Showing 10 results for Respiration
J. Mohammadi, H. Khademi, M. Nael,
Volume 9, Issue 3 (10-2005)
Abstract
In order to achieve a sustainable management of land resources and to improve land quality, quantitative assessment of effective factors and soil quality indicators are required. The aim of this study was to evaluate variability of selected soil quality attributes in central Zagros affected by such factors as region, land use and management practices. Twelve sites were selected in three provinces including Chahar Mahal va Backtiari (Sabzku, Broujen), Isfahan (Semirum), and Kohkeloyeh va Boyerahmad (Yasodje). Different management practices were considered such as: protected pasture, intensive grazing, controlled grazing, dryland farming, irrigated wheat cultivation, legume-farming practice, protected forest, and degraded forest. Systematic sampling with taking 50 samples of surface soil in each site was carried out. The results of univariate and multivariate analysis revealed that all factors significantly influenced the spatial variability of selected soil quality attributes namely phosphatase activity, microbial respiration, soil organic matter, and total nitrogen. The results obtained from discriminant analysis indicated that all selected soil quality parameters could significantly be used as soil quality indicators in order to recognize and discriminate sustainable agricultural and forestry ecosystems and/or optimal management practices.
R. Hajiboland, M. K. Khosrowpanah,
Volume 9, Issue 4 (1-2006)
Abstract
Manganese toxicity occurs in many agricultural and natural ecosystems under the various soil conditions such as the nature of substrate, acidity, flooding or vicinity to the mining areas. The objective of this work was to study the effects of excess Mn in the growth medium on three important crop species, namely rice (Oryza sativa L. cv. T. Hashemi), maize (Zea mays L. cv. SC.704) and sunflower (Helianthus annuus L. Mehr). Plants were cultured in the hydroponic medium under controlled environmental conditions and treated with 0 (control), 25 50, 75 and 100 µM Mn for 12 days. Dry mass production, the effect of supplemental Mg and Ca on the toxicity expression, root respiration and K+ leakage from shoot and root tissues were studied under the Mn treatments. In order to study the effect of light intensity on the expression of toxicity symptoms, plants were cultured under the different light conditions, thereafter their growth and metal uptake and transport were studied. Sunflower plants treated with the 50 µM Mn and higher, showed dark-brown spots associated with the trichomes on the leaves and petioles. Maize plants developed interveinal chlorosis and any visual leaf symptoms was observed in rice. In all of the studied species, a great portion of the absorbed Mn was translocated into shoot, the highest transport was observed in sunflower and the lowest in maize. No significant correlation was observed between the expression of Mn toxicity and the accumulation rate of Mn. Growing under the low light intensity, in addition to the lowering biomass production, increased or decreased the toxicity effect depending on species. Mn-toxicity-induced root respiration was not associated with the differential response of species to Mn toxicity. In contrast the change of K+ leakage from shoot and root tissues was well correlated with the toxicity response of tested plants.
M. Boyerahmadi, F. Raiesi , J. Mohammadi,
Volume 14, Issue 51 (4-2010)
Abstract
Similar to plants, soil salinity may reduce microbial growth and activities in different ways. The aim of this study was to determine the effects of different levels of salinity on some microbial indices in the presence and absence of plant's living roots. In this study, five levels of salinity using NaCl, CaCl2, MgCl2 and KCl and three soil media (soil with no plant, soil cultivated with wheat and clover) replicated three times consisted our factorial experiment arranged in a completely randomized design. Results show that salinity caused a significant reduction in accumulated microbial respiration, microbial biomass carbon, substrate-induced respiration, and carbon availability index in uncultivated soil and in the soils planted with clover and wheat. Results also show that salinity caused a significant increase in metabolic quotient (qCO2) in uncultivated soil, and soils planted with clover and wheat. Microbial activity of cultivated soils at high salinity levels was almost similar to that of the uncultivated soils. We observed a small difference in soil microbial activity among the three media at high salinity levels, indicating the role of indirect effects of salinity might be less important with increasing salinity levels. We also found out that at low salinity levels, the available carbon was not a limiting factor for soil microflora, while at high salinity levels the activity of soil microbes might be carbon-limited. The lower values of qCO2 in cultivated soils compared with the uncultivated soil support the positive influence of root and its exudates on soil microbial activity in saline soils. The existence of plants in saline environments may help in alleviating the detrimental influence of low to medium salinity on most soil microbial activities, likely via the added root exudates and root turnover.
A.a. Besalatpour , M.a. Hajabbasi, V. Dorostkar , Gh. Torabi,
Volume 14, Issue 53 (10-2010)
Abstract
Presence of petroleum contaminants in soil may be toxic to human and organisms and act as a source of ground water contamination hence, remediation of these compounds from environment is vital. In this study, first the feasibility of remediation of two petroleum-contaminated soil samples around Tehran Oil Refinery (oil refinery landfill and agricultural soils) was assessed using landfarming technique during a four month experimental period. The elimination of total petroleum hydrocarbons (TPHs) from soils treated through landfarming technique was then investigated in the rhizosphere of agropyron and fescue. The results showed that microbial respiration increased due to landfarming processes in both soils. Urease activity in the landfarming treatment for agricultural soil was 21, 45, 26, and 23% higher than the control at the end of first to the 4th months of experiment, respectively. However, no significant differences were observed between the landfarming and control treatments for landfill soil at the end of experiment. Furthermore, about 50 and 57% reduction in TPH-concentration was observed in the landfarming treatment for landfill and agricultural soils at the end of experiment, respectively. In the phytoremediation study, presence of TPHs in both landfarming and control treatments reduced dry matter yield of the studied plants. Urease activity in the rhizosphere of fescue and agropyron was higher than in the unplanted soil. Degradation of petroleum-compounds in the landfill soil under landfarming treatment was more than 20 and 40% in the presence of fescue and agropyron, respectively. The influence of agropyron on TPH-removal from agricultural soil under the landfarming treatment was also higher than fescue.
H. Dehghan-Menshadi, M. A. Bahmanyar, S. Salek Gilani, A. Lakzian,
Volume 16, Issue 60 (7-2012)
Abstract
Biological indicators are considered soil quality elements, due to their dependence on soil organisms. In order to investigate The effect of compost and vermicompost enriched by chemical fertilizers and manure on soil organic carbon, microbial respiration, and enzymes activity in basil plant's rhizosphere, a field experiment was conducted as a split-plot design with randomized complete blocks and three replications in 2006. The main plot involved six levels of fertilizer including: 20 and 40 tons of compost enriched, 20 and 40 tons of vermicompost enriched per hectare, chemical fertilizer and control without fertilizer and sub-plot, and period of application (two, three and four years). The results showed that application of compost and vermicompost at all levels increased soil organic carbon (OC) and soil microbial respiration, microbial biomass and urease activity compared to the controls (p<0.05), but increasing trend among the treatments was not similar. The maximum amounts of OC, soil microbial respiration and enzyme activity were observed in 40 tons of vermicompost enriched with chemical fertilizer ha-1 with four years of application. In high levels of compost application, the urease activity was decreased.
F. Parsadoust, Z. Eskandari, B. Bahreyninejad, A. Jafari Addakani,
Volume 19, Issue 71 (6-2015)
Abstract
Evaluation of chemical and biological indicators of soil in different land uses could be helpful in sustainable range management, preventing degradation of soil quality trend. This study was conducted in Friedan in Isfahan province in 2010 to compare chemical and biological indicators in three land uses (rangeland, degraded dry land and dry land), during two growing seasons (May and September) in three slopes (0-10, 10-20, 20-30 %). Nitrogen, phosphorus, potassium, organic matter, cation exchange capacity and microbial soil respiration were measured. Results showed that all measured characteristics except potassium decreased over an increase in the slope. Maximum values of phosphorus, organic matters, cation exchange capacity and soil respiration were obtained in pasture (28.4 mg/kg, 0.62%, 20.38 cmol/kg, 33.2 mgC/day, respectively)but potassium maximum rate was seen in dry land form (406.8 mg/kg).The effect of season on all measured parameters was significant except for N, while the highest amounts of phosphorus, potassium, cation exchange capacity and soil respiration (28.7 mg/kg, 377.3 mg/kg, 19.6 cmol/kg and 25.9 mgC/day, respectively) were seen in May and the highest organic matter rate (0.68%)in September. The results of this study showed that an increase in the slope, poor range management, and the end of the growing season could be major factors degrading the soil quality indices and soil productivity.
Sh. Ghorbani Dashtaki, N. Karimian, F. Raeisi,
Volume 21, Issue 1 (6-2017)
Abstract
The use of organic matter such as urban sewage sludge may help sustainable soil fertility via improving the physical, chemical and biological soil characteristics. The main purpose of this study was to determine the effect of urban sewage sludge on chemical properties, soil basal respiration and microbial biomass carbon in a calcareous soil with silty clay loam texture. Therefore, three levels of water repellency (zero, weak and strong) were artificially created in a silty clay loam soil by adding urban sewage sludge (S0=0:100; S50=50:50 and S80=80:20 sludge weight: soil ratio). Water repellency was determined by water drop penetration time (WDPT) method. Also some chemical properties such as soil acidity (pH) and Electrical Conductivity (EC), Soil Organic Carbon (OC), soluble sodium (Na+) and soluble potassium (K+) were measured. The samples were incubated at 23-25 ºC for 30 days and their moisture was maintained at 70-80 % under field capacity and soil basal respiration and microbial biomass carbon of incubation period were evaluated. The results showed that the effect of urban sewage sludge on chemical properties was significant (P ≤0.0001). The application of urban sewage sludge led to significant increase in basal respiration (16 and 27 times) and microbial biomass carbon (15.2 and 26.5 times) in the water repellency soils (S50 and S80) compared to control soil. The observed positive effect of sewage sludge might be due to a high content of organic carbon and nutrients in urban sewage sludge and decrease in the labile organic matter and nutrients during incubation period.
E. Esfandiary Ekhlas, M. Nael, J. Hamzei, A. A. Safari Sinegani, M. Sheklabadi,
Volume 22, Issue 2 (9-2018)
Abstract
Evaluation of the ecological sustainability of different cropping systems is crucial to achieve sustainable agriculture. This evaluation is accessible via soil quality assessment. Therefore, to study the mid-term effects of different conservation tillage systems (no tillage and minimum tillage) and cover cropping on the biological indicators of soil quality, a factorial experiment in a completely randomized block design was conducted in Dastjerd region (Hamedan). Three levels of tillage (NT: no tillage, MT: minimum tillage and CT: conventional tillage) and two levels of cover cropping (C1: Lathyrus sativus and C2: no cover crop) were applied for four consecutive years. Soil sampling was performed in the fourth year of experiment in two steps (1- before cover crop plantation, and 2- after harvesting main crop) with three replications. Most indices (total organic carbon, active carbon, basal respiration, phosphatase activity) were significantly affected by cover crop, tillage systems and sampling time, as the highest values were obtained in NT-C1 in time 2 and the lowest ones in CT-C2 in time 1. For instance, after four years application of treatments, the mean active carbon content was increased from 927 mg/kg in the conventional tillage + no cover crop to 1350 mg/kg in the conservation tillage systems + cover crop. Therefore, conservation tillage practices combined with Lathyrus sativus cover crop were shown to be the most appropriate management for soil quality maintenance and improvement.
N. Enayatizamir, M. Noruzi Masir, A. Ghadamkhanii,
Volume 23, Issue 4 (2-2020)
Abstract
The soil organic matter plays an important role in increasing agricultural products and various nutrient cycle in the soil due to its effect on the physical, chemical and biological properties of soil. There is, however, little information regarding the effect of growth promoting bacteria on biological indices and different forms of carbon in agricultural soils of the country. Therefore, this study was aimed to investigate the effect of plant growth promoting bacteria on soil respiration, microbial quotient, organic carbon, microbial carbon biomass, permanganate oxidizable carbon, cold water extractable organic C, and hot water extractable organic C under the cultivation of wheat, Chamran cultivar. The experiment was conducted in greenhouse condition as a randomized complete design with 9 replications. Treatments consisted of bacterium inoculation (without inoculation, Enterobacter cloacae Rhizo_33, Enterobacter cloacae Rhizo_R1
and mixof both bacteria). During the experiment, some characteristics such as plant height and chlorophyll index were measured. At the end of the cultivation period, root and aerial part dry weight and grain yield were determined. Biological properties and different forms of carbon in the soil were measured after cultivation. The results indicated the applied plant growth promoting bacteria increased chlorophyll index, height, root and shoot dry weight and grain yield, as compared to the control. The minimum value of pH and the highest amount of each carbon forms were obtained by soil inoculation with different strains of bacteria, as compared to the control. The highest value of organic carbon was observed in the presence of the consortium of both bacteria with 22.7% increase, as compared to the control. The highest amount of microbial carbon biomass was, respectively, measured in the treatments containing consortium of bacteria, Enterobacter cloacae Rhizo_R1, Enterobacter cloacae Rhizo_33 with 87.67, 42 and 26.5% increment, as compared to the control. A positive and significant correlation was observed between cold and hot water extractable organic carbon, dissolved organic carbon and permanganate oxidizable carbon with soil respiration and there was a negative correlation between mentioned properties and the soil pH. The use of microbial inoculants increased the carbon content of the soil, which can play a positive role for improvement of physical and chemical properties of the soil and plant yield.
H. Owliaie, F. Mehmandoost, E. Adhami, R. Naghiha,
Volume 23, Issue 4 (2-2020)
Abstract
The conversion of forests to agricultural lands generally has damaging effects on soil qualitative indices. This study was conducted to investigate the effects of land use change on the physico- chemical and biological characteristics of the soils of Mokhtar Plain, Yasouj Region. Five soil samples (0- 30 cm) were taken from three land uses of dense forest, degraded forest, and dry farming. The physical, chemical and biological analyses were carried out in a completely randomized design. The results showed that by following the change in the forest land use to dry farming, the EC (56%), organic matter (67%), total nitrogen (71%), exchangeable potassium (48%), Basal respiration (42%), exhaled respiration (63%), fungi community (23%), acid phosphatase (59%), and alkaline phosphatase (79%) were decreased in the dry farming land use. However, the bacterial community (20%) and pH (5%) were increased in the dry farming land use and the amount of available phosphorus did not show any significant difference, as compared to the dense forest. In general, it can be concluded that by following forest degradation and change in land use, soil organic matter and its related indices, especially biological ones, are more affected. So, in order to maintain soil quality, appropriate management practices such as managed land use change, avoidance of tree cutting, especially on steep slopes, preventing of overgrazing, and addition of organic matter should be carried out in dry farming land use.
