p leaching
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Processes ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 151
Author(s):  
Vicky Shettigondahalli Ekanthalu ◽  
Satyanarayana Narra ◽  
Tommy Ender ◽  
Edward Antwi ◽  
Michael Nelles

Phosphorus (P) recovery from alternative P-rich residues is essential to meet the growing demands of food production globally. Despite sewage sludge being a potential source for P, its direct application on agricultural land is controversial because of the obvious concerns related to heavy metals and organic pollutants. Further, most of the available P recovery and sludge management technologies are cost-intensive as they require mandatory dewatering of sewage sludge. In this regard, hydrothermal carbonization (HTC) has gained great attention as a promising process to effectively treat the wet sewage sludge without it having to be dewatered, and it simultaneously enables the recovery of P. This study was conducted to analyse and compare the influence of acid (H2SO4) addition during and after HTC of sewage sludge on P leaching and the characteristics of hydrochar. The obtained results suggested that despite using the same amount of H2SO4, P leaching from solid to liquid phase was significantly higher when acid was used after the HTC of sewage sludge in comparison with acid utilization during the HTC process. After HTC, the reduction in acid-buffering capacity of sewage sludge and increase in solubility of phosphate precipitating metal ions had a greater influence on the mobilization of P from solid to liquid phase. In contrast, utilization of H2SO4 in different process conditions did not have a great influence on proximate analysis results and calorific value of consequently produced hydrochar.


2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Jianhong Liang ◽  
Liuhuan Chen ◽  
Ding Liu ◽  
Chenxu Yi ◽  
Jing Zhu

Phosphorus (P) is one of the key limiting factors for the growth of forests and their net primary productivity in subtropical forest ecosystems. Phosphorus leaching of the forest soil to the catchment and groundwater in karst region is the main source of water eutrophication. Strong P sorption capacity of minerals is generally assumed to be a key driver of P leaching in subtropical ecosystems which varies among different soil types. Here, we estimated P adsorption capacity of the O/A and AB horizon in both limestone soil and red soil of subtropical forests by fitting the Langmuir and Freundlich isotherm to investigate the potential environmental risks of P. The maximum P sorption capacity ( Q m ), P sorption constant ( K L ), P sorption index (PSI), degree of P saturation (DPS), and maximum buffer capacity (MBC) were calculated. The results indicate that Q m of the O/A horizon in both soils were similar. Comparing these two soils, the red soil had a higher K L and MBC in the AB horizon; Q m of limestone soil was larger but K L was lower, indicating that the adsorption capacity of limestone soil was weaker and MBC was lower. There was no significant difference in PSI between the two soils. The DPS values of both soils were below 1.1%, indicating that P saturation is low in both subtropical forest soils due to the lack of marked anthropogenic disturbance. In the O/A horizon, P saturation associated with available P (DPSM3 and DPSOlsen) and that associated with P in the Fe-Al bound state (DPScitrate) were higher in the red soil than in the limestone soil. DPS did not differ significantly in the AB horizon, except for higher DPSM3 and DPScitrate in the red soil. The findings highlight the influence of the soil types on P adsorption. The P adsorption and buffering of red soils were higher than those of limestone soils, indicating a lower risk of P leaching in red subtropical forest soils.


2021 ◽  
Vol 33 (1) ◽  
Author(s):  
Zijian Xie ◽  
Fan Zhang ◽  
Chun Ye ◽  
Hao Wang ◽  
Weiwei Wei ◽  
...  

Abstract Background The soil P leaching change point (CP) has been widely used to evaluate soil P leaching risk. However, an automation calculation method for soil P leaching CP value, and an effective risk grading method performed for classifying soil P leaching risk evaluation have not been developed. Results This study optimized the calculation process for soil P leaching CP value with two different fitting models. Subsequently, based on the Python programming language, a computation tool named Soil Phosphorus Leaching Risk Calculator (SPOLERC) was developed for soil P leaching risk assessment. SPOLERC not only embedded the calculation process of the soil P leaching CP value, but also introduced the single factor index (SFI) method to grade the soil P leaching risk level. The relationships between the soil Olsen-P and leachable P were fitted by using SPOLERC in paddy soils and arid agricultural soils in the Xingkai Lake Basin, and the results showed that there was a good linear fitting relationship between the soil Olsen-P and leachable P; and the CP values were 59.63 and 35.35 mg Olsen-P kg−1 for paddy soils and arid agricultural soils, respectively. Additionally, 32.7, 21.8, and 3.64% of arid agricultural soil samples were at low risk, medium risk, and high risk of P leaching, and 40.6% of paddy soil samples were at low risk. Conclusions SPOLERC can accurately fit the split-line model relationship between the soil Olsen-P and leachable P, and greatly improved the calculation efficiency for the soil P leaching CP value. Additionally, the obtained CP value can be used for soil P leaching risk assessment, which could help recognize key area of soil P leaching.


Agronomy ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2223
Author(s):  
Prisca Divra Johan ◽  
Osumanu Haruna Ahmed ◽  
Latifah Omar ◽  
Nur Aainaa Hasbullah

Soil-available P for crop use is limited because of fixation reaction and loss of organic matter through erosion and surface runoff. These factors cause an imbalance between inputs and outputs of P nutrients in acid soils. Several approaches to improve P availability have been proposed, however, little is known about the effectiveness of amending humid mineral acid soils with charcoal and sago bark ash on P dynamics. Thus, pH buffering capacity and leaching studies were conducted to determine: (i) pH buffering capacity upon application of charcoal and sago bark ash and (ii) the influence of charcoal and sago bark ash on P leaching in acid soils. pH buffering capacity was calculated as the negative reciprocal of the slope of the linear regression (pH versus acid addition rate). A leaching study was carried out by spraying distilled water to each container with soil such that leachates through leaching were collected for analysis. The ascending order of the treatments based on their pH buffering capacity and regression coefficient (R2) were soil alone (0.25 mol H+ kg−1 sample), soil with charcoal (0.26 mol H+ kg−1 sample), soil with sago bark ash (0.28 mol H+ kg−1 sample), charcoal alone (0.29 mol H+ kg−1 sample), soil with charcoal and sago bark ash (0.29 mol H+ kg−1 sample), and sago bark ash alone (0.34 mol H+ kg−1 sample). Improvement in the soil pH buffering capacity was partly related to the inherent K, Ca, Mg, and Na contents of charcoal and sago bark ash. In the leaching study, it was noticed that as the rate of sago bark ash decreased, the pH of leachate decreased, suggesting that unlike charcoal the sago bark ash has significant impact on the alkalinity of leachate. Soil exchangeable acidity, Al3+, and H+ reduced significantly following co-application of charcoal and sago bark ash with ERP. This could be attributed to the neutralizing effects of sago bark ash and the high affinity of charcoal for Al and Fe ions. The amount of P leached from the soil with 100% charcoal was lower because charcoal has the ability to capture and hold P-rich water. The findings of this present study suggest that combined use of charcoal and sago bark ash have the potential to mitigate soil acidity and Al toxicity besides improving soil pH buffering capacity and minimizing P leaching. A field trial to consolidate the findings of this work is recommended.


Geoderma ◽  
2021 ◽  
Vol 402 ◽  
pp. 115322
Author(s):  
Shuai Zhang ◽  
Shuo Chen ◽  
Owen Fenton ◽  
Yuhong Li ◽  
Qing Chen

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mir Zaman Hussain ◽  
Stephen K. Hamilton ◽  
G. Philip Robertson ◽  
Bruno Basso

AbstractExcessive phosphorus (P) applications to croplands can contribute to eutrophication of surface waters through surface runoff and subsurface (leaching) losses. We analyzed leaching losses of total dissolved P (TDP) from no-till corn, hybrid poplar (Populus nigra X P. maximowiczii), switchgrass (Panicum virgatum), miscanthus (Miscanthus giganteus), native grasses, and restored prairie, all planted in 2008 on former cropland in Michigan, USA. All crops except corn (13 kg P ha−1 year−1) were grown without P fertilization. Biomass was harvested at the end of each growing season except for poplar. Soil water at 1.2 m depth was sampled weekly to biweekly for TDP determination during March–November 2009–2016 using tension lysimeters. Soil test P (0–25 cm depth) was measured every autumn. Soil water TDP concentrations were usually below levels where eutrophication of surface waters is frequently observed (> 0.02 mg L−1) but often higher than in deep groundwater or nearby streams and lakes. Rates of P leaching, estimated from measured concentrations and modeled drainage, did not differ statistically among cropping systems across years; 7-year cropping system means ranged from 0.035 to 0.072 kg P ha−1 year−1 with large interannual variation. Leached P was positively related to STP, which decreased over the 7 years in all systems. These results indicate that both P-fertilized and unfertilized cropping systems may leach legacy P from past cropland management.


2021 ◽  
Author(s):  
Zijian Xie ◽  
Fan Zhang ◽  
Chun Ye ◽  
Hao Wang ◽  
Weiwei Wei ◽  
...  

Abstract BackgroundAs the key factor of soil P leaching risk assessment, soil P leaching change point (CP) has been widely reported. However, there was no report have clearly described the calculation method of soil P leaching CP value and its automation calculation. Additionally, there was no effective risk grading method performed on the classification of soil P leaching evaluation.ResultsThis study has optimized the calculation process of soil P leaching CP value under two different models. Subsequently, based on the Python programming language, a computation tool named SPOLERC (Soil Phosphorus Leaching Risk Calculator) was developed for soil P leaching risk assessment. SPOLERC not only embedded the calculation process of soil P leaching CP value, but also introduced the single factor index (SFI) method to grade the soil P leaching risk level. Considering the relationships between soil Olsen-P and leachable P fitted by using SPOLERC in paddy land soils and arid agricultural land soils in the Lake Xingkai basin, results have shown that there is a good linear fitting relationship between soil Olsen-P and leachable P; and the CP values were 59.63 and 35.35 mg Olsen-P kg-1 in paddy land soils and arid agricultural land soils, respectively. Additionally, 32.7%, 21.8%, and 3.64% of arid agricultural soil samples are at low risk, medium risk, and high risk of P leaching, and 40.6% of paddy land soil samples are at low risk. ConclusionsThe SPOLERC can accurately fit the split-line model relationship between soil Olsen-P and leachable P, and greatly improve the calculating efficiency for soil P leaching CP value. Additionally, the obtained CP value can be used for soil P leaching risk assessment, which can provide support for the quantitative study of soil P leaching loss and the control technology of soil P leaching loss.


Horticulturae ◽  
2021 ◽  
Vol 7 (7) ◽  
pp. 199
Author(s):  
Dexter Brown Watts ◽  
George Brett Runion ◽  
Henry Allen Torbert

In response to agriculture’s contribution to surface water quality, considerable effort is being made to develop best management practices to reduce nutrient loss. To evaluate the efficacy of gypsum as a horticultural media amendment for controlling phosphorus (P) leaching, flue gas desulfurization (FGD) gypsum was added to a standard horticultural growth medium at 0, 2.5, 5, 10 or 15% (v/v). FGD gypsum was either mixed with the growing medium or placed at the bottom of the containers. A fast-release or a control-release fertilizer was top-dressed to containers. The greatest P leaching occurred with the fertilizer-only treatments (no gypsum). Dissolved reactive P (DRP) losses were highest on the initial day of measurement for the fast-release fertilizer and then decreased rapidly. There was a delayed release of DRP from the controlled-release fertilizer. Increasing rates of FGD gypsum addition resulted in decreasing DRP leaching concentration loss and load. The FGD gypsum decreased leachate DRP concentration loss by a maximum of 75%, with an average decrease of 46%. Mixing the FGD gypsum with the medium (an easier/less expensive means of incorporation) was most effective with the fast-release fertilizer. These preliminary results indicate that less gypsum may be needed to reduce P loss from fast-released fertilizer as opposed to control-release fertilizer. FGD gypsum remained effective in reducing DRP loss throughout the experiment.


2021 ◽  
Vol 4 ◽  
Author(s):  
Jasmin Fetzer ◽  
Sebastian Loeppmann ◽  
Emmanuel Frossard ◽  
Aamir Manzoor ◽  
Dominik Brödlin ◽  
...  

Phosphomonoesterases play an important role in the soil phosphorus (P) cycle since they hydrolyze P monoester to phosphate. Their activity is generally measured in soil extracts, and thus, it remains uncertain how mobile these enzymes are and to which extent they can be translocated within the soil profile. The presence of phosphomonoesterases in soil solutions potentially affects the share of labile dissolved organic P (DOP), which in turn would affect P leaching. Our study aimed at assessing the production and leaching of phosphomonoesterases from organic layers and topsoil horizons in forest soils and its potential effect on dissolved P forms in leachates obtained from zero-tension lysimeters. We measured phosphomonoesterase activities in leached soil solutions and compared it with those in water extracts from litter, Oe/Oa, and A horizons of two beech forests with a contrasting nitrogen (N) and P availability, subjected to experimental N × P fertilization. In addition, we determined phosphate and DOP. In soil solutions leached from litter, Oe/Oa, and A horizons, phosphomonoesterase activities ranged from 2 to 8 μmol L–1 h–1 during summer, but remained below detection limits in winter. The summer values represent 0.1–1% of the phosphomonoesterase activity in soil extracts, indicating that enzymes can be translocated from organic layers and topsoils to greater soil depths. Activities of phosphomonoesterases obtained by water extracts were greater in the organic layer of the P-poor site, while activities of those in soil solutions were similar at the two sites. Nitrogen addition increased phosphomonoesterase activities in leached soil solutions of the organic layer of the N- and P-poor soil. Using a modeling approach, we estimated that approx. 76% of the initial labile DOP was hydrolyzed to dissolved inorganic P within the first 24 h. Back calculations from measured labile DOP revealed an underestimation of approx. 15% of total dissolved P, or 0.03 mg L–1. The observed leaching of phosphomonoesterases implies that labile organic P could be hydrolyzed in deeper soil horizons and that extended sample storage leads to an underestimation of the contribution of DOP to total dissolved P leaching. This has been neglected in the few field studies measuring DOP leaching.


2021 ◽  
Vol 4 ◽  
Author(s):  
Lukas Gerhard ◽  
Heike Puhlmann ◽  
Margret Vogt ◽  
Jörg Luster

Foliar phosphorus (P) concentrations in beech trees are decreasing in Europe, potentially leading to reductions in the trees’ growth and vitality. In the course of climate change, drying and rewetting (DRW) cycles in forest soils are expected to intensify. As a consequence, P leakage from the root zone may increase due to temporarily enhanced organic matter mineralization. We addressed the questions whether sites with different soil properties, including P pools, differ in their susceptibility to DRW-induced P leaching, and whether this is affected by the DRW intensity. A greenhouse experiment was conducted on naturally structured soil columns with beech saplings from three sites representing a gradient of soil P availability. Four DRW cycles were conducted by air-drying and irrigating the soils over 4 hours (fast rewetting) or 48 hours (slow rewetting). Leachates below the soil columns were analyzed for total P, and molybdate reactive P (considered as inorganic P). The difference was considered to represent organically bound P. Boosted regression trees were used to examine the effects of DRW and soil characteristics on P leaching. Contrary to a first hypothesis, that P leaching increases upon rewetting with the intensity of the preceding desiccation phase, intense soil drying (to pF 3.5 to 4.5) did not generally increase P leakage compared to moderate drying (to pF 2 to 3). However, we observed increased inorganic P concentrations and decreased organic P concentrations in leachates after drying to matric potentials above pF 4. Also against our expectations, fast rewetting did not lead to higher leakage of P than slow rewetting. However, the results confirmed our third hypothesis that the site poorest in P, where P recycling is mainly limited to the humus layer and the uppermost mineral soil, lost considerably more P during DRW than the other two sites. The results of our experiment with naturally structured soils imply that intensified drying and rewetting cycles, as predicted by climate-change scenarios, may not per se lead to increased P leaching from forest soils. Soil properties such as soil organic carbon content and texture appear to be more important predictors of P losses.


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