Compact Treatment Research Articles

Enhanced Coalescence of Fine Droplets by Medium Coalescence under an Electric Field

As more and more oilfields enter later stages of extraction, demulsification of water-in-oil (W/O) emulsions with high water content has become a challenging problem. To upgrade the current offshore oil treatment process, a compact and efficient demulsification treatment is highly desirable. In this paper, a novel enhanced treatment combining a direct current (DC) electric field and medium coalescence was proposed. Based on this idea, an electric-medium demulsifier was also designed for deep purification of W/O emulsions. The effects of operating conditions, emulsions characteristics and medium bed parameters on demulsification performance were investigated. The enhanced treatment showed better performance compared to electrostatic demulsification and medium coalescence alone, and was especially suitable for treating emulsions with strong emulsification. In short, at U = 3 kV, the demulsification efficiency increased by approximately 30% compared to that at U = 0 kV. This research provided a new approach for the treatment of W/O emulsions that has the advantages of wide operational flexibility, a tolerance for deteriorated characteristics and a rapid and thorough treatment process.

Changing winter climate and snow conditions induce various transcriptional stress responses in Scots pine seedlings.

In northern boreal forests the warming winter climate leads to more frequent snowmelt, rain-on-snow events and freeze-thaw cycles. This may be harmful or even lethal for tree seedlings that spend even a half of the year under snow. We conducted a snow cover manipulation experiment in a natural forest to find out how changing snow conditions affect young Scots pine (Pinus sylvestris L.) seedlings. The ice encasement (IE), absence of snow (NoSNOW) and snow compaction (COMP) treatments affected ground level temperature, ground frost and subnivean gas concentrations compared to the ambient snow cover (AMB) and led to the increased physical damage and mortality of seedlings. The expression responses of 28 genes related to circadian clock, aerobic and anaerobic energy metabolism, carbohydrate metabolism and stress protection revealed that seedlings were exposed to different stresses in a complex way depending on the thickness and quality of the snow cover. The IE treatment caused hypoxic stress and probably affected roots which resulted in reduced water uptake in the beginning of the growing season. Without protective snowpack in NoSNOW seedlings suffered from cold and drought stresses. The combination of hypoxic and cold stresses in COMP evoked unique transcriptional responses including oxidative stress. Snow cover manipulation induced changes in the expression of several circadian clock related genes suggested that photoreceptors and the circadian clock system play an essential role in the adaptation of Scots pine seedlings to stresses under different snow conditions. Our findings show that warming winter climate alters snow conditions and consequently causes Scots pine seedlings various abiotic stresses, whose effects extend from overwintering to the following growing season.

A sustainable municipal solid waste system under leachate treatment impact along with leakage control and source separation

Over the past few decades, inefficient waste management has caused environmental problems, such as leachate leakage, high pollution in the surface and groundwater, and soil contamination. In this regard, it is essential to adopt proper pre-discharge leachate management and treatment in the case of municipal waste. This study proposes a novel sustainable network design model by determining the optimal combination of transfer stations and separation units equipped with waste compaction and leachate treatment technologies, waste treatment facilities with different efficiencies, and optimal waste and leachate flow allocation along with waste separation at the source for municipal solid waste (MSW) systems. The uncertainty in the generated amount of waste is also considered in different urban areas. Therefore, a two-stage stochastic programming has been developed to minimize the total cost and the leachate pollution potential of MSW network systems, considering leachate types, collection and garbage-bin-cleaning truck types, and recyclable waste quality. Furthermore, the social objective is to maximize the number of job opportunities. The sample average approximation approach and the augmented ε-constraint method have been implemented to address the model uncertainty and solve the proposed multi-objective model, respectively. The results have indicated that considering the leachate treatment in the MSW network and waste separation at the source, despite increasing the total cost, has decreased leachate pollution potential by 41.3% and has created the number of job opportunities by 29.2% compared to the current situation in Tehran as a case study. Moreover, complete waste separation at the source in the proposed model has shown that it can have a positive effect on decreasing the total cost and leachate pollution potential.

Short‐term effects of organic matter and compaction manipulations on soil temperature, moisture, and soil respiration for 2 years in the Oregon Cascades

AbstractUnderstanding the factors controlling nutrient dynamics can help guide forest management plans to promote their long‐term productivity. We used experimental treatments with three levels of biomass removals and two levels of compaction to monitor the impacts to soil biophysical characteristics in an intensively managed forest. Soil temperature, moisture, and respiration observations began 6 mo after treatment installation completion and continued for 2 yr. Compaction had few consistent significant effects on measured variables, and there were negligible differences in volumetric soil water content between whole tree (WT) and bole only (BO) harvesting. Compared with BO, the 10‐cm average and maximum growing season temperatures in WT significantly increased by 1.2 and 2.5 °C, respectively. The effects of WT removals resulted in whole profile (10–100 cm) increases in the average and maximum growing season soil temperatures. The WT removals resulted in an increase of 1.4 times more soil growing degree days (SGDD) at 10 cm and 1.6 times more at 100 cm compared with BO. Despite favorable temperature and moisture conditions, differences in soil respiration could not be explained by biomass or compaction treatments. The uncut reference forest was consistently cooler and drier, but respired more CO2 throughout both years of observation compared with treated areas. The large physical disturbance of forest harvesting on the site likely masked any incremental treatment differences by homogenizing the microbial response in the ensuing 2‐yr study period. Future research should continue to investigate whether these soil biophysical changes influence site productivity or more sensitive indices of soil C dynamics.

Sustainable Mini ETP for Small Industries: A Case Study of Powder Coating Industry

Effluent Treatment Plants (ETPs) are considered as one of the viable solution for small to medium enterprises for effective wastewater treatment. An Effluent Treatment Plant (ETP) is an integral part of production processes with relevance to wastewater, the pollutants with their respective limit values that have to be reduced. In addition, the ETP also facilitates in reduction of number of discharge points in an industrial estate for better enforcement by environmental regulatory agencies in terms of pollution reduction and environmental improvements. However, many of the operating ETPs are not performing optimally due to various technical and managerial reasons. Small scale industries usually do not have access to latest technological advancements in effluent treatment process. To address the pollution discharge of industries, adoption of cleaner production technologies and waste minimization initiatives are now gaining ground. Treatment of such industrial effluent is very important and necessary from environmental point of view. Also, to meet the Standards for emission or discharge of environmental pollutants from various Industries set by the Government and to avoid hefty penalties ETP is a need for the industries. In present case study anattempt is made to design a compact but sustainable mini effluent treatment plant for small scale industry i.e. powder coating unit. This mini ETP requires smaller space as compared to traditional ETP with old technology. By using such compact modular mini ETP for small scale industry issue of non-treating or partly treating effluent can be overcome with cost and space efficiency. This will enable small scale industries to cater their need to avoid pollution and also to safeguard environment.

Foundation filling performance of calcareous soil on coral reefs in the South China Sea

Atoll reef flats in the South China Sea are ideal sites for land reclamation and engineering construction. Calcareous soil deposited in atoll lagoons is an excellent filling material for land reclamation. This brittle material with irregular particle shapes is prone to obvious particle breakage under impact or vibration loads. First, this manuscript introduced the geomorphology and geological conditions of coral reefs, and explored the selection of reclamation sites and the source of filling materials. Then, compaction characteristics of calcareous soil were studied, and particle breakage was analyzed. On this basis, the optimal compaction test method was proposed based on the test results. Finally, a new method of “impact rolling + water spray” for coarse-grained calcareous soil, which proved effective in engineering practice in the South China Sea, was put forward. According to in-situ test results, after 20 passes of “impact rolling + water spray” on calcareous soil foundation, the compactness within the depth range of 1.0 m exceeded 80%; the foundation compactness at 0.3 m, 0.7 m, and 1.0 m deep increased by 8.4%, 4.8%, and 4.1%, respectively. This method significantly improved foundation compaction efficiency, offering important references for the compaction treatment of coarse-grained calcareous soil in coral reef regions.

Swine manure treatment technologies as drivers for circular economy in agribusiness: A techno-economic and life cycle assessment approach

Anaerobic digestion has been employed as a technology capable of adding value to waste coupled with environmental impact mitigation. However, many issues need to be elucidated to ensure the systems viability based on this technology. In this sense, the present study evaluated technically, environmentally, and economically, four configurations of swine waste treatment systems focused on the promotion of decarbonization and circularity of the swine chain. For this, a reference plant, based on a compact treatment process named SISTRATES® (Portuguese acronym for swine effluent treatment system) was adopted to serve as a model for comparison and validation. The results showed the importance of prioritization of the energy recuperation routes through anaerobic digestion, providing increased economic benefits and minimizing environmental damage. Thus, the SISTRATES® configuration was the one that presented the best designs in a circular context, maximizing the recovery of energy and nutrients, along with the reduction of greenhouse gas emissions, ensuring the sustainability of the pig production chain.

Combined slaughterhouse wastewater treatment via pilot plant chemical coagulation followed by 4th generation downflow hanging sponge (DHS-4G)

The article aimed to investigate performance and evaluation of combining chemical coagulation pretreatment unit with a pilot-scale fourth generation downflow hanging sponge (DHS-4G) for slaughterhouse wastewater (SWW) treatment. This combination of compact treatment technique was tested as a novel system for the treatment of SWW. A DHS-4G reactor with a capacity of about 100 liters was installed after a 1 m3 chemical treatment unit and operated under two different hydraulic retention times (HRT) namely 12 h and 8 h. The integrated treatment system gave reasonable organic and nitrogen removal efficiencies and the removal efficiency was 91%, and 87% for COD, 92%, and 88% for BOD and 94%, and 84% for TSS at HRT 12 h, and 8 h respectively. Profile analysis showed that most of solids and organic matter particles were entrapped in the top segments of the reactor, while in the middle part residual and soluble organic matter were biologically degraded and the bottom segment slightly removes small residuals and nitrogen compounds. Also, analysis of retained biomass indicated that sludge retention time (SRT) was 27 days, which indicated low sludge amount produced from the reactor. Accordingly, the use of the studied integrated treatment system is very effective in terms of treatment cost and quality as it achieved required treatment in shorter time and minimum requirements for construction and operation.

Effect of aeration on nitrogen removal-associated microbial community in an innovative vertical cork-based constructed wetland for winery wastewater treatment

The wine industry produces large quantities of wastewater that often contains high levels of organic matter and nutrients, like nitrogen and phosphorous. In particular, nitrogen pollution can be harmful, even at low levels, since infants are vulnerable to nitrates in drinking water, and excess nitrogen can harm the health of soils and waterways. Herein, an innovative compact, modular, and mobile treatment wetland (TW) using cork by product as the only granular media was used to treat the final effluents from the Codorniu winery (Sant Sadurní d'Anoia, Spain). The TW was operated during two 5-month periods with or without intermittent induced aeration (40 min cycles, 90 L/min air flow rate). Nitrate (N-NO3) and total nitrogen (TN) removal were higher (52.8% and 46.8%, respectively, p < 0.05) during TW operation under aerated-condition. Additionally, qPCR analysis of 16S rRNA, nirS and nosZ genes revealed that intermittent induced aeration facilitates N-NO3 reduction by the stimulation of denitrifying bacteria in the TW biofilm (11.4% increase in nirS copies number/g cork sample, p < 0.05) as well as increasing the number of heterotrophic bacteria adhered to cork (25.5% increase in 16S rRNA copies number/g cork sample, p < 0.05). Moreover, SEM images demonstrated the suitability of cork as a resistant filter media for TW after long-term system operation (1.5 years). In conclusion, our results suggest that aeration improved nitrogen compounds removal compared to the non-aerated period, without affecting phosphorous elimination. Additionally, residual cork is presented here in a circular bioeconomy view, as a suitable filling media to treat winery wastewater that can provide additional carbon source to increase C/N rate stimulating denitrification, as well as a reliable organic substrate for biomass growth.

Quantifying the impact of induced topsoil and historical subsoil compaction as well as the persistence of subsoiling

Mechanical soil compaction increasingly occurs in arable land but the state and effects of historical compaction from regular operations are still poorly documented. Therefore, a typical field was selected and the effects of both newly formed topsoil compaction and historical developed subsoil compaction (below 30 cm) on soil physical and hydraulic properties, soil water movement, soil mineral nitrogen leaching potential and crop parameters were evaluated on a Luvisol under a winter rye (Secale cereale L.) and summer maize (Zea mays L.) rotation system. Three subsoil compaction levels were included, i.e., a i) highly compacted headland zone, and a moderately compacted in-field zone ii) without and iii) with deep tillage by subsoiling in the winter of 2016. Topsoil compaction on the other hand was induced by one machine pass with a rotary cultivator in addition to the regular machine passes during field preparation for the summer maize season of 2017, and compared with a control without extra compaction. For subsoil compaction treatments, both visual evaluation and lab or field based measurements indicated that soil physical and hydraulic properties were deteriorated in the headland compared with in-field zones. As a result, both winter and summer crop above-ground biomass were decreased in the highly compacted headland zone because of the restricted root growth, which further increased the risk of soil mineral nitrogen leaching. The alleviation effect of deep tillage remained after ∼ 2 years, which significantly increased maize height in the extremely dry and hot summer of 2018. For topsoil compaction, one traffic pass with a rotary cultivator increased topsoil penetration resistance and water content but summer maize above-ground biomass was not affected. Overall, prevention and alleviation of subsoil compaction are essential in increasing the resistance and resilience to the continuing deteriorating climatic conditions.

DMBA induced mammary tumor study of Phyto-fabricated sliver nanoparticles from Russelia Equisetiformis flower extract in rat

The mammary tumor is the world's most frequent ailment, and it is substantially more common in women. There are several forms of treatment and care available in the globe for tumors, the most common of which being chemotherapy, radiation therapy, and surgery with lots of harmful responses. Cancer has been treated since ancient times by herbs with various herbs and metals. synthesized AgNPs-REEE were characterized by Analytical methods such as dynamic light scattering (DLS), Zeta potential, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and Dynamic Light Scattering (DLS).All of the animals in this study had tumors caused by DMBA Apart from the vehicle control group, and they were divided into different groups such as only DMBA(7,12-dimethylbenz[a]anthracene) induced group, treatment group of ethanolic extract of Russelia equisetiformis (REEE) flower and sliver nanoparticles of ethanolic extract of Russelia equisetiformis (REEE) flower and sliver nanoparticles of ethanolic extract (AgNPs -REEE).the dose were decide by acute toxicity study. After compaction treatment time all animal were sacrifices and evaluate parameter like tumor weight, Tumor volume, biochemical parameter, hormonal assay and histopathology of breast tumor. It is observed that the size distribution of AgNPs ranges from 50 to 950 nm.

Design-oriented evaluation of the hydrodynamics in a full-scale combined filter-lamella separator for urban stormwater treatment.

The development of compact treatment devices with high removal efficiencies and low space requirements is a key objective of urban stormwater treatment. Thus, many devices utilize a combination of sedimentation and upward flow filtration in a single system. This study, for the first time, evaluates the flow field inside a combined filter-lamella separator via computational fluid dynamics. Herein, three objectives are investigated: (i) the flow field for different structural configurations, (ii) the distribution of particulate matter along the filter bed and (iii) the dynamic clogging in discrete filter zones, which is addressed by a clogging model derived from literature data. The results indicate that a direct combination of a filtration stage with a lamella separator promotes a uniform flow distribution. The distribution of particulate matter along the filter bed varies with configuration and particle size. Clogging, induced by particles in the spectrum <63 μm, creates gradients of hydraulic conductivity along the filter bed. After treating about half of Germany's annual runoff-efficient precipitation at a rainfall intensity of 5 L/(s·ha), the filtration rates increase in the front of the filter bed by +10%. Thus, long-term operating behavior is sensitive to efficient filter utilization in compact treatment devices.

Infrastructure under pressure: Water management and state-making in southern Iraq

Water infrastructure is an active element of state-making in southern Iraq, although major failings in water governance have in recent years triggered violent protests. Informed by scholarship on state clientelism and the political ecology of infrastructure, I examine the conflict-affected trajectories affecting public water management in Basra governorate. The degraded water treatment network manifests a post-2003 political system structured by embedded clientelism and politically sanctioned corruption. However, broad categorisations of clientelism can miss context-laden political effects produced by the spatial and technological configurations of infrastructure. I consider the state effects of water infrastructure practices in Basra governorate–how water supply networks and treatment technologies project state (in)capacity by means of volumetric and qualitative control over water flows. The empirical focus is on compact water treatment units (CWTUs), which are the main technology of public water supply in Basra governorate. I undertake an analysis of the deployment and management of CWTUs, as experienced by local actors responsible for, or politically contesting, the workings of water infrastructure in Basra city. Clientelist practices targeting public procurement and maintenance contracts have disrupted and delayed the upgrading of water infrastructure; yet these practices were enabled by neoliberal state-building that promoted the privatisation of public resources. Shortfalls in state capacity to provide clean drinking water in Basra are compounded by the growing hydro-climatic unpredictability of water flows.

The Impact of Head and Neck Multidisciplinary Clinic on Treatment Package Time During the COVID-19 Pandemic: A Single Institutional Experience

Purpose/Objective(s)The onset of the COVID-19 pandemic in the United States has had a profound impact on the delivery of medical care in this country, particularly in the outpatient clinical setting. A result of the pandemic has been the introduction of delays in the diagnosis and treatment of head and neck cancer which are strongly associated with inferior oncologic outcomes. Efforts to minimize these delays are therefore a high priority in this patient population. Here, we report the results from one particular intervention taken at our institution - the formation of a multidisciplinary clinic (MDC) - on treatment times.Materials/MethodsIn July 2020, our institution initiated a pilot program establishing a MDC combining otolaryngology and radiation oncology visits. Clinics were held on a half-day every two weeks and consisted of both new patient consults and follow-up patients who had received radiation as part of their treatment course. We measured and compared treatment package time of the MDC patients with those seen at our institution in the standard clinic setting.ResultsA total of 25 new patients requiring radiation were seen in our MDC between 7/31/2020 and 9/3/2021. This included 8 patients who underwent definitive radiation, 12 patients who underwent adjuvant radiation, and 5 patients who underwent palliative radiation. A total of 54 patients received radiation through standard clinics during this time frame, with 21 definitive cases, 28 adjuvant cases, and 5 palliative cases. There was no difference in median radiotherapy duration between the patients seen in MDC vs standard clinics (41 vs 41 days, p = NS). In comparison, however, the patients seen in MDC started adjuvant radiotherapy sooner (median 34 vs 41.5 days, p=0.002) and had a more compact treatment package times (median 76.5 vs 84.5 days, p=0.002). Three patients in the standard clinics cohort had treatment package times exceeding 100 days while no patient seen in MDC had a treatment package time exceeding 84 days.ConclusionDespite the many challenges associated with the ongoing COVID-19 pandemic, we found that patients seen in our MDC setting maintained timely treatment package times that were significantly better than those seen in our standard clinics. This is potentially due to the identification of patients likely to require adjuvant radiotherapy earlier in their clinical presentation. This in turn allowed for more advanced planning and minimization of delays in initiation of adjuvant radiotherapy. While previous studies have demonstrated improved oncologic outcomes when head and neck multispecialty care is delivered at tertiary care facilities, we found a further improvement in care delivery with colocalization of clinic visits by the treatment team.

Austenite reversion and nano-precipitation during a compact two-step heat treatment of medium-Mn steel containing Cu and Ni

Breaking the strength-ductility paradox of very-low (≤0.05 wt.%)-C medium (3–12 wt.%)-Mn steels (MMnS) has been a hard-wired topic, since in these steels multi-step heat treatments are usually required to obtain austenite for improved ductility and precipitates for higher strength. In this study, a compact two-step heat treatment comprising short (2 min) annealing and tempering was developed to investigate the synergetic effect of austenite reversion and nano-precipitation on the tensile behavior of a very-low-C MMnS containing 1.5 wt.% Cu and 1.5 wt.% Ni. The annealing step promoted considerable amount of reverted austenite (33 vol.%), and the annealing was short to prevent Cu and Ni from partitioning into austenite, since they were supposed to maintain in the ferrite phase and then promote the nano-precipitation in the subsequent tempering stage. During the subsequent tempering step, the nano-precipitates with Cu concentration of 20–50 at.% in the precipitation core and enriched with Cu, Ni, Al and Mn were observed in the ferrite phase. The volume fraction of reverted austenite reached 38.5 vol.% after tempering, which led to the ultimate tensile strength of 1222 MPa and total elongation of 29% by the transformation induced plasticity during plastic deformation. The current study demonstrates the beneficial influence of the compact two-step heat treatment on the austenite reversion and nano-precipitation behavior of very-low-C MMnS with the addition of Cu and Ni, which subsequently enables an enhanced strain hardening behavior, thereby improving the mechanical property profile of the MMnS.

Effects of subsoiling tillage on structure, permeability, and crop yields on compacted Solonetzic and Chernozemic dryland soils in Western Canada

Compaction induced by field wheel traffic and dense layers in the subsoil may adversely alter soil structure, impede soil aeration, restrict water infiltration and nutrient uptake, and inhibit plant root development, negatively affecting plant yields. Reclaiming compacted Chernozemic and Solonetzic soils with hardpan B horizons may be possible through subsoiling operations to loosen the soil to depth, e.g. ~0.30 m. The objective of this study was to evaluate the effect of subsoiling on soil physical properties and plant yield in wheel traffic compacted and non-compacted Chernozemic and Solonetzic soils in southern Saskatchewan Canada. Subsoiling increased air permeability in the compacted Chernozemic soil from 4.5x10-7 m sec-1 to 2.9x10-6 m sec-1. In the compacted Solonetzic soil, subsoiling significantly decreased soil cone index to 1579 kPa compared to 2376 kPa in the non-subsoiled treatment. Crop yields (hard red spring wheat, dry peas) in the two years following the treatment were similar among tillage and compaction treatments in the Chernozemic soil. However, subsoiling of the compacted Solonetzic soil resulted in a seed yield increase of canola of ~ 1000 kg ha-1 in the first year of study and no treatment effect in the second year when wheat was grown. Overall, subsoiling of the compacted soils tended to improve soil physical properties, especially in the Solonetzic soils.

Long-term investigations on ammonium removal with zeolite in compact vertical flow treatment wetlands under field conditions.

The scope of this study was to investigate if using zeolite as a reactive material in a vertical-flow wetland under field conditions improves ammonium removal from domestic wastewater in the long term. The experimental setup consisted of two pilot-scale first stage French vertical flow treatment wetlands (2.3 m2 surface area each), which were implemented under field scale conditions inside a wastewater treatment plant in the central region of France (L'Encloitre, 37360). The filters were operated during 27 months. A compact pilot containing Leca® as a main filtration layer (Ø 1-5 mm) was compared to a similar one filled with natural zeolite (Ø 2-5 mm). The pilots were fed according to regular feeding/resting periods (3½/7 days) and the nominal loading rate was of 300 g COD m-2 d-1 and 33 g·N·m-2·d-1 during operation. In both pilots, results showed a removal efficiency of more than 90 and 85% for TSS and COD, respectively. They also showed an increased NH4-N removal of 9% on average (total removal efficiency of 84%) with the use of zeolite compared to Leca®. The ion exchange capacity of zeolite seemed not to be affected after 27 months of experiments; however, the material was compacted and more friable after operation.

Enhanced nutrient removal from stormwater runoff by a compact on-site treatment system

Efficient and space-saving technologies for on-site treatment of stormwater runoff are required to control water pollution in the urban surface. The intermittent nature of stormwater runoff and extremely limited land available greatly hindered the application of current wastewater treatment technologies, and thus synchronous removal of multiple contaminants (especially for nutrient) efficiently was failed by current processes. In this study, a new compact CFFA treatment system, consisting of coagulation, flocculation, filtration and ammonium ion exchange units, was constructed for on-site treatment of stormwater runoff based on batch test optimization and pilot-scale test verification. The coagulation process effectively aggregated particles and precipitated phosphorus by dosing Al2(SO4)3, while flocculation using anionic polyacrylamide further enlarged particle size for efficient micromesh filtration. The dynamic micromesh filtration obtained turbidity and phosphorus removal efficiencies comparable to 30 min gravity settling with greatly smaller footprint. Ion exchange by zeolite showed higher exchange capacity owing to lower initial ammonium nitrogen concentration in the stormwater runoff. The pilot-scale experiments with treatment capacity of 1 L/s showed that the CFFA treatment system achieved synchronous removal of particles (97.2%), nitrogen (79.7%), phosphorus (95.0%) and organic matters (83.3%) efficiently within short hydraulic retention time of 0.35 h, yielding effluent with chemical oxygen demand, suspended solids, total phosphorus and total nitrogen of 38.7, 7.80, 0.22 and 2.80 mg/L, respectively. The CFFA treatment system had the highest pollutant removal loads compared to reported runoff treatment processes in literatures, and was well suited to on-site treatment of stormwater runoff with high space utilization efficiency.

Harvest impacts to stand development and soil properties across soil textures: 25-year response of the aspen Lake States LTSP installations

In addition to long-standing concerns about sustaining forest productivity, maintaining forest ecosystems under changing conditions and emerging threats has become increasingly important when planning forest management. With the aim of understanding effects of management on both productivity and recovery, we quantified the 25-year impact of varying degrees of organic matter (OM) removal and soil compaction on above-ground biomass, soil carbon and nutrients, soil bulk density, and stand development in aspen-dominated forests in the upper Lake States region of the US. Treatment impacts were assessed at three different sites with comparable overstory composition, but with varying soil texture, site quality, and climate. Across all sites, soil C and N generally decreased with increasing OM removal, and bulk density increased with increasing compaction; 25-year observations indicate recovery of bulk density at the surface (0–10 cm) but not at deeper portions of the soil profile. At the most productive site (loamy soils) with favorable initial soil porosity, severe compaction decreased mean aboveground biomass (-46%), particularly of trees (-73%). Biomass at 25 years did not differ among organic matter removal treatments (e.g. stem-only harvest), but a greater increase in soil C occurred with stem-only harvest relative to whole-tree harvest plus forest floor removal. In contrast, at a less productive site with sandy soils poorly buffered to nutrient and C removals, whole-tree harvest reduced biomass by 25% (tree biomass declined 35%) relative to stem-only harvest while compaction treatments did not differ in effects on biomass production, soil C or soil N. On clay soils, compaction treatments did not significantly impact biomass production, but whole-tree harvest plus forest floor removal reduced tree biomass by 47% relative to whole-tree harvest alone. Assessment of mean relative density indicates canopy closure has not yet occurred at the least productive site (clay soils) or the more severely disturbed stands at the intermediate site (sandy soils), suggesting the possibility for treatment impacts not yet discernible to become more pronounced as stands develop and nutrient uptake continues in the future. Our results align with concepts of soil quality and texture-specific limitations to growth, underlying a need to understand key soil limitations when considering forest management impacts to aboveground structure and productivity.

Localized nutrient supply can facilitate root proliferation and increase nitrogen-use efficiency in compacted soil

Soil compaction constrains root growth and crop yield. Previous studies have shown that localized nutrient supply can significantly improve maize plant growth in field conditions at the early growth stage. However, this promoting effect has not been tested in the compacted soil. We describe 2-year field experimentation on a fluvo-aquic soil in the North China Plain to investigate the effect of localized vs. broadcast ammonium and phosphorus supply on maize under three soil compaction treatments (NC: non-compacted, C: compacted and SC: severely compacted) during 2012 and 2013. Results showed that compared with broadcast ammonium and phosphorus (BNP), localized ammonium and phosphorus supply (LNP) resulted in significantly higher PFPN in the NC (by 31–37%), C (by 43–44%) and SC (by 45%) treatments at harvest. When soil was compacted (C and SC), the enhancement of nitrogen (N) utilization in the LNP treatment was attributed to the increased root growth, including greater specific root length (a greater proportion of fine roots), lower root tissue density and deeper rooting at the seedling stage, especially in the compacted treatment (C). The enhanced root penetration capacity contributed to the increased N and water uptake from the deep soil layers. Our study highlighted the importance of nutrient management for mitigating negative impacts of soil compaction on crops, and will underpin new soil compaction management practices by considering optimal fertilization to strengthen the root-soil interactions.