Soil Phosphorus Loss Research Articles

Planted species influences soil phosphorus losses in a historically fertilized pasture system: A mesocosm study

AbstractThe gradual accumulation of phosphorus from historical fertilization can contribute to the eutrophication of surface waters by increasing the potential for subsurface leaching losses. Grazing lands areas are a priority for concern, and phytoremediation efforts in grazing lands have prioritized grasses that may be used as forage for cattle. This study investigated the influence of three different forage species—Paspalum notatum, Hemarthria altissima, and Cynodon nlemfuensis—on the loss of phosphorus in leachate from surface soils. The experiment used a nested pot mesocosm design that allowed us to monitor leachate volume and concentration biweekly over the course of 3 months. Pots containing P. notatum plants leached significantly more phosphorus than pots containing C. nlemfuensis or empty pots with no plants growing in them, despite losing an equivalent amount of water. H. altissima lost equivalent amounts of phosphorus in leachate water, but each H. altissima plant removed approximately 33.6 mg of phosphorus, approximately 2.5× that removed by P. notatum (13.4 mg). C. nlemfuensis had lower average leachate phosphorus concentrations at each biweekly sampling than either plant species (C. nlemfuensis‐P. notatum, padj = 0.001; C. nlemfuensis‐H. altissima, padj = 0.02), averaging only 0.110 ppm in leachate relative to 0.175 ppm and 0.200 ppm in pots beneath H. altissima and P. notatum, respectively. This, combined with C. nlemfuensis' slightly higher‐than‐average aboveground P content and overall aboveground biomass expression suggest it is the best possible phytoremediation candidate. As even minor leachate P loads can be critically threatening to neighboring oligotrophic water bodies, if the conservation of downstream environments is the priority, the short‐term threat of increased leachate must be considered. Further research is needed to explore the underlying mechanisms and field‐scale implications of these findings.

Pervasive soil phosphorus losses in terrestrial ecosystems in China

AbstractFuture phosphorus (P) shortages could seriously affect terrestrial productivity and food security. We investigated the changes in topsoil available P (AP) and total P (TP) in China's forests, grasslands, paddy fields, and upland croplands during the 1980s–2010s based on substantial repeated soil P measurements (63,220 samples in the 1980s, 2000s, and 2010s) and machine learning techniques. Between the 1980s and 2010s, total soil AP stock increased with a small but significant rate of 0.13 kg P ha−1 year−1, but total soil TP stock declined substantially (4.5 kg P ha−1 year−1) in the four ecosystems. We quantified the P budgets of soil–plant systems by harmonizing P fluxes from various sources for this period. Matching trends of soil contents over the decades with P budgets and fluxes, we found that the P‐surplus in cultivated soils (especially in upland croplands) might be overestimated due to the great soil TP pool compared to fertilization and the substantial soil P losses through plant uptake and water erosion that offset the P additions. Our findings of P‐deficit in China raise the alarm on the sustainability of future biomass production (especially in forests), highlight the urgency of P recycling in croplands, and emphasize the critical role of country‐level basic data in guiding sound policies to tackle the global P crises.

Effect of ecological restoration on topsoil phosphorus following afforestation on abandoned ponds in northern Chaohu Lake, China

Afforestation is an approach for ecological restoration. Soil total phosphorus is one of the important ecological and evolutionary elements for carbon cycles and plant growth following afforestation. However, studies on soil total phosphorus of afforestation on abandoned ponds with different slopes are still lacking. Soil total phosphorus and other soil properties from afforestation sites with different slopes were investigated. Soil total phosphorus, total nitrogen, bulk density, soil water contents and pH of poplar (Populus spp.) plantation sites (Slope 1) with a steep slope and pond cypress (Taxodium spp.) plantation sites (Slope 2) with a flat slope were determined. Soil total nitrogen stocks, soil total phosphorus stocks and the ratio of soil total nitrogen to total phosphorus (N:P) were calculated. Results showed that soil bulk density, soil water content, total phosphorus, total phosphorus stocks and total nitrogen stocks of three soil layers at Slope 1 were significantly lower than those of Slope 2. N:P of Slope 1 was significantly higher, but no significant difference of total nitrogen and pH were found between the two sampling sites. Soil bulk density, soil water content and total nitrogen had significant positive relationships with both total phosphorus and total phosphorus stocks. No obvious correlation was found between pH and total phosphorus or total phosphorus stocks. Redundancy analysis (RDA analysis) suggested that soil water content and bulk density had the most important individual effect on total phosphorus and total phosphorus stocks with values at 59.3% and 59.5%, respectively. It is recommended that afforestation on a flat or gentle slope rather than on a steep gradient could be helpful for accumulation of soil total phosphorus and phosphorus stocks and could decrease the risk of soil phosphorus loss, when afforestation is used for ecological restoration.

Soil chronosequence derived from landslides on the upper reach of Minjiang River, western China

Soil chronosequences derived from landslides with certain time series are the great avenue to elevate our understanding on the processes of pedogenesis, nutrient dynamics, and ecosystem evolution. However, the construction of reliable soil chronosequence from historical landslides remains intricate. Here, we presented a 22,000-year soil chronosequence from multiple landslides on the upper reach of Minjiang River, western China. The variation in a variety of pedogenesis indices and soil nutrients verified the reliability of the chronosequence. The silica-alumina ratio and silica sesquioxide ratio decreased significantly with soil age. This reflected the enrichment of Al/Fe/Ti oxides but the depletion of Si oxides with the soil development. Meanwhile, the values of the Chemical Index of Weathering and the Chemical Index of Alteration increased significantly with soil age, especially from 5 to 89 years. These variations were attributed to the soil weathering, which led to the destruction of soil minerals with the rapid loss of most of cations (e.g., K, Na, Ca, and Mg) during the soil development. The concentrations of carbon and nitrogen in topsoil increased with soil age, and the carbon accumulation rate slowed significantly from 5,500 to 22,000 years. The total phosphorus concentrations decreased with soil age, suggesting the gradual loss of soil phosphorus with soil development. The results indicate that the landslide chronosequence established on the upper reach of Minjiang River is reliable and delineates a long-term soil development process, which will provide a great platform for further improvement of biogeochemical theories and understanding sustainable vegetation restoration.

Weighted risk assessment of critical source areas for soil phosphorus losses through surface runoff mechanisms

In intensive livestock areas, soils commonly contain elevated nutrients above the agronomic optimum which increases the risk of nutrient losses and contributing to poor ecological status waterbodies. Large within-field variability in soil nutrient content exists, and at-risk phosphorus (P) hotspots are rarely quantified due to sub-optimal soil sampling regimes. This study aims to address this issue by developing and evaluating an improved classification of P transfer risk at a sub-field scale through a weighted risk assessment model that combines gridded soil sampling data with modelled in-field surface runoff pathways. Within-field soil P variability was quantified at six field-scale sites in Northern Ireland using two different sampling techniques; traditional bulked field soil sampling (i.e. bulk analysis of W pattern sampling) and gridded sampling (at 35 m resolution) alongside interpolation. Results show that traditional bulked sampling failed to account for the sub-field scale spatial variability in soil P content. This may contribute to the poor chemical and ecological status of surface waters by frequently under-predicting soil nutrient content, and failing to identify potential contributing sources of soil P losses. In contrast, higher intensity gridded sampling and interpolation revealed wide in-field spatial variability in soil P content, facilitating the identification of contributing sources of P losses to poor water quality and aiding in the characterisation of risk for nutrient losses to waterways. Hydrological modelling of in-field runoff pathways indicated several P sources potentially contributing to runoff-based P losses. Our weighted risk assessment model was successful in identifying P hotspots and transfer potential to water courses, illustrating that a similar approach could be applied anywhere in the world where excess P poses a problem for water quality. Model validation took place using instream water quality sampling data, which showed that higher risk weighting model results correlated to poorer water quality conditions. This methodology could be a useful management tool to help countries meet their national water quality targets.

Embedding trait‐based ecology within indigenous knowledge to advance sustainable management of Tibetan rangeland

AbstractQuestionsTraditional pastoralists attribute high numbers of plateau pikas (Ochotona curzoniae) to impoverished soils that favor more and better forage for pika, suggesting a bottom‐up control of pika density. Conversely, government policies focus on excessive numbers of this small mammalian herbivore as the primary top‐down cause of degradation in Tibetan rangeland. Despite concerted campaigns to reduce pika abundance in recent decades, the sustainability of Tibetan rangelands remains uncertain.LocationAlpine meadows on the Tibetan Plateau.MethodsWe proposed a conceptual model based on indigenous knowledge that predicted pika numbers from soil condition and plant traits. At three alpine meadow sites lightly grazed by livestock, we tested whether spatial variation in pika burrow density could be explained by changes in the functional composition of the plant community attributable to species turnover and intraspecific trait variation associated with changes in soil fertility.ResultsDue primarily to intraspecific trait variation, changes in the functional composition of the meadow community accounted for 56%–68% of the spatial variation in pika density, changes in the proportion of plant functional groups for 62%–74%, and changes in edaphic conditions for 71%–82%. Greater pika density was associated with a decline in soil phosphorus availability and a lower‐growing vegetation profile enriched in both the quantity and quality of forage preferred by pikas.ConclusionsThese results, which are in accord with indigenous knowledge, suggest that compensating soil phosphorus losses and maintaining a well‐calibrated grazing rotation can better manage pika populations and improve the sustainability of Tibetan rangelands. By combining trait‐based ecology and traditional knowledge, our study provides new insight into both understanding the dynamic complexity of grazing regimes and managing rangeland sustainability.

Effects of Cd addition on soil phosphorus mineralization in reclaimed coastal wetlands along a 100-year reclamation chronosequence in the Pearl River Estuary (China)

The relationship between Cd and soil phosphatase activity has been given some concerns due to serious soil Cd contamination. However, the effects of high-risk Cd pollution on the soil phosphorus mineralization process are still kept unclear in reclaimed coastal wetlands. Here, we investigated the impacts of Cd additions at three levels on phosphorus mineralization and phosphatase activities in reclaimed coastal wetland soils with different reclamation ages (e.g., 100-year, 40-year, and 10-year) in the Pearl River Estuary by a 40-day laboratory incubation experiment. The results showed that lower soil phosphatase activity was observed in the reclaimed wetlands with longer reclamation age, which led to the lower increase in cumulative net phosphorus mineralization and Occluded P. High Cd exposure facilitated the phosphatase activities and phosphorus mineralization through the promotion of Occluded P and Al/Fe-P contents in the 100-year and 10-year reclaimed wetland soils, respectively. The addition of the low-dose of Cd to the soil inhibited phosphorus mineralization in the middle of incubation in 40-year reclaimed wetland soils, while the high-dose Cd addition had little effect. The findings of this work indicate that the older reclaimed wetlands might have lower phosphorus mineralization potentials, while higher Cd pollution might lead to soil phosphorus loss by improving phosphorus mineralization in reclaimed coastal wetlands.

Enrichment and Ecological Risk Assessment of Available Phosphorus in Paddy Soil of Fujian Province Over Past 40 years

The ecological risks such as water eutrophication caused by soil phosphorus loss have attracted extensive attention, and its dynamic changes and enrichment effects are the basis for formulating reasonable control measures. In this study, based on the paddy soils of 1.8×106 hm2 in Fujian province, the dynamic changes and ecological risks of available phosphorus in paddy soils over the past 40 years were analyzedusing a soil database of 1:50000. The soil database contained 1471, 215534, and 2895 paddy soil samples in different periods, respectively. The paddy soil samples were derived from the 1982 Second National Soil Census, the 2008 Ministry of Agriculture and Rural Areas Soil Testing and Formulated Fertilization Project and the 2018 Ministry of Agriculture, and the Rural Areas Arable Land Quality Monitoring Project, respectively. The results showed that from 1982 to 2018, the content of available phosphorus in paddy soils increased by 47 mg·kg-1, and the enriched area reached 1.65×106 hm2, accounting for 91% of the total paddy soils in Fujian province. From 1982 to 2008, the available phosphorus content of paddy soils in Fujian province increased by 28 mg·kg-1, with the enriched area reaching 1.47×106 hm2, accounting for 82% of the total paddy soils in Fujian province. From 2008 to 2018, the available phosphorus content of paddy soils in Fujian province increased by 19 mg·kg-1, with the enriched area reaching 1.22×106 hm2, accounting for 69% of the total paddy soils in Fujian province. Further ecological risk assessment showed that from 2008 to 2018, the area of paddy soil with ecological phosphorus enrichment risk in the province gradually increased, mainly distributed in percogenic paddy soils and hydromorphic paddy soils with a slope of less than 2°. In the future, effective phosphorus fertilizer management measures should be formulated for different types of paddy soil to prevent the occurrence of environmental problems such as water eutrophication.

Soil phosphorus loss increases under drought-flood abrupt alternation in summer maize planting area

Phosphorus (P), critical nutrient for plant growth and environment, has been greatly concerned. Abundant studies have been focused on soil P loss, while only sparse studies have concerned on soil P loss under extreme hydrological events, even less on drought-flood abrupt alternation (DFAA). This study explored the P migration in summer maize farmland systems based on field experiments, further obtained the proportion of soil P loss. We also simulated the soil P loss to DFAA in summer maize planting area in the Northern Anhui Plain based on history, future, and hypothetical natural (assuming no DFAA events) scenarios. The field experiments revealed that DFAA events reduced plant P storage by 47.7% than that in the natural control systems (CS). The mean proportion of soil P loss increased in the DFAA treatments (8.96%) than that in the CS treatments (1.60%). The numerical simulation results show that the proportion of average annual soil P loss due to DFAA has been increasing in the Northern Anhui Plain, with 7.98–10.34% during 1964–2017, 2.07–14.16% during 2020–2050. The spatial distribution of annual soil P loss changed as well. The soil P loss in hypothetical natural scenario was 5.1 times and 5.9 times lower than that in history and future scenarios, which indicates significantly negative impacts of DFAA on environment. This study can provide references for estimating the environmental effects of DFAA on P in farmland systems.

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.

Characteristics of phosphorus adsorption and desorption in erosive weathered granite area and effects of soil properties.

Highly weathered acidic soils tend to have high phosphorus adsorption rates. Studying the differential phosphorus adsorption and desorption characteristics of these soils is of great significance to improve phosphorus utilization efficiency and reduce soil phosphorus loss in agricultural management. Erosive weathered granite soil (TL-Tillage layer, LL-Laterite layer, and SL-Sand layer) in Anji County, Zhejiang Province were selected for batch experiments and phosphorus fractionation test. The soil properties that are generally considered to have a greater impact on phosphorus adsorption and desorption are also studied. Derived from the Langmuir adsorption isotherm, the maximum absorption capacity (Qmax) of phosphorus in TL soil was greater than that in LL and SL soil. With a pH of 4.3-5.0, the three soils have the most phosphorus adsorption. The desorption ratio (Dr) in the SL soil is larger than the LL and TL soil. Six key soil property indicators can fit Qmax and Dr values well. Al-P is the main fraction in the phosphorus adsorption-desorption process. The particle size classification (PSC) method can be used to accurately calculate soil-specific surface area. The results of the soil phosphorus adsorption-desorption test can be used as an explanation of the results of artificial rainfall tests. Our results reveal the differential adsorption-desorption mechanism of eroded weathered granite soil, and provide a reference for selecting soil indicators for soil adsorption-desorption studies in different regions.

Effect of Optimized Fertilization and Biochar Application on Phosphorus Loss in Purple Soil Sloping Farmland

Phosphorus is an essential nutrient for crop growth, but the input of excess phosphorus is a significant cause of eutrophication. This study explored the relationship between fertilization methods and phosphorus loss in actual production, providing a theoretical basis for scientific fertilization and rational reduction of fertilizer application. In the experiment, a wild-type OD flow plot was used to monitor the occurrence of multiple rainfall runoff and sediment yield in purple soil sloping farmland in 2017-2018. Four different schemes of non-fertilizer treatment, conventional fertilization treatment, optimized fertilization treatment, and reduced fertilization combined with biochar were studied. The effects of soil flow, surface runoff, and sediment phosphorus loss on purple soil sloping farmland were analyzed. The results showed that:①The total yield of each treatment was optimized (20737.23 L) > conventional (18513.17 L) > CK (18134.58 L) > biochar (13594.85 L), and the total sediment yield of each treatment was CK (1998 kg·hm-2) > biochar (1884 kg·hm-2) > optimized (1681 kg·hm-2) > conventional (910 kg·hm-2). The middle stream of soil is the main type of runoff in the rainy season, accounting for 60.14%-87.34% of the total output flow. The total amount of sediment produced by each treatment was not significantly different from that of the conventional treatment (P>0.05). ②The flux of total phosphorus loss in each treatment was characterized by sediment > surface runoff > soil middle flow. Phosphorus lost through the middle stream of soil is the least, accounting for only 2.63%-12.91% of the flux of total phosphorus loss, while the flux of sediment loss of phosphorus can reach 63.74%-78.74%, and thus is the main output route of soil phosphorus loss. ③The application of biochar can effectively reduce the abortion flow in the soil of purple soil sloping land, and the loss flux of orthophosphate in the middle stream, which are 49.94% and 56.45% lower than the conventional treatment, respectively. However, the interception effect on surface runoff is not good, and there is no significant influence on the flux loss of particulate phosphorus. At the same time, the flux of total phosphorus in surface runoff and sediment is significantly increased by 73.28% and 123.53%, respectively, compared with conventional treatment (P<0.05). Therefore, to control the loss of phosphorus in purple soil sloping farmland in southwest China, we should focus on reducing the occurrence of soil sediment loss. Bio-carbon should be further optimized in the practical application of agricultural production with the phosphorus fertilizer input ratio.

Assessing the Impacts of Tillage and Mulch on Soil Erosion and Corn Yield

Conventional tillage practices have been regarded as the major reason for the loss of fertile topsoil in the sloping agricultural lands of the middle hills of Nepal. Reports on the effects of no-till and mulch on soil and corn yield in these regions are scarce, although these farming practices have been recommended to reduce soil erosion and increase crop yields. To assess the impacts of tillage (with +T, without −T) and mulch (with +M, without −M) on soil and soil nutrient losses, and corn yield, we conducted an experiment with five treatments: −T+M, −T−M, +T+M, +T−M, and bare fallow (BF), replicated four times each in an unbalanced complete random block design in Salyan district of Nepal. The results showed the presence of corn and no-till significantly lowered the soil losses. Losses of soil organic matter (SOM) and total nitrogen were also significantly reduced by the presence of corn, no-till, and mulch. However, no effects of mulch on soil losses, and no effects of tillage, mulch and corn on soil phosphorus losses were observed. Soil loss was found to be significantly and positively correlated with total seasonal rainfall, monsoon being the most severe season for soil erosion. While no-till and mulch did not affect corn height, cob height, and stover yield, no-till significantly increased the corn yield by 0.52 Mg ha−1 compared to conventional till. We confirm the synergistic interaction of mulch with tillage to reduce the losses of SOM and total nitrogen, and effectiveness of no-till to reduce the soil losses and increase the corn yield in the middle hills of Nepal. As this study is based on the results of two year’s data, long-term studies are required to identify the long-term impacts of no-till and mulch on soil losses and corn yield across the country.

Measuring the Fate of Compost-Derived Phosphorus in Native Soil below Urban Gardens.

The heavy reliance on compost inputs in urban gardening provides opportunities to recycle nutrients from the urban waste stream, but also creates potential for buildup and loss of soil phosphorus (P). We previously documented P in leachate from raised-bed garden plots in which compost had been applied, but the fate of this P is not known. Here, we measured P concentrations in soils below four or six-year-old urban garden plots that were established for research. We hypothesize that the soil P concentration and depth of P penetration will increase over time after gardens are established. Soil cores were collected in five garden plots of each age and quantified for inorganic weakly exchangeable P. Inorganic weakly exchangeable P was significantly elevated in native soil below garden plots (>35 cm deep) relative to reference soil profiles, and excess P decreased with increasing depth, although differences between garden plots of different ages were not significant. Our analysis shows that excess P from compost accumulates in native soil below urban garden plots. While urban agriculture has the potential to recycle P in urban ecosystems, over-application of compost has the potential to contribute to soil and water pollution.

The influence of no-till coupled with straw return on soil phosphorus speciation in a two-year rice-fallow practice

Conservation tillage is well known to reduce the loss of soil phosphorus (P). However, the effects of different conservation practices on soil P speciation are still unclear. To delineate these effects, two field experiments were conducted during 2-year rice-fallow seasons with four treatments: conventional tillage/straw harvest (CTH), conventional tillage/straw return (CTR), no-till/straw harvest (NTH), and no-till/straw return (NTR). A combination of Liquid-state 31P-NMR and P K-edge XANES was used to investigate the variations in P species present in two paddy soils. Liquid-state 31P-NMR results showed that P monoesters significantly increased under NTR, and after the 2-year rice-fallow practice, the proportion of P monoesters relative to total P in the different treatments ranked as: NTR (23.25%) > NTH (22.18%) > CTR (20.29%) > CTH (19.79%) and NTR (8.61%) > NTH (8.49%) > CTR (8.31%) > CTH (8.03%) in a loam and a clay loam soil, respectively. Orthophosphate (ortho-P) also increased over time, but with no differences among treatments for the two soil types at the end of the experiment. P K-edge XANES spectra further revealed that the relative proportions of iron oxide-bound P (Fe-Pi) and calcium dihydrogen phosphate (Ca-Pi) were highest in the NTR treatment, higher by 27.6% and 11.1% in a loam soil and by 10.4% and 12.7% in a clay loam soil than that in the first rice season. However, the relative proportion of aluminum oxide-bound P (Al-Pi) was lower by 38.6% and 40.7% in the loam and the clay loam soil, respectively. Our results suggested that no-till coupled with straw return can significantly increase the soil pool of organic P, and that this treatment was beneficial to the conversion of inorganic P species to labile forms in rice paddy soils. This study highlights the transformational relationship between different P species in conservation tillage systems.

Inhibiting effects of flue gas desulfurization gypsum on soil phosphorus loss in Chongming Dongtan, southeastern China.

To explore the possibility of using flue gas desulfurization gypsum (FGDG) for inhibiting phosphorus (P) loss due to agricultural runoff, a 3-year study was performed in the farmlands of Chongming Dongtan between 2012 and 2015. Five different quantities of FGDG were used to treat the soil, and the effects of different treatments on the characteristics of soil P and crop growth were investigated. The results showed that 2years after application of FGDG, the soil density at a depth of 0-10cm decreased by 4.35-7.97%, the porosity increased by 1.77-11.0%, and the topsoil permeability increased by 0.87-3.81 times. Although the use of FGDG did not change the total P concentration in the soil, it decreased the concentration of sodium bicarbonate extractable P in the soil. Compared to the control, the average extractable P concentration at depths of 0-10cm, 10-20cm, and 20-30cm decreased by 22.0-46.1%, 26.9-40.5%, and 22.8-34.8%, respectively. The inorganic P in the soil increased as the amount of FGDG increased, and the increase was mainly as Ca-P in the forms Ca2-P and Ca10-P. The decrease in bicarbonate extractable P and increase in inorganic P in the soil did not affect the growth of the crops, and the biomass and output of the crops increased compared to the control. Therefore, FGDG can enhance soil P immobilization, thus reducing soluble P runoff from farm fields, and improving water quality in receiving lakes and rivers while maintaining P nutrition to the crops.

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

Effect of slope farmland soil and water and soil nitrogen and phosphorus loss based on different crop and straw applications and ridge patterns in the basin of the main stream of the Songhua River

For soil and water erosion control in slope farmland, field experiments consisting of corn + no straw application + longitudinal ridge (CNL-CK), corn + stubble standing + cross ridge (CSSC), corn + straw application + cross ridge (CSC), soybean + straw application + cross ridge (SSC) and alfalfa + straw application + cross ridge (ASC) were conducted. Compared with the traditional CNL cropping pattern, soil loss in CSSC, CSC, SSC, and ASC was decreased 43.6%, 48.6%,58.2% and 62.1%, respectively, soil nitrogen loss load was decreased 53.8%, 50.8%, 62.1% and 66.2%, respectively, and soil phosphorus loss load was decreased 50.7%, 50.7%, 60.0%, and 66.7%, respectively. Runoff volume was decreased 42.4%, 52.3%, 54.6% and 61.0%, runoff nitrogen loss load was decreased 52.8%, 56.8%, 46.1% and 50.2%, respectively, and runoff phosphorus loss load was decreased 46.9%, 78.2%, 67.2%, and 62.7%, respectively. Soil and water erosion control of soybean and alfalfa were better than that of corn. Soil loss was decreased 19.2% and 26.7%, soil nitrogen loss load was decreased 22.9% and 31.3% respectively, soil phosphorus loss load was decreased 18.9% and 32.4% respectively, runoff volume was decreased 4.8% and 18.4% respectively, runoff nitrogen loss load was decreased −24.9% and −15.3% respectively, and runoff phosphorus loss load was decreased −50.4% and −71.2% respectively. Though runoff volume of SSC and ASC were lower than CSC, the concentration of nitrogen and phosphorus in SSC and ASC runoff liquid were higher than CSC, so the runoff nitrogen and phosphorus of SSC and ASC were increased. The runoff nitrogen and phosphorus loss load could be negligible because the soil nitrogen and phosphorus loss load were large. The concentration of nitrogen and phosphorus of all treatment runoff liquid was less than the environmental quality standards for class III surface water, so the runoff from slope farmland did not influence the water quality of the Songhua River.

Effects of Flooding and Drying on the Transformation of Soil Inorganic Phosphorus in the Water-Level-Fluctuating Zone of the Three Gorges Reservoir, China

The implementation of the Three Gorges Project formed a water-level-fluctuating zone, and flooding and drying affects the soil properties and water quality of the Water-Level-Fluctuating Zone. The laboratory simulation or field sampling were conducted; however, the results cannot reflect the real conditions in practice. The effects of flooding and drying on the physical and chemical properties of soil and the transformation characteristics of inorganic phosphorus were studied in order to provide a theoretical reference for soil phosphorus loss and water eutrophication in water-level-fluctuating zone of the Three Gorges Reservoir. To investigate the conversion of soil phosphorus, plastic pots with soil were suspended at different depths (0, 2, 5, and 15 m) and submerged for 30, 60, and 180 d, and exposed for 180 d. The effects of submerged depth and time on the soil physical and chemical properties and inorganic phosphorus forms were studied. The results showed that soil pH, organic matter, total phosphorus, and available phosphorus decreased and then increased subsequently during the flooding period. After exposure for 180 d, soil pH, organic matter, and total phosphorus content decreased, while available phosphorus content increased. After flooding, the ratio of various forms of inorganic phosphorus to total phosphorus was Fe-P > Al-P > Ca8-P > Ca2-P. The content of Ca2-P and Ca8-P decreased at 0 m and 2 m and decreased at 5 m and 15 m and then increased with increased flooding time. After exposure for 180 days, the content of inorganic phosphorus increased significantly, and the content of inorganic phosphorus decreased as flooding depth increased. Al-P content increased with the flooding time, but there was no obvious change with flooding depth. The content of Fe-P did not change with the time and the depth of flooding.