Showing 34 results for Organic Matter
M. A Hajabbasi, A. F Mirlohi, M. Sadrarhami,
Volume 3, Issue 3 (10-1999)
Abstract
A two-year study (1996-97) was conducted to verify tillage effects on several soil properties and corn yield. The soil (fine loamy, Thermic, typic Haplargids) was treated by conventional (CT) and no-till (NT) systems. Soil organic matter (OM), mean weight diameter (MWD), penetration resistance (Cl), bulk density (BD), total nitrogen (TN) and aggregate size distribution at depths of 0-20 and 20-40 cm were measured.
No-till system caused the OM to be twice as much as that in the conventional tillage system. Total nitrogen in the NT and at depths of 0-20 and 20-40 cm were higher by 30% and 20%, respectively. No differences obtained in bulk density and penetration resistance, but MWD in the NT was 20% and 10% higher than CT in the 0-20 and 20-40 cm depths, respectively. Mean weight diameter of the aggregates in the CT was smaller than that in NT. Aggregates of less than 0.25 mm at 0-20 cm depths were almost 25% higher in CT compared to NT system. The yield in the NT system was significantly lower than CT. Although reduced cultivation could bring a better soil physical condition, low initial organic matter, weak structure and heavy-textured soil produced unsuitable conditions for the crop roots and, consequently, resulted in low yield. Therefore, no-till system in this region would not be recommended.
A.r. Barzegar, A. Koochekzadeh,
Volume 5, Issue 2 (7-2001)
Abstract
The main sources of cadmium in soil-plant continuum in amounts that might present a hazard are liquid and solid wastes of sewage sludge, farm manures and fertilizers. In the southwest of Iran (Khuzestan Province) over 50,000 ha of land is under sugarcane (Saccarum officinarum) cultivation and more than 80,000 ha will be under sugarcane by the end of the year 2000. In these sugarcane fields, about 400 kg ha-1 diamonium phosphate (DAP) and 400 kg ha-1 urea are applied annually. There is no data available to show the fertilizers impact on soil, water and plant contaminations in Iran with respect to cadmium. The objective of this research was to compare the extractable cadmium of virgin soils with that of soils under sugarcane.
Four sugarcane growing stations viz. Haft-tapeh, Karoon, Shoeibieh and Ghazali with cultivation histories of 36, 20, 2 and 1 year, respectively, were selected. In each site, along a transect soil samples from 0-30 cm of both furrows and ridges of cultivated soils and of virgin soils were collected. Electrical conductivity (EC), pH, clay and organic carbon contents, CI and Cd of 101 soil samples were measured according to standard methods. Results showed that increasing either EC or CI increased Cd concentration with its maximum in virgin soils and its minimum in furrows.
Results also indicated a slight decrease in the Cd content of cultivated soils.
B. Azizi Agh-Ghale,
Volume 5, Issue 3 (10-2001)
Abstract
The effects of three kinds of organic matter on the physical characteristics of two soil series (Coarse Loamy, Mesic, Typic, Xerofluvents and Fine Mixed, Calcixerollic, Xerochrepts) were studied along with the measurement of maximum dry bulk density (MDBD) and the corresponding critical moisture content (CMC). Soil samples were taken from a depth of 0-20 cm and the percentage of organic matter and soil texture were determined. Three kinds of organic matters (peat, farmyard manure and filter press apple) were mixed with the soils at four levels (0, 4, 8 and 12% by mass), and were compacted using 10, 20 and 30 proctor hammer blows. The compaction tests on soils were carried out at different moisture contents. The present experiment, using factorial design, was randomly conducted in three replications. The results of this study showed that while the mean MDBD declined significantly (P<0.01) from 1.53 to 1.28 gr.cm-3, the mean CMC increased from 23.32 to 33.28% as the organic matter increased from 0.12%. In all the experiments, CMC decreased with increasing compaction efforts, so that the effect of mixed organic matter and soil in terms of MDBD reduction and CMC increase was decreasing in the order, peat, farmyard manure and filter press apple. The clay loam soil showed lower values of MDBD but higher values of CMC as compared to the sandy loam. The significant interaction effect observed between incorporation of organic matter and soil compaction were meaningful. Finally an equation as to the relationship between MDBD and CMC was proposed for the purpose of mixing the three organic materials with soil.
F. Tajik, H. Rahimi, E. Pazira,
Volume 6, Issue 3 (10-2002)
Abstract
The general characteristics of salt-affected soils and soil structure degradation process are partially known, but the effects of saline and sodic conditions on mechanical properties of soils are not well recognized. In this study, the effects of electrical conductivity (EC) and sodium adsorption ratio (SAR) on tensile strength of soils with different organic carbon contents were assessed under laboratory conditions. The soil samples were collected from Dasht-E-Naz, at Sari region in the North of Iran. The samples had the same clay mineral (Illitic) and the main difference between them was the organic carbon content, subjected to different cropping systems. The tensile strength was determined on soil samples which had been treated by solutions having defined EC (0.5 and 4 dS/m) and SAR (0, 5, 15).
The tensile strength was positively related to organic carbon content, but negatively to SAR. With increasing SAR, tensile strength decreased, and at a given SAR, the treatments with higher EC showed higher tensile strength. The analysis of variance showed significant differences (at 0.01) between soil samples (four levels), soil sampling depth (two levels), EC (two levels), and SAR (three levels) for all variables under investigation. For soil factor, the order of averages were: Virgin soil > Permanent pasture (Festuca) > Intensive cropping > Permanent pasture (Agropyron).
J. Yasrebi, N. Karimian, M. Maftoun, A. Abtahi, A. Ronaghi, M. T. Assad,
Volume 7, Issue 4 (1-2004)
Abstract
Twenty-five surface samples of calcareous soils of Fars Province were used to study the distribution of different nitrogen (N) forms to determine the relationship between the N forms and soil charcteristics, and to obtain regression equations for prediction of N forms from soil characteristics. The forms determined were: soil total nitrogen NO3-N by phenol disulfunic acid NO3-N extractable by 2 M KCl NH4-N extractable by 2 M KCl, 1 N sulfuric acid, and 0.25 N sodium hydroxide oxidative released N by acid permanganate and alkaline permanganate and NH4-N extractable by 2 M KCl at 100 oC. The highest amount of N was that released by alkaline permanganate which constituted 4.47% of soil total N and the lowest form was exchangeable NH4+ which amounted to only 0.6% of total N. Water soluble and exchangeable forms accounted for less than 2% of total N. Highly significant correlations were found between total N and acid permanganate-N (r=0.931) and total N and alkaline permanganate-N (r=0.850). Highly significant regression equations were obtained for prediction of soil total N, acid permanganate-N, and alkaline permanganate-N from soil organic matter (OM), which is an indication of a close relationship of these N forms with OM.
H. Emami, G. Savaghebi, M. Shorafa,
Volume 9, Issue 2 (7-2005)
Abstract
Increasing soil contamination by chemicals has become an issue of increasing environmental concern. Leaching of chemicals into and through the vadose zone creats serious problems due to the contamination of the soil matrix, soil solution and groundwater. Therefore, in order to study the effect of the preferential flow, macropores and organic matter on mobility and leaching of the metals such as cadmium lead, and zinc, an experiment was conducted as a factorial-split plot based on the completely randomized design with three replications. Three treatments of the undisturbed soil (U), the disturbed soil (D) and the disturbed soil containing 3 percent organic matter (O) were leached by the solutions with the concentration of 20 mg.L-1 of Cd, Pb, and Zn for a month. Then the concentrations of Cd, Pb and Zn in the leachate were measured at different time intervals. The ANOVA results indicated that the metals had a significant difference in the leachate at 1% and the order of their mobility was: Zn>Pb>Cd. Also, there was a significant difference between different soil treatments at 1% and the concentration of the three metals in U and O treatments was more than their concentrations in D treatment. Furthermore, a significant difference between the time intervals of leaching (pore volumes) was observed at 1%. So that, Cd in leachate of U, O and D treatments indicated a significant difference after leaching for 3, 3 and 5 days, respectively (1%). But, Pb in the leachate of the three soil treatments after leaching for 11 days had a significant difference. Zn concentration only in O treatment had a clear trend at different time intervals of leaching and a significant difference was observed after leaching for 8 days.
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.
A. Halajnia, G. H. Haghnia, A. Fotovat, R. Khorasani,
Volume 10, Issue 4 (1-2007)
Abstract
Study of phosphorus reactions over time and the role of organic matter in the calcareous soils are important for the development of P fertilizer and manure management practices. The objective of this study was to determine the effect of applied manure on P availability and its chemical forms in the soil, over time. Eight samples were collected from semi-arid calcareous soils of Mashhad plain. The samples were treated with two levels of inorganic P (0 and 300 mg P kg-1 soil as KH2PO4) and two levels of organic matter (0 and 1% cattle manure). The experiment was conducted in a completely randomized design with factorial arrangement. The treated soil samples were incubated for 2, 5, 10, 30, 60, 90 and 150 days, then analyzed for available P (Olsen-P). The result showed that only 17% of added phosphorus was available in P treatment at the end of experiment. In manure treated soils, this figure reached 34% for the same period of time. Application of manure along with P increased the recovery of applied P and CBD-P (Citrate-Bicarbonate-Dithionite). This may be due to the formation of P-organic complexes with Fe oxides. Application of manure in soil increased NaCl-NaOH-P considerably compared with P and P+OM treatments. It can be concluded that P originating from manure compared with inorganic-P may be more available for plants over the time.
M. Yoosefi, H. Shariatmadari, M.a. Hajabbasi,
Volume 11, Issue 42 (1-2008)
Abstract
Adopting proper agricultural management and conserving soil organic matter are important components of sustainable agriculture. Soil organic matter content is a key attribute in soil quality. Labile organic matter pools can be considered as suitable indicators of soil quality that are very sensitive to changes in soil management practices. This research was carried out to investigate some organic carbon labile pools as an indicator evaluating the effects of different managements on some quality parameters of two calcareous soils. The study was conducted in 2 locations: 1- plots that receiving 0 (C1), 25 (C2), 50 (C3) and 100 (C4) Mg/ha of manure for five years successively with a cropping rotation of wheat –corn every year and plots under three cropping rotations (C5, C6 and C7) at Lavark experimental farm and 2- inquiry research station of Fozveh at different plots with three different cropping rotations (C8, C9 and C10) with a given cropping history recorded for the last 5 years. Soil samples were taken from the center of each plot and the depths of 0-5 cm and 5-15 cm. Their organic carbon, hot water soluble carbohydrate, particulate organic matter (POM), organic carbon and hot water soluble carbohydrate of POM, mean weight diameter of water stable aggregates were determined. Different managements consisting of different levels of manure and types of cropping rotation had significant effects on the soil characteristics measured. The greateast amount of carbohydrate and aggregate stability was obtained in the plots of 100 Mg/ha of manure in Lavak and in alfalfa plots in Fozveh station. Also, the results showed that aggregate stability has a better correlation with hot water soluble carbohydrate in comparison with other soil organic pools. Therefore, the carbohydrate extracted by hot water may be used as an index to assess the impacts of different agricultural management systems on soil quality.
M.a. Hajabbasi, A. Besalatpour, A.r. Melali,
Volume 11, Issue 42 (1-2008)
Abstract
Applying of intensive cultivation especially in marginal and sensitive regions, after conversion of rangelands to cropland farms, commonly causes reduction in soil quality, and thus an increase in soil degradation, erosion and runoff. This study was conducted to evaluate the land use change effects on some soil physical and chemical properties such as mean weight diameter (MWD), soil organic matter (SOM), bulk density (BD) and saturated electrical conductivity (ECe). For the experiment, soil samples were collected from 8 regions (rangeland and cultivated range) from west and southwest of Isfahan. Samples were taken from two soil layers 0-15 and 15-30 cm. Results showed that after conversion of range to cultivated lands, in some regions, SOM content was increased about 39% but in some regions decreased about 26%. This is due to the initial conditions of the regions. The ECe also increased by 41% due to this conversion. However, no changes were observed to the MWD, BD and pH in different treatments. Although there were little change to the physical and chemical properties of soil as a result of this conversion, those properties which were changed, could have a degradation effect and lower the soil quality.
A. Khazaei, M.r. Mosaddeghi, A.a. Mahboubi,
Volume 12, Issue 44 (7-2008)
Abstract
Soil physical and chemical properties, and test conditions might affect soil structural stability. In this study, the effects of test conditions as well as intrinsic soil properties on structural stability were investigated for selected soils from Hamedan Province. Mean weight diameter (MWD) and tensile strength (Y) of aggregates were determined by wet sieving method and indirect Brazilian test, respectively. The soil samples were pre-wetted slowly to matric suction of 200 kPa before the wet sieving. The pre-wetted samples were wet-sieved for 5, 10 and 15 min in order to simulate different hydro-mechanical stresses imposed on soil structure. Tensile strength of soil aggregates were also measured at air-dry and 500 kPa matric suction conditions. Short duration shaking (i.e. 5 min) could effectively discriminate the Hamedan soils in terms of structural stability due to their fairly low aggregate stabilities. The soil organic matter content had the highest impact on MWD followed by both clay and CaCO3 content. The same was true for the Y values i.e. OM played the highest role in mechanical strength of soil aggregates. The highest coefficient of determination (R2) was obtained between Y and the intrinsic soil properties for matric suction of 500 kPa. The organic matter content had an important role in water and mechanically stable soil aggregates. The results indicated that short-duration wet sieving (i.e. 5 min) and measurements of tensile strength at matric suction of 500 kPa could be recommended for aggregate stability assessment in Hamedan soils
S. A. Kazemeini, H. Ghadiri, N. Karimian, A. A. Kamgar Haghighi, M. Kheradnam,
Volume 12, Issue 45 (10-2008)
Abstract
In order to evaluate the interaction effects of nitrogen and organic matter on growth and yield of dryland wheat, an experiment was conducted at the research station of the College of Agriculture, Shiraz University at Bajgah in 2005 and 2006. The experimental design was split plot in which three levels of nitrogen (0, 40, and 80 kg N ha -1) were main factors and additive organic matters including liquorice root residue at 15 and 30 Mg ha -1, municipal waste compost at 10 and 20 Mg ha -1, and wheat residues at 750 and 1500 kg ha -1 (all rates equivalent to 50 and 100%) were sub factors. A check treatment (no additive materials) was also included in the experiment. Results indicated that with increasing nitrogen level from zero to 40 and 40 to 80 kg ha-1, wheat yield increased significantly. Among yield components, number of seeds per spike increased significantly with zero to 40 and 40 to 80 kg nitrogen ha-1, but number of spikes m-2 increased significantly only when nitrogen level was increased from zero to 80 kg ha-1. Compared to check (no additive materials), maximum wheat grain yield (32%) was obtained from 100% compost application. Results of nitrogen and organic matters interaction effects indicated that 100% compost application and increasing nitrogen level from 40 to 80 kg ha -1 had no significant effect on dryland wheat yield. This showed the positive impact of compost application on the reduction of nitrogen fertilizer. Thus, it appears that 50% of the required nitrogen fertilizer could be replaced by compost. Applying organic matter increased soil water in both years, however, among organic matters, compost had a more pronounced effect on increasing soil water.
A Razavinasab, A Tajabadi, H Shirani, H Dashti,
Volume 13, Issue 47 (4-2009)
Abstract
To study the effect of nitrogen, salinity and organic matter on growth and root morphology of pistachio (Cv. Badami), a greenhouse experiment was conducted. Treatments consisted of four nitrogen (N) levels (0, 60, 120 and 180 mg kg-1 soil as urea), four salinity levels (0, 800, 1600 and 2400 mg NaCl kg-1 soil) and three organic matter (OM) levels (0, 2 and 4% soil as farmyard manure). Treatments were arranged in a factorial manner in a completely randomized design with three replications. As the salinity levels increased, leaf, stem and root dry weights and root density, were significantly reduced. Addition of N up to 120 mg kg-1 soil, had no significant effect on growth, but the highest N level (180 mg kg-1), due to nutrient imbalance, reduced abovementioned plant parameters. In low salinity levels, N application improved the growth of pistachio seedlings, but at the highest salinity level, N addition didn’t suppress the adverse effects of soil salinity. Due to useful physical and nutritional properties of soil organic matter, addition of OM significantly increased leaf, stem and root dry weights, stem height, shoot/root ratio and root density.
F Ahmadloo, M Tabari, A Rahmani, H Yosefzadeh,
Volume 13, Issue 48 (7-2009)
Abstract
This research was carried out to improve the growth and performance of Arizona cypress (Cupressus arizonica) and Medite cypress (C. sempervirens var. horizantalis) seedlings in different combinations of organic matter in nursery of Koloudeh, located in Amol city (north of Iran). Seeds in plastic pots were sown as a completely randomized design (RCD) with four replications at different soil treatments including: T1) nursery soil (control), T2) control soil: cattle manure (5:1), T3) control soil: decomposited litter (5:1), T4) control soil: cattle manure: decomposited litter (5:1:1). The results after one year showed that the seedlings of both species grown on T4 obtained the greatest shoot height, collar diameter, seedling Vigor Index, shoot dry weight, root dry weight, total dry weight and seedling Quality Index (QI) among all the soils examined. The response of most attributes to soil was better in Cupressus arizonica than in C. sempervirens. It is concluded that organic matter caused the increase of growth and biomass of seedlings in both species. It can be proposed that in order to enhance the performance and improvement of Quality Index of seedlings in nurseries, the status of physico-chemical of soil-media should be seriously evaluated.
O Hashemi Beni, M.h Salehi, H Beigi Harchegani,
Volume 13, Issue 50 (1-2010)
Abstract
Although soil organic matter (SOM) constitutes a small portion of soil bulk weight, it has a tremendous effect on physico-chemical and biological properties of soils. It is also one of the most important indicators of soil quality and its production. Soil organic matter determination is required for soil fertility management and soil pollution purposes. Wet oxidation procedure of Walkley-Black is a routine, relatively accurate and popular method for the determination of soil organic matter, but it involves the use of chromate and high cost of analysis. Therefore, loss-on-ignition (LOI) procedure as a simple and cheap method of SOM estimation which also avoids chromic acid waste has got more attention. The aims of this study were (i) to establish the relationships between LOI method and SOM as determined by Walkley-Black method for four major plains of Chaharmahal-va-Bakhtiari province and (ii) to determine the optimal temperature of the LOI. To do this, 205 soil surface samples were randomly collected from 0-25 cm depth of Shahrekord, Farsan, Kohrang and Lordegan plains to determine soil organic matter by Walkley-Black method and LOI procedure at 300, 360, 400, 500 and 550 oC for two hours. To determine the optimum temperature for ignition, 40 soil samples were selected to compare the SOM and CCE before and after ignition for each temperature. Results showed a positive, linear significant relationship existed between LOI and wet oxidation in each plain. Coefficient of determination (R2) of the equations was higher for individual plain than the overall equation. Coefficient of determination and line slope decreased and error (RMSE) increased with increasing ignition temperature. At higher contents of calcium carbonate, the rate of line slope decrease with increasing ignition temperature was more noticeable. This may be due to the destruction of carbonates at higher temperature. A temperature of around 360 oC was identified as optimum as it burned most organic carbon, destroyed less inorganic carbon, caused less clay structural water loss and used less electrical energy.
Zolfi Bavariani, Nouruzi,
Volume 14, Issue 52 (7-2010)
Abstract
Most part of the applied phosphorus is fixed in the calcareous soil. Some part of residual phosphorus can be recovered by the plants of the following years. It is reported that organic matter is one of most important factors in phsphorus recovering. This expriment was designed in permanent plot to evaluate the effect of organic matter on residual phosphorus recovering in a calcareous soil. The expriment was conducted on randomized complete block design in a factorial manner with three replications in four years. Treatments were consisted of farm yard manure(FYM) in three levels ( 0, 15, and 30 ton ha-1) and three levels of phosphrus ( 0, 90 and 180 kg ha-1 as P2O5 from triple super phosphate (TSP). Phosphorus fertilizer was applied only in the first year of expriment, but FYM was used in all of the years. Onion, canola, bean and spinage were planted in the four years of experiment, respectively. Results showed that maximum yield, P concentratin in plant and soil phosphorus availability were followed by application of FYM and P(residual) together in all of the years. This increase was mainly by direct effect of P in the first year of expriment, but recovered phosphrus by FYM had maximum role in the later years. More than 53% of increase in phosphrus availability in soil and 21% of increase in yield resulted from recovered phosphprus by FYM in the treatment of 30 ton.ha-1 FYM and 180 kg.ha-1 P2O5 together in the last year.
Mahdipuor, Landi,
Volume 14, Issue 52 (7-2010)
Abstract
An increase in the emission of greenhouse gases such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) from the soil surface to the atmosphere has been of worldwide concern over the last several decades. Carbon dioxide is recognized as a significant contributor to global warming and climatic change, accounting for 60% of total greenhouse effect. The aim of this research was to determinate the emission of greenhouse gases from different land under agricultural uses. Four types of agricultural land farm, including wheat field, canola field, citrus garden and fallow land were selected to investigate the fate of CO2 in these fields. Gas chromatography technique and close chamber method were used to analyze soil gas samples. Total carbon losses from soil in form of greenhouse gases was 4.47, 3.72, 3.38 and 1.89 Mg C ha-1 yr-1 for wheat field, canola field, citrus garden and fallow land, respectively. Total additional carbon to soil from biomass for wheat field and canola field was 4.1 and 4.6 Mg C ha-1 yr-1, respectively. ECB (ecosystem carbon budget) = ∑ C input - ∑ C output. For wheat field and canola field ECB was -0.37 and +0.88, respectively. This indicated that in wheat field carbon was lost and in canola field carbon was sequestrated. Under citrus garden due to changes in soil organic carbon form previous year has showed that carbon was sequestrated.
J. Fallahzade , M. A. Hajabbasi,
Volume 15, Issue 55 (4-2011)
Abstract
The salt–affected lands in arid regions of central Iran are characterized by low rainfall, low fertility, high evaporation and salinity. The cultivation of salt–affected lands may have a major influence on soil quality. The aim of this study was to determine the response of soil quality indicators to reclamation and cultivation of salt–affected lands occurring in Abarkooh plain, central Iran. Soil quality indicators were evaluated in three land use systems including salt-affected land, wheat, and alfalfa fields. Composite soil samples were collected at 0–10, 10–20, 20–30, and 30–40 cm layers and analyzed for soil organic carbon, total nitrogen, carbohydrate, particulate organic carbon in macro-aggregates (POCmac) and micro-aggregates (POCmic), organic carbon mineralization and wet aggregate stability. The cultivation of salt–affected land caused a significant decrease in electrical conductivity at all layers and increased the amount of soil organic carbon, total nitrogen, carbohydrate, POCmac, POCmic, and organic carbon mineralization. At all layers, the POCmac/POCmic ratio in the alfalfa fields was higher than that in the wheat fields. The cultivation of salt-affected land caused a significant increase in soil aggregate stability (MWD) at all layers. In most cases, the amounts of soil organic matter and MWD were greater in alfalfa than in the wheat fields, reflecting a better soil quality and thus higher potential for increasing soil organic carbon sequestration in the alfalfa fields
Z. Naderizadeh , H. Khademi ,
Volume 15, Issue 56 (7-2011)
Abstract
Many studies have been carried out on the effect of organic matter on soil physical, chemical, biological, and nutritional properties, including the effect of organic matter on the availability of such elements as P, N and heavy metals. There is, however, no information on the effect of organic matter on potassium uptake from micaceous minerals. The objective of this study was to investigate the effect of organic matter on potassium uptake from micaceous minerals released by alfalfa. An experiment was laid out in a completely randomized design with factorial combination and three replicates. Growth medium was a mixture of quartz sand, micaceous mineral (muscovite or phlogopite) and organic matter (0, 0.5 and 1 %). Rehnani cultivar of alfalfa was used in the experiment. During 120 days of cultivation, plants were irrigated with either complete or K-free nutrient solution and distilled water as needed. At the end of cultivation, plant shoots and roots were separately harvested and their K concentration was measured by flame photometer following dry ash extraction. Under the K-free nutrient solution, a significant increase in biomass occurred in pots containing phlogopite and organic matter as compared to those with no organic matter amendment. Also, under K-free condition, potassium concentration in shoot was above the threshold value only in phlogopite amended pots. There was no significant difference in K concentration among different levels of organic matter in control treatment as well as in muscovite added treatment. Under both nutrient solutions treatments, significant increase of K uptake occurred in pots containing phlogopite and organic matter, as compared to those without it. In contrast, under K free nutrient solution, organic matter amendment could not enhance the K uptake in pots containing dioctahedral mica (muscovite). Root activities and organic matter decomposition appear to have increased rhizosphere acidity which, in turn, facilitate the K release from trioctahedral mica (phlogopite) in K deficient medium. Thus, the effect of organic matter on K release greatly depends on the type of micaceous mineral.
Y. Kooch, S. M. Hosseini, J. Mohammadi, S. M. Hojjati,
Volume 15, Issue 58 (3-2012)
Abstract
Uprooting trees and pit – mound micro topographies are due to creation of heterogeneity condition in soil ecosystem. Pay attention to mountainous condition of hyrcanian forests in Iran and presence of trees with high diameters (old trees), therefore, it is imagined that many of trees are prone to uprooting. Thus, the aim of this research is studying variability some of soil physico - chemical characters in uprooted trees location and pit – mound position. For this purpose, twenty hectare areas of Tarbiat Modares University Experimental Forest Station studied that is located in Mazandaran province, northern Iran. Numbers of thirty four uprooted trees were found. Five microsites were distinguished including mound top, mound wall, pit bottom, pit wall and closed canopy. Soil samples were taken at 0 - 15, 15 - 30 and 30 - 45cm depths from all microsites using core soil sampler (81cm2 cross section). Soil acidity, water content, organic matter, total nitrogen and carbon to nitrogen ratio measured in the laboratory. A statistical result is indicating that the most water content, organic matter and nitrogen devoted in pit bottom. Mound top and wall included maximum of acidity. The most value of carbon to nitrogen ratio found in mound wall, as well. Soil acidity showed no significantly differences among different depths. The results of this research can be considered in forest soils survey and forest management.
