Risk Of Phosphorus Loss Research Articles

Environmental influences on soil phosphorus dynamics and eutrophication risks in the Three Gorges reservoir Area, Chongqing section

The spatial distribution of soil phosphorus fractions (SPFs) in the Three Gorges Reservoir area (TGRA) is crucial for evaluating water quality and lake eutrophication in the lower reaches of the Yangtze River. Besides, it is also unclear whether climate change and rising elevation will alter the risk of phosphorus loss in this region. To address this knowledge gap, soil samples were extensively collected in Chongqing section of the TGRA and extracted SPFs using a rapid sequential extraction method. Results indicated that Ustifluvents, Haplustepts, and Kanhaplustults are suitable for cultivation but also prone to the risk of phosphorus leaching due to high labile phosphorus concentration. Increased temperature positively affected labile and medium-stable phosphorus, while increased precipitation accelerated phosphorus leaching. Solar radiation has significant effects on medium-stable and stable phosphorus. Additionally, multivariate and redundancy analysis showed that different SPFs were influenced by various environmental factors, but elevation is the predominant factor affecting most SPFs in the TGRA. Northeastern TGRA and areas with lower elevations on both sides of the Yangtze River were more susceptible to phosphorus leaching. This study is expected to provide decision-makers with references and help manage the regional environment in the context of climate change.

Manure derived hydrochar reduced phosphorus loss risk via an alteration of phosphorus fractions and diversified microbial community in rice paddy soil

Phosphorus (P) loss caused by the irrational use of manure organic fertilizer has become a worldwide environmental problem, which has caused a potential threat to water safety and intensified agricultural non-point source pollution. Hydrothermal carbonization is method with a low-energy consumption and high efficiency to deal with environmental problems. Application of pig manure-derived hydrochar (PMH) to soil exhibited potential of sustainable development compared with the pristine pig manure (PM). However, the effects of PMH on the distribution of P among the fractions/forms and the interaction between microorganisms and P forms and its relevance to the potential loss of P in paddy fields has not been clarified. Therefore, in this study, a soil column experiment was conducted using the untreated soil (control), and the PM, PMH1 (PMH derived at 180 °C), and PMH2 (PMH derived at 260 °C) treated soils (at the dose of 0.05 %) and rice was cultivated to investigate the effects of PM and PMH on the P fractions, mobilization, ad potential loss via the induced changes on soil microbial community after a complete growing season of rice. The trend of P utilization was evaluated by P speciation via continuous extraction and 31P NMR. The addition of PMH reduced the proportion of residual P in soil by 23.8–26.3 %, and increased the proportion of HCl-P and orthophosphate by 116.2–158.6 % and 6.1–6.8 % compared to PM. The abundance of gcd gene developed after the application of PMH2, which enhanced the mobile forms of soil P utilization via secreting gluconic acid. The network diagram analysis concluded that the changes in various P forms were mainly related to Proteobacteria, Bacteroides, Firmicutes and Acidobacteria. The results illustrated that PMH mitigate the potential risk of P loss more than PM by altering P fractions and affecting soil microbial community.

Urbanization increases the risk of phosphorus loss in sandy soils of tropical ecosystems

Phosphorus (P) is naturally present in soils. However, urbanization can promote additional inputs of P into the soil that lead to saturation of the binding sites exceeding the maximum sorption capacity. Soils saturated with P act as important diffuse sources of pollution of water resources. The flow of P from the soil to aquatic ecosystems is an aggravating factor for water scarcity, especially in the semiarid region. Knowing phosphorus dynamics in the soil is essential to protect water quality and ensure its multiple uses. In this paper, a total of fifty soil samples, twenty-five from natural soils and twenty-five from urban soils, were evaluated for the effect of urbanization on P sorption characteristics and their relationship with the physical and chemical attributes of the soil. The soil samples were characterized physically and chemically, and the P sorption characteristics were obtained from the adjustment of Langmuir and Freundlich equations by nonlinear regression. Urbanization results in increased soil P saturation and reduced P sorption capacity. Our results show that the sandy texture of the soils studied had a standardizing effect on the soil's physical properties, maintaining, even after urbanization, the physical quality similar to natural soil. In contrast, pH (in water and KCl), base saturation, sodium saturation, potential acidity, exchangeable Al3+, exchangeable Mg2+, available P, and P-rem are valuable indicators in the segregation between natural and urban soils. The reduction of P sorption capacity in urban soils increases the risks related to P loads in aquatic ecosystems that experience urban expansion worldwide. These data serve as a basis for decision-making regarding the appropriate soil monitoring and management of urban expansion areas in watersheds to control P flow to aquatic systems.

Biochar or Straw Substituting Chemical Fertilizer Increase the Risk of Phosphorus Loss in Subsurface Runoff in Sloping Farmland

The purple soil slope farmland is an important agricultural land in southwest China but is also one of the main sources of agricultural non-point source pollution in the Three Gorges Reservoir area. Taking reasonable measures to control the loss of soil nutrients is of great significance to the treatment of non-point source pollution in the region. Here, a three-year (2018-2020) field runoff experiment was conducted to monitor and evaluate the phosphorus (P) loss in sloping farmland via surface runoff (i.e., surface flow, 0-20 cm) and subsurface runoff (i.e., subsurface flow, 20-60 cm), with five treatments including no fertilization (CK), conventional fertilization (CF), optimal fertilization (OF), biochar combined with 85% of OF (BF), and straw combined with 85% of OF (SF). The results showed that fertilization application reduced the sediment yields and surface runoff flux but increased the subsurface runoff flux. The total loss flux of phosphate (PO3-4-P), total phosphorus (TP), and particulate phosphorus (PP) in surface flow were the highest in the BF treatment and the lowest in the SF treatment. All fertilization applications increased the P loss fluxes in subsurface flow relative to that in CK. The highest PO3-4-P and TP loss flux in subsurface flow was found in the BF (213.88 g·hm-2 and 694.54 g·hm-2, respectively) treatment, followed by that in the OF and SF treatments. Redundancy analysis (RDA) results showed that surface runoff flux and biochar application were the main factors contributing to increased P loss in surface flow, and subsurface runoff flux was the main factor contributing to increased P loss in subsurface flow. In summary, the SF treatment reduced the amount of sediment yield and surface runoff flux in sloping farmland of purple soil and was the most effective for controlling P loss, whereas the risk of subsurface runoff flux requires further attention.

Responses of total, reactive and dissolved phosphorus pools and crop yields to long-term fertilization

Maintaining an appropriate soil phosphorus level is key to ensure sustainable phosphorus management for crop production and to minimise phosphorus losses to water bodies. However, the effects of long-term fertilization on different soil phosphorus pools, crop yields and phosphorus loss risk remain unclear. This requires insights into the responses of soil phosphorus pools, crop phosphorus uptake with related crop yields and phosphorus loss to long-term phosphorus inputs. Changes in four soil phosphorus pools (PCACL2, POLSEN, POX and PTOTAL, respectively) and crop yield responses to various fertilization rates were examined in a 29-year long-term phosphorus fertilization experiment in China. Results showed that the increase in the four soil phosphorus pools was proportional to the accumulated phosphorus surplus, i.e., the input minus uptake. POLSEN and POX increased linearly with continuous phosphorus application and peaked at a phosphorus accumulation near 3200 kg P ha−1. Beyond this threshold, continuous phosphorus application caused a gradual increase in PTOTAL and a linear increase in PCACL2, which implies an increasing risk for leaching. The POX pool accounted for 87% of the accumulated phosphorus surplus until soil phosphorus saturation occurred. The crop yields of wheat and maize responded clearly to changes in PTOTAL, POX, POLSEN and PCACL2, with POX explaining most of the yield variation. Furthermore, POX was highly correlated with PCACL2, being a risk indicator for phosphorus leaching. Given that POX explains best how much of phosphorus surplus accumulates in soil, the variation in crop yield, and the risk for P leaching, it can be used as a valuable and reliable indicator to manage phosphorus sustainably.

Targeting the critical source areas of phosphorus based on hydrological sensitive area delineation to control nonpoint source pollution in watersheds

To pursue higher agricultural output, farmers have invested heavily in fertilizers, pesticides and other factors of production, which inevitably causes agricultural nonpoint source pollution (ANPSP) and seriously restricted the sustainable development of global agriculture. Accurate and efficient integrated prevention and control of ANPSP requires scientific identification of critical source areas and influencing factors of nonpoint source pollution, which is particularly important in geographic conditions where steep-slope agriculture dominates and landscape features are complex. In this study, a typical small watershed in the mountainous area of the Three Gorges Reservoir area was selected, and the risk of nonpoint source phosphorus loss in the watershed was assessed using the Phosphorus Index (PI) on the basis of Soil Topographic Index (STI) prediction of runoff production area in the watershed. Finally, the critical source areas (CSAs) for its loss were identified. The results showed that the area of hydrologically sensitive areas in the watershed was approximately 22.87% of the total study area, with an area of 37.05 hm2. The hydrology of variable source areas within hydrologically sensitive areas plays a dominant role and is more likely to produce runoff and increase the risk of agricultural nonpoint source phosphorus pollution. The results of PI analysis showed that the risk of phosphorus loss was low in most areas of the watershed (45.77%), the areas at high risk of phosphorus loss accounted for 29.33% of the entire watershed with an area of 47.52 hm2, and tea plantation was the most dominant land use type. The critical source area of nonpoint source phosphorus output accounts for 5.47% of the watershed area and is mainly distributed along the watershed system, 82.55% of which is tea plantation. Compared with the traditional phosphorus index evaluation system, this method is important for the accurate identification of critical source areas of nonpoint source pollutants, for strengthening the efficient prevention, control and management of ANPSP, and for improving the utilization rate of arable land as well as land management and sustainable development of watersheds.

Periodic phosphorus fertilization is beneficial to lowering potential risk of phosphorus loss from Inceptisols

Periodic phosphorus fertilization is beneficial to lowering potential risk of phosphorus loss from Inceptisols

Distribution Characteristics and Risk Assessment of Agricultural Land Use Non-Point Source Pollution in Typical Biofuel Ethanol Planting Areas.

Speeding up the promotion and application of bio-fuel ethanol was a national strategy in China, which in turn affected changes in the raw material planting structure. This study analyzed the distribution of nitrogen and phosphorus forms in water bodies and the soil of the typical maize and cassava fuel ethanol raw material planting areas. The results revealed that the maize planting area faced more serious TN and TP pollution. The river pollution was greatly affected by TN, TP, Ex-P and Fe/Al-P in soil, while soil TN and NO3−-N were the main factors influencing its counterpart. Furthermore, the risk assessment of soil nitrogen and phosphorus loss was carried out based on planting structures of crops. We investigated whether the water quality indexes or soil nitrogen and phosphorus loss risk assessment results showed that the Yujiang River stayed significantly less polluted. It was proven that the cassava planting area was more suitable for vigorously developing fuel ethanol. As for the high-risk areas, ecological agriculture promoting and fertilizer controlling measures were suggested. Under the change of the fuel-ethanol policy, this study could provide scientific support for the assessment of the impact of the Chinese national fuel ethanol policy on the water environment of the raw material planting area.

Impact of sewage sludge, nanoparticles, and clay minerals addition on cucumber growth, phosphorus uptake, soil phosphorus status, and potential risk of phosphorus loss

There is little information about the impact of sewage sludge, nanoparticles, and clay minerals on cucumber ( Cucumis sativus L.) growth and phosphorus content in different plant parts. In this study we treated a soil with different rates of sewage sludge (1%, 5%, and 10%), along with two nanoparticles (SiO 2 and nano-montmorillonite at 0 and 1%), and two clay minerals (zeolite and vermiculite at 0 and 3%). We aimed at investigating the impact of these amendments on cucumber growth, phosphorus content in root, shoot, and fruit, phosphorus content in rhizosphere and non-rhizosphere soils, and determining the impact of these amendments on the potential risk of phosphorus loss from soil. Plant growth in the soil treated with sewage sludge at 1% and 5% was higher than that at 10% sewage sludge, while the cucumber in the 10% sewage sludge plus 1% nano-montmorillonite-treated soil dried out. Phosphorus content in fruit was higher than in root and phosphorus in root was higher than that in shoot. Cucumber plant in the 10% sewage sludge treated soil had the highest amount of phosphorus compared to the other treatments, while plants in the nanoparticles and clay minerals treatments had lower content of phosphorus than the control. The highest phosphorus content was extracted from soil treated with 10% sewage sludge, while the lowest was extracted from the soil treated with nanoparticles and clay minerals. In average of all treatments, soil phosphorus extracted by water-extractable phosphorus in the rhizosphere soil was higher than phosphorus in the non-rhizosphere soil. The results indicated that calcium chloride-extractable phosphorus was more effective in predicting phosphorus uptake than water-extractable phosphorus and Olsen-extractable phosphorus. Also, the soil treated with sewage sludge at 5% and 10% would potentially increase the risk of phosphorus losses. We concluded that the soil treated with 1% sewage sludge, with or without nanoparticles or clay minerals, could provide the amount of phosphorus required for the growth of cucumber, while there was no obvious potential risk of phosphorus loss, making this treatment more beneficial for cucumber. • Cucumber growth increased in soil at 1% sewage sludge; no phosphorus loss occurred. • Highest plant phosphorus was observed in soil at 10% sewage sludge. • Correlation of root P and CaCl 2 -extracted P was highest.

One size does not fit all: Toward regional conservation practice guidance to reduce phosphorus loss risk in the Lake Erie watershed.

Agricultural phosphorus (P) losses to surface water bodies remain a global eutrophication concern, despite the application of conservation practices on farm fields. Although it is generally agreed upon that the use of multiple conservation practices ("stacking") will lead to greater improvements to water quality, this may not be cost effective to farmers, reducing the likelihood of adoption. At present, wholesale recommendations of conservation practices are given; however, the application of specific conservation practices in certain environments (e.g., no-till with surface application, cover crops) may not be effective and can even lead to unintended consequences. In this paper, we present the Lake Erie watershed as a case study. The Lake Erie watershed contains regions with unique physical geographies that include differences in climate, soil, topography, and land use, which have implications for both P transport from agricultural fields and the efficacy of conservation practices in mitigating P losses. We define major regions within the Lake Erie watershed where common strategies for conservation practice implementation are appropriate, and we propose a five-step plan for bringing regionally tailored, adaptive, and cost-conscious conservation practice into watershed planning. Although this paper is specific to the Lake Erie watershed, our framework can be transferred across broader geographic regions to provide guidance for watershed planning.

Simple assessment of farmland soil phosphorus loss risk at county scale with high landscape heterogeneity

In order to improve the existing phosphorus index assessment methods, using the interactive evaluation index (IEI) as an auxiliary variable, the geographically weighted regression (GWR) was adopted as prediction means. A method of regional soil phosphorus risk assessment was constructed by modifying phosphorus index model (MPIM). The GWR-IEI method more accurately predicted available phosphorus (AP) and soil organic matter (SOM), and the prediction precision and goodness of fit were high. Compared with the ordinary least square (OLS) method, the relative improvement of the root mean squared errors (RMSE) with the GWR-IEI method reached 28.95% for available phosphorus predicted, while that of SOM was 21.24%. The phosphorus loss risk of most of the study area (95.29%) was moderate to low. The areas featuring an extremely high phosphorus loss accounted for merely 0.33% of the total research area. Phosphorus loss depends on the effects of many factors. Areas which have strong source or transfer factors are not necessarily high-risk areas for phosphorus loss. Only the co-occurrence of transfer and source factors leads to high risk and greater potential for phosphorus loss. The GWR-IEI-MPIM method accurately reflected the degree of risk for phosphorus at the regional scale, which provides a valuable reference for risk assessment of phosphorus. Keywords: high landscape heterogeneity, GWR, county scale, simplified assessment DOI: 10.25165/j.ijabe.20211402.6185 Citation: Ning H R, Liu Q M, Zhang S W, Ye H C, Shen Q, Zhang W T, et al. Simple assessment of farmland soil phosphorus loss risk at county scale with high landscape heterogeneity. Int J Agric & Biol Eng, 2021; 14(2): 126–134.

Simple assessment of farmland soil phosphorus loss risk at county scale with high landscape heterogeneity

In order to improve the existing phosphorus index assessment methods, using the interactive evaluation index (IEI) as an auxiliary variable, the geographically weighted regression (GWR) was adopted as prediction means. A method of regional soil phosphorus risk assessment was constructed by modifying phosphorus index model (MPIM). The GWR-IEI method more accurately predicted available phosphorus (AP) and soil organic matter (SOM), and the prediction precision and goodness of fit were high. Compared with the ordinary least square (OLS) method, the relative improvement of the root mean squared errors (RMSE) with the GWR-IEI method reached 28.95% for available phosphorus predicted, while that of SOM was 21.24%. The phosphorus loss risk of most of the study area (95.29%) was moderate to low. The areas featuring an extremely high phosphorus loss accounted for merely 0.33% of the total research area. Phosphorus loss depends on the effects of many factors. Areas which have strong source or transfer factors are not necessarily high-risk areas for phosphorus loss. Only the co-occurrence of transfer and source factors leads to high risk and greater potential for phosphorus loss. The GWR-IEI-MPIM method accurately reflected the degree of risk for phosphorus at the regional scale, which provides a valuable reference for risk assessment of phosphorus. Keywords: high landscape heterogeneity, GWR, county scale, simplified assessment DOI: 10.25165/j.ijabe.20211402.6185 Citation: Ning H R, Liu Q M, Zhang S W, Ye H C, Shen Q, Zhang W T, et al. Simple assessment of farmland soil phosphorus loss risk at county scale with high landscape heterogeneity. Int J Agric & Biol Eng, 2021; 14(2): 126–134.

鹭鸟栖息对杭州湾湿地土壤磷累积及形态分布的影响

土壤中磷含量对维持生态系统平衡起着重要作用。为研究杭州湾湿地迁徙候鸟栖息以及鸟粪的输入对栖息地土壤生态环境的影响，开展了鹭鸟筑巢树林下（影响区）和无鹭鸟筑巢树林下（对照区）土壤磷累积、土壤及鸟粪磷形态分布研究。结果表明：鹭鸟影响区土壤有机碳（Soil Organic Carbon，SOC）、全氮（Total Nitrogen，TN）、全磷（Total Phosphorus，TP）、有效磷（Available Phosphorus，AP）含量显著高于对照区（P<0.05）；对照区土壤TP含量为718.33 mg/kg，影响区土壤TP平均含量最高可达2040 mg/kg，其中钙结合态磷（Ca-bound P，Ca-P）含量最高，约占55.22%-62.96%，其次是残渣态磷（Residual Phosphorus，RP）、有机磷（Organic Phosphorus，OP）、铁铝结合态磷（Fe/Al-bound P，（Al+Fe）-P））、交换态磷（Exchangeable P，Exch-P）。鸟粪中有机碳（Organic Carbon，OC）、TN、TP含量分别是表层土壤的11.18-40.90倍，94.22-148.11倍，15.41-43.22倍，差异极显著（P<0.01）。TP含量与Exch-P、（Fe+Al）-P、Ca-P、AP极显著正相关，与RP显著正相关，与pH显著负相关。结果表明鸟粪输入使杭州湾湿地土壤TP含量显著提高，Exch-P、（Fe+Al）-P、Ca-P、AP含量均有提高，且占TP百分比增大，鸟粪输入造成了该地土壤磷素累积的同时增加了土壤磷素的流失风险。;The content of phosphorus in soil plays an important role in maintaining the balance of the ecosystem. In order to study the impact of migratory birds inhabiting and dropping guano on the soil ecological environment in Hangzhou Bay wetland, the research of phosphorus accumulation and distribution of various forms of phosphorus in soil and guano was carried out in the area with or without egrets inhabiting (affected area and controlled area). The results showed that the content of Soil Organic Carbon (SOC), Total Nitrogen (TN), Total Phosphorus (TP) and Available Phosphorus (AP) in the egrets effecting area was significantly higher than that in the controlled area (P<0.05). The soil TP content in the controlled area was 718.33 mg/kg, which was up to 2040 mg/kg in the affected area. The content of Ca-bound P (Ca-P) rank first among all these forms of phosphorus, accounting for about 55.22—62.96%, followed by Residual Phosphorus (RP), Organic Phosphorus (OP), Fe/Al-bound P ((Fe+Al)-P) and Exchangeable P (Exch-P). The contents of Organic Carbon (OC), TN, and TP in guano were 11.18—40.90 times, 94.22—148.11 times and 15.41—43.22 times of the soil, showing significant difference (P<0.01). TP content showed extremely significantly positive correlations with Exch-P, (Fe+Al)-P, Ca-P, AP, significantly positively correlated with RP, while significantly negatively correlated with pH. Generally, the content of TP in soil of Hangzhou Bay wetland was significantly increased due to guano input. The content of Exch-P, (Fe+Al)-P, Ca-P and AP were all increased, so as the percentages of them did in TP. Input of guano caused the accumulation of phosphorus in the soil which increased the risk of phosphorus loss from the soil, as well.

Evidence and perception of phosphorus loss risk factors in farmyards

Farmyards present potential point sources of phosphorus loss to watercourses, affecting their ecological quality and attainment of environmental goals. Unlike many relatively simple point sources, farmyards are complex sub-systems within the wider agricultural setting, including individual runoff, management and infrastructure factors which influence the risk (likelihood and magnitude) of phosphorus loss. Comparison across these factors is confounded by heterogeneity in farmyard design and management, however, weighting of individual factors will support estimation of the relative riskiness of farmyards. This will allow identification of appropriate mitigation measures and evaluation of cost-benefit ratios. The aim of this study is to evaluate the riskiness of runoff, management, and infrastructure factors on phosphorus loss from farmyards to water, using expert opinion and to evaluate whether those estimates are supported by the literature. A survey of research, advisory and policy stakeholders was conducted (147 respondents) in which individuals rated the importance of individual factors from 0 (having no impact) to 10 (having critical impact) on phosphorus loss from farmyards. The most highly ranked factors were within the infrastructure category, followed by runoff and finally management factors. Factors relating to silage effluent and slurry storage were assigned the greatest risk (≥8.4). Runoff factors were also high risk but may be difficult to mitigate compared to infrastructure. Management factors were rated lower by all stakeholder groups but may offer low cost options to offset more intransigent risks. High consensus was observed between stakeholder groups, with significant differences in risk ratings for only 8 out of 29 individual factors.

Risk of phosphorus losses from Andosols under fertilized pasture.

Fertilization of grassland pastures may be a non-point pollution source in the Azores archipelago, despite the high phosphorus (P) retention of Andosols. To evaluate the risk of P desorption, representative Andosols samples (0-15cm) were subdivided in five layers and different P pools were measured. The risk of P unloading into waters was assessed by the degree of phosphorus saturation (DPS), and by the P concentration in equilibrium solutions (0.01M CaCl2). The higher contents in the superficial layers suggest P accumulation due to pasture overfertilization. The organic P represented about 54% of the total P, with an overall average of 2.66g Pt/kg. Despite being above the agronomic threshold, the soil with the highest average mean values of extractable inorganic P, 77mg POlsen/kg and and 73.7mg PAL/kg, is still below environmental thresholds and none of the soils had DPS values above 25%, which is the critical value associated with eutrophication of surface waters. Similarly, all the P concentrations in the equilibrium CaCl2 solutions were below the critical limits. Therefore, P desorption from these soils did not seem to be the main process responsible for effective waterbodies eutrophication in the Azores. Since mineral fertilizers are applied superficially, the hypothesis of their direct runoff during rainfall events, even before their complete dissolution and interaction with the soil matrix, must be considered. Consequently, P fertilization with deep-banding systems may be the alternative to the interdiction of fertilizers in the most sensitive and hilly areas of the watersheds.

Risk of phosphorus losses in surface runoff from agricultural land in the Baltic Commune of Puck in the light of assessment performed on the basis of DPS indicator.

BackgroundIn order to counteract the eutrophication of waterways and reservoirs, a basic risk assessment of phosphorus (P) losses in the surface runoff from agricultural land should be included in water management plans. A new method has been developed to assess the risk of P losses by estimating the degree of P saturation (DPS) based on the P concentration of the water extract water-soluble P.MethodsThe risk of P losses in surface runoff from agricultural land in the Puck Commune on the Baltic Sea Coast was assessed with the DPS method. The results were compared to an agronomic interpretation of the soil test P concentration (STP). Research was conducted on mineral and organic soils from 50 and 11 separate agricultural plots with a total area of 133.82 and 37.23 ha, respectively. Phosphorus was extracted from the collected samples using distilled water on all soil samples, acid ammonium lactate on mineral soils, and an extract of 0.5 mol HCl·dm−3 on organic soils. The organic matter content and pH values were also determined. The results of the P content in the water extracted from the soils were converted into DPS values, which were then classified by appropriate limit intervals.Results and discussionThere was a high risk of P losses from the soil via surface runoff in 96.7% of the agricultural parcels tested (96% of plots with mineral soils and 100% of plots with organic soils). Simultaneously, a large deficiency of plant-available P was found in soils from 62% of agricultural plots. These data indicate that the assessment of P concentration in soils made on the basis of an environmental soil P test conflicts with the assessment made based on STP and create a cognitive dissonance. The risk level of P losses through surface runoff from the analyzed plots as determined by the DPS indicator is uncertain. This uncertainty is increased as the DPS index is not correlated with other significant factors in P runoff losses, such as the type of crop and area inclination.

Change in the Distribution of Phosphorus Fractions in Aggregates under Different Land Uses: A Case in Sanjiang Plain, Northeast China.

Phosphorus in agro-ecosystems has attracted much attention due to its impact on the nutrient supply of plants and the risk of loss of non-point source pollution. This study investigated the fraction distribution and release of phosphorus from soil aggregates structure under different land uses (rice, maize and soybean). The soil aggregates were characterized as large macro-aggregates (L-mac, >1 mm), small macro-aggregates (S-mac, 0.25–1 mm), micro-aggregates (MIC, 0.053–0.25 mm) and silt clay (SC, <0.053 mm) with the wet-sieving method. A sequential chemical extraction scheme was used to separate phosphorus into labile inorganic phosphorus (L-Pi), labile organic phosphorus (L-Po), moderately labile organic phosphorus (Ml-Po), iron-aluminum bound phosphorus (Fe.Al-P), calcium-magnesium bound phosphorus (Ca.Mg-P), humic phosphorus (Hu-P) and residual phosphorus (Re-P). Experimental results indicated that soil aggregates were mainly S-mac and MIC, followed by L-mac and SC, and they accounted for 52.16%, 25.20%, 14.23% and 8.49% in rice fields, 44.21%, 34.61%, 12.88% and 8.30% in maize fields, and 28.87%, 47.63%, 3.52% and 19.99% in soybean fields, respectively. Total nitrogen (TN), soil organic matter (SOM), Fe and Mn in soil aggregate fractions decreased with the reduction in soil aggregate grain-sizes. For phosphorus fractions (P-fractions), Fe.Al-P and Re-P tended to condense in L-mac and S-mac. MIC and SC were the primary carriers of Ca.Mg-P. Adsorption isotherm simulation results demonstrated that L-mac and S-mac have a strong capacity to retain phosphorus. In rice fields, phosphorus bioavailability and utilization rate were high. However, the P-fractions there were easily changed under aerobic-anaerobic conditions. Therefore, the risk of phosphorus loss during drainage should be given considerable attention.

长三角平原区县域土壤磷素流失风险及其空间不确定性的快速评估

PDF HTML阅读 XML下载 导出引用 引用提醒 长三角平原区县域土壤磷素流失风险及其空间不确定性的快速评估 DOI: 10.5846/stxb201810072156 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41771249）；国家科技支撑计划课题（2015BAD06B02-2）；南京土壤研究所"一三五"计划和领域前沿项目（ISSASIP1623）；中国科学院青年创新促进会（2018348） Rapid assessment of soil phosphorus loss risk and its spatial uncertainty in county areas of the Yangtze River Delta Plain 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:磷素是水体富营养化的关键限制因子，其中从农田土壤中流失的磷往往是水体磷素的主要来源。然而，土壤磷素的流失风险不仅与土壤磷素水平直接相关，其他环境因子，如距受纳水体距离、磷肥施用量、地表径流潜力等也强烈影响其流失风险。同时，基于有限样本预测得到的流失风险必然具有一定的空间不确定性。以长三角典型县域金坛区为研究案例，首先结合多个环境因子构建快速磷指数（RPI）评估模型，再利用稳健地统计学方法识别土壤全磷的空间离群值，并利用序贯高斯模型（SGS）模拟土壤全磷可能的空间分布格局，最后将其多个可能的模拟结果及上述主要因子输入到RPI模型，用以快速评估土壤磷素流失风险及其空间不确定性。结果显示，金坛区土壤磷素流失的高风险区和土壤全磷高值区分布格局在研究区北部、中部具有一定的相似性，而在中西部的旱地区两者出现差异性。高风险区主要沿着河流呈现条带状及斑块状分布，较高及以上风险区（快速磷指数值大于0.93）的面积占金坛区面积的65.88%。概率阈值分别设定为0.50、0.75、0.85、0.95时，其超标面积占金坛区总面积分别达到16.71%、5.74%、2.84%、1.04%。引入多个相关环境因子并结合经稳健处理的SGS进行流失风险指数的空间模拟和不确定性评估，可以快速评估区域农田土壤磷素流失风险及不确定性，进而为区域土壤磷素调控提供必要的空间决策支持。 Abstract:Phosphorus is a key limiting factor for the eutrophication of water bodies. The phosphorus migrating from farmland soils is commonly recognized as the main source of phosphorus in water bodies. Therefore, a better understanding of the loss risk and its spatial uncertainty of soil phosphorus are important for the decision maker to regulate the loss of soil phosphorus at the local and regional scale. In this study, a total of 259 farmland topsoil samples (0-20 cm) was collected from the Jintan District, Changzhou City, Jiangsu Province, for the analysis of soil total phosphorus contents. Apart from soil total phosphorus, we introduced other environmental factors, such as the distance from receiving water body, phosphate fertilizer application rate, and surface runoff potential, into the assessment of the loss risk of soil phosphorus. Furthermore, the prediction of risk indices based on limited samples inevitably has certain spatial uncertainty. Here, a rapid phosphorus index (RPI) assessment model was firstly constructed based on the multiple environmental factors introduced above. And then, the robust geostatistical methods were applied for identifying possible spatial outliers of soil phosphorus data, and the sequential Gaussian simulation (SGS) model with the dataset being removed the spatial outliers was used to simulate the possible spatial distribution pattern of soil total phosphorus. Finally, multiple equiprobable realizations of soil total phosphorus and related environmental factors were input into the RPI model to evaluate the risk of soil phosphorus loss and represent associated spatial uncertainty. The results showed that the high-risk areas of soil phosphorus loss were mainly located in the eastern and middle parts of the Jintan District, which were similar with the high-value areas of soil total phosphorus. The dryland soil total phosphorus located in the mid-west of the study area was relatively low, while the loss risk of soil phosphorus was still at a high level. Such spatial distribution patterns of soil phosphorus loss risk were mainly caused by agricultural inputs. Moreover, the environment factors (i.e., the distance from receiving water body, surface runoff potential, etc.) in these areas were also favorable for soil phosphorus loss. The areas with high level risk of soil phosphorus loss represented zonal distribution along the rivers in the study area. The highest risk area with RPI value exceeding 1.06 made up 24.94% of the study area, whereas the high-risk area (RPI value from 0.93 to 1.05) was relatively larger, accounting for an area percentage of 40.94%. Overall, the risk of soil phosphorus loss was high across the study area. In the process of the uncertainty assessment, the critical threshold value was set to be 1.06 for identifying the highest risk area. When the critical probabilities were set to be 0.50, 0.75, 0.85, and 0.95, respectively, the area exceeding the critical threshold value accounted for 16.71%, 5.74%, 2.84%, and 1.04% of the total area of Jintan District. The critical probability of rapid phosphorus index value exceeding the threshold value was greater than 85% in the north area, and around the Taohu Lake. We introduced environmental factors (the distance from receiving water body, phosphate fertilizer application rate, surface runoff potential) to assess the soil phosphorus loss, which can assess the spatial uncertainty of soil phosphorus loss at a county scale quickly. The knowledge of spatial uncertainty is helpful for the decision maker to delimit the critical source areas and regulate the regional soil phosphorus loss. 参考文献 相似文献 引证文献

Influence of recurrent rainfall and oxalic acid on phosphorus releasing from rocks phosphate in the Chaohu watershed, China

In order to understand the spatial distribution characteristics, loss risk and leaching behaviors of phosphorous from exposed rocks in typical small-area of Chaohu watershed, phosphorus-rich rock was selected for conducting a series of column leaching experiments to investigate the phosphorus leaching. By simulating the intermittent cycle of acid rainfall, effects of oxalic acid on the weathering of phosphate rocks were studied. Total phosphorus contents, pH and phosphate leaching capacity from phosphorus rocks were tested in the presence of oxalic acid at different dry-wet intervals. The results indicated that the cumulative release of phosphorus increased first and then decreased with the duration of dry-wet intervals increasing. Four typical kinetic equations can describe phosphorus release from phosphate rocks with the action of oxalic acid. The best fitting models were the weight function and parabolic equation, with a mean correlation coefficient R2 of 0.9727 and 0.9941, respectively, which reached significance level. Total phosphorus (TP) leaching distribution in each column showed a tendency of gradually decreasing from top to bottom except for time interval of 5 d and 7 d. Occluded-bound P (Oc-P) is the dominant form in rocks. The change point value of rocks phosphorus is 4.11 mg kg−1 after intermittent leaching, and the phosphorus loss risk is relatively large in some rocks formations.

Nitrogen- or phosphorus-based pig manure application rates affect soil test phosphorus and phosphorus loss risk

Pig manure is an effective source of plant nutrients that must be properly managed to prevent these nutrients from reaching surface and ground water. We conducted a 3-year study in southern Manitoba to investigate how the choice of cropping system and manure management practices affect soil test phosphorus (STP) concentration and loss of phosphorus (P) to groundwater. The experiment had a split-plot design with two cropping systems (annual and perennial) as main plots, and five nutrient management treatments as subplots: N-based liquid pig manure, P-based liquid pig manure, N-based solid pig manure, P-based solid pig manure and an unfertilized control. We did not measure an appreciable increase in STP concentration below the 0.15 m depth. However, manure application at an N-based rate resulted in increased STP concentration in the 0–0.15 m depth interval. After 3-year, STP concentration in the N-based treatments (48 and 43 mg Olsen P kg−1 for solid and liquid respectively) were significantly greater than for the P-based treatments (26 and 17 mg Olsen P kg−1 for solid and liquid respectively). The mass of P in the leachate was small, ranging from a low of 1 g P ha−1 in 2009 to a high of 100 g P ha−1 in 2011. Both P- and N-based manure application rates produced no apparent risk of P leaching at our site, but the N-based manure application rate increased STP concentration in the surface soil, which could lead to the loss of P in surface runoff.