Alfalfa Residues Research Articles

Investigation of Physiomorphological Characteristics of Sirvan Wheat Cultivar Using Amendment Materials

In order to investigate the effect of some amendment materials on physiomorphological characteristics of the Sirvan wheat cultivar, a randomized complete block design experiment and replicated three times, was carried out in the years 2018-2019 on a farm in Dasht-e Armou, Dareshahr Ilam Province, Iran. The aim of this study was to investigate and compare the effects of two factors, namely the type of amendment materials and the number of insoluble matters (alfalfa residues at 5, 10, and 15 t/ha, straw and wheat straw at 5, 10 and 15 t/ha, poultry manure at 2, 4 and 6 t/ha and the required 100-percent mineral fertilizer) on the plant. The results showed that the use of amendment materials significantly increased the number of spikes (15 to 143 percent), chlorophyll index (18 to 122 percent), number of leaves (8 to 51 percent), relative water content (6 to 21 percent), plant height (5 to 16 percent) and leaf area index (5 to 33 percent) of wheat. The highest number of leaves (19), plant height (115 cm), leaf area index (5.76), and relative water content (70 percent) were observed in 15 t/ha of alfalfa residues while the highest number of spikes (5.67) and chlorophyll index leaf (18.6) was obtained in 6 t/ha of poultry manure. Based on findings, it can be stated that the use of amendment materials, especially in raw form and poultry manure, will have beneficial effects on the growth and yield of wheat.

High-efficiency adsorption of heavy metals on sulfur nanoparticles coated biochar derived from alfalfa residues and its biological effects

High-efficiency adsorption of heavy metals on sulfur nanoparticles coated biochar derived from alfalfa residues and its biological effects

The effects of Fe- and Mn-oxides and imogolite in the presence of kaolinite on organic nitrogen mineralization and soil enzyme activities

ABSTRACT An incubation experiment was conducted to study the effect of clay content and composition on organic nitrogen mineralization. The experiment measured the mineralization of organic nitrogen from alfalfa residues, enzyme activities, and microbial biomass nitrogen in mixtures of sand, kaolinite, and non-layered colloids (NLCs) with sand as a control. The study found that as the contents of kaolinite and NLCs increased, the mineralization of organic nitrogen and enzyme activity decreased, but microbial biomass nitrogen increased. The maximum decrease in organic nitrogen mineralization was 88.6%, and microbial biomass nitrogen increased from 4.7 to 15.5%. The acid and alkaline phosphatase activities also decreased by 86.0 and 93.6%, respectively, with an increase in clay content. The specific surface area (SSA) of the mixtures showed an inverse relationship with enzyme activity and mineralization of organic nitrogen. Inactivation of extracellular enzymes by adsorption on the surfaces of kaolinite and NLCs, and decreased accessibility of organic nitrogen substrate molecules due to adsorption, reduced the mineralization of organic nitrogen. Microbial biomass nitrogen increased as the water holding capacity of the mixtures increased, indicating the importance of water-filled pores in accommodating active microbial biomass and protecting it from desiccation and predators.

Applicability of alfalfa and goldenrod residues after supercritical CO2 extraction to plant micronutrient biosorption and renewable energy production

The residues of alfalfa and goldenrod, after supercritical CO2 extraction, were examined against raw plant materials to determine the capacity to carry micronutrients and energy production.Materials were enriched with Cu(II), Mn(II) and Zn(II), via biosorption and subjected to multielemental analysis and determination of nitrogen. The materials showed a high capacity for Cu(II)>Zn(II) > Mn(II), whose content increased by 104–1262 and 54–2460 times in post- and prior-extraction samples, respectively. The goldenrod residues provided the best results for Mn(II) (14,000 mg/kg) and Zn(II) (18,500 mg/kg), while alfalfa residues bound more Cu(II) (13,800 mg/kg). Materials meet the EU regulation requirements for organo-mineral fertilisers.During thermal breakdown, two combustion steps lead to 83–85% weight loss. The thermal response included two exothermic effects at 120–400 °C and 400–620 °C releasing the energy of 3.4–4.5 μV/mg and 6.1–7.0 μV/mg, respectively. Alfalfa matrices provided stronger thermal effects. The materials emit H2O, CO2 and SO2. Extraction caused an increase and a slight decrease of the energy released by alfalfa during the first and second combustion steps, respectively.The residues contained less water than the raw materials and could be applied as solid biofuel or as combustion promoters. Laboratory-scale experiments proved that the residues after extraction were suitable in both applications.

Multi-residue analysis of 206 pesticides in grass forage by the one-step quick, easy, cheap, effective, rugged, and safe method combined with ultrahigh-performance liquid chromatography quadrupole orbitrap mass spectrometry.

A novel method for detecting pesticide multi-residue in grass forage (alfalfa and oat) was established based on the one-step automatic extractionand purification technology of quick, easy, cheap, effective, rugged, and safe combined with ultrahigh-performance liquid chromatography quadrupole Orbitrap high-resolution mass spectrometry. The crushed sample was extracted with acetonitrile with 1% acetate, followed by a cleanup step with a primary-secondary amine, octadecylsilane, and graphitized carbon black. The extraction and purification were carried out using the one-step automatic pretreatment equipment. The target pesticides were acquired in positive ion electrospray ionization mode and full scan/data dependent secondary scan mode. The calibration curve shows good linearity over the corresponding concentration range, with the coefficient of determination greater than 0.99. The screening detection limits were 0.5-50μg/kg, and the limit of quantification for the 206 pesticides was set at 1-50μg/kg. At the spiking levels of one, two, and 10 times of limit of quantification, more than 95% of pesticides had recovery between 70-120%, with a relative standard deviation ≤20%. The method was proved to be simple, rapid, high-sensitivity, and could be routinely used for the high throughput screening and quantitative analysis of pesticide residues in alfalfa and oat.

Crop residues differ in their decomposition dynamics: Review of available data from world literature

Decomposition of crop residues may affect soil organic carbon (C) stocks, which are key for soil fertility improvement and mitigation of climate change. Numerous independent studies across the world point to contradictory results but their existence provides an opportunity to conduct a comprehensive analysis of the impact of crop type on residue decomposition. In the present study, data from 394 trials from across the world were used to assess cumulative CO2 emissions from residues of 17 crops during 0–30, 0–90 and 0–120 days (i.e. CR30, CR90 and CR120; 1-[CR30/CR120] ratio as a stability index of C emissions) and to relate the results with residue quality (C, N and lignin concentrations) and selected soil properties (texture, pH, soil organic carbon concentration). At all durations, legumes exhibited the highest CO2 emissions per gram of C added (1003 mg CO2-C g−1C after 120 days) followed by grasses (9 4 7), oilseed crops (9 4 4) and cereals (8 4 6), with the legumes and grasses showing the lowest temporal stability of C emission as pointed out by a 1-[CR30/CR120] of 0.78 and 0.79, respectively, versus 0.82 and 0.83 for cereals and oilseed crops. At all durations, maize residues emitted the least C-CO2 (86, 275 and 495 mg CO2-C g−1C), followed by two other lignin rich crops (cotton and sunflower), while the highest emissions were from Alfalfa residues that produced about 4 times more CO2 (e.g. 359 at CR30 and 1319 at CR120) than maize. Overall, CO2 emissions were positively correlated with soil clay concentration (r > 0.22), residue C concentration (e.g. r = 0.46 at CR90 and r = 0.37 with emission stability, P < 0.05) but negatively to residue N concentration (r = −0.26 at CR120, P < 0.05). The global trend pointed to decreased CO2 emissions with increasing residue lignin. Contrary to what is generally believed, providing the soil with high lignin and high N concentration may foster C stabilization into soils by soil microbes.

Reductive soil disinfestation with biochar amendment modified microbial community composition in soils under plastic greenhouse vegetable production

Reductive soil disinfestation (RSD) and biochar amendment are considered sustainable management practices to improve degraded vegetable soil. However, the combined effects of these two remediation methods on soil microbial communities and vegetable yields remain unclear. In the present field study, the interactive impacts of conventional RSD treatment and biochar were tested in plastic greenhouse soils under a continuous vegetable cultivation system. Six treatments consisted of different management practices: soil untreated (CK), soil amended with biochar (BC), soil flooded (SF), soil flooded and mulched with plastic film (SFM), soil amended with alfalfa residue, flooded and mulched with plastic film (RSD), and soil amended with alfalfa residue plus biochar, flooded and mulched with plastic film (RSD+BC). Analysis of the soil samples collected at 0–20 cm for a range of physicochemical and microbial properties revealed that both RSD and RSD+BC treatments decreased soil nitrate (NO3-) concentrations while increasing soil pH, ammonium (NH4+), dissolved organic carbon (DOC), and the low-valent ion (Fe2+, Mn2+) concentrations (P < 0.05). Unlike the BC, SF and SFM treatments, the RSD and RSD+BC treatments decreased the bacterial and fungal diversity (P < 0.05) compared to the CK, and altered microbial community composition. The RSD treatment significantly reduced the relative abundance of genus Fusarium while increasing the relative abundances of genera Bacillus and Clostridium, and the increase was more evident in the RSD+BC treatment, suggesting the potential of the latter to suppress pathogenic fungi while increasing beneficial bacteria. The structural equation model revealed the key role of soil redox potential (Eh) and NH4+ concentration in the regulation of microbial community composition. Furthermore, BC, RSD, and RSD+BC treatments increased pepper yield by 27.4%, 55.3% and 44.4%, respectively, compared to CK. The yield of pepper was positively correlated with the contents of DOC, NH4+, and the relative abundance of Bacillus and Clostridium in soil (P < 0.01), and negatively correlated with NO3- and relative abundance of Fusarium (P < 0.05). This study provides evidence for the efficiency of the combined application of RSD and biochar to amend the quality of degraded soils in plastic sheds under continuous cultivation.

Reclamation of a calcareous sodic soil with combined amendments: interactive effects of chemical and organic materials on soil chemical properties

Concerns about population growth and producing adequate and nutritious food from the limited available resources have made soil conservation a top priority worldwide. This study assessed the effects of alfalfa residue (AR), sugarcane-bagasse biochar (SBB), and walnut-shell biochar (WSB) with or without gypsum (G), aluminum sulfate (AlS), and mixture of both chemical amendments on the chemical properties of a carbonated sodic soil. The organic and chemical ameliorants were added to the soil at rate of 2.5% (w/w) and the soil gypsum requirement, respectively. After a 4-month incubation, amended soils were measured for pH, electrical conductivity of saturated extract (ECe), sodium adsorption ratio (SAR), and exchangeable potassium (K) and available phosphorus (P) concentrations. Both chemical and organic amendments significantly lowered soil pH through enhancing CO2 partial pressure and/or dissolution of native soil calcites. The combined chemical and organic amendments performed more effectively than organics alone to increasing soil EC; the highest EC value was obtained by the application of G+AR (11.0 dS m−1). A synergistic effect of organic and chemical ameliorants on the replacement of exchangeable sodium by calcium was observed, which was reflected by the increased SAR values in treated soils compared with the control. Of the applied amendments, AR-alone has the best efficacy to improve soil available P by enhancing soil P concentration from 4.05 mg kg−1 in the control to 11.87 mg kg−1. Irrespective of chemical amendments, the most increase in soil exchangeable K concentration (from 45.16 mg kg−1 in the control to 274.00 mg kg−1) was obtained by applying WSB-alone to the soil. These results suggest that the partly degraded sodic soils could evolve for agricultural use by amending soils with specific kind of biochars and combined with best soil management practices.

Waste processing method and environmental protection in the agro-industrial complex

The article presents the features of conservation of leafy mass of high-protein crops of the legume family, the disadvantages of traditional preparation of biomass for silage in fodder production. The results of studying the possibility of reducing plant moisture by mechanical means, using the press residue as a raw material for making haylage, and brown juice as a preservative are presented. The results of the development of a method for silage of the pressed alfalfa residue with the introduction of fermented brown juice enriched with the metabolic products of lactic acid and propionic acid bacteria - organic acids, to intensify the process of fermentation of feed. The analysis of the chemical composition of plant raw materials and the obtained haylage was carried out, the value of fodder, energy value and potential harmlessness for feeding to animals was determined.

Mineralization of organic carbon and formation of microbial biomass in soil: Effects of clay content and composition and the mechanisms involved

Mineralization of soil organic carbon and CO2 emission from the soil is slowed by interactions between organic matter and minerals. The main minerals involved are clay minerals and oxides but there is limited understanding of their effects when combined, as occurs in soil. We aimed to determine the effects of clay content and composition on organic carbon stabilization in soil, and the mechanisms involved. This was achieved by studying the decomposition of alfalfa residues in artificial soils made from quartz sand and kaolinite with and without additions of the non-layered colloids (NLCs) goethite, manganese oxide or imogolite. The artificial soils were inoculated with microbes from natural soil and incubated at 23 °C in the dark at 60% of water holding capacity for 180 days. With increasing contents of clay and NLCs, organic carbon mineralization decreased, whereas carbohydrate and microbial biomass carbon contents increased. Of the NLCs, goethite had the least effect and imogolite the greatest effect on carbohydrate content. The effects of the treatments on mineralization and carbohydrate content were explained mostly by specific surface area (> 83% of variation), presumably due to the effects on sorption. The effects of the treatments on microbial biomass were related to the volume of habitat (water-filled pore space) and availability of substrate (influenced by sorption). These results showed that clay content and composition influenced the stabilization of soil organic carbon mostly through the supply of surfaces for sorption reactions rather than via interactions unique to particular colloids.

Effect of Different Vermiwash Sources on Germination and Seedling Growth of Fenugreek (Trigonella foenum-graecum L.)

Physiological process of germination depends on several factors such as temperature, water potential, light and nutrients. A laboratory study was carried out to asses, the effect of different Vermiwash sources on germination and seedling growth of fenugreek. A factorial design was used with four replications. Treatments were factorial of different Vermiwash (water as a control=W0, Vermicompost extract of wheat straw=W1, horse manure=W2, sheep manure=W3, 25% straw + 75% horse manure =W4, 25% straw + 75% sheep manure =W5, 50% straw + 50% horse manure =W6, 50% straw + 50% sheep manure =W7, 25% alfalfa residue + 75% sheep manure =W8, 50% alfalfa residue + 50% sheep manure =W9, 25% chicken manure + 75% straw manure =W10) and two levels of Vermiwash concentration (20% and 40%). Results showed that germination rate was significantly affected by all treatments. The maximum germination rate was observed at concentration of 40 percent of vermiwash with 25% alfalfa residue + 75% sheep manure. The maximum percentage of germination was obtained in 20 percent of vermiwash with sheep manure treatment and concentration of 40% in wheat straw. A significant difference was observed through treatments at 1% level in root length. In addition, root dry weight differed significantly among treatments at the 5% level. Also, a significant increasing was considered in root length by increasing the concentration of vermiwash.

N- Mineralization of Organic Residues in Flooded and Aerated Saline Soils under Different Temperature

Serious of incubation studies were conducted at Department of soil Science and Water Resources, College of Agriculture, university of Basrah to study the effect of temperature incubation and soil salinity levels (3, 6, 12 and 24) dS.m-1 on N mineralization of cow manure and alfalfa residue under aerobic and flooded conditions. Fifteen gram of air dry soil with salinity levels of 3, 6, 12 and 24 dS.m-1 treated with 5% of cow manure or alfalfa residue were incubated at 10, 20 or 30 ?C for 28 days. Moisture level of incubated soil was kept at either field capacity or flooded condition. NH4+ -N and NO3--N concentration of incubated samples were determined at the end of incubation period. Results showed that organic residues added to soils of all salinity levels increased NH4+ -N and NO3- - N. Concentrations of both ions were higher in alfalfa residue treatment than those of cow manure at all treatments. Highest concentrations of NH3+ -N and NO3-- N ions in all treatments obtained at samples incubated at 30 ?C and E.C. of 3 dS.m-1. Organic N mineralization under F.C. was higher than under logged water for all treatments.

Temporal Dynamics of Snowmelt Nutrient Release from Snow-Plant Residue Mixtures: An Experimental Analysis and Mathematical Model Development.

Reducing eutrophication in surface water is a major environmental challenge in many countries around the world. In cold Canadian prairie agricultural regions, part of the eutrophication challenge arises during spring snowmelt when a significant portion of the total annual nutrient export occurs, and plant residues can act as a nutrient source instead of a sink. Although the total mass of nutrients released from various crop residues has been studied before, little research has been conducted to capture fine-timescale temporal dynamics of nutrient leaching from plant residues, and the processes have not been represented in water quality models. In this study, we measured the dynamics of P and N release from a cold-hardy perennial plant species, alfalfa ( L.), to meltwater after freeze-thaw through a controlled snowmelt experiment. Various winter conditions were simulated by exposing alfalfa residues to different numbers of freeze-thaw cycles (FTCs) of uniform magnitude prior to snowmelt. The monitored P and N dynamics showed that most nutrients were released during the initial stages of snowmelt (first 5 h) and that the magnitude of nutrient release was affected by the number of FTCs. A threshold of five FTCs was identified for a greater nutrient release, with plant residue contributing between 0.29 (NO) and 9 (PO) times more nutrients than snow. The monitored temporal dynamics of nutrient release were used to develop the first process-based predictive model controlled by three potentially measurable parameters that can be integrated into catchment water quality models to improve nutrient transport simulations during snowmelt.

ACTIVITY AND THERMODYNAMIC PARAMETERS OF UREASE IN SOILS AMENDED WITH ORGANIC RESIDUES

An experiment was conducted to study the thermodynamic parameters (Q10, Ea, Ha, Sa and Ga) of urease in loamy sand and silty clay soils treated with different sources of organic residues (cow residue, alfalfa leaves, wheat straw and poultry residue). Residues were mixed with soil at rate of 2%. The amended soils were incubated at 30°C for 30 days to undergo biochemical, chemical and physico-chemical reaction. Amended soils were incubated at 10, 20, 30, 40, 50, 60, 70 and 80°C. Urease activity was assayed and thermodynamic parameters were calculated. Results indicated that urease activity of amended soil was higher than that of control soils at various temperatures of incubation. Urease activity increased by increasing temperature of incubation from 10 to 40°C. Q10, Ea, Ha, and Sa values of silty clay soil were in the order of : poultry manure &gt; cow manure &gt; alfalfa residue &gt; wheat residue &gt; control soil. However, in loamy sand soil the order was cow manure &gt; alfalfa residue &gt; wheat residue &gt; control &gt; poultry manure. Order of Ga was control &gt; wheat residue &gt; alfafa residue &gt; cow manure &gt; poultry manure at both soils. Except at poultry manure, all thermodynamic parameters values were higher in loamy sand soil as compared with their values in silty clay soil.

Interactive effect of salinity and cadmium toxicity on soil microbial properties and enzyme activities

Salinity has been proposed to increase the mobility and availability of heavy metals, with a potentially significant consequence for greater metal toxicity. However, the interactive effect of salinity and metal pollution on soil microbial properties and functions is still unknown. This investigation was performed to examine the response of several soil microbial properties and processes to the combined salinity and cadmium (Cd) toxicity in a clay loam soil amended with plant residue. The NaCl salt (0, 32.5 and 78.3 mM NaCl kg−1 soil), Cd (0 and 30 mg kg−1 soil) and alfalfa residue (0 and 1%) were added to the soil and the mixtures were incubated for 90 days under standard laboratory conditions (25 ± 1 °C and 70% of water holding capacity). Similar treatments without residue addition were also included in the experimental arrangement. Salinity increased soil Cd availability and toxicity, and subsequently decreased soil microbial respiration rate, microbial biomass and enzyme activity. The negative effect of increasing salinity on soil microbial and biochemical properties was stronger in Cd-polluted than unpolluted soils and at high than low salinity levels. The declines in soil microbial attributes and enzyme activity were linearly related to the concentration of soil available Cd. Nevertheless, the negative effect of salinity was reduced with addition of alfalfa residue in Cd-polluted soils. The interactive effect of Cd and NaCl was synergistic in residue-unamended soils, but antagonistic in residue-amended soils. It is concluded that (i) the multiple stresses induced by salinity and Cd pollution may synergistically affect soil microbial processes and attributes and (ii) application of organic residues has a high potential for lowering the synergistic effect of salinity in Cd-polluted environments and improving the important microbial indicators of soil quality.

Interactions between humic substances and organic amendments affecting soil biological properties and growth of Zea mays L. in the arid land region

Application of organic amendments to the arid land soils is a sustainable tool to improve soil fertility. A greenhouse experiment was conducted to find the effect of humic acid (HA), alfalfa residues (AR) (Medicago sativa L.), and sheep manure (SM) on soil respiration, soil organic carbon content, soil structure, total bacteria, total fungi, and growth of corn plant Zea mays L. Results showed that the highest aggregate stability was 44.2% for the HA + SM treatment whereas it was 9% for the HA treatment. The higher stability was associated with higher organic carbon 4.60%, and higher bacterial and fungal densities of 190 × 106 g−1 dry soil and 101 × 106 g−1, respectively. The HA + AR treatment did not increase aggregate stability significantly (27.7%), nor did the AR treatment (25.9%). Soil respiration over 70 days was significantly (p < 0.05) higher in the SM (42.9 CO2–C mg g−1) compared to the AR treatment (33.3 CO2–C mg g−1). In contrast, the HA + SM treatment had lower soil respiration (27.4 CO2–C mg g−1) compared to the SM treatment (42.9 CO2–C mg g−1). The HA + AR treatment recorded higher plant weight (20.6 g) compared to HA (10.2 g) and control treatments (8.11 g). This study proved that HA did not enhance soil structure or the microbial community, whereas the combination of HA with SM or AR is more effective at promoting the soil microbial community, soil aggregation, organic carbon content and plant growth in the saline, arid land.

Influence of alfalfa residue and different-source biochars on the chemical properties of a saline-sodic soil

A pot experiment was done aimed to improve the chemical properties of a saline-sodic soil using individual application of alfalfa residue and two biochars, produced from sugarcane bagasse and walnut shell and their concomitant application with gypsum, aluminum sulfate and mixture of these two chemical amendments. Organic and chemical amendments were added to the soil at the weighting ratio of 2.5% and as the soil gypsum requirement, respectively. After two months of incubation, soil samples were measured for soil pH, electrical conductivity (EC) and sodium adsorption ratio (SAR) and the results were analyzed by SPSS software applying ANOVA. The results showed that organic amendments caused a reduction in soil pH and enhanced soil EC and SAR; whereas addition of gypsum and/or aluminum sulfate with biochars intensified their regulatory effects. It can be concluded that application of walnut-shell biochar with mixture of gypsum and aluminum sulfate to the saline-sodic soils has the best efficiency to reclaim the chemical soil properties. Soil leaching, as a supplementary procedure, however, is necessary to complete the improving effects of organic and/or chemical application to the soil.

Influence of alfalfa residue and different-source biochars on the chemical properties of a saline-sodic soil

A pot experiment was done aimed to improve the chemical properties of a saline-sodic soil using individual application of alfalfa residue and two biochars, produced from sugarcane bagasse and walnut shell and their concomitant application with gypsum, aluminum sulfate and mixture of these two chemical amendments. Organic and chemical amendments were added to the soil at the weighting ratio of 2.5% and as the soil gypsum requirement, respectively. After two months of incubation, soil samples were measured for soil pH, electrical conductivity (EC) and sodium adsorption ratio (SAR) and the results were analyzed by SPSS software applying ANOVA. The results showed that organic amendments caused a reduction in soil pH and enhanced soil EC and SAR; whereas addition of gypsum and/or aluminum sulfate with biochars intensified their regulatory effects. It can be concluded that application of walnut-shell biochar with mixture of gypsum and aluminum sulfate to the saline-sodic soils has the best efficiency to reclaim the chemical soil properties. Soil leaching, as a supplementary procedure, however, is necessary to complete the improving effects of organic and/or chemical application to the soil.

Salinity stress accelerates the effect of cadmium toxicity on soil N dynamics and cycling: Does joint effect of these stresses matter?

The objective of this study was to determine responses of soil nitrogen (N) transformation, microbial biomass N, and urease activity to the combined effect of cadmium (Cd) toxicity (0 and 30 mg kg−1) and NaCl stress (0, 7.5 and 15 dS m−1) in a clay loam soil unamended (0%) or amended with alfalfa residues (1%, w/w). Cd, NaCl, and alfalfa residues were added to the soil, and the mixtures were incubated for 90 days under standard laboratory conditions (25 ± 1 °C and 70% of water holding capacity [WHC]). The results showed that salinity increased soil Cd availability and toxicity and subsequently decreased soil microbial N transformations (i.e., potential ammonification and nitrification as well as net N mineralization), arginine ammonification and nitrification rates, microbial biomass N, and urease activity. The adverse effects of salinity on soil microbial properties were greater in Cd-polluted than unpolluted soils, at high than low salinity levels, but were lower in residue-amended than unamended soils. These effects were mainly attributed to the increased Cd availability under saline conditions or the decreased Cd availability with residue addition. All the measured soil microbial attributes showed a negative correlation with the available Cd content in the soil. The interaction or combined effects of Cd and NaCl on soil microbial attributes were mostly synergistic in residue-unamended soils but antagonistic in residue-amended soils. The addition of organic residues to Cd-polluted soils may moderate salinity effect, and thus could stimulate the activity of ammonifiers and nitrifiers, as well as urease.

Phytoremediation of a petroleum-polluted soil by native plant species in Lorestan Province, Iran.

Petroleum hydrocarbons are potentially toxic for organisms due to the inherent properties, such as solubility, volatility, and biodegradability. The petroleum materials released from corroded old pipelines would pollute soils, shallow groundwater and air as a consequence, and threat the health of human and environment. Therefore, the removal of these compounds from environment is vital. The stability of these pollutants at the soil and their gradual accumulation over time would disrupt the normal function of the soil, such as reduced agricultural capability. In this research, the influence of two plant species (Bromus tectorum L. and Festuca arundinacea) with different amendments including arbuscular mycorrhizal fungi, alfalfa residues, and nutrient solution on the degradation rate of petroleum hydrocarbons in soil was studied. The results showed that the most effective treatment for petroleum remediation was related to B. tectorum L. plant when treated with mycorrhizal fungi and nutrient solution. The degradation rate during 40days was about 83.27% when compared to the control. Arbuscular mycorrhizal associations are important in the restoration of degraded ecosystems because of the benefits to their symbiotic partners. This fungal phytotechnological mechanism is still in its infancy and there has been little research on aged-contaminated soils.