جستجوی مقالات مرتبط با کلیدواژه « عناصر خاک » در نشریات گروه « کشاورزی »

The exciting growth of various sciences and technologies and the complexity of decision-making in recent decades, have marked new ways for humanity to use information systems and artificial intelligence, accurately and quickly and provide a solution for its time-consuming scientific and technical predictions and calculations. This study was conducted to evaluate the predictive outcome of two stepwise regression models and the M5 decision tree model under the influence of different water and soil properties on saffron flower and stigma yield in 2019 in Sabzevar saffron fields (located at longitude "57.43" Latitude "36.12") and was performed in the laboratory of the Faculty of Plant Production of Gorgan University of Agriculture Sciences and Natural Resources. In April, after the end of the saffron growing season, soil samples from a depth of zero to 30 cm and 12 irrigation water samples from 69 saffron farms were prepared and transferred to the laboratory to analysis and measuring the physical and chemical properties of soil samples. Around 13 parameters including pH, acidity, and percentage of soil components, soil elements, etc. and acidity, bicarbonate, etc. were measured in soil and water samples, respectively. Flowers were collected at the time of flower emergence from the specified areas of the fields and the desired measurements were made. The results showed that, as the soil and water analysis is relatively expensive, the M5 decision tree model has more accuracy due to the speed and lower cost than the regression model. So that, in the result of predicting the stepwise regression model, in the most ideal case and entering all the measured parameters, dry stigma weight and flower weight with correlations of 70 and 74%, respectively, and the error value is 0.23 RMSE and RMSE 16.38 were predicted. While the M5 decision tree model with lower parameters had a high capability to predict flower weight and dry stigma weight. It estimated the weight of dry stigma and flower weight with 90% correlation and error value equal to RMSE = 0.12 and RMSE = 9.4 at the end of modeling for the study area. Therefore, the M5 decision tree method is recommended in evaluating and predicting various factors on saffron yield.

The aim of this study was to assess the regional effects of fire on the surface cover and soil characteristics of mountainous rangelands of Delfan County, Lorestan province, Iran. which seems has significant effect on vegetation characteristics on the study area. Four fire affected sites were selected for sampling and a close area without fire was considered as control. Sampling was carried out using random systematic method and the size of plots was determined using the minimal area framework. The number of plots was determined using statistical method. Totally, the data of eight sites including four fire affected sites and four control sites were measured during four consecutive years in early July of each year after fire. In each site, four transects of 50m length were selected in the direction of slope as well as perpendicular to the slope and five plots were established along each transect. Soils samples from the beginning, middle and end of each transect were taken from a depth of 0-30 cm. Independent t-test was used to compare the mean of the factors in two control and fire zones, and one-way ANOVA and Duncan test were used to compare the years. The results showed that fire caused a significant increase in forage production, cover percentage, perennial grasses density and forbes and percentage of litter cover. Also, the density and percentage of shrub species and bare soil cover decreased significantly. The fire caused an increase in organic matter, electrical conductivity, nitrogen, potassium, phosphorus and soil texture.

Dust is occurred when a vehicle passes from the dry surface of unpaved roads. Dust particles can affects negatively on plant growth, water quality and road life. In this study the effects of some environmental friendly anti-dust agents including different dosage of sugarcane molasses, polyacrylamide and bentonite were investigated on road dust control. Research was done in 3, 9, 27 and 81-dat time frame.

Rear-mounted solution spray system equipped with 8 nozzles was used for implementation of treatments in rate of 2-2.5 l m-2 in three sites in forests of Golestan provinces including Loveh, Kouhmian and Shastkalateh. Besides, dust sucker instrument was applied to collect dust particles. Data were collected when a vehicle is passed with speed of 40 km h-1. Moreover, soil samples were collected from the margin of forest roads to measure the changes in soil Na, K, Ca and Mg due to washing.

Results showed that dust of forest roads decrease with increasing the anti-dust agent concentration and increased with time. In Loveh forest roads, polyacrylamide with concentration of 6% and sugarcane molasses with concentration of 20% were the most appropriate treatments. Bentonite was unsuitable due to the high amount of fines in surfacing materials. In Kouhmian forest roads, polyacrylamide with concentration of 4% and sugarcane molasses with concentration of 20% and in Shastkalateh forest roads, polyacrylamide with concentration of 2% was the most appropriate treatments. Bentonite increased the Mg and pH and Molasses increased the K and decreased the pH of soil at margin of forest roads. In other cases, there wasn’t a significant effect from the treatments on chemical properties of soil at margin of road. In Kouhmian forest roads, polyacrylamide with concentration of 4% and sugarcane molasses with concentration of 20% and in Shastkalateh forest roads, polyacrylamide with concentration of 2% was the most appropriate treatments. Bentonite increased the Mg and pH and Molasses increased the K and decreased the pH of soil at margin of forest roads. In other cases, there wasn’t a significant effect from the treatments on chemical properties of soil at margin of road.

Base on findings, sugarcane molasses in roads with high fine particles was most efficient, but in roads with low fine particles polyacrylamide was most efficient. These additive materials hadn’t significant effects on adjacent soil chemicals due to their low amount.Base on findings, sugarcane molasses in roads with high fine particles was most efficient, but in roads with low fine particles polyacrylamide was most efficient. These additive materials hadn’t significant effects on adjacent soil chemicals due to their low amount.

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.

Land use changes such as conversion of forest to cultivated lands, significantly affect soil properties and modify soil forming processes. Land use changes can drastically affect the soil environment, which in turn markedly affect soils and soil processes. Human activities that are not associated with proper planning have undesirable effects on natural resources such as soil, including land use change. The results of the investigations in different parts of the world show that changing the use of natural ecosystems to managed ecosystems has destructive effects on soil properties. Cutting off the forest trees and converting pastures into agricultural lands will destroy or disrupt natural ecosystems and reduce the current or future production capacity of the soil. One of the important issues in the world is the destructive effects of agriculture on soil quality. These destructive effects can include a wide range of soil changes including physical properties such as soil compaction, soil water depletion, soil structure destruction and soil texture change, chemical properties such as accumulation of some elements such as N, P, K, and soil salinity, and soil biological properties such as soil microbial population and soil fauna activity changes, soil organic matter reduction and also effect on useful soil enzymes. Land use change from forest to agriculture does not necessarily lead to soil degradation. Land use changes and forest destruction in Yasouj region has increased in last decades. In this study, we investigated the effects of land use change on some soil characteristics in Servak plain, Yasouj region.

Servak region is located in 4 km south of Yasouj city. Three main land uses of dense forest, degraded forest, and dry farming were chosen to study the role of land use change on some soil properties.. The elevation of the region varies from 1833 to 1869 m above sea level. Five soil samples (0-20 cm) were taken from each land use. Samples from each land use were taken from almost similar elevation and slope to minimize the effect of topography. Soil samples were transferred to the laboratory, air dried and passed through a 2mm sieve. The chemical and biological analyses were carried out. The determination of soil organic carbon was carried out based on the Walkley-Black chromic acid wet oxidation method. Available K was extracted with 1N ammonium acetate at pH=7 and was determined by flame photometry. The Olsen method was used for the determination of available phosphorus. Total nitrogen was measured using the Kjeldahl method. Soil bacterial communities were counted using culture medium (Nutrient agar. The basal respiration rate was estimated by back-titration of the unreacted NaOH to determine CO2 evolved over 10 h. The substrate-induced respiration was measured by adding 2 ml of 1% glucose to soil samples over 6 h. Soil suspensions were prepared by 10-fold serial dilutions with 1g soil. Counting the soil fungal community was done using a culture medium (Potato dextrose agar) and was prepared by 10-fold serial dilutions. The activity of alkaline and acid phosphate enzymes was measured based on a colorimetric method using p-nitrophenol.

The land use change from a dense forest to dry farming has modified many chemical and biological soil properties. The results of analysis of variance and comparison of the means of data obtained from this study showed that as a result of land use change from dense forest to dry farming, Organic matter, total nitrogen, exchangeable potassium, basal and substrate-induced respiration, fungal community, acid phosphatase and alkaline phosphatase enzymes contents were decreased. Also, soil bacterial communities were increased at 1% level in dry farming land use. The amounts of phosphorus did not show any significant difference. In general, it can be concluded that following the degradation of the forest and land use change, the soil organic matter and relevant properties, especially biological indices, are more affected compared to the other properties. Soil organic matter plays a key role in ensuring agroecosystem productivity and the long-term conservation of soil resources.

Large-scale conversion of indigenous forests to cultivated land, driven by long-term agricultural development in the Servak region, has greatly affected the physicochemical and biological properties of the soils. Generally, the conversion of the natural ecosystem to agroecosystems decreased organic carbon content and relevant indices such as basal and substrate-induced respiration, fungal community, acid phosphatase and alkaline phosphatase enzymes contents in the top-soils at depth of 0 to 20 cm. The decrease of organic carbon in cropped farms could be attributed to the enhanced oxidation of soil organic C caused by cultivation. The results of this study showed that any management and type of land use that decreases soil capabilities can reduce soil quality and increase the susceptibility to degradation. So, in order to maintain soil quality, appropriate management practices should be done.

Cations of sodium, potassium, magnesium and calcium play important roles in adaptation of plant species to arid conditions. The research in 93 years to evaluate the uptake of cations of sodium, potassium , magnesium and calcium cations such Halocnemum Strobilaceum in Meghan and compared to the depth ( 0 to 30 cm ) soil samples were analyzed and plant feet in three season ( winter, spring , summer ) was performed . For this purpose, 10 samples from the aboveground plant parts Ha. Strobilaceum and the soil under the plant in three seasons to just completely random sampling was conducted . By transferring the samples to the lab, cations of sodium, potassium, magnesium and calcium were measured. Finally, using one-way ANOVA was used to examine the significant difference values between samples. Results showed, The results showed that the highest amount of 4 cations starting in the spring than in winter and summer growing season plants there and vice versa least the same amount of cations in the soil in the spring event , which shows high absorption and herbal Ha. Strobilaceum at the start of the growing season , as well as the cations accumulation of soil in direct connection with the distribution of the species Ha. Strobilaceum there .

This study was done to evaluate the effect of afforestation in sand dunes at the vicinity of Shush, because of the importance of soil protection and wind erosion in sand dunes, also sand dunes afforestation as an effective and long lasting fixation mechanism. The study site was covered by petroleum mulch about 20 years ago and afforested by Prosopis juliflora. To study the effects of afforestation on sand dunes, two 10 ha afforested sites (25-50 and 75-100 percent canopy coverage) and control were selected. In each of studied site 15 plots were established and soil physiochemical properties were determined. Our result indicated that afforestation caused soil texture to change from sandy to sandy-loam. Also, soil phosphorus, potassium, organic carbon and nitrogen increased in 0-5 cm soil depth by afforestation that could be because of nutrient absorption from soil depth and returning to the surface by litter fall compared to the control. This study revealed that 25-50 percent canopy coverage resulted in better soil physiochemical properties compared to control site. In conclusion, sand dunes afforestation not only resulted in sand dunes fixation but also soil fertility and long lasting fixation.

Biofilm formation in bacteria is an important survival strategy. Biofilm of probiotic Bacillus subtilis consist of long chains of cells that are covered by a polymeric matrix of exopolysaccharides. This bacterium is known as one of the most effective biocontrol agents against plant pathogens and has a high ability in biofilm formation. This study was aimed to investigate the effect of some environmental conditions including temperature, pH and osmotic pressure; nutritional elements such as sugars and amino acids secreted from wheat root and important soil elements like Ca2, Mn2, Mg2, Fe 2, Zn2, Mo6, Co2, B3 and Cu2 on biofilm formation of mentioned bacterium using polystyrene plate. Results of this study indicated that the most amount of biofilm in three studied strains produced at 30°C, pH 7 and the osmotic pressure using concentration of 75% sucrose. Cations of magnesium, calcium, zinc, iron, manganese and copper increased but cations of molybdenum, cobalt and boron decreased biofilm formation. All sugars and amino acids secreted from wheat root increased biofilm formation of studied strains. Among sugars, arabinose and glucose; and among amino acids, lysine and asparagine showed the greatest increasing effect on biofilm formation. According to our results, environmental conditions and the content of nutrient can influence on biofilm formation and consequently, the survival and establishment of probiotic bacteria in their environments, host colonization and biological control against plant pathogens.

The protection and improvement of natural resources especially for desert vegetation need a comprehensive recognition of natural resources and relationship on Soil characteristics. One of the most important species growing in sabzevar desert is Stipagrostis pennata and in the current research the relationship between the physicochemical properties of the soils and growth characteristics of the S. pennanta including density, canopy cover and amount elements of soil have been studied in the land. A random systematic design has been applied in 4 sites called A, B, C, and D within a distincthabitat of S. pennanta. Soil samples have been taken from 2 depths (0 - 30 cm) and 30-60 and prop Hon of clay, silt and sand content, amount of N, P, K, C, Na, Ca and Mg have been determined in a soil lab. The soil physico–chemical and plant growth data have been analyzed through statistical methods using the SPSS software. Further finding of this study show that the growth characteristics of S. pennanta such as density, canopy cover and forage production rarely depend on soil chemical properties but there is a statistically significant positive correlation between the canopy cover and amount of Ca. This has been shown by higher canopy cover in site B which has higher Ca..The results show that there is direct relationship between the amount of nitrogen and growth properties off of Stipagrostis pennata and other elements of the soil was not significant.