Loss Of Organic Matter Research Articles

Soil priorities for Italy. A multi-stakeholder consultation, barriers and opportunities for research system

Soil can play a primary role to address key global challenges, such as climate change mitigation and adaptation; ensuring food security and human livelihood; preserving ecosystem services, biodiversity and water quality. Nevertheless, identifying and addressing key soil challenges requires a cross cutting and tailored approach that considers local context and needs. On the other hand, advancing soil science research is essential for bridging the gap between societal needs and state-of-the-art on soil knowledge. This study summarizes the outcomes of multi-stakeholder consultations carried out in Italy with the aim to identify and prioritize the key soil challenges and the main knowledge barriers/gaps that prevent to address and the main opportunities to overcome them. Soil sealing, soil erosion and the losses of soil organic matter were identified as the most relevant soil challenges in the Italian context, as their incidence is already alarming in the country. The study showed that there are many areas of soil research improvement to respond adequately to the existing soil challenges in Italy.

Signals of low grade organic matter alteration in the Upper Permian Kupferschiefer (Spremberg area, Eastern Germany) – A by-product of copper mineralization?

Organic matter (OM) is known to be an important reductant in many sediment-hosted base metal deposits. However, the precise nature of the interactions between OM and hydrothermal fluids is still debated, as is just how such interconnected reactions develop over geological timescales. We investigated the Kupferschiefer mineralization in two drill cores from the Spremberg-Graustein field in Eastern Germany focusing on the inventory of organonitrogen, -sulfur and -oxygen (NSO) compounds, which are most affected by organic–inorganic interactions with mineral surfaces, metals and aqueous fluids. Rather homogeneous deposition of type II marine organic matter, prevailing photic zone euxinia and an early oil window thermal maturity were documented using conventional hydrocarbon analysis. Furthermore, a slight level of hydrothermal alteration was detected in the lower part of drill core 121 h/72, in proximity to the epigenetic hematitic alteration zone known as ‘Rote Fäule’. A minor loss of extractable organic matter and especially long-chain n-alkanes was accompanied by significant enrichment in oxygenated compounds and increased molecular oxygen content detected by ultra-high resolution mass spectrometry (FT–ICR–MS). A strong enrichment of deuterium observed in the n-alkanes (up to −36‰) and isoprenoids (up to −20‰) indicates that hydrogen exchange with an evaporitic fluid occurred in the Spremberg Kupferschiefer over geological timescales at maximum temperatures not exceeding 110 °C. We therefore conclude that FT–ICR–MS, combined with determination of stable hydrogen isotope compositions, can provide valuable information about interaction time scales and the origin of mineralizing hydrothermal fluids.

Spatiotemporal variation in soil degradation and economic damage caused by wind erosion in Northwest China

Wind erosion causes significant dust emissions in northwest China, resulting in large amounts of soil organic matter and nutrient losses. It has a significant impact on air quality, climate change, vegetation growth, and economic growth at the regional scale. In this work, the Weather Research Forecasting with Chemistry atmospheric chemical transport model was used to simulate the temporal and spatial processes of dust emissions in northwest China from 1980 to 2015. The temporal and spatial variation characteristics of the loss of soil organic matter and nutrients (total nitrogen and total phosphorus) due to dust emissions, and the economic damage from wind erosion, were simulated and calculated. Spatial patterns of soil organic matter and nutrient losses are consistent with dust emission rates across the research region. The average annual dust emissions were approximately 65.17 million tons, with losses of soil organic matter, total nitrogen, and total phosphorus resulting from dust emissions of 531,494 tons, 30,754 tons, and 37,095 tons, respectively. In addition, the average annual economic loss caused by wind erosion was 309.25 million yuan in northwest China during the entire study period. This research is valuable for understanding the role of wind erosion on the carbon and nutrient cycles and the mechanism of soil degradation in northwest China and estimating the economic impacts of wind erosion.

Evaluation of Physio-Chemical Characteristics of Bio Fertilizer Produced from Organic Solid Waste Using Composting Bins

Background: The possibility of converting the organic fraction of municipal solid waste to mature compost using the composting bin method was studied. Nine distinct treatments were created by combining municipal solid waste (MSW) with animal waste (3:1, 2:1), poultry manure (3:1, 2:1), mixed waste (2:1:1), agricultural waste (dry leaves), biocont (Trichoderm hazarium), and humic acid. Weekly monitoring of temperature, pH, EC, organic matter (OM percent), and the C/N ratio was performed, and macronutrients (N, P, K) were measured. Trace elements, including heavy metals (Cd and Pb), were tested in the first and final weeks of maturity. Results: Temperatures in the first days of composting reached the thermophilic phase in MSW compost with animal and poultry manure between 55–60 °C, pH and EC (mS/cm) increased during the composting period in most composting bin treatments. Overall, organic matter (OM percent) and the C/N ratio decreased (10.27 to 18.9) as result of microbial activity during composting. Organic matter loss percent was less in treatments containing additives (biocont l humic acid) as well agricultural waste treatment. Composting bin treatments with animals and poultry showed higher K and P at the mature stage with an increase in micronutrients. Finally heavy metals were (2.25–4.20) mg/kg and (139–202) mg/kg for Cd and Pb respectively at maturation stage. Conclusion: Therefore, the results suggested that MSW could be composted in the compost bin method with animal and poultry manure. The physio-chemical parameters pH, Ec and C/N were within the acceptable standards. Heavy metals and micronutrients were under the limits of the USA standards. The significance of this study is that the compost bin may be used as a quick check to guarantee that the outputs of long-term public projects fulfill general sustainability requirements, increase ecosystem services, and mitigate the effect of municipal waste disposal on climate change particularly the hot climate regions.

Increasing the energy production in an urban wastewater treatment plant using a high-rate activated sludge: Pilot plant demonstration and energy balance

The use of high-rate activated sludge (HRAS) reactors for the removal of COD in urban wastewater treatment plants (WWTPs) has been investigated because its potential contribution to energy generating WWTPs. A one-year operation period of a pilot plant treating the effluent of the primary settler of a full-scale WWTP was analyzed. The HRAS pilot plant operated without iron salts addition at temperatures between 12 and 28 °C at an average organic loading rate 2.8 ± 0.5 kg COD m−3 d−1 and with an average inflow COD concentration of 330 ± 86 mg O2 L−1. The influence of sludge retention time (SRT) on COD recovery and biomethane potential of the produced sludge was investigated and compared to the full scale WWTP performance. The highest observed sludge yield coefficient and biomethane potential of the sludge were achieved at SRT of 0.6 days. The weak point of the HRAS performance at STR of 0.6 days is the high loss of organic matter in the effluent due to the limited efficiency of the solids separation in the secondary settler. At higher SRT (in the range 1.0–2.1 days), the secondary settler efficiency and the COD recovery are higher than those achieved at SRT of 0.6 days but part of the inlet ammonium can be nitrified in the HRAS system at temperatures above 20 °C. A detailed energy balance indicated that two-thirds reduction of aeration requirements and one-third increase of biogas production could be achieved in a plant configuration in which HRAS is coupled to autotrophic biological nitrogen removal (BNR) compared to the heterotrophic BNR configuration, yielding a net energy production of ca. 0.1 kWh m−3 of treated water.

Priorities for UK soils

The predominance of agriculture in the UK is a major factor determining the main soil threats and priorities. The main soil degradation processes are compaction, erosion and soil organic matter loss, while soil contamination and sealing is also a significant issue. Agricultural land take threatens soil ecosystem services but receives little attention. An urgent need to tackle climate change has resulted in a new direction for land use and soil policy.

Biomeliorant for the restoration of saline and degraded soils in the arid zone

The methods of gypsum application in degraded soils to increase and restore saline and degraded soils, to grow vegetables and fruits in the arid zone are considered in the paper. The issues of soil alkalinity reduction to increase soil fertility with the use of a new biomeliorant at standard of ST RK 2208-2012 containing phosphogypsum, calcium, sulfur and cattle manure with the addition of crushed camel thorn were studied. According to calculations this meliorant application reduces the loss of nitrogen and organic matter by 40%,, which being a highly effective fertilizer that improves the physico-chemical and biological properties of the soil, which contributes to an increase in crop yields. Field studies have shown that the joint anaerobic fermentation of phosphogypsum and manure, camel thorn led to intensive aggregation and the creation of favorable conditions of the soil structure for the crops. The results showed that the biomeliorant application into the soil led to a noticeable improvement in its structure, increases alkalinity, soils become more fertile and crop yields increase.

The Biological Origins of Soil Organic Matter in Different Land-Uses in the Highlands of Ethiopia

In the Ethiopian highlands, clearance of Afromontane dry forest and conversion to crop and grazing land lead to land degradation and loss of soil organic matter (SOM). Eucalyptus is often grown on degraded soils, and this results in the partial recovery of soil carbon stocks. The aim of this work was to assess the biological sources of SOM in this land-use sequence. In top-soils (0–10 cm) of four land-use systems, namely remnant natural forest, eucalyptus plantation, cropland, and grazing land, in the Ethiopian highlands, the origin of SOM was investigated. For this, a sequential extraction method was used, involving a solvent extraction, base hydrolysis, and a subsequent CuO oxidation. In these extracts, biomarkers (molecular proxies) were identified to characterize the SOM of the soil of the four land-uses. Putative lipid monomers of leaf, root, and microbial degradation products suggest that root inputs and microbial inputs dominate in SOM of all the land-uses, except grazing land. The ratios of syringyls, vanillyls, and cinnamyls showed that non-woody angiosperm plants were the predominant source for lignin in eucalyptus, cropland, and grazing land soil. In the soils of the natural forest, lignin originates from both woody angiosperms and woody gymnosperms. Our study shows the importance of root and microbial inputs in the formation of SOM, but also that, in the natural forest, legacies of previous forest cover are present.

Influence of Organic and Mineral Fertilizers on Soil Organic Carbon and Crop Productivity under Different Tillage Systems: A Meta-Analysis

The intensive use of mineral (M) fertilizers may cause harm the environment via leaching or greenhouse gas emissions, destroy soil fertility as a consequence of loss of soil organic matter, and, due to their high price, they are economically unviable for producers. It is widely accepted that organic (O) fertilizers may deal with pressing challenges facing modern agriculture, even if farmers need to improve their knowledge for applying in fertilization programs. A meta-analysis approach has been adopted to evaluate the effects on soil organic carbon (SOC) and crop yield of O fertilizers, applied alone or in combination with mineral fertilizers (MO) under conventional (CT), reduced (RT), and no-tillage (NT) regimes. The analysis was performed in different climatic conditions, soil properties, crop species, and irrigation management. Organic fertilizers have a positive influence in increasing SOC compared with M (on average 12.9%), even if high values were observed under NT (20.6%). The results highlighted the need for flexible and environment-specific systems when considering organic fertilization subjected to different tillage regimes. Similarly, MO application showed a better crop yield response in CT and RT under coarse soils when compared with M fertilizer applied alone (on average 13.4 and 12.7%, respectively), while in medium-textured soils, CT and RT yielded better than NT under O fertilizers (9.5 and 11.2 vs. 2.5%, respectively). Among the crop species, legumes performed better when O fertilizers were adopted than M fertilizers (on average 15.2%), while among the other crop species, few differences were detected among the fertilization programs. Under irrigated systems, RT and NT led to higher productivity than CT, especially under MO treatments (on average 9.2 vs. 3.4%, respectively). The results highlighted the importance of the environmental and agronomical factors and how their understanding could affect the impact of these conservation farming practices on crop productivity to improve the sustainability of the farming system in a specific region.

Correction to: Continuous maize cropping accelerates loss of soil organic matter in northern Thailand as revealed by natural 13C abundance

Correction to: Continuous maize cropping accelerates loss of soil organic matter in northern Thailand as revealed by natural 13C abundance

GIS Application for Modelling Erosion Hazard in Batam Island

Soil erosion disaster is a disaster that occurs simultaneously with landslide events that occur due to the destruction of the soil layer which then causes erosion followed by landslides. The phenomenon of land erosion occurs due to high rainfall, the influence of slopes and slope length, as well as due to development resources according to Mamarodia (2014). Erosion can also occur due to land degradation, namely the loss of organic matter and nutrients from the root area, this study aims to determine the erosion hazard model in Batam Island which can be displayed in the form of a RUSLE model by utilizing a geographic information system (GIS). The data used in the form of slope maps, land use maps, maps of soil types and rainfall maps on Batam Island using the data processing method used is the RUSLE method to provide information in the form of erosion hazard categories and produce a two-dimensional erosion hazard model map. The result is a map of the erosion hazard model in a two-dimensional form with categories obtained from the combination of the four maps that have been classified. The results of this research are information on the area of ​​soil erosion with very light categories (24,200.42 Ha), light (5,488, 20 Ha), medium (5,100.42 Ha), heavy (3,029.43 Ha), and very heavy (2,929.64 ha) spread over Batam Island. The slope with the highest slope height is class 129,284 ft to 148,627 ft, and the lowest height elevation is in class -6,11 ft to 13,232 ft. the Batam area tends to have an area with an elevation of 13,232 ft to an altitude of 32,574 ft.

Soil Organic Carbon Distribution and Its Response to Soil Erosion Based on EEM-PARAFAC and Stable Carbon Isotope, a Field Study in the Rocky Desertification Control of South China Karst.

Ecological restoration plays an important role in enhancing carbon sequestration ability in karst areas, and soil organic matter is one of the main carbon reservoirs in karst key zones. The serious soil erosion in karst areas leads to the loss of soil organic matter (SOM). However, the distribution characteristics of SOM and its response mechanism to soil erosion in the process of rocky desertification control have rarely been reported. In this study, soil samples of five restoration types (abandoned land, AL; grassland, GL; peanut cultivated land, PCL; Zanthoxylum bungeanum land, ZBL; forest, FS) were collected in typical karst rocky desertification drainage, south China. By measuring soil organic carbon (SOC), dissolved organic carbon (DOC), and δ13Csoc values and combining with spectral tools, the distribution and isotopic composition of soil shallow organic carbon in definitized karst drainage was definitized and the response of DOM spectral characteristics to soil erosion was explored. The results showed that three kinds of fluorescence components were detected by fluorescence excitation emission matrix (EEM)-parallel factor analysis (PARAFAC), C1 and C2 were humus-like, and C2 was protein-like. Abandoned could be a more suitable control measure for enhancing SOC quality in the karst regions of south China. The variation trend of SOC content, δ13Csoc values, spectral indexes, and the distribution of fluorescence components from the midstream to downstream of the drainage indicated the soil redistribution. This study provides basic scientific data for karst rocky desertification control and for enhancing the soil carbon sequestration ability of karst.

Continuous maize cropping accelerates loss of soil organic matter in northern Thailand as revealed by natural 13C abundance

AimsThe loss of soil organic matter (SOM) has widely been reported in the tropics after changing land use from shifting cultivation to continuous cropping. We tested whether continuous maize cultivation accelerates SOM loss compared to upland rice and forest fallow.MethodsBecause litter sources include C4 plants (maize in maize fields and Imperata grass in upland rice fields) in Thailand, C3-derived and C4-derived SOM can be traced using the differences in natural 13C abundance (δ13C) between C3 and C4 plants. We analyzed the effects of land use history (cultivation or forest fallow period) on C stocks in the surface soil. Soil C stocks decreased with the cultivation period in both upland rice and maize fields.ResultsThe rate of soil organic carbon loss was higher in maize fields than in upland rice fields. The decomposition rate constant (first order kinetics) of C3-plant-derived SOM was higher in the maize fields than in the upland rice fields and the C4-plant-derived SOM in the forest fallow. Soil surface exposure and low input of root-derived C in the maize fields are considered to accelerate SOM loss. Soil C stocks increased with the forest fallow period, consistent with the slow decomposition of C4-plant-derived SOM in the forest fallows.ConclusionsContinuous maize cultivation accelerates SOM loss, while forest fallow and upland rice cultivation could mitigate the SOM loss caused by continuous maize cultivation.

Ecological Assessment of Disturbances in the Landscape Structure of Alluvial Soils of Floodplains Under Technogenesis Influences

The article considers the problem of disturbances in the landscape structure when extracting constructional sand causes the formation of a technogenic relief. The objective of this study was to determine the change in the main fertility indicators for alluvial turf and meadow soils disturbed by open-pit mining and building communications. The study included tasks stated below. The research tasks included identifying the quantitative changes in the composition and properties of alluvial soils disturbed by construction sand extraction. Determination of the change in the organic matter content of the upper layer in the artificial soil-like formations (technozems) in comparison with undisturbed soils. Specifying the nature of changes in the texture of the humus horizon of donor soils and technozems bulk layers. Determination of the change in the pH of the aqueous extract, and the content of the accessible forms of K2O and P2O5 in the soils disturbed by mining. The objects of the study were: plots of agricultural land with soil samples of alluvial turf and alluvial meadow soils, sampled at a depth of 0-20 cm. In the floodplain zone, the research was conducted on soils with a disturbance within the upper 50 cm thickness on alluvial turf soil. Technozem, an artificial soil-like structure consisting of one bulk layer of technogenic soil, was studied in the central floodplain. The studies found that open-pit mining has an impact on the composition and properties of alluvial soils. Disturbances in the landscape structure at open-pit mining cause significant destruction of a fertile layer as the soil texture changes. There is also a loss of organic matter in the disturbed soils depending on the degree of manifestation of anthropogenesis.

Liming and Phosphate Application Influence Soil Carbon and Nitrogen Mineralization Differently in Response to Temperature Regimes in Allophanic Andosols

Andosols are characterized by high organic matter content and play a significant role in carbon storage. However, they have low phosphorus fertility because of the high phosphate-fixing capacity of active aluminum. For agricultural use of Andosols, it is necessary to ameliorate its poor phosphorus fertility by applying lime and high doses of phosphate fertilizers. The objective of the present study was to clarify how such soil amendments affect the mineralization of soil organic carbon (C) and nitrogen (N) in allophanic Andosols under different temperature regimes. The soil was treated using combinations of liming and heavy phosphate application, followed by incubation under different temperature conditions. The N mineralization and the soil CO2 evolution rate were measured periodically. The patterns of N mineralization were analyzed by fitting them to first-order kinetics. Liming increased C and N mineralization irrespective of temperature, and the increase was further enhanced by phosphate application. Kinetic analysis of the N mineralization curve indicated lowering of the activation energy of N mineralization reactions with phosphate application, suggesting that P application may accelerate N mineralization at lower temperatures. These findings provide a basis for developing soil management strategies to reduce the loss of soil organic matter.

Perceived Causes and Solutions to Soil Degradation in the UK and Norway

Soil quality is declining in many parts of the world, with implications for the productivity, resilience and sustainability of agri-food systems. Research suggests multiple causes of soil degradation with no single solution and a divided stakeholder opinion on how to manage this problem. However, creating socially acceptable and effective policies to halt soil degradation requires engagement with a diverse range of stakeholders who possess different and complementary knowledge, experiences and perspectives. To understand how British and Norwegian agricultural stakeholders perceived the causes of and solutions to soil degradation, we used Q-methodology with 114 respondents, including farmers, scientists and agricultural advisers. For the UK, respondents thought the causes were due to loss of soil structure, soil erosion, compaction and loss of organic matter; the perceived solutions were to develop more collaborative research between researchers and farmers, invest in training, improve trust between farmers and regulatory agencies, and reduce soil compaction. In Norway, respondents thought soils were degrading due to soil erosion, monocultures and loss of soil structure; they believed the solutions were to reduce compaction, increase rotation and invest in agricultural training. There was an overarching theme related to industrialised agriculture being responsible for declining soil quality in both countries. We highlight potential areas for land use policy development in Norway and the UK, including multi-actor approaches that may improve the social acceptance of these policies. This study also illustrates how Q-methodology may be used to co-produce stakeholder-driven policy options to address land degradation.

Analysis of raw materials and products characteristics from composting and anaerobic digestion in rural areas

Chinese food waste (FW) production is enormous which brings many economic and environmental benefits. There is an urgent need for proper and efficient treatment technology. Anaerobic digestion (AD) is a popular technology for centralized large-scale treatment of FW. Composting technologies including static composting (SC), forced aerated composting (FC), and machine composting (MC) have been applied in rural areas owing to their low cost and simplicity. The characteristics of products in different FW treatment are still unclear, preventing agricultural use of the products. In order to elucidate the properties of different samples and to realize the resource utilization of products, compost samples (FC, SC and MC) and AD biogas residue samples were collected on site. By analyzing the physicochemical properties (pH, moisture content, maturity, salinity, lignocellulose, etc.) and phytotoxicity, the quality of different products was evaluated to determine the most appropriate rural FW treatment technology. MC products showed poor performance in maturity, salt concentration and plant toxicity. SC products cannot be used due to phytotoxicity. High moisture content limited the prospects of AD products utilization. FC products were of good quality with 32.91% in organic matter loss, good performance in lignocellulose degradation, 6.76% in water-soluble salts, and 79.61% in germination index. FC technology is worth promoting in rural areas of China.

Considerations on the use of carbon and nitrogen isotopic ratios for sediment fingerprinting

Carbon and nitrogen stable isotopic ratios are increasingly used in sediment fingerprinting studies. However, questions remain regarding tracer conservativeness during sediment transport and other error considerations. We investigate conservativeness processes, including carbon oxidation and nitrogen mineralization, using experiments. We also test how other considerations impact the isotopic ratios including algae accrual into temporary sediment deposits in the river, the physical loss of organic matter via disaggregation, concentration dependent mixing, and time-varying isotopic ratios of sediment sources. Results show all processes and considerations can change isotope abundance, however, significance varied. Carbon oxidation, nitrogen mineralization and upland seasonality of sediment sources did not significantly change isotopic ratios. Algae accrual, concentration dependency mixing, physical loss of organic matter during transport, and seasonality of the in-stream sediment source significantly changed the isotopic ratios for the conditions tested. Fertilization significantly impacted the stable carbon isotopic ratio in one case considered. Results from sediment fingerprinting simulations and testing how well the virtual mixture fits the mass balance equation agreed with significance results for tracer changes, and some uncertainty considerations changed fractional contribution of sources by as much as 50%. A noteworthy recommendation is the mean isotopic ratios of sediment sources should be separated by at least 1‰ to lessen tracer conservativeness concerns in fingerprinting simulation. We recommend concentration dependent mixing becomes the accepted practice when using isotopic ratios, however, we warn against using particle size corrections. We recommend the loss of organic matter during disaggregation be accounted for in fingerprinting estimates. We recommend algae accrual in in-stream sediment deposits should either be accounted for or in-stream sediment should be treated as a time-varying source in sediment fingerprinting simulations. Finally, we recommend both the carbon and nitrogen isotopic ratio should be tested as potential tracers because the two tracers performed similarly when testing how well the virtual mixture fits the mass balance equations.

Effects of Soil Quality on the Microbial Community Structure of Poorly Evolved Mediterranean Soils.

Physical and chemical alterations may affect the microbiota of soils as much as the specific presence of toxic pollutants. The relationship between the microbial diversity patterns and the soil quality in a Mediterranean context is studied here to test the hypothesis that soil microbiota is strongly affected by the level of anthropogenic soil alteration. Our aim has been to determine the potential effect of organic matter loss and associated changes in soil microbiota of poorly evolved Mediterranean soils (Leptosols and Regosols) suffering anthropogenic stress (i.e., cropping and deforestation). The studied soils correspond to nine different sites which differed in some features, such as the parent material, vegetation cover, or soil use and types. A methodological approach has been used that combines the classical physical and chemical study of soils with molecular characterization of the microbial assemblages using specific primers for Bacteria, Archaea and ectomycorrhizal Fungi. In agreement with previous studies within the region, physical, chemical and biological characteristics of soils varied notably depending on these factors. Microbial biomass, soil organic matter, and moisture, decreased in soils as deforestation increased, even in those partially degraded to substitution shrubland. Major differences were observed in the microbial community structure between the mollic and rendzic Leptosols found in forest soils, and the skeletic and dolomitic Leptosols in substitute shrublands, as well as with the skeletic and dolomitic Leptosols and calcaric Regosols in dry croplands. Forest soils displayed a higher microbial richness (OTU’s number) and biomass, as well as more stable and connected ecological networks. Here, we point out how human activities such as agriculture and other effects of deforestation led to changes in soil properties, thus affecting its quality driving changes in their microbial diversity and biomass patterns. Our findings demonstrate the potential risk that the replacement of forest areas may have in the conservation of the soil’s microbiota pool, both active and passive, which are basic for the maintenance of biogeochemical processes.

The potential of using corn straw biochar to compensate the loss of available soil organic matter

The process of migration of organic carbon from the biochar into the substrate and the aqueous phase was simulated. The process of organic carbon migration in passive and washing mode was evaluated. Part of the organic carbon was washed with water and passed into the aqueous phase, the other part remained in the mass of biochar. Biochar can be a source of available organic carbon, providing nutrition to rhizosphere microorganisms that improve the mineral nutrition of plants, both in the short and long term.