نشریه مدیریت خاک و تولید پایدار
سال دوازدهم شماره 4 (پیاپی 42، زمستان 1401)

Soil organic carbon is very important in increasing the production of agricultural products and reducing soil erosion and greenhouse gas emissions. A better understanding of the amount and storage of soil organic carbon is essential to the use of soil and maintaining its productivity. The extended pastures of Fandoqloo region in Ardabil province potentially could support and sequestrate considerable amounts of carbon but they are subjected to land use change, high population and tourism. Such tensions led to land degradation and low carbon sequestration in some parts. This study aimed to find effective natural variables on soil carbon density and sequestration. Such variables could be applied for remediation and resilience of degraded pastures and croplands in Fandoghloo region. By application of Latin Hypercube techniques and spatial variables like soil, land use and geological maps the location of sample points was determined. For each land use unit (pasture or cropland) 70 composite surface soil samples (in total 140 samples) were collected from zero to 15 cm deep. After pretreatments of soil samples, soil's physical and chemical properties were measured according to standard protocols. A digital elevation model of the study area was formed using digital isolines of topographic maps and primary and secondary derivates were constructed. Landsat 8 bands were extracted from the Geology Department site of the USA and Normalized difference vegetation index and thermal map of the study area were calculated. Multiple linear regression and artificial neural network models were applied and soil data, digital elevation model and its derivates, normalized difference vegetation index and land surface temperature map have entered the models as independent variables for the prediction of soil organic carbon density. To evaluate the results of the models, the coefficients of determination and root mean square error was used. Application of multiple linear regression model indicated that total soil nitrogen, normalized difference vegetation index and mean weight diameter of aggregates justified 53% of soil organic carbon density in the pasture while 46% of soil organic carbon density in croplands land use was explained by total soil nitrogen and plane curvature. The results of the paired t-test showed a significant difference (P< 0.01) between soil organic carbon density of the pasture and cropland land use. An artificial neural network with an arrangement of 1-10-24 and tan-sigmoid transfer function in the hidden layer justified 71% and 82% of the soil organic carbon density in the pasture and croplands, respectively. Root mean square error of multiple linear regression models for predicting soil organic carbon density in the pasture and croplands were 1.07 and 1.04, respectively but of artificial neural network model was decreased to 0.85 and 0.58 for pasture and cropland, respectively. Sensitivity analysis revealed that the artificial neural network model was severely sensed to digital elevation model and soil moisture content at wilting point. The result of this study indicated the significance of natural vegetation cover and the mean weight diameter of soil aggregates for carbon sequestration in the pastures. Artificial neural networks performed to simulate changes in soil organic carbon density showed that these networks are successful in tracking an important part of soil organic carbon density changes at pasture and cropland land uses. In other words, artificial neural networks were able to identify the effects of these variables on soil organic carbon density using tracing and identifying the effects and interactions between an independent variable series with organic carbon density status. The results showed that transmission functions can be used by the data of primary and secondary topographic parameters for estimating soil organic carbon density in the region.

Hyssop (Hyssopus officinalis L.) is a woody and perennial plant. Drought stress is one of the abiotic stresses that have the adverse effects on growth, development and other metabolic processes of the plant. In this regard, it is necessary to use targeted methods to deal with dehydration, therefore, this study was conducted based on the evaluate the rate of changes in hyssop treated with transpiration-reducing compounds such as kaolin and chitosan as well as the amino acid glycine under drought stress. This research was conducted as a factorial split plots experiment based on a completely randomized design with 3 replications, during 2016-2017 at the Agricultural and Natural Resources Center of Yazd Province. Experimental factors include the drought stress at 3 levels (25, 50 and 75% of the the available water discharge from the soil), the foliar application at 4 levels [water (control), kaolin (2.5%), chitosan (0.4 g/l) ), glycine amino acid glycine (2.5 per thousand)] and the foliar application time (vegetative and flowering, just flowering). The results showed that in the control stress treatment ( 25% of the the available water discharge from the soil), the foliar application of glycine and kaolin, increased the canopy diameter by 30.59% and 27.21%. Also the chitosan and kaolin spraying at flowering time decreased the electrolyte leakage by 6.1% and 6.3%. The highest canopy diameter was obtained on th the interaction of the control stress and glycine amino acid (619 cm2) and the lowest leakage was obtained on the interaction of control stress and the foliar application of chitosan and kaolin at flowering. The increasing drought stress until the level of 50%, increase of 4.79% in chlorophyll a and the total chlorophyll and the highest chlorophyll a, and total chlorophyll (153 and 216 mg/g FW) respectively were observed in the foliar application of control at vegetation and flowering. The increasing the amount of available water discharge to the level of 75%, a decreasing trend in the amount of leaf area (91%) dry weight (51.95%), chlorophyll a (34.64%), chlorophyll b (43.86%) and total chlorophyll (32.87%), also an increasing trend in superoxide dismutase activity (25.92%) was observed. The highest leaf area in the interaction of control stress and the foliar application of control (4947cm2) at flowering, dry weight (140.5 g/m2), chlorophyll b (69.3 mg/g FW) in the interaction of control stress and the foliar application of control and superoxide dismutase activity in the interaction of sever stress and foliar application of kaolin (0.34 (U. mg protein -1. min -1) at vegetation and flowering Was obtained. Also, the foliar application of control, kaolin and chitosan at vegetation and flowering compared to other experimental treatments had the greatest effect on chlorophyll b, canopy diameter and dry weight. Drought stress reduced the amount of morphological parameters. This decrease had less negative effects on physiological parameters, so the mentioned parameters had an increasing trend to the mild stress level and a decreasing trend was observed with the increase of dryness up to the sever level The severe stress also increased biochemical parameters. Foliar application with glycine and chitosan at vegetation and flowering was effective in increasing morphological parameters dependent on growth and foliar application of chitosan and kaolin during flowering as well as kaolin spraying during vegetation and flowering played a useful role in increasing the biochemical parameters related to the antioxidant activity of plant to. Due to the changes in the hyssop, the application of this substances can be recommended to reduce the adverse effects of stress on other medicinal plants

The widespread use of chemical fertilizers became common by coming the Haber-Bosch reaction product to the market in the second decade of the twentieth century, and thereafter the agricultural industry flourished. Nowadays, increasing usage of chemicals has caused adverse and harmful consequences against the environment and also increased costs of production of crop plants. The use of biofertilizers, which potentially solubilizes phosphorus compounds in the agricultural soil, is considered as an environmental friendly option and a superior alternative to further usage of chemical fertilizers. New collections of phosphate-solubilizing bacteria with a vast biodiversity are required to be used for greater varieties of crop plants in more different climates. The aim of this study was verification and characterization of some active phosphate-solubilizing bacteria isolated from several areas of wheat arable soils located in Yazd province.

In this study, soil microorganisms were screened and all the isolates were examined in PVK agar culture medium for halo formation and then phosphate solubilization index and efficiency were calculated. Phosphate release rate in liquid culture medium was measured in µg/ml. Nitrogen fixation test using two carbon sources (glucose and sucrose) was evaluated comparatively. All the isolates were examined for tolerance to various environmental conditions such as temperature, salinity and pH. Finally, the production of several types of organic acids by the isolates was examined using thin layer chromatography.

Among the bacteria, 10 isolates created a halo zone in culture medium containing calcium phosphate and showed growth and discoloration in nitrogen-free medium with bromothymol blue reagent. Five isolates out of 10 showed the highest efficiency in phosphate solubilization (equal to or more than 200% Z/C) and 5 isolates showed the highest phosphate solubility index (between 2- 4). The highest index belonged to YC isolate (4.1), while statistical analysis showed no significant difference between the means of solubility efficiency of different isolates. The quantitative study showed that the amount of phosphate released for 4 superior isolates was 150.25-203.91 µg/ml. Statistical analysis shows that among the 10 strains tested, YS and YG showed the highest efficiency with the release of 203.9 and 194.8 μg/l phosphate, respectively. These two strains were not significantly different from YK and YC isolates. Isolates YX, YA, YP, YH, YJ and YI also showed the least ability at the same statistical level. All the isolates were able to fix nitrogen in the presence of glucose and 4 isolates were able to fix nitrogen in the presence of sucrose as two different carbon sources. Experiments carried out to show the resistance of the isolates to environmental factors and indicated that almost all isolates can grow adequately in the range of acidic to alkaline pH (5-9) and temperatures of 25-37 ºC. The isolates were also able to tolerate salinity up to 10% (w/v). The use of thin layer chromatography confirmed the excretion of organic acids such as citric acid and oxalic acid by the examined bacteria.

The present study indicates that the isolated microorganisms with high phosphate solubilizing ability show significant potential as a suitable substitute to chemical fertilizers with harmful side effects.

Drought is one of the most widespread abiotic stresses which has a negative effect on the growth and yield of plants in most parts of the world. Drought stress reduces plant yield by reducing the uptake of water and nutrients. The dry and semi-arid weather conditions of Iran have caused many problems in the production of plants, including wheat (Triticum aesivum L.). Phosphorus, as one of the essential nutritional elements for wheat, can be effective in alleviating the effects of drought stress. In recent years, to deal with drought stress, the use of plants and cultivars efficient in uptake nutrients, including phosphorus, as an appropriate strategy to increase crop yield has been the focus of researchers. Therefore, it is necessary to pay attention to the mechanism of efficient cultivars against drought stress for accurate fertilizer recommendations.

To evaluate Sirvan wheat cultivar (resistant to drought stress), in the uptake of nutrients and its growth and development at different levels of moisture and phosphorus, a research in the greenhouse was performed as factorial based on a completely randomized design with two factors and three replications during the vegetative growth period. The factors included phosphorus from mono-calcium phosphate monohydrate source (0, 15 and 25 mg P kg soil-1) and three moisture regimes including 50 and 70% of field capacity (T1, T2: stress conditions) and 95% of field capacity (T0: control).

According to the results, it was observed that the interaction effect of drought stress and phosphorus levels on total dry weight, uptake of iron, zinc and potassium nutrients, total soluble sugar, root growth (cumulative length, diameter and root area) and chlorophyll index was significant at the 0.01 % and 0.05 % level of probability, respectively in Sirvan cultivar. The results showed that the increase of phosphorus (25 mg kg-1) in the presence and absence of drought stress was effective on the growth and development of the studied wheat cultivar; So the addition of phosphorus in the amount of 25 mg kg-1 in the drought stress condition of 50% of the field capacity increased the total dry weight of Sirvan variety from 5.80 to 8.52 g pot-1 compared to the level without phosphorus application. The increase of phosphorus in the condition of drought stress (50%), increased the uptake of iron nutrients by about 2 times, zinc and potassium by 60 and 50%, respectively, compared to the control level that this increase in uptake can be due to the increase in root growth and its characteristics (cumulative length, area and diameter); Also, according to the results of this experiment, it was observed that the resistance of Sirvan cultivar to drought stress was due to the increase in the amount of total soluble sugar, root growth and uptake of iron, zinc and potassium which led to an increase in total dry weight and its good growth and development under drought stress conditions.

The application of the appropriate amount of phosphorus at the level of 25 mg kg-1 under drought stress conditions increased the total dry weight, root area, root diameter and length, uptake of nutrients, chlorophyll index, height, number of tillers and the amount of total soluble sugar in the plant, this level of phosphorus with a positive effect on the growth and development of Sirvan variety in the vegetative growth stage made it adapt to drought stress conditions; Considering the importance of cultivar selection in adjusting drought stress, Sirvan cultivar was able to show a good response to phosphorus fertilizer to reduce drought stress.

The application of organic matter and soil conditioners is essential to maintain soil efficiency and achieve sustainable agriculture. The aim of this study was to investigate the effect of application of biochar and wood vinegar on penetration resistance and stability of soil aggregates under forage corn cultivation.

For this purpose, a study was conducted in greenhouse conditions at ShahreKord University. The experiment was performed as a factorial experiment in a completely randomized design with 30 treatments in 3 replications. The studied treatments included wood vinegar in 6 amounts of zero (W0), 0.02 (W1), 0.04 (W2), 0.1 (W3), 0.2 (W4) and 0.4 (W5) g/Kg (first factor) and conditioner including raw material (pomegranate and plum wood) in 2 levels 1 (B01) and 2 (B02) weight-weight percentage and biochar in 2 levels 1 (B1) and 2 (B2) weight-weight percentage (second factor) was applied. Soil penetration resistance of the undisturbed samples at 0, 10, 50, 100, 500, 1000 and 1500 Kpa matric suctions by penetrometer and mean weight diameter of aggregates by dry sieving was measured.

The results showed that the main effect of wood vinegar and conditioner (raw material (pomegranate and plum wood) and biochar) application and the interaction effect of wood vinegar and conditioner (raw material (pomegranate and plum wood) and biochar) application on bulk density and aggregate stability and soil penetration resistance at 0,10, 50, 100 and 500 Kpa matric suctions were significant at the level of 1%. The application of wood vinegar and raw material increased bulk density and aggregate stability that the highest aggregate stability was related to W2B2 treatment, which increased the stability of aggregates by150% of the control. Also the application of wood vinegar and raw material increased the reduction of soil penetration resistance. So that at 0, 10, 50, 100 and 500 Kpa matric suctions, the greatest decrease in penetration resistance was related to W5B2 treatment, which soil penetration resistance was observed in 81.7, 82.89, 86.89, 78.65 and 78.65% of the control.

Wood vinegar and biochar has high organic carbon, which is effective in increasing the aggregates stability and creating larger aggregates and increasing mean weight diameter of aggregates and the cause can be attributed to the increase of the bonding force between the aggregates by the compounds in organic matter. Also, biochar and wood vinegar reduced soil penetration resistance by increasing soil organic carbon and reducing soil bulk density.

Today, in most pistachio farming areas, the reduction in the quantity and quality of irrigation water, followed by the reduction in the absorption of nutrients by the roots, has reduced the amount of pistachio fruit and its quality. The use of organic materials in sustainable agriculture, such as humic acid, causes the physical modification of the soil, including the increase of pores and water retention capacity and the reduction of evaporation from the soil surface. These substances increase the absorption of nutrients through the improvement of root growth and the formation of chelates of elements, and with the properties of stimulating growth, regulating plant growth hormones and increasing the tolerance of plants against plant stresses, it ultimately increases plant growth and Finally increasing the economic performance of pistachios. This research was carried out in the form of a randomized complete block design with 5 treatments including zero (control), 500, 1000, 1500, 2000 kg per hectare of humic acid produced by Shimi Golfaiz Khorasan Company in three replicates and for two years of cultivation on fertile trees of 35-year-old Kale Ghochi trees. Each plot included 5 trees and a total of 75 trees were tested. Based on the soil test, the lack of nutrients was determined and the required amount of chemical fertilizers (the same amount for all treatments) was used in a mixture with humic acid, and only chemical fertilizers were used in the control treatment. The results of analysis of variance and comparison of treatment averages based on composite analysis of two-year data indicated that the difference between treatments was statistically significant for most of the assessed traits. The fresh and dry weight of the tree showed an increase of 39% and 38%, respectively, in the treatment of 1500 kilos of humic acid compared to the control. The treatment of 500 kg/ha of humic acid had the lowest amount of blank (25% reduction compared to the control) and the highest percentage of non-splitting (48% compared to the control). The treatment of 1000 kg/ha of humic acid caused the highest branch growth with 21% compared to the control. The 1500 kilo humic acid treatment had the highest amounts of calcium (23%), iron (25%), zinc (22%), and manganese (24%) compared to the control. According to the results obtained from this research, the treatment of 1500 kgha-1 of humic increased the fresh and dry yield and the concentration of calcium and micro nutrients elements of iron, zinc and manganese and is introduced as the best treatment. Of course, it should be kept in mind that regardless of the type and concentration of humic acid used, the method of application, the physical and chemical conditions of the soil, the management of the farm are also effective in the results obtained.