جستجوی مقالات مرتبط با کلیدواژه « bulk density » در نشریات گروه « کشاورزی »

Afforestation has been growing worldwide in recent decades and is expected to continue in this trend due to the increased use of wood. Therefore, the mass planting of pine trees and other fast-growing species for industrial wood production has intensified since the beginning of the 20th century. In Iran, with a low forest per capita (0.17 ha), per capita plans to create a forest and rehabilitate degraded forests to increase green space have been implemented with non-native species. For this reason, many non-native conifer species have been introduced to the country, which has not been successful in some areas. Therefore, for the success of afforestation with non-native species, it is necessary to select those that are suitable for the habitat conditions, adapt the ecological needs to the environment, and consider the effect of afforestation on the soil, understory plants, and living organisms. Ensuring sustainable management depends on knowing the effects of planted tree species on species diversity, structure, and ecosystem function. Since different tree species have different effects on soil characteristics in ecosystems, they can change soil properties with different mechanisms. In other words, the differences in litter quality, the state of nutrients, the performance of roots in nutrient uptake, the leaf structure, the crown of the tree, the microclimate under the crown, and finally the biological communities in different tree populations change the soil physicochemical properties. In general, the restoration of degraded forest lands through afforestation has a significant effect on the variability of soil characteristics, in which a major difference is observed between native and non-native species as well as broadleaf and coniferous species. Since broad-leaved tree species can positively affect the soil quality of conifer stands, this research aims to compare some soil physicochemical characteristics under the influence of pure and mixed Norway spruce (Picea abies L.) afforestation.

The studied area is in the southeast of section 101 of the Makarood series, watershed 36 (Kazemroud) in Kalardasht city and at an approximate height of 1200 m. It includes the afforested areas of pure Norway spruce (PS) (2 ha), mixed Norway spruce (MS) (2.5 ha) forestry areas, and barren land (BL) (3 ha). Three transects in each area were planned due to the smallness of the areas and the need to adopt a method that best describes the condition of the soil in each area. Then, on the 10, 50, and 90 m points of the transects, soil samples were taken in layers of 0-10 and 10-30 cm (in each area, nine soil samples for each layer). The texture, saturation percentage (SP), electrical conductivity (EC), pH, neutralizing substances or lime (T.N.V), organic carbon (O.C), nitrogen (N), phosphorus (P), potassium (K), and bulk density (BD) was examined in the laboratory.

The bulk density was lower in the 0-10 cm layer in the MS stand (2.28 g/cm3) than in the other two areas. The soil saturation was higher in the upper layer in the PS stand (85.77%) than in the MS stand (59.83%) and BL (51.07%). On the contrary, it was greater in the lower layer of the BL (94.40%) than in the two forest stands. EC values were lower in both upper (0.40 ds/m) and lower (0.38 ds/m) layers in the BL than that in PS and MS stands. The pH was significantly lower in the 0-10 cm layer in the PS (4.84) and MS (4.88) stands than in the BL (5.75). In each of the three areas, the amount of lime was zero in the upper and lower layers. O.C. in the upper layer was significantly higher in the PS (2.57%) and the MS (2.96%) stands than in the BL (1.45%), and the highest value was measured in the MS stand (0.94%) in the lower layer. Nitrogen was higher in the upper layer of PS (0.197%) and MS (0.270%) stands than that in the BL (0.143%). It was higher in the lower layer of the MS stand (0.09%) than the PS (0.02%) and BL (0.03%) stands. The C/N was highest in the upper layer in the PS stand (12.97), but this ratio was not significantly different in the lower layer of the three areas (10.82-11.50). The amount of P was highest in the upper layer in the MS stand (8.4 ppm), but no significant difference in P was detected in the lower layer among the three areas (3.57-5.60 ppm). K content was higher in the upper layer of the PS stand (203.43 ppm), but it was higher in the BL (193.50 ppm) in the lower layer than in the two forest stands. 

In the upper soil layer (0-10 cm), pH, C, and N values did not differ between MS and PS stands, but BD and C/N were lower in the MS stand; on the contrary, soil porosity and P and K contents were higher than those in the PS stand. From this research, it is generally concluded that afforestation with MS has a better effect on the optimization of physical and chemical characteristics in the soil layers than PS, which can provide the basis for more suitable growth of trees and a better balance of the forest.

Soil erosion threatens sustainable agriculture by reducing soil organic carbon, soil degradation, and reducing soil fertility. Organic amendments, with their effect on the physical, chemical, and biological properties of the soil, are a good way to protect the soil, improve soil properties and reduce the use of chemical fertilizers. The aim of this study was to investigate the effect of organic amendments on the physical, chemical, and biological properties of soil on agricultural land.

In this regard, plots with dimensions of 1×2 m2 were established in a completely randomized design with 3 repetitions in 3 agricultural lands. Organic modifiers (control (without a modifier), sheep manure, and municipal waste compost) were added to the plots in the amount of 1.5 kg for each plot. The plots were in wheat-fallow-barley crop rotation. The modifiers were added on the first of June, and soil sampling was done from the plots 3 months after adding the modifiers. During these 3 months, once every 15 days, the plots containing the modifier were moistened (60% of Field Capacity) for the better effect of the added modifier. The experimental was a Randomized Complete Block Design (RCBD). Physical, chemical and biological characteristics of soil including bulk density, electrical conductivity, pH, soil organic carbon, available phosphorus and potassium, microbial biomass carbon, basal respiration and substrate-induced respiration (SIR), microbial metabolic quotient (qCO2) and enzyme activity such as urease, invertase and alkaline phosphatase were measured after experimental treatments.

The results showed that the application of amendments reduced the bulk density and increased soil organic carbon, soil pH, EC, phosphorus, and potassium. The addition of amendments increased carbon microbial biomass and basal respiration and decreased metabolic quotient. The addition of sheep manure and municipal waste compost amendments increased the activity of invertase and alkaline phosphatase enzymes compared to the control.

The use of organic amendments in agricultural soils can increase the productivity of these lands and increase the yield of agricultural products due to the improvement of soil characteristics and the increase of organic matter and microbial biomass. The results of the comparison of the two organic amendments indicate the greater effect of sheep manure than urban waste compost in improving soil characteristics. Other tests should be conducted on the effect of long-term use of this modifier in the soil, as well as the effect of urban waste compost on the concentration of heavy metals or other pollutants so that one of the modifiers can be accurately suggested for wide use in agricultural soils.

In this experiment, physical and chemical characteristics of sugar beet seed and its relationship with germination traits was studied. This traits were evaluated on 10 sugar beet singles crosses that obtained from three locations including Ardabil, Firuzkuh, and Karaj. Results showed that bulk density, true density and electrical conductivity are influenced by environment and genotype. Percentage of solids soluble in sugar beet pericarp (germination inhibitors) it was only affected by the seed production environment. Both genetics and environmental conditions on the maternal plant during seed development and maturing were effective on germination percentage, germination velocity and mean germination time. But the germination uniformity of sugar beet seeds was only affected by genotype. On the other, the correlation between bulk density, true density, electrical conductivity, porosity and percentage of solids in pericarp solution of sugar beet seeds with some germination traits was significant. But, the germination uniformity had no correlation with the physical and chemical properties of seed. Increased density of the seed pericarp caused decrease of seed quality factors including electrical conductivity and percentage of solids solution on pericarp. Therefore, germination uniformity, which is less affected by the environment, can be used in breeding programs as indicator of seed quality selection. Physical and chemical traits that was a significant correlation with germination traits, in the management of sugar beet seed production with the aim of increasing the extraction coefficient and quality of sugar beet seeds are recommended.

Despite the many benefits of tillage to crop establishment and production in the past, new herbicide and minimum-tillage management systems have drastically changed today's methods of crop production. Although tillage systems are used to increase soil porosity, they are a short-term solution that has negative consequences on surface soil structural stability, surface crop residue, and surface soil organic carbon, which are critical features that control water infiltration and subsequent water transmission and storage in soil. Physical and chemical properties of soil such as organic matter of soil is a key attribute of quality that affects water infiltration and soil aggregation. The use of conservation tillage along with the application of appropriate management methods such as conservation of residues, the use of proper rotation and weed control caused to stabilize the particles of soil, prevent the destruction of soil structure and increase soil organic matter. Therefore, changing the method of tillage systems from conventional to conservation, especially in crop rotation cycles, is inevitable. Our objectives were to summarize these findings and present additional information with particular emphasis on changes physical and chemical characteristics in different soil depths due to adoption of conservation tillage in corn-wheat crop rotation.

The present study was performed to investigate tillage systems (4 levels including ZT-ZT: Zero Tillage-Zero Tillage; ZT-CT: : Zero tillage-Conventional Tillage; CT-CT: Conventional Tillage-Conventional Tillage and CT-ZT: Conventional Tillage-Zero Tillage) and 4 levels of weed management (including W1: Control; W2: Post-emergence Nicosulfuron herbicide + hand weeded in cultivation of corn and post-emergence Metribuzin herbicide + hand weeded in cultivation of wheat; W3: Pre-emergence Atrazine + post-emergence Nicosulfuron herbicides in cultivation of corn and post-emergence Clodinafop + post-emergence Bromoxynil+MCPA herbicides in cultivation of wheat; W4: Wheat residues as a mulch + post-emergence Nicosulfuron herbicide in cultivation of corn and corn residues as a mulch + Metribuzin herbicide) on some physical and chemical properties of soil depths (D1: 0 -15 and D2: 15-30 cm) in corn-wheat rotation during the 2021-22 croping year in the farms of Shavur Agricultural Service Center of Shush city was implemented as a split-factorial in the form of a randomized complete block design with three replications and 96 samples.

The results showed that interaction of the studied treatments significant effects of the all studied traits except for soil pH. The minimum of soil bulk density was observed in conventional tillage-zero tillage × Wheat residues as a mulch + post-emergence Nicosulfuron herbicide in cultivation of corn and corn residues as a mulch + Metribuzin herbicide as weed management treatment × 0-10 cm soil depths treatment with an average of 1.390 g/cm3, also, the highest hydraulic conductivity of the soil was obtained in conventional tillage-conventional tillage × pre-emergence Atrazine + post-emergence Nicosulfuron herbicides in cultivation of corn and post-emergence Clodinafop + post-emergence Bromoxynil+MCPA herbicides in cultivation of wheat × 0-15 cm soil depths treatment (with an average of 0.994 cm/h). The highest amount of organic matter (with an average 0.771 percent) and phosphorus and potassium elements was achieved in zero tillage-zero tillage × wheat residues as a mulch + post-emergence Nicosulfuron herbicide in cultivation of corn and corn residues as a mulch + Metribuzin herbicide × 0-15 cm soil depths treatment (with averages of 13.96 and 234.7 mg/kg, respectively). Interaction effects results (tillage system × sampling depth) indicated that highest amount of total nitrogen was achieved in the zero tillage-zero tillage (ZT-ZT) on soil surface layer (0-15 cm sampling depth) with an average 122.0 kg / ha with an increase of 40.1% compared to the other treatment such as zero tillage-conventional tillage (ZT-CT), conventional tillage-conventional tillage (CT-CT) and conventional tillage-zero tillage (CT-ZT) and soil substrate (15-30 cm sampling depth, with an average of 0.87 kg/ha). In addition, the preservation of residues in the form of mulch and the use of post-emergence Nicosulfuron and Metribuzin herbicides led to maintaining the balance of soil pH in the corn-wheat rotation.

Steady-state soil chemical and physical properties was greater under zero tillage than under conventional tillage as a result of soil structural improvements associated with surface residue accumulation and lack of soil disturbance. In addition, our data indicate that conservation tillage along with the application of crops residues in corn-wheat crop rotation is a viable management strategy to improve soil quality in the warm, semiarid region of Khuzestan Province. This strategy could lead to high production, minimal negative environmental impacts, and a socially acceptable farming system. Therefore, the use of previous crop residues in tillage systems will have a positive effect on improving the physical and chemical properties of the soil.

Tillage is defined as disturbing the soil and changing soil physical condition of seedbed and root zone and making it suitable for cultivation. Soil physical characteristics like soil moisture and temperature conduction, bulk density, porosity and particle size are changed in the following of soil tillage. Tillage also increases water infiltration rate and plays an important role in soil moisture protection and decreasing flood hazards in arid and semi-arid regions. Molboard plough is currently implemented for tillage in different parts of Iran including Chaharmahal va Bakhtiari province. There are evidences which show Moldboard plough triggers physical soil characteristics deterioration and soil tillage erosion. Tillage translocation coefficient, as a component of tillage erosion, is defined as the amount of soil transition for 1 m width of tillage instrument. Comparing the impacts of available tillage instruments on physical soil characteristics, soil transition and their efficiency with of Moldboard plough may encourage field managers to substitute other instruments with Moldboard plough. This research aimed to: 1) study the impacts of the currently available tillage instruments (Moldboard, Disk and Chisel plough) on some prominent physical soil characteristics and 2) compare soil translocation coefficients of the mentioned tillage instruments.

This research was executed in Research-Training Field of Shahrekord University, Shahrekord county, Chaharmahal va Bakhtiari Province, Iran. A split plot experimental design with complete randomize block was considered with 3 major treatments of tillage instruments (Molboard, Disk and Chisel plough), minor treatments of slope (0, 3, 6 and 8%) and tillage speeds (2, 5, and 8 km h-1) and 3 replications. The conventional tillage depth of 25 cm was adjusted for all three tillage instruments. Standard protocols were applied and soil electrical conductivity (EC), pH, calcium carbonate equivalent (CCE), organic matter and soil texture components were measured before tillage application and soil field capacity (FC), mean weight diameter (MWD) of aggregates, geometric mean diameter (GMD) of aggregates, aeration porosity (Fa), bulk density (ρb) and water stable aggregates (WSA) were measured using standard protocols after tillage implementations. Colored gypsum cylinders were used as indicators for detecting soil translocation. The transition distance of the colored gypsum cylinders of each layer of tillage depth (0-9, 9-18 and 18-25 cm) was measured using tape meter or ruler and mean transition for each layer were calculated. In the next step the depth weight soil translocation was calculated for each tillage instrument.

Results and Discussions:

 Chemical analysis of soil samples showed that soils were non-saline, soil OM content was less than 1% and CCE of soil samples was relatively high. Physical soil analysis of soil samples before tillage implementation indicated that there was not any restriction for plant root development and aeration as ρb was relatively low and aeration porosity was 10% <, respectively. Analysis of variance (ANOVA) indicated that the effects of tillage type on MWD and ρb were significant (P < 0.05). Comparing the means of MWD and ρb induced by tillage instruments (Duncan method) revealed significantly higher values of MWD and lower values of ρb for soils which were treated by MB plough, the results were corresponded to the finding of other researchers. There were not significant differences between MWD and ρb of soils which were treated by disk and chisel plough. The results also showed that tillage instruments did not impact on physical characteristics like FC, WSA, GMD and FA. Non-significant impact of MB plough on soil moisture condition also was reported by other researchers in the northwest of Iran. The ANOVA was calculated for soil translocation and showed that the effects of tillage instruments were significant (P < 0.05) for all three layers of soil depth. Mean soil translocation of surficial layer of tillage depth (0-9 cm) was significantly higher than of other layers of tillage depth. Despite other researchers' findings, our research indicated that the slope levels were not significant for soil translocation. This research also revealed that tillage speed significantly (P < 0.05) impacted on soil translocation which was corresponded to findings of other researches in different parts of the world. Interaction of slope-speed and tillage type-speed were significant (P < 0.05) which could be due to accelerated impacts of speed on soil translocation in steep areas. Amount of coefficient of translocation for MB plough was 141 kg m-1 per application. This value was about one third of soil translocation which was reported by others from Belgium (545 kg m-1 y-1) or Denmark (456 kg m-1 y-1) and very closed to the finding of Spanish researchers (164 kg m-1 per application). The coefficient of translocation for disk and chisel plough were 114 and 93 kg m-1 per application, respectively. According to researchers from Portugal, the coefficients of translocation for disk and chisel plough were in ranges of 0-333 kg m-1 and 18-770 kg m-1 per application, respectively. The magnitude of soil translocation coefficients for tillage instruments were in order of MB plough > disk plough > chisel plough.

Assessment and management of environmental impacts imposed by forest harvesting activities are one of the key factors that are increasing important. The purpose of this study was to investigate the effect of ground-based system on soil physical and chemical properties and the recovery process of these properties over the course of seven years. Hence, the compartments no. 316, 318, 310, and 309 of the Gorazbon District in the Kheyrud educational and research forest were selected. In this study, a completely randomized factorial design was applied and the treatments included duration (years) from timber extraction (one, two, five, and seven years), three traffic intensities (low, medium, and high) and soil depths (0-10 and 10-20 cm). The soil bulk density after seven years has not yet returned to the original state. There is still a significant difference between the control area and the skid trail. The amount of organic matter after seven years showed a recovery process compared with the first year after timber extraction, so that in the seventh year no significant difference was observed between the amount of organic matter in the control area and timber extraction track, while the amount of organic matter in the first year of timber extraction track is much lower than that of adjacent control areas. The recovery of some soil properties such as organic matter occurs faster than other ones like bulk density and porosity.

Sugarcane is widely cultivated in Khuzestan province. After each harvest, a ratooning operation is performed to remove the impact of compaction due to traffic on the harvesting machines and recelennce furrow. This experiment was conducted to investigate the effect of machine type and forward speed on the quality of sugarcane ratooning operations.

Research treatments included conventional ratooning device (4-shanks subsoil + reshaper) and combined ratooning device (4-shanks subsoil + reshape disk and 10-shanks subsoil) and three- rates speeds (5, 6 and 7 km / h). The experimental design was a split plot design based on randomized complete block design with three replications in the cultivation industry of Amir Kabir farm ALC 408 with clay loam texture, 15% moisture, crop variety 1069-69CP and first year ratoon. The physical properties of interest in this study were Mean Weight Diameter (MWD) of clods, bulk density, soil surface uniformity, and water infiltration in soil. ANOVA and Duncan tests were used to compare the treatments.

There was a significant difference between the two types of ratooning machine and the three forward speeds in the mean weight diameter of clods, bulk density, surface uniformity and soil water infiltration. Comparison of means showed that the ratooning treatment with the combined machine at the speed of 7 km / h had the smallest mean weight diameter of clods. The use of an integrated device also significantly reduced the bulk density of the soil. The mean soil bulk density in the ratooning operation was reduced to 1.33 g / cm3. The lowest coefficient of variation of surface uniformity in ratoon treatment with combined machine at 7 km / hwas obtained equal to 16%. Also, the water infiltration rate in soil was significantly different between the conventional and combined ratooning machine treatments. Soil water infiltration rate was 1.6 and 2.3 cm / h, respectively, after the ratooning operation with a conventional ratooning machine and combined ratooning machine treatments. The effect of forwarding speed on soil water infiltration rate also showed that the highest water infiltration rate occurred at 5 km / h, equal to 1/2 cm per hour.

Finally, due to the significant difference between conventional and combined ratooning treatments, sugarcane ratooning combined machine had the greatest impact on soil physical parameters. This is due to the movement of the 10-shanks subsoil during the ratooning operation and the greater turbulence of the soil.

Sugarcane cultivation in Khuzestan province is in the form of planting in-furrow. Due to the fact that in a machine harvesting, the reaper is not able to fully harvest the straw in the furrow, in the planting in-furrow method, it is necessary to transfer the rows of straw to the stack. So one of the measures at the time was hilling up operations or stacking reeds planted in the furrow. Therefore, due to the salinity of irrigation water and high groundwater levels, which have increased the salinity of sugarcane fields in Khuzestan province, planting this product in summer to protect the seedlings against salinity is mandatory in the furrow. On one hand, due to the difficulty of harvesting operations in the furrow during the harvest season, and on the other hand, because of the reduction of waste during harvesting, the plant needs to be located on the ridge. Therefore, in sugarcane fields, when the seedlings are established and grown, the furrow and ridges are replaced, and to perform this operation special machines are required. According to the study, so far there has been no scientific and reasoned report on the study and evaluation of different types of hilling up devices and different speeds in sugarcane cultivation, and the use of machines in sugarcane cultivation and industry is based solely on objective observations. Therefore, in this study, three different types of devices have been evaluated in two soil textures and three different forward speeds as a step towards choosing the best type of machine and optimal speed of hilling up operations in sugarcane cultivation.

The purpose of this study was to evaluate three different methods of sugarcane hilling up in two soil textures and three different forward speeds. Research treatments include: soil texture (clay loam and silty clay loam), hilling up methods (6-shanks subsoil + 10-shanks subsoil, 8-shanks subsoil + hilling up device No. 1 and 8-shanks subsoil + hilling up device No. 2), and forward speeds (5, 6, and 7 kilometers per hour). Design of a factorial experiment based on randomized complete block design with three replications in Amirkabir field 208 (ALC 200 field 8) with clay loam texture and cultivar CP69-1062 and farm ARC14-22 with silty clay loam texture and cultivar CP69-1062, 15% moisture, and first-year cultivation was performed. The test plot includes 108 furrows. The area of each plot was two furrows. The length of each furrow was 250 meters (equal to the length of the sugarcane rows). To avoid affecting the interactions of the treatments, a distance was given between the treatments. The farms being tested were newly cultivated farms. The surface of the farm was furrowed and ridged. Care was taken in selecting the farm so that the humidity was similar in its different sections. After setting the right time for the hilling up and before starting the operation, soil sampling is required to determine the soil cone index and soil moisture. The physical properties of this study include Mean Weight Diameter (MWD), bulk density, soil surface uniformity, soil water permeability, and furrow depth (stack height). Analysis of variance and Duncan test were used to compare the treatments using SAS 9.4 software.

The results showed that there was a significant difference between soil Mean Weight Diameter, bulk density, soil surface uniformity, and soil water permeability in soil texture treatments, type of hilling up machine, and forward speed. Furrow depth index (stack height) was significantly different in treatments of type of machine and forward speed but not in soil texture treatments. The comparison of means showed that the whole loam texture treatment had 6-shanks + 10-shanks at a speed of 7 km h-1 with the smallest mean weight diameter (16.06 mm). The use of 6-shanks subsoil + 10-shanks subsoil in hilling up in whole texture and speed of 5 km h-1 significantly reduced soil bulk density. The lowest coefficient of variation of soil surface uniformity was obtained with 8-shanks subsoil + hilling up device No. 1 in clay loam texture and 7 km h-1 forward speed. The highest rate of water permeability in the soil was obtained after the hilling up operation with 6-shanks subsoil + 10-shanks subsoil in a total texture of 2.32 cm h-1. Furrow depth index (stack height) was also within the acceptable range (10-15 cm) in all treatments. But in addition to height, the appearance of the ridges is also important. In the treatment of 6-shanks + 10-shanks in plant stacking and embankment operations, sometimes in fields, there are parts where this operation is not done well and the machine is not capable enough and is in the middle of the created ridges. Harvesting operations do not cause proper reed flooring. Therefore, to solve this problem, it is necessary to perform the hilling up operation at the appropriate speed and humidity so that the soil is well placed on the rows of reeds and the proper appearance of the ridge is maintained.

In this study, three different types of devices have been evaluated in two soil textures and three different forward speeds as a step towards choosing the best type of machine and optimal speed of hilling up operations in sugarcane cultivation. The physical properties of the soil, including the soil Mean Weight Diameter, bulk density, soil surface uniformity, soil water permeability, and the size of the furrow depth (ridge height) were measured, and the best treatments were identified. Considering the importance of hilling up operations in sugarcane cultivation and to complete the results of this experiment, the following items that could not be studied in this study are suggested. The effect of using different methods on hilling up should be investigated on the yield of sugarcane. The effect of using different devices on hilling up in terms of tensile strength, work efficiency, and time required to do the work, fuel consumption, cost of timely work, and maintenance costs in operations on sugarcane hilling up should be investigated.

Biochar is a carbon-rich organic compound that has recently been recommended for use as a soil conditioner. Little research has been done on the effect of biochar amount and elapsed time after biochar addition on soil physical properties. This research performed at Shahrekord University, in 2018. The aim of this study was to evaluate the long-term effects of different amount of rice straw biochar on soil bulk density (ρb), total porosity (n), mean weight diameter of dry (MWDdry) and wet (MWDwet) aggregates, air filled porosity (AFP) and capillary porosity (CP) of clay loam soil. This experiment was performed as a factorial experiment based on completely randomized design with three replications in a greenhouse. Biochar have four levels of zero as control (B0), 0.5 (B1), 1 (B2) and 2 (B3) weight percentage and the time have four levels of 2 (T1), 3 (T2), 6 (T3) and 9 (T4) months after biochar adding to the soil. The results indicated that two months after adding rice straw to the soil, ρb decreased by 6% compared to the control. At the same time, ‘n’, ‘MWDdry’ and ‘MWDwet’ increased by 3, 11 and 13%, respectively, compared to the control. Means comparison showed that the lowest ρb was obtained in B1T2, the highest ‘n’, ‘AFP’ and ‘CP’ were obtained in B1T2, B0T1 and B1T3, respectively, and the highest ‘MWDdry’ and ‘MWDwet’ were obtained in B3T4 and B0T4 respectively. Different times are needed for the effect of biochar on soil physical properties improvement. Based on the findings of this study, 1% of rice straw biochar can be used to durabil improvement of the physical properties of clay loam soil.

The purpose of this research was investigation of soil physicochemical and particle distribution in three agricultures, rangeland and forest park land use in two surface (0-15 cm) and subsurface (15-30 cm) depths in Oshtorninan city on the Lorestan province. Soil sampling was done in 45 points in three land use. Some soil physico-chemical properties were determined in laboratory. This experiment was arranged in a factorial manner. The results showed that the change of rangeland use to agriculture has resulted in a decrease in clay content, cation exchange capacity, soil carbon, nitrogen and soil particle size. Changing the land use of pasture to forest park has led to an increase in the amount of clay, silt and soil acidity. Mean comparison showed that there was no significant difference between bulk density and electrical conductivity in the three land uses (p ≤ 0.01). Analysis of the data showed that the soil cation exchange capacity, organic carbon, clay and silt content in three land uses and two depths were significantly different (p ≤ 0.01). Land use factor also showed a significant different on soil sand and lime percentage (p ≤ 0.01). The soil granulation did not change with the conversion of the rangeland in to a forest. Increased organic carbon and soil clay content could be the reason for this. In general, land use change from pasture to agriculture similar to other research is unfavorable, but land use change to forest park has improved clay content, cation exchange capacity and soil organic carbon.

The four-wheel drive and rear-wheel drive tractors are commonly used in agricultural operations. In order to investigate the effect of a type of driving system a series of tests were performed usin the three driving systems of foour wheel drive, rear wheel drive and front wheel drive in different axle loads of 0, 150 and 300 kg, tire inflation pressures of 170, 200 and 230 kPa and travel speeds of 1.26, 3.96 and 6.78 km/h. Bulk density was measured as an indicator of soil compaction at different depths of 10, 20, 30 and 40 cm. Also, under the different conditions, the drive wheel slip was measured. To carry out the tests, the four-wheel tractor of Goldoni 240 was used which has the ability to work with mentioned driving systems. The experiments were carried out under controlled conditions in a soil channel  with the length of 3 m and a width and depth of 1 and 0.6 m, respectively. Test were conducted in completely randomised block design with three repetations and results were analysied using SPSS 22 software. The results showed that by changing the driving system from 4WD to RWD and FWD, there was a significant increase in soil density, with the lowest density associated with 4WD system and the highest density related to FWD. The reason for increasing the density by changing the driving system can be attributed to different slip levels in each of these systems due to the lower slip percentage of the 4WD system than the other two systems.  Increasing axial load increased soil boulk density. Of note that with increasing the axial load, the stress was transferred from the surface soil to the subsoil layers. As the axial load on tire increases, the subsoil density was closer to the surface layer. Increased axial load on tire and decreasing tire pressure reduced wheel slip. Stepwise regression model with determination coefficient of 0.92 and according to calculated standard coefficients showed that axial load, soil depth, type of driving system, tractor speed, and finally tire pressure, have the greatest effect on soil bulk density, respectively.

Tillage intensity and tillage system can affect biological, physical, and chemical properties of the soil. Suitable soil management is essential to achieve sustainable agricultural production especially in drought-prone regions. More application of machineries in a tillage system will result in more soil compaction which in turn increases soil bulk density and decreases its air and water permeability. Additionally, it has been well documented that the compact soil hampers the downward growth of the crop roots. The soil with good physical quality will provide aeration and water as well as non-impeditive mechanical resistance for root proliferation. Moldboard plowing is currently applied in around 65% of tillage practices although the agricultural extension services have tried to convince farmers to apply reduced tillage system by replacing moldboard plow with chisel plow to mitigate adverse effects of moldboard plowing especially in arid and semi-arid regions. Conservation tillage practices, especially reduced tillage, have been introduced to Iranian farmers since 1999. Mycorrhiza is the product of an association between a fungus and plant root that enhance the tolerance levels of plants against the drought, salinity and high heavy metal contents. The aim of the present study were to evaluate the effects of tillage systems, nitrogen levels, and mycorrhiza inoculation on yield and yield components of mung bean and soil criteria.

The experiment was conducted in Darehshahr research field in two growing seasons (2017 and 2018). The experimental layout was split plot based on a randomized complete block design with three replications. Treatments consisted of three tillage systems as conventional, conservation and no tillage as main plot, four nitrogen levels including 0% (as control), 33%, 66% and 100% of recommended fertilizer as sub plot, and two levels of mycorrhiza fungi inoculation (Contains arbuscular mycorrhiza fungi of Glomus mosseae strains, counting 107 to 108 (CFU / g.) Prepared by Soil and Water Research Institute) (no symbiosis (as control) and with symbiosis) as sub-sub-plot. Studied traits were yield components (such as 1000-seed weight, No. of seeds per pod, No. of pods per plant), seed yield and harvest index of mung bean and moisture content, cone index and organic carbon percent of soil. For analysis of variance SAS 9.4 was used. All the means were compared according to Duncan test (p≤0.05).

The results revealed that the highest 1000-seed weight (57.48 g) was obtained from no-tillage and the highest number of seeds per pod (10.64 seeds per pod) and the number of pods per plant (61.04 pods per plant) were obtained from conservation tillage. The highest seed yield was obtained from conservation tillage + application of 100% N fertilizer with 2941 kg.ha-1. The highest seed weight, number of seeds per pod, and number of pods per plant were obtained from 66% N fertilizer application. Mycorrhiza inoculation increased harvest index, seed yield and its components. The soil bulk density in the no-tillage system had the highest value. The maximum and the minimum soil moisture contents were observed for non-tillage and conventional tillage systems, respectively.highest soil cone index (2.25 MPa) was obtained from no-tillage and 66% N fertilizer and the lowest (1.07 MPa) was for conventional tillage system+ without nitrogen application. The highest and the lowest soil organic carbon were related to no-tillage and conventional tillage systems with 0.68% and 0.32%, respectively.

In general, the conservation tillage system+ application of 66% N fertilizer and inoculation with mycorrhiza had a relative advantage impact on yield and related traits. In addition, the soil physical traits and organic carbon content were improved affected as declined tillage systems. The long-term field experiment points out the beneficial impacts of reduced tillage and no tillage systems that, in addition to preserving both soil physical (such as cone index) and chemical criteria (and organic carbon), fertility and biological activity, could increase yield and exhibit a comparable yield over a long-term period as in conventional plough. Currently, there is no mung bean variety appropriate to Iran. Improving some varieties with higher yield which are tolerant to warm climate and water deficiency seems essential to improve the sustainability of local seed production. Investigating into the effect of mung bean tillage and fertilizer consumption on the weed type and density is also suggested for future studies.

 Sustainable production in agriculture is closely related to the proper soil chemical, physical, and biological conditions which are considered as the main functions of soil organic matter. The amount of soil organic matter, especially soil organic carbon (SOC), in agricultural ecosystems depends on the tillage practices. Conventional tillage (CT) which generally uses moldboard plow, results in soil losses by intense erosion, a net loss of nutrients and organic carbon. Toward sustainable agriculture, decreasing plow intensity of CT through application of conservation tillage strategy in which tillage practices are omitted or limited to a considerable extent, has been reported as an essential alternative. The objective of this study was to evaluate the effect of tillage management practices and N application on soil chemical and physical properties as well as SOC in a corn-based rotation on a clay loam textured soil in semi-arid climate of Hashtgerd, Iran.

 A field experiment as the split plot design with three replications carried out in the research farm of agricultural research department of Atomic Energy Organization of Iran in two successive growing seasons during 2011-13. The tillage systems were (CT) conventional tillage (moldboard, rotary, and leveler) and; (MT) minimum tillage (disk) assigned as the main plot; and N rates of application, as the subplots, were 0, 50, 150, 250 kg ha-1. In CT treatment, moldboard plow to a depth of 25-30 cm was used as the primary tillage once in autumn and once in spring each year. As the secondary tillage, CT plots were rotavated to 10 cm depth in spring. MT treatment included two trips over the plots with disk harrow cutting to a soil depth of approximately 10 cm prior to sowing. Soil pH, bulk density (BD), total nitrogen (TN), soil organic carbon (SOC), exchangeable K and available P were then evaluated. Soil samples were collected in September 2013 after the end of three growing seasons from 0-30 cm depth at 5 locations per plot using a 3.5 cm diameter coring tube.

 The results showed that short-term (2 years) effect of tillage systems on soil pH, BD, TN, SOC and exchangeable K as well as available P, was not significant (p ≤ 0.05). However, N application rate significantly (p ≤ 0.05) changed soil TN, BD, exchangeable k and available P. Soil TN increased significantly (p ≤ 0.05) by increase in N application rate as the highest amount of TN was 1036 and 968 mg kg-1 in 250 and 150 kg ha-1, respectively. As the soil samples were taken after crops harvest, soil TN is illustrative of the residual soil N and high amount of TN implies the excessive N application. Soil BD decreased significantly in 250 kg N ha-1. Increasing the N application rate would decrease soil BD by increasing root growth. Exchangeable K and available P decreased significantly (p ≤ 0.05) by increasing N application rate. The lowest amount of soil exchangeable K, and available P was detected for N rate of 250 and 150 kg ha-1, 127 and 130 mg kg-1 for K, and 13.43 and 14.24 mg kg-1 for P, respectively. Increased N application promotes plant growth and improves nutrient uptakes such as K and P, consequently, the amount of soil exchangeable K and available P would decrease.

 Toward sustainable agriculture, conservation tillage seems to be an effective strategy to maintain crop yields as well as soil chemical, physical, and biological properties in the long-term. However, based on the results, tillage systems (CT and MT) had no significant effects on SOC as well as other investigated soil properties in the studied site in the short-term. However, N application rate increased soil TN and decreased BD, exchangeable K and available P. It seems that longer-term investigations are needed to evaluate the probable effects of different tillage systems on soil properties particularly SOC

Biochar is a carbonaceous substance obtained from heating plant residues and wastes in an oxygen-containing medium with or without oxygen. Thermal decomposition of biomass in an oxygen-free medium is called thermophilicity (pyrolysis). Temperature is one of the factors influencing the characteristics of biochar. One of the objectives of this experiment is to investigate the effect of different temperatures on the biochar characteristics of cattle manure. The use of biochar as a soil conditioner and source of organic carbon in agricultural soils with minimal environmental damage is considered. Marigold is an annual plant that is used in industry and pharmacy in addition to food. Another aim of this experiment is to investigate the effect of biochar use from different temperatures on marigold under salinity stress.

For biochar preparation, after collecting cattle manure from Bardsir farms, air drying and sieving were used for pyrolysis process for four hours at different temperatures (300, 400, 500, 600 °C). Then pH, EC, carbon stability, ash and biochar performance were measured. In order to evaluate the effects of biochar resulting from different heat-treated temperatures on salinity tolerance of marigold, a factorial experiment was conducted in a completely randomized design in the greenhouse. The two factors studied included salinity levels (0, 4, 8 and 12 dS.m-1) and biochar resulting from different thermocouple temperatures (0, 300, 400, 500 and 600 °C). The biochar rate was considered to be 20%. One month after salinity treatment, seedlings were evaluated for osmotic metabolites activity and growth characteristics of marigold seedlings.

The results of ANOVA showed that all biochar properties were significantly affected by temperature factor. With increasing the pyrolysis temperature from 300 to 600 °C, pH and EC increased by 16.29% and 60.37%, respectively, and the ash content increased by 1.5 folds, but biochar performance and bulk density decreased by 52.28% and 48.1%, respectively. The highest carbon stability was observed at 500 °C, which increased by 20% compared to 300 °C. The results showed a significant negative effect of salinity stress on stem height, number and area of marigold leaves, so that with increasing salinity to 12 dS.m-1, 31.09, 17.28 and 45.7% decrease were observed in these traits, respectively. The physiological characteristics of marigold were significantly affected by the simple and interaction effects of salinity and biochar stress. In salinity treatments (0, 4, 8 and 12 dS.m-1) with increasing pyrolysis temperature from 300 to 600 °C 2.2, 2.04, 1.97 and 1.92 folds increase in leaf potassium concentration and 1.54, 2.26, 3.00 and 2.45 folds less than the control treatment in the amount of leaf proline was observed,  respectively. The activities of catalase, ascorbate peroxidase and guaiacol peroxidase enzymes were also significantly affected by the interaction of salinity stress and heat temperature. The highest enzyme activity in biochar was from 600 °C, which increased up to 8 dS.m-1 for catalase and up to 4 dS.m-1 for ascorbate peroxidase and guaiacol peroxidase.

In general, biochar salinity is its most important undesirable properties, which increases with increasing pyrolysis temperature, so the recommendation of biochar application in saline soils requires further studies. In the present study, the use of biochar under salinity stress did not have a significant positive effect on the development of marigold resistance and salinity stress tolerance.

In this applied experiment, in order to investigate the effect of conventional agricultural tractors on soil density, the effect of tractor traffic at two levels (one and three passes) at different soil moisture levels at three levels (plastic limit, 0.8 and 0.6 plastic limit) With two low and medium speeds of tractor (3 and 4.5 km / h), by measuring the density indices including bulk density and soil cone index in a type of clay in Kashmar city was performed. Experiments using Messi Ferguson 285 tractor as a factorial experiment in a randomized complete block design with three repetitions and the results were analyzed at three different soil depths (0-10, 10-20, 20-30) cm. The results showed that the soil moisture and tractor traffic treatments in the first and second depths had a significant difference on the value of the cone index. Moisture treatment only at a depth of 10-20 cm in the soil had a significant effect on the bulk density of the soil. Also, the highest increase in density occurs at a depth of 10-15 cm, and at depths lower than 20 cm, due to the lightness of the tractor, no significant changes in the amount of density.The results show that the soil at the plastic limit moisture has the highest response to compaction.

It is necessary to find solutions for soil recovery of skid trail. Water-bar construction is one of the ‎best management practices to improve the compaction and prevent the erosion of skid trail soil. ‎Recovery of soil physical properties 11 years after water-bar construction on skid trail was ‎investigated on 40 square meter sample plots in two slope (0-10% and 10-20%) and three traffic ‎classes (Low, Medium, High) in the forests of Nav district in the west of Guilan province. The ‎studied variables included soil bulk density, total porosity, penetration resistance and rutting depth. ‎Soil bulk density, penetration, and rutting depth were measured by steel cylinder, pocket ‎penetrometer, and a 5-m leveling rod. The parameters in each treatment were studied in three ‎replications. The effect of slope and traffic variation on soil physical properties was performed on 72 ‎sample plots. The results showed that the effect of slope, traffic and their interaction were ‎significant on soil bulk density, total porosity, penetration resistance, and depth of rutting. The ‎value of soil bulk density, total porosity, and penetration resistance in LSLT (Low Slope-Low ‎Traffic) class was recovered, and there was no significant difference between this class and the ‎control area. The results of the study showed a positive effect of water-bar construction on the ‎recovery of soil properties in skid trail with low slope and low traffic.

Compost leachate is a liquid resulting from physical, chemical and biological decomposition of organic materials. The main objective of this study was to evaluate the influence of leachate compost on the physical, hydraulic and soil moisture characteristic curves. Also, the effect of leachate on the aerial organ fresh weight of corn was investigated. Leachate was added to clay loam and sandy clay loam soils at the rate of zero, 1.25 and 2.5 weight percent. The soil water characteristic curve and the estimation of the parameters of the van Gnuchten and Brooks and Corey models were performed using RETC software. Leachate increased the bulk density and decreased the available water of the clay loam soil. Only 1.25% of the leachate increased the available water in the sandy clay loam soil. Two levels of leachate decreased the bulk density of sandy clay loam soil. Leachate decreased the saturation hydraulic conductivity of the clay loam and increased this parameter of sandy clay loam soil. Leachate was more successful in increasing the aerial organ fresh weight of corn in the sandy clay loam soil. Therefore, leachate was more useful in sandy clay loam than in clay loam soil, and 1.25% treatment was better in the sandy clay loam soil. Also, the used leachate increased the repellency of both soils. Leachate caused the parameters of van Gnuchten and Brooks and Corey models to increase, as compared to the control in both soils.

Saturated hydraulic conductivity is one of the main parameters in agricultural and environmental studies that is essential for the estimation and management of water and solute transport in soil. In this research, 1200 series of data related to loamy soils were used to prediction and modeling saturated hydraulic conductivity using soil physical properties such as bulk density, available water capacity, organic carbon content and percent of clay, silt and sand content. From studied data series, 900 series were allocated for use in training models and 300 series for testing models in three designed scenarios. The performance of SVM, MLP and M5 models was evaluated in estimating saturated hydraulic conductivity of loamy soils. The performance of the models was compared using the statistical indices such as coefficient of determination (R2), root mean square error (RMSE) and mean bias error (MBE). The results showed that all three models used have good ability in saturated hydraulic conductivity modeling, but the M5 model with a high coefficient of determination over 0.95 in all three scenarios and a lower RMSE than other models was selected as the superior model. The results showed that intelligent data mining models make it possible to estimate unknown values based on ready patterns in a database. Therefore, the applied models can be used to predict solute transport in soil and soil physical parameters.

The aim of this study was to investigate the effects of tillage, planting method and the levels of nitrogen fertilizer on the grain yield and some properties of soil in planting Rapeseed (Brassica napus L.) as a second crop after rice.

A split factorial experiment in complete randomized block design was conducted with three replications at research fields of Rice Research Institute of Iran in Rasht during two cropping seasons of 2016-2018. In the experiment, three tillage methods including the conventional tillage (moldboard plow at a depth of about 25-30 cm + double-disc), minimum tillage (once using tractor-mounted rotavator at a depth of about 10-15 cm) and no-tillage were considered as the main plots. In addition, two planting methods of direct planting and transplanting as well as the four amounts of nitrogen fertilizer of 0, 100, 200 and 300 kg.ha-1 urea source were considered as factorial in sub plots.

Results showed that the minimum tillage at 200 kg ha-1 of nitrogen had the highest grain yield with the average of 4144.3 kg.ha-1. The system of no-tillage had the maximum soil bulk density (1.58 g.cm-3), cone index (3.74 MPa), soil moisture (72.13%), minimum root length (20.65 cm) and root weight (61.43 g.m-2). The treatment of without nitrogen consumption showed the minimum values of soil nitrogen, organic carbon as well as root length and weight.

Based on the results, the combination of minimum tillage by using 200 kg.ha-1 of nitrogen in both planting methods could be recommended for rapeseed production in Guilan region due to the high grain yield.

Soil bulk density (BD) is important because of its direct effect on soil properties such as porosity, soil moisture availability, and hydraulic conductivity and its indirect effects on root growth and crop yield. Environmental processes and agronomic practices induce soil bulk density to vary greatly in both space and time. On the other hand, measuring it on a large scale requires a lot of time and is not economical. As a result, indirect methods are used to measure the bulk density when performing large-scale field activities. Pedotransfer Functions (PTFs) have been broadly implemented as indirect cost-effective and time-saving methods in predicting soil bulk density. The purpose of this study is to evaluate the existing Pedotransfer functions in order to determine the bulk density for different soils of Sistan region as well as calibration and provide new Pedotransfer functions for the study area.

After reviewing different reference, 64 different Pedotransfer functions (PTFs) published in different sources were selected to estimate the bulk density. These Pedotransfer functions were selected in such a way that 1)in a wide range of time scale (from 1957 up to date), 2) from wide regional, 3) from various soil land uses 4) from all types of regression techniques and 5) only using common and easily measured predictors such as sand, silt, clay and organic carbon. The soil samples collected in this study was 224 data, which was obtained from 112 points at two depths of 0-15 and 15-30. Three indicators of absolute mean error (ME), root mean square error (RMSE) and standard deviation of the predicted error (SDPE) were used to evaluate.

Among the existing Pedotransfer functions, Benites et al. (2007) with ME value equal to -0.0008, RMSE value equal to 0.1038 and SDPE equal to 0.1033 had the best results. Based on the RMSE value of Yang et al. (2007) with a value of 0.1038 with a rank of 1 and based on SDPE function with a value between 0.0976 Leonaviciute (2000) had the best results. For the study area, 5 presented relationships including linear relationship between BD and OC, linear relationship between OC and BD squares, exponential relationship between BD and OC, linear relationship between BD and OC logarithm and polynomial relationship between OC and BD were presented.

Based on the results it can be concluded that soil organic carbon (OC) is the most important factor in predicting soil bulk density and using soil organic carbon alone, soil bulk density can be predicted with relative accuracy. It can also be concluded that the 5 relationships developed in this study can be used to obtain the apparent density in the study area.