Phosphorus Stocks Research Articles

The enrichment of phosphorus in floodplain subsoils – A case study from the Antrift catchment (Hesse, Germany)

Deep phosphorus (P) stocks are considered a potential driver of freshwater eutrophication because they may temporarily transfer P to the groundwater and adjacent surface waters. The build-up of deep P stocks is not yet understood. Hence, their contribution to water quality impairment cannot be mitigated effectively. We conducted a field study with soil sampling and P fractionation in the laboratory to assess five scenarios how deep P stocks might develop. Our data show that deep P stocks result neither from primary bedrock/substratum features (geogenic loading) nor from primary pedological characteristics. Instead, they seem to originate from secondary processes, i.e., underground P translocation. The build-up of deep P stocks is indicated to be specifically driven by downslope translocation of P in the interflow, which leads to P enrichment of toeslope subsoils. Moreover, under low flow conditions, floodplain subsoils might become enriched with P by increased sorption of P from groundwater which is hydrologically connected with surface waters with high P concentrations. Gleysol groundwater dynamics did not prove to be a systematic driver of the build-up of deep P stocks. However, on certain sites, intensive groundwater dynamics might foster vertical P translocation and could hence contribute to deep P enrichment. Thus, enrichment of phosphorus in floodplain subsoils probably results interactively from several subsurface P translocation processes which might be weighted site-specifically.

Effects of spatial expansion of Phragmites australis and Cyperus malaccensis on distributions and stocks of phosphorus in marshes in the Minjiang River estuary, China.

To investigate the distributions and stocks of total phosphorus (TP) in plant-soil systems of marshes in Shanyutan of the Minjiang River estuary and explore its influencing factors, Phragmites australis (PA) marsh and Cyperus malaccensis (CM) marsh before spatial expansion and ecotonal marsh (EM, P. australis and C. malaccensis in EM were denoted by PA' and CM', respectively) during spatial expansion were studied. Results showed that, as affected by spatial expansion, the contents of TP in both plant and soil in different marshes showed great variations. Compared with PA and CM marshes, soil TP in EM increased by 20.0% and 7.1%, respectively. The variation of soil TP in EM might be attributed to the alteration of soil particle composition, plant bio-mass and root/shoot ratio during spatial expansion. Except for leaves, TP in organs of P. australis in P. australis-C. malaccensis community (PA') was lower than that in C. malaccensis in P. australis-C. malaccensis community (CM'), due to the differences in absorption, utilization and translocation way of P among organs between the two species. The competition effect caused by spatial expansion greatly changed plant P allocation ratio of the two species. Compared with PA and CM, the allocations of P in roots and leaves of PA' increased, while only that in roots of CM' rose. During spatial expansion, the two species might adopt different adaptation strategies for P absorption and utilization to maintain their competitiveness. The PA might compete primarily by strengthening the P accumulation capacities of its roots and promoting leaf photosynthesis, whereas the CM might resist the spatial expansion of PA by increasing its underground biomass to enhance P absorption.

Modeling Soil Responses to Nitrogen and Phosphorus Fertilization Along a Soil Phosphorus Stock Gradient

In this study, we investigate the responses of soil organic carbon (C) to nitrogen (N) and phosphorus (P) additions along a soil P stock gradient of five beech forest stands in Germany, using a modelling approach. Two different soil models with coupled C, N, and P cycles are used to simulate fertilization experiments conducted at the study sites. The first model, the stand-alone soil module of QUINCY (QUINCY-soil, Thum et al. 2019), is a conventional soil model that uses first-order kinetics to describe soil organic matter (SOM) turnover and represents microbial biomass only implicitly. The second model, the Jena Soil Model (JSM) (Yu et al. 2020), is a novel microbial soil model, which explicitly simulates microbial dynamics and describes the turnover of SOM as the consequence of several interactive processes, such as microbially mediated depolymerisation of litter and SOM, organo-mineral association, and vertical transport. We applied both site-level models to five study sites and compared the modeled soil profile with observations. In addition, model scenarios were conducted to simulate the fertilization of N and P, and we further evaluate the effect of soil P stock, plant litter quality, and SOM CNP stoichiometry, on the responses of soil (heterotrophic) respiration (Rs) to nutrient addition. We found that the fitness between simulated and observed SOM profiles (defined as normalized root mean square ratios, Knrmsr) were generally better in JSM than in QUINCY-soil (Knrmsr larger by 0.03±0.10 to 0.16±0.06 for various soil measurements at all sites); The general pattern of observed Rs responses to nutrient fertilization, that N addition decreases Rs whereas P addition increases it, can be reproduced by JSM but not by QUINCY-soil. Our results indicated that detailed explicit description of microbial processes and organo-mineral association is required to model plant-soil-microbial interactions, thus to better reproduce SOM profiles and their responses to nutrient additions. It highlights the need to better represent these processes in future model developments.

Hydrothermal carbonization of microalgae for phosphorus recycling from wastewater to crop-soil systems as slow-release fertilizers

Due to the finite stocks of phosphate rock and low phosphorus (P) use efficiency (PUE) of traditional mineral P fertilizers, more sustainable alternatives are desirable. One possibility is to culture microalgae in wastewater to recover the P and then convert the microalgae biomass into slow-release fertilizers through hydrothermal carbonization (HTC). Therefore, this study aimed to recycle P from wastewater to agricultural field using microalgae and HTC technology. Chlorella vulgaris (CV) and Microcystis sp. (MS) were cultured in poultry farm wastewater with an initial concentration of 41.3 mg P kg−1. MS removed 88.4% P from the wastewater, which was superior to CV. CV- and MS-derived hydrochars were produced at 200 or 260 °C, in solutions using deionized water or 1 wt% citric acid. The MS-derived hydrochar using 1 wt% citric acid solution at 260 °C (MSHCA260) recovered the highest amount of P (91.5%) after HTC. The charring promoted the transformation of soluble and exchangeable P into moderately available P (Fe/Al-bound P), and using citric acid solution as feedwater increased the P recovery rate and formation of Fe/Al-bound P. With the abundant moderately available P pool, hydrochar amendment released P more slowly and enhanced the soil P availability more persistently than chemical fertilizer did, which helped to improve PUE. In a wheat-cultivation pot experiment, MSHCA260 treatment improved wheat PUE by 34.4% and yield by 21.6% more than chemical fertilizer did. These results provide a novel sustainable strategy for recycling P from wastewater to crop-soil systems, substituting the mineral P fertilizer, and improving plant PUE.

Use of fermentation processes for improving the dissolution of phosphorus and its recovery from waste activated sludge

ABSTRACT Recycling phosphorus from waste activated sludge has attracted a lot of interest to tackle the problem of phosphorus stocks depletion and the increase in food demand. In this study, the use of fermentation processes was investigated to enhance phosphorus dissolution from waste activated sludge to improve its recycling. Two fermentation processes, bioacidification and dark fermentation, were used on two different sludges fermented with wheat starch syrup in continuous operating conditions. Hydrogen yield from the co-substrate fermentation with waste activated sludge reached 3.9 mmolH2.gCODcosubstrate −1 yield during dark fermentation process and was negligible during bioacidification. Dissolved phosphorus in the waste activated sludge increased by 68% during bioacidification and by 43% during dark fermentation. In both processes, phosphorus dissolution was accompanied by iron, calcium and magnesium dissolution. Results show that fermentation enhances phosphorus dissolution in waste activated sludge to improve its recovery along with hydrogen and organic acids.

ESTIMATION OF THE MINERAL PHOSPHORUS BALANCE STRUCTURE IN THE MOZHAISK STORAGE RESERVOIR BASED ON THE RESULTS OF MODEL CALCULATIONS

Based on the results of the calculation of 55‑year-long changes in mineral phosphorus in the Mozhaisk storage reservoir, the structure of its balance over the annual cycle and during the spring refill are considered. The flowchart of the processes modeled in the simulation model and the general equation for calculating mineral phosphorus concentrations are presented. The components of the phosphate balance studied here are phosphorus influx from bottom sediments during anoxic conditions near the bottom, phosphorus influx resulting from the metabolism of phytoplankton, zooplankton and fish, phosphorus influx as a result of dissolved organic matter mineralization, phosphorus discharge to the reservoir’s tailwaters, phosphorus intake in bottom sediments as a result of sorption and co-deposition, phosphorus consumption during phytoplankton photosynthesis. The ratio of external and internal mineral phosphorus flows was determined, and the dominant influence of phosphate inflow with river runoff on the amount of its accumulation in the reservoir was revealed. Variations of the above components of the phosphate balance across phases of the reservoir’s water regime were analyzed. The patterns in the fluctuations of the phosphate stock and the main components of phosphorus balance during the refill period are highlighted. The maximum phosphate storage ranged from 8.3 to 54.9 tons, with an average at 22.9 tons. The trend line for the maximum content of phosphates in spring since the initial filling of the reservoir until now has the form of a parabola with the maximum in the late 1990s. It is shown that the change of the mineral phosphorus stock in the reservoir is controlled by serial changes in inflow, sedimentation and consumption by phytoplankton.

Phosphorus stocks and flows in an intensive livestock dominated food system

Current use and management of phosphorus (P) in our food systems is considered unsustainable and considerable improvements in the efficiency of P use are required to mitigate the environmental impact of poor P stewardship. The inherent low P use efficiency of food production from animals means food systems dominated by livestock agriculture can pose unique challenges for improving P management. This paper presents the results of a substance flow analysis for P in the Northern Ireland (NI) food system for the year 2017 as a case study for examining P stewardship in a livestock dominated agricultural system. Imported livestock feed was by far the largest flow of P into the NI food system in 2017 (11,700 t ± 1300 t) and P from livestock excreta the largest internal flow of P (20,400 ± 1900t). The P contained in livestock slurries and manures alone that were returned to agricultural land exceeded total crop and grass P requirement by 20% and were the largest contributor to an annual excess soil P accumulation of 8.5 ± 1.4 kg ha−1. This current livestock driven P surplus also limits the opportunities for P circularity and reuse from other sectors within the food system, e.g. wastewater biosolids and products from food processing waste. Management of livestock P demand (livestock numbers, feed P content) or technological advancements that facilitate the processing and subsequent export of slurries and manures are therefore needed.

Long-term drought decreases ecosystem C and nutrient storage in a Mediterranean holm oak forest

Aridity has increased in recent decades in the Mediterranean Basin and is projected to continue to increase in the coming decades. We studied the consequences of drought on the concentrations, stoichiometries and stocks of carbon (C), nitrogen (N), phosphorus (P) and potassium (K) in leaves, foliar litter of a three dominant woody species and soil of a Mediterranean montane holm oak forest where soil-water content was experimentally reduced (15 % lower than the control plots) for 15 years. Nitrogen stocks were lower in the drought plots than in the control plots (8.81 ± 1.01 kg ha−1 in the forest canopy and 856 ± 120 kg ha−1 in the 0−15 cm soil layer), thus representing 7 and 18 % lower N stocks in the canopy and soil respectively. δ15N was consistently higher under drought conditions in all samples, indicating a general loss of N. Foliar C and K stocks were also lower but to a lesser extent than N. Decreases in biomass and C and N stocks due to drought were smallest for the most dominant tall shrub, Phillyrea latifolia, so our results suggest a lower capacity of this forest to store C and nutrients but also substantial resulting changes in forest structure with increasing drought.

Soil Phosphorus Translocation via Preferential Flow Pathways: A Comparison of Two Sites With Different Phosphorus Stocks

Weather events where a dry period is followed by a heavy rainfall event appear to affect phosphorus (P) exports through preferential flow pathways from forest soils. Furthermore, the P stock of a site seems to influence the amount of exported P. To explore this, we installed zero-tension lysimeters in three trenches at two sites with contrasting soil P stocks. Lysimeters were installed in three different depths (topsoil, upper subsoil and deep subsoil) to explore P depth transport. We covered the forest floor above the lysimeters with tarpaulins to simulate a dry period and afterwards artificially irrigated the area. This experiment was repeated three times at each site. Lysimeter samples were analyzed for concentrations of total P, organic and inorganic dissolved P and particle bound P (> 0.45 µm). Loads of P and water flow rates were calculated. Results reveal differences between sites, events and depths. At both sites, concentrations and loads of P in the topsoil lysimeters were higher than in the subsoil lysimeters. This difference was particularly evident at the low P site and emphasized its nutrient recycling efficiency. Dissolved inorganic P showed clear peaks in the topsoil lysimeters, whereby in the subsoil, particle-bound P peaks were partly noticeable at both sites. Depth transport of P into the subsoil depended on initial soil moisture, soil texture and the spatial distribution of flow pathways. Further, we observed large heterogeneity within a single site, dependent on profile-specific characteristics. We conclude that under certain conditions, there is a depth transport of P into the subsoil and therefore a potential of P loss, especially for particle-bound P. Heterogeneity of the sites hampered the clear identification of effects and illustrated the need for further research with a specific focus on the role of soil heterogeneity.

Cover cropping increased phosphorus stocks in surface sandy Ultisols under long‐term conservation and conventional tillage

AbstractLow use‐efficiency and high environmental significance of phosphorus (P) requires a better understanding of its stocks and behavior in soils. We investigated P fractions in sandy Coastal Plain Ultisols, where long‐term conservation agriculture driven by conservation tillage and residue return for ∼40 yr and the integration of cover cropping for 4 yr has been demonstrated to improve soil organic matter. Soils were collected from fields at 0‐ to 5‐ and 5‐ to 15‐cm depths to study the effects of tillage (conservation vs. conventional) and cover crop (with vs. without) on soil stocks of various chemically defined P pools and the phosphatase potential activities. Conservation tillage increased KCl‐extractable inorganic P (KCl‐Pi) stocks in top soils (0–5 cm) when compared to conventional tillage, but had no effects on other pools at both soil depths. Cover cropping caused significant accumulations of NaOH‐extractable organic P (NaOH‐Po) in top soils (0–5 cm). Nonetheless, neither conservation tillage nor cover crop changed the contributions of the chemically defined pools to soil total P with NaOH‐Po dominating at both soil depths followed by NaOH‐extractable inorganic P (NaOH‐Pi) and HCl‐extractable Pi (HCl‐Pi). Conservation tillage increased phosphatase potential activities by 128% in the 0‐ to 5‐cm soils, whereas no cover crop effects were observed. Conservation tillage improved P availability potentially through its effects on microbial activities, whereas cover cropping increased P stocks and availability by promoting Po accumulations.

Dynamics of carbon, nitrogen, and phosphorus stocks and stoichiometry resulting from conversion of primary broadleaf forest to plantation and secondary forest in subtropical China

Large-scale primary native broadleaf forests (BF) have been converted to secondary forests (SF) and plantation forests (PF) in subtropical China over the past decades. However, how and what magnitude of plant and soil carbon (C), nitrogen (N), and phosphorus (P) stocks and stoichiometry are affected by forest conversion is still vague. Here, we addressed this issue by systematically measuring tree biomass and the C, N, and P concentrations in tree organs and soils (0–100 cm) collected from 300 plots in Fujian province. With forest conversion of BF to PF, the tree C, N, and P stocks declined by 43.8, 47.9, and 63.1%, respectively, and the soil C and N stocks across whole soil depth decreased by 19.1% and 13.0%, respectively, and these decreases were more evident after conversion of BF to PF than SF. However, soil P stock showed a tendency of decreasing at 0–20 cm soil depth but increasing at 20–100 cm soil depth following conversion of BF to SF and PF. This unconformity of the vertical pattern of P stock in contrast to C and N stocks, was perhaps due to higher C and N inputs and greater P uptake from the subsoil and its redistribution to the topsoil in BF than in SF and PF. The tree and soil C, N, and P stoichiometry was strongly related to tree biomass, indicating that tree biomass was a vital factor driving soil inputs and retention of nutrients, and thus affecting their stoichiometry. The leaf N:P ratios ranging from 16.7 to 17.2 at our study sites suggested that co-limitations of N and P for forest growth could occur in the studied region. Our results provided insights into the C, N, and P linkages between soils and trees as affected by forest conversion, and advised that predicting these linkages could be an effective approach to identify the impacts of forest conversion, thereby implementing targeted conservation and rehabilitation actions.

Carbon and Macronutrient Budgets in an Alder Plantation Grown on a Reclaimed Combustion Waste Landfill

Combustion waste landfills are unfavorable for revegetation due to nitrogen deficiency, and therefore, the introduction of nitrogen-fixing organisms, such as alder species (Alnus sp.), may be promising for reclamation and restoration of these sites. We investigated the carbon and macronutrient stocks in the combustion waste technosols and biomass of black alder (Alnus glutinosa) and grey alder (Alnus incana) 10 years after introduction onto a combustion waste landfill. The alder species were planted with or without lignite addition in planting holes, the latter acting as control plots. Black alder biomass was higher than that of grey alder. The total macronutrient stocks were higher in the uppermost technosol layer (0–30 cm) than in the biomass nutrient stocks. However, the K and P stocks in the black alder biomass were still greater than the exchangeable K+ and available phosphorus (Pav) stocks in technosols. This is important for the nutrition of the trees planted in combustion waste landfills and confirms the Pav deficit in investigated technosols. The differentiation of nutrients in biomass shows that the largest stock was found in the wood of trunks and branches (40–70% of the stock of individual biomass macronutrients). Although foliage biomass represented approximately 7% of the total tree biomass, the nutrient stocks therein represented a significant proportion of total nutrient stocks: approximately 27–29% nitrogen, 17–22% calcium, 28% magnesium, 7–10% potassium and 12–16% phosphorus. This is particularly important in the context of the turnover of nutrients from litterfall and soil organic matter and the circulation of nutrients in the ecosystem developed on combustion waste technosols.

Poor physical structural components restrict soil fertility and crop productivity for wheat–maize cropping

Improving poor physical structural components has been gaining increasing recognition for its role in enhancing soil fertility. This study was conducted to identify the key physical structural barriers for soil fertility and their effects on crop productivity in Aquic Inceptisol. Based on the strip sampling in Fengqiu County, arable soils from 0–0.40 m profile pits were collected to determine the physical structural components including plough layer thickness, textural composition, soil aggregation and bulk density, as well as stocks of soil organic matter (SOM), total nitrogen (TN) and total phosphorus (TP). The grain yields of wheat and maize and amounts of fertilizer applications were also investigated. The tested soil was dominated by a plough layer of 0.15–0.18 m and sandy loam texture, which constituted 50% and 59%, respectively, of the studied profile pits. Compared to the soil with < 0.15 m plough layer, the bulk density was 4–11% lower in the plough layer and 4–12% lower in subsoil with increasing the thickness of plough layer. The soil with ≥ 0.15 m plough layer had over 21-fold macroaggregation at the expense of microaggregation, whereas the high content of sand particle in soil restrained macroaggregation. Increasing the plough layer thickness averagely improved the stocks by 176% in SOM, 153% in TN and 59% in TP at the 0–0.40 m depth. Soil macroaggregation was also significantly positively correlated with these nutrient accumulations. The factor analysis revealed that soil fertility was significantly influenced by the plough layer thickness and soil texture. The soil with 0.20–0.25 m plough layer and loam clay texture displayed the highest integrated fertility index and consequently, was beneficial to increasing the grain yields of wheat and maize and nutrient use efficiency from applied N fertilizer in the study area. These results would be informative to improve soil fertility and then crop productivity during a long-term cultivation.

Changes in Carbon Stocks and Chemical Attributes of an Oxisol as a Result of Adoption Period of No-tillage System in the Brazilian Eastern Amazon

The conversion of forest areas to grain cropping has promoted a decrease in soil organic matter stocks in the Amazon. This process is most striking when the conventional cultivation system is used. In order to evaluate the changes in soil carbon and nutrient stocks resulting from the time of adoption of the no tillage system in a dystrophic Yellow Oxisol of the Brazilian Amazon biome, a study was conducted in a grain producing area in the northeastern of Pará, Brazil. The treatments corresponded to the following systems: CT6- conventional tillage system with six years of implementation; No-tillage system with 3 (NT3), 4 (NT4) and 7 (NT7) years of implementation. All systems were always cultivated in corn / soybean rotation. Deformed and non-deformed soil samples were collected on a the 2013 crop year at 0-10, 10-20 and 20-40 cm depths. Stocks of carbon (SC) and phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) were calculated by using the equivalent soil mass methodology. Regardless of depth, the NT showed higher SC values than the CT. The adoption of NT showed a tendency of increasing SC of the soil over time. Such increases were up to 36% of the NT7 compared to the CT6. In NT7, the stocks of K, Ca and Mg were higher in relation to PC6. The EC correlated positively with the stocks of K, Ca and Mg in the areas under NT, regardless of the time of system adoption, up to 40 cm deep, indicating improvements in the soil fertility.

Grassland conversion along a climate gradient in northwest China: Implications for soil carbon and nutrients

AbstractSoil organic carbon (SOC) stocks and nutrient availability are key indicators of soil quality, and both can be influenced by land‐use change. However, it is still unclear whether the impact of land‐use change on SOC and nutrient stocks differs between ecoregions. Grasslands near the northeast border of the Qinghai‐Tibetan Plateau (QTP) occur across several ecoregions that have recently been subjected to substantial land‐use change. Based on long‐term land‐use history, we conducted a field investigation comparing soil C and nutrient stocks between natural grassland (NGL) and three types of converted grassland (agricultural grassland, AGL; farmland, FL; and abandoned farmland, AFL) in three ecoregions along a climate gradient: alpine meadow, temperate steppe and temperate desert. Compared with NGL, soil C stocks in converted grasslands were 22%–30% lower in the alpine meadow, but 60–82% higher in the temperate steppe and 6%–76% higher in the temperate desert. Converted grasslands also contained higher stocks of available nitrogen and phosphorus than NGL in the temperate steppe and desert. Soils (0–40 cm) in NGL contained 14.8 ± 0.1 kg C m−2 in alpine meadow, 6.7 ± 0.6 kg C m−2 in temperate steppe and 1.7 ± 0.3 kg C m−2 in temperate desert. Together, our results indicate that the responses of soil C and nutrients to grassland conversion differed between ecoregions. Thus, to optimize soil C sequestration rates and overall soil quality, we suggest that land‐use policies in this area should take into account local environmental conditions.

闽江口芦苇与短叶茳芏空间扩展对湿地土壤磷赋存形态的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 闽江口芦苇与短叶茳芏空间扩展对湿地土壤磷赋存形态的影响 DOI: 10.5846/stxb201906041194 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金面上项目（41971128）；福建省"闽江学者奖励计划"项目（闽[2015]31） Effects of spatial expansion of Phragmites australis and Cyperus malaccensis on distribution and stock of different phosphorus forms in marsh soils of the Min River estuary Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:选择闽江口鳝鱼滩的芦苇湿地、短叶茳芏湿地以及芦苇与短叶茳芏空间扩展形成的交错带湿地为对象，研究了不同湿地土壤磷赋存形态的分布特征及其主要影响因素。结果表明，不同湿地土壤中各形态磷含量整体表现为HCl-Pi > NaOH-Pi > Residual-P > NaHCO3-Pi > NaOH-Po > Sonic-Pi > Resin-Pi > NaHCO3-Po。其中，难分解态磷占TP的比例最高（Resin-Pi、NaHCO3-Pi、NaHCO3-Po），为48.3%-51.1%；中等易分解态磷次之（NaOH-Pi、NaOH-Po、Sonic-Pi、Sonic-Po），为37.4%-38.8%；而易分解态磷最低（HCl-P、Residual-P），为11.5%-12.9%。交错带湿地土壤中易分解态磷、中等易分解态磷和难分解态磷含量相对于纯群落湿地均发生了明显改变，其值相比芦苇湿地分别提高了10.6%、19.2%和22.6%，相比短叶茳芏湿地分别提高了1.6%、11.5%和16.6%，原因主要与二者空间扩展过程中交错带湿地土壤的理化性质特别是粒度组成、pH以及Fe、Al含量均较纯群落湿地发生明显改变有关。芦苇与短叶茳芏的空间扩展整体改变了湿地土壤的全磷（TP）含量和储量，相对于芦苇湿地和短叶茳芏湿地，交错带湿地土壤的TP含量分别增加了20.0%和7.1%，而磷储量分别增加了12.0%和18.0%。研究发现，芦苇与短叶茳芏的空间扩展不但改变了湿地土壤中磷的赋存状况，而且亦可能改变不同磷形态之间的转化。交错带湿地土壤磷赋存状况有助于缓解芦苇与短叶茳芏空间扩展过程中对磷养分的竞争压力，从而可能在一定程度上维持交错带湿地系统的相对稳定。 Abstract:To investigate the distributions and stocks of different phosphorus (P) forms in marsh soils in Shanyutan of the Min River estuary, the Phragmites australis marsh (PA), Cyperus malaccensis marsh (CM) and ecotonal marsh (P. australis-C. malaccensis marsh,PA-CM) were studied. The results showed that easily decomposed phosphorus (Resin-Pi, NaHCO3-Pi and NaHCO3-Po) in total phosphorus (TP) were 48.3%-51.1%, followed by moderately decomposition phosphorus (NaOH-Pi, NaOH-Po, Sonic-Pi, Sonic-Po) (37.4%-38.8%) and hardly decompose phosphorus (HCl-P and Residual-P) (11.5%-12.9%). The contents of easily decomposed phosphorus, moderately decomposed phosphorus, and hardly decomposed phosphorus forms in soils of PA-CM significantly increased by 10.6%, 19.2% and 22.6% compared with those in soils of PA, while increased by 1.6%, 11.5% and 16.6% compared with those in soils of CM, respectively. The reasons for it should be attributed to the alterations of physical and chemical properties in soils of PA-CM such as grain composition, pH, Fe and Al contents during spatial expansion. The spatial expansion of PA and CM also changed the contents of TP and the stocks of P in soils of PA-CM. Compared with PA and CM, the levels of TP in soils of PA-CM increased by 20.0% and 7.1% and the stocks of P increased by 12.0% and 18.0%, respectively. This paper found that the spatial expansion of PA and CM not only altered the distributions and stocks of phosphorus forms in marsh soil, but also changed the transformation of different phosphorus forms. The distributions and stocks of phosphorus forms in the soils of ecotonal marsh were favorable for alleviating the competitive pressure of phosphorus for P. australis and C. malaccensis during their spatial expansion, which, to some extent, might maintain the stability of the ecotonal marsh ecosystem. 参考文献 相似文献 引证文献

Effects of shrimp pond effluents on stocks of organic carbon, nitrogen and phosphorus in soils of Kandelia obovata forests along Jiulong River Estuary

Global aquaculture discharges are typical anthropogenic carbon and nutrient sources to nearby mangrove forests. In this study, we quantified total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP) stocks (0–50 cm) in soils from three sites of Kandelia obovata forests with different shrimp-pond discharge histories of 0, 8 and 14 years (i.e. 0DK, 8DK and 14DK, respectively). Results showed that shrimp pond effluents increased soil TOC densities at 8DK. TP densities gradually increased with discharge histories, whereas TN densities were similar between 8DK and 14DK. Besides, IsoSource analyses demonstrated that the high δ13C values of shrimp pond effluents contributed 30.00%–33.60% of mangrove soil TOC at 0–10 cm depth. These results suggested that shrimp pond effluents altered soil TOC, TN and TP stocks and added carbon source to mangrove soils, which was related to discharge histories and soil depth. Moreover, the discharge changed carbon and nutrient patterns, which warrant attention.

Carbon, Nitrogen, and Phosphorus Stocks from Fallow of Forage Legumes on Alfisols of Guinea Savanna Nigeria

The aim of this study was to assess soil carbon (C), nitrogen (N), and phosphorus (P) stocks from fallow of two forage legumes: Centrosema pascuorum (Cp) and Macrotyloma uniflorum (Mu) on Alfisols of Guinea Savanna, Nigeria. The study was conducted at the Institute for Agricultural Research (IAR) experimental field Samaru Zaria, Nigeria (2008 to 2009). Treatment consisted of 3 plots (Cp planted, Mu planted, and control - natural vegetation regrowth). Plot size was 5 m * 3 m = 15 m2 replicated three times for each treatment. Pre-experimental composite soil samples were taken with an auger at 0-15 depth. The soil samples collected were air-dried, grounded, sieved with a 2 mm sieve, and the less than 2 mm fraction was analysed for C, N, and P. The results of the analysis of soil organic C, total N, and available P were 6.1 gkg-1, 0.53 gkg-1, and 8.75 mgkg-1 respectively. Soil pH was 5.9. The plots were left fallow for one year and again soil samples were collected at 0-15 cm depth and analysed. The results showed that Cp significantly improved and had higher soil available P (13.74 mgkg-1) after one year followed by Mu (7.68 mgkg-1) and control (4.6 mgkg-1). On the other hand, the control plots significantly had highest soil organic C (5.9 gkg-1) compared to 5.2 and 3.7 gkg-1 from Cp and Mu. Similarly, higher total N (2.9 gkg-1) was recorded from control plots compared to 1.4 and 0.5 gkg-1 from Mu and Cp respectively. Results from this study indicate that one year fallow of cultivated Cp has potential to improve soil available P compared to Mu and natural vegetation regrowth. In terms of plant nutrient uptake, the N and P content of Mu was the highest (4.28 and 2.65 % respectively). The natural vegetation from the control plots had the lowest (1.95 %) N concentration. There was no significant difference in the P content of the natural vegetation from the control plots and Cp (1.92 and 1.84 % respectively). Fallow periods of more than a year of cultivated Centrosema pascuorum and Macrotyloma uniflorum or their incorporation into soils are suggested for further studies.

Phosphorus recovery from sewage with a sustainable and low-cost treatment system.

This study proposes a technology conceived based on an integrative approach that aims to promote phosphorus recovery and to recycle ferric water treatment sludge (FWTS), using it as a phosphorus adsorbent which may be applied as a soil ameliorant after reaching saturation. The assessed pilot plant operated with a daily influent flow of 360 litres and presented a removal efficiency of 94.4% ± 3.2% for chemical oxygen demand (COD) and of 91.2% ± 7.8% for suspended solids. It also presented promising results for phosphorus removal. The maximum efficiency of dissolved reactive phosphorus removal was 95% on the first day and it decreased until reaching adsorbent saturation. The estimated breakthrough time was one year in the condition in which the filling medium of a second constructed wetland was only FWTS. In this situation, the effluent phosphorus concentration was 0.2 mg·L-1. The authors concluded that the application of FWTS in a constructed wetland bed is an interesting alternative. Batch adsorption experiments were run using phosphorus stock solution. Langmuir and Freundlich adsorption isotherm models were obtained for different initial pH values. The maximum adsorption capacity decreased as the initial pH was increased; values ranged from 4.76 mg P·g-1 (pH = 3.9) to 1.44 mg P·g-1 (pH = 9.0).

Changes in the stocks of soil organic carbon, total nitrogen and phosphorus following afforestation of post-arable soils: A chronosequence study

The objective of this study was to investigate the effect of afforestation of post-arable sandy soils (Dystric Arenosols) with Scots pine (Pinus sylvestris L.) on the amount and distribution of Corg, Ntot and Ptot stocks between genetic soil horizons. The study was performed at three locations with five classes of afforestation each: 10-, 20-, 30-, 40-, 50-year-old stands, which additionally included the arable and the continuous forest soils as reference. The soil was sampled by genetic horizon, including the organic one, down to 100 cm, from its whole thickness, and from A horizon of the afforested soils from: 0–5, 5–10 and 10–20 cm. In the organic horizon of the afforested soils, the stock of Corg, Ntot and Ptot increased significantly with stand age, and an average rate of accumulation was 33.6, 1.30 and 0.04 g m−2 year−1 respectively. Corg stocks in the former plough layer were found to decrease within the first decade of afforestation, and subsequently, the values gradually increased. With organic horizon included the respective stocks reached the level comparable with the related horizon of the arable soil after approx. 20–30 years. Subsoil B, BC and C horizons together accounted for approx. 35% of the Corg stocks in the entire profile. Ntot stocks in mineral soil horizons initially dropped in the first decade after afforestation, which was subsequently followed by an increase; however, after 50 years, still the observed values were lower in comparison with both the respective arable and continuous forest soils. Ptot stocks in the mineral soil horizon declined over the chronosequence, and in the profile at 50-year-old stands, they were lower in comparison with both the arable and the continuous forest soils. Stand age and sampling by genetic horizons, including the organic horizon, from the entire soil profile should be considered for estimation of changes in Corg, Ntot and Ptot stocks following afforestation of agricultural soils.