditions and in the soils of the microdepressions with spring perched water on two levels. In the Fe-Mn nodules of the agrogray soils, lignin of higher plants was found. Its fractional composition was correlated with the predominant vegetation. With the increasing size of the nodules, the amount of products of lignin oxidation in the nodules decreased due to its mineralization. Drainage caused a deep transformation of lignin in the Fe-Mn nodules, especially in the coarse fractions of concretions. The mineralization of lignin aromatic compounds under aerobic conditions was accompanied by the significant increase in the share of phenol acids.     

Physical properties of soils and the simulation of the hydrothermal regime for the complex soil cover of the Vladimir Opol’e region

A methodological approach to the physically sound mathematical simulation of the hydrothermal regime for a complex soil cover on an agricultural field scale was proposed. To realize the approach, it is necessary (1) to restore the hydrothermal regime of two contrasting soils using a physically sound mathematical model on the basis of the experimental thermophysical and hydrophysical characteristics, (2) to adapt and optimize the model using the available experimental regime data, (3) to determine the hydrophysical and thermophysical properties for the entire plot under study using pedotransfer functions, and (4) to restore the hydrothermal regime of the entire soil plot using a mathematical model and the meteorological data for a specific time period. The proposed procedure allows simulating the hydrothermal regime of an agrogray soil complex in the Vladimir Opol??e region with a normalized standard error of about 8%. The analysis of the hydrothermal regime for the soil cover of the studied plot calculated from the meteorological data for the period from May to August of 2009 showed that the lower temperature values were confined to the areas of the agrogray soils with the second humus horizon: their average temperature was lower than the temperature of the agrogray soils by 0.44, 0.93, and 1.32°C at depths of 20, 40, and 70 cm, respectively, and the differences between their sums of the active temperatures for the considered period of 2009 reached 89 and 74°C at depths of 20 and 40 cm, respectively.     

施加粪肥对潮土有机磷形态转化的影响

施加粪肥是提高土壤肥力的重要措施,为了解粪肥磷在潮土中的化学行为,通过室内培养试验,采用NaOH-EDTA 浸提和 31P 核磁共振技术分析比较了鸡粪、牛粪及施肥后土壤中的磷形态及含量,并研究了施肥对潮土有效磷的影响。结果表明,粪肥磷主要以无机态形式存在,2 种粪肥的有机磷形态及含量有明显不同,肌醇六磷酸在鸡粪中的含量明显高于牛粪。粪肥施加到潮土后丰富了土壤有机磷的形态。随时间延长,潮土中各形态磷发生相互转化,以肌醇六磷酸为主的正磷酸单酯含量明显降低,核酸等正磷酸双酯显著升高。鸡粪处理的土壤有效磷含量逐渐升高,牛粪处理则表现出相反的趋势。施加粪肥后,土壤有效磷呈现不同的变化规律可能是无机磷在土壤中固定或沉淀,有机磷矿化和无机磷被微生物固持这三方面综合作用的结果。     

The regulatory role of soil in the functioning of undisturbed biogeocenoses of the southern taiga

The results of complex investigations concerning the specific features of undisturbed southern taiga biogeocenoses’ functioning were summarized for the biogeocenoses at the Central Forest State Biosphere Nature Reserve (Tver oblast). In the soils of the different topographic elements, the water and temperature regimes and the pools of carbon, nitrogen, phosphorus, and potassium in the litter and mineral horizons were studied, as well as the rate of the falloff and litter decomposition in field and laboratory tests, the microbial biomass pool and structure, the abundance and diversity of the soil mesofauna, and the microbial transformation of the nitrogen compounds. In the biogeocenoses investigated, the transformation of carbon and nitrogen compounds is shown to be controlled by the biochemical composition of the falloff and the structure of the soil biota, which, in turn, are determined by the specific features of the water regime and the acid-base soil properties.     

Soil phosphorus characterisation by 31p nuclear magnetic resonance

Abstract

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.     

Characterisation of organic phosphorus in overland flow from grassland plots using 31P nuclear magnetic resonance spectroscopy

Grazing animals are known to change the characteristics of agricultural grasslands as a source of and pathway for phosphorus (P) loss to water. Previous work, using physico-chemical analysis of the overland flow revealed that the presence of grazing animals increased the overall quantity of P being lost, in particular the unreactive and particulate P fractions. The aim of this study was to characterise the organic P (Po) fraction in overland flow from grazed and non-grazed grassland small plots using phosphorus-31 nuclear magnetic resonance (³¹P NMR) spectroscopy to give greater insight into P loss to water under simulated rainfall. The effect of the grazing animal was most pronounced in the dissolved unreactive P (DUP) and particulate unreactive P (PUP) fractions measured in overland flow from the grazed plots, over four times higher than from the non-grazed plots. Five distinct classes of P compounds were detected in the ³¹P NMR spectra, inorganic orthophosphate (δ = 6.83 ppm), orthophosphate monoesters (δ = 4.95–5.69 ppm), orthophosphate diesters (δ = 1.89 ppm), phosphonates (δ = 19.38 ppm), and pyrophosphates (δ = −3.26 ppm). Distinct signals at 5.69, 5.37, 5.10, and 4.95 ppm in the overland flow extracts from the plots indicated significant concentrations of myo -inositol hexakisphosphate in the orthophosphate monoester region. Orthophosphate diesters (assigned to phospholipids) and phosphonates were also only detected in overland flow collected from the grazed plot. These results indicate that normal grazing management practices may not only affect the concentrations of Po but also the forms of Po being transferred from grassland systems to water.