نشریه مدیریت خاک و تولید پایدار
سال یازدهم شماره 1 (پیاپی 35، بهار 1400)

Heavy metals enter naturally in the soil environment from the pedogenic processes during weathering of parent materials or through a variety of human activities. Determining the source of heavy metal in agricultural soil is necessary to management the soil pollution. This study aimed to investigate soil pollution by selected heavy metals and determine their sources in agricultural soils in Southern Sabzevar.

The study area is located in the piedmont of ophiolotic belt in the South of Sabzevar city, Northeastern Iran. Surface soil samples from 0 to 20 cm depth of cultivated lands were regularly collected up to 2 km from the main road. Also, three profiles were studied at a distance of 1 km intervals. Five samples were taken from the depths of 0-20, 20-40, 40-60, 60-80, 80-100 cm. The total concentrations of Al, Fe, Mn, Ni, Cr, Zn, Cu, Pb, and Cd were measured by Inductively Coupled Plasma (ICP-OES). In this study, Pollution indices were calculated for the studied heavy metals. Multivariate statistical techniques were also applied to assess the sources of the heavy metals using SPSS software V 24.

Mean concentrations of Ni, Cr, Mn, Cu, and Zn were 306.2, 217.5, 781.4, 268.3, and 302.2 mg kg-1 was found to be higher than EU, WHO, and USEPA standards. Cadmium with an average concentration of 2.7 mg kg-1 was higher than WHO and USEPA standards and Pb with an average concentration of 18.8 mg kg-1 was higher than USEPA standards. Based on Pearson correlation coefficients, statistically-significant positive correlations (P < 0.01) were found between Ni and Cr, Cu and Zn (P < 0.01), and also between Pb and Cd (P < 0.05). In addition, based on principal component analysis (PCA), three components accounting for 76.97% of the total variance explained. The first component contained Fe, Mn, Cr, and Ni, the second and third components included Pb, Cd and Cu, Zn, respectively. According to the pollution indices (enrichment factor and geoacumulation index), Cd, Cu, and Ni are important pollutants, with the highest EF and Igeo index among the analyzed elements. Potential ecological risk factor (Er) also showed that Cd, Cu, and Ni are important pollutants responsible for ecological threats.

According to the results of correlation and multivariate statistical analyses the heavy metals were classified in three groups of (Mn, Cr, Ni), (Cu, Zn) and (Pb, Cd), which indicates their similar sources. Elevated amounts of Cd and Ni in the soil, based on EF, Igeo, and Er, were attributed to the long-term and extended applications of the chemical fertilizers and traffic emission for Cd and ophiolitic parent material for Ni. In comparison, the elevated amount of indexes for Cu were associated with both anthropogenic and geogenic sources. Hence, control of elements from geogenic and anthropogenic sources into the soil seems necessary. In case of non-observing environmental considerations such as excreting proper management in the region, The environmental cycle will face irreparable damage in the long-term; therefore, it seems necessary to make decisions to reduce these pollutants and, if possible to eliminate them.

To achieve sustainable agriculture and improve soil quality, it is necessary to use organic sources such as animal manure in combination with suitable amount of chemical fertilizers. The purpose of this study was to investigate the effect of animal and chemical fertilizer on vegetative growth, yield and qualitative properties of Thomson Navel orange (Citrus sinensis L. Osbeck) fruit to reduce chemical fertilizer consumption.

The experiment was carried out as a factorial experiment in a randomized complete block design with three replications. Treatments included three levels of sheep manure (0, 6 and 12 kg per tree) and three levels of macronutrient fertilizers: nitrogen, phosphorus and potassium (0, 30 and 60% recommended amount, based on soil test) on five years old Thomson Navel orange trees (each treatment including two trees) in the Sari Baharestan citrus orchard for four years. Based on the growth of the trees, the above-mentioned values were added 20% annually. At the end of each growth period, vegetative growth including the length of spring and summer shoots and diameter of the collar (top and bottom of the graft union) were measured. Fruit yield and mean weight and diameter, total soluble solids (TSS), total acidity (TA), pH and vitamin C of harvested fruits were also measured.

The results showed that the highest spring growth (shoot length) of Thomson Navel oranges was obtained as a result of the combined application of chemical fertilizer and manure (60% of the recommended amount) and manure (12 kg/tree). The lowest spring vegetative growth of 21.6 cm was observed in the control. The Interaction between different levels of chemical fertilizer and manure on summer growth was not significant. Collar diameter (at the bottom of the graft union) reached its maximum level (132 mm) in 60% recommended fertilizer and 6 kg of manure per tree treatment. The highest fruit yield of Thomson Navel trees was obtained with an average of 49.6 kg/tree, in a combination of chemical fertilizers (60% of the recommended amount) and manure (12 kg/tree). The fruit TA in different levels of chemical fertilizer and manure increased and decreased, respectively. The Interaction between chemical fertilizers and manure on TSS was significant and the highest (11.08%) was observed at 60% of the recommended amount of chemical fertilizers and 6 kg/tree of manure. This treatment and the treatment of 60% of the recommended amount of chemical fertilizer and 12 kg/tree of manure were located in the same group. The 60% recommended chemical fertilizer treatment + 6 kg of manure produced the highest amount of vitamin C in the fruit extract (80.8 mg/100 ml of extract), however the combination of high levels of chemical fertilizer and animal manure reduced the vitamin. The Interaction of chemical fertilizer and manure levels was not significant on fruit diameter but it was significant on average weight and volume of extract. The highest mean weight (352g) and fruit volume (176cc) was obtained in the treatment of 60% chemical fertilizer + 12 kg of manure per tree.

The results showed that 60% of the recommended amount of chemical fertilizers + 12 kg of rotten sheep manure per tree is recommendable to achieve the highest quality and quantity of Thomson Navel orange fruit.

Modern technologies, such as biotechnology and nanotechnology, play an important role in increasing production and improving the quality of food produced by farmers. Salinity also directly affects the absorption of nutrients elements. This study aims to investigate the use of nano-chelate with ethylene diamine tetra-acetic acid (EDTA) and Humic Acid (HA) base as fertilizer agents on Sunflower.

This study was done as a pot experiment as a factorial in a completely randomized design including two levels of iron nano-chelate fertilizer (ethylene diamine tetra-acetic acid and Humic Acid) and two methods of application of fertilizers (foliar application with the level of one gram per Liter and soil application with the level of one gram per kilogram with the control) in three replications in the research greenhouse of Zabol University. Five sunflower seeds were used for cultivation. The treatments were applied in two ways that are soil use and spraying form, when plants are 4 to 6 leaves the tratments have been used in 4 steps and at intervals of 15 days. The pots were irrigated by distilled water and weighting method during the experiment period. Some growth parameters, chlorophyll content as well as nutrients (Fe, Zn, P, K) of sunflower shoot (Helianthus annuus) under permanent salinity conditions were investigated about two months after planting. Statistical analysis was performed on the basis of SAS software and Analysis of data variance was done based on ANOVA software. The mean of measured indices was categorized using Duncan test at the level of 0.05.

Results showed that the interactions of fertilizer type and its method of use have a significant effect on the shoot indexes (dry weight, leaf number and plant height), leaf chlorophyll content (a, b, total and carotenoids) and nutrient concentration (Fe, Zn, P, K) of sunflower plant (p≤0.01). Comparison of the means showed that spraying EDTA-based iron nano-chelate increases dry weight of shoot, the number of leaves and plant height (1.15, 1.21 and 1.05 times, respectively), the level of leaf carotenoid (1.76 times) and also Fe concentration in the shoot (2.37 times) compared to the control. Moreover, in EDTA-based iron nano-chelate soil application, the concentration of phosphorus and potassium elements is respectively increased 1.59 and 1.94 than control.

According to the results, spraying EDTA-based iron nano-chelate improved most of the sunflower growth parameters, which shows the superiority of this Nano-fertilizer to HA-based iron Nano-chelate in saline soils.

Choosing the best land suitability method to determine land suitability classes has always been questioned and researched. Many land suitability surveys are conducted using four conventional methods, including: 1-simple limitation, 2- number and intensity of limitations, 3- Khiddir (square root) and 4- storie. In the parametric approach, the land index is calculated using the Khiddir method or the Storie method, and then based on this index, the land suitability classes are determined. The land index is in two forms: the uncorrected land index and the corrected land index. Numerous studies on land suitability evaluation have shown that the results of different land suitability methods are very different. However, the results of many studies suggest that the two methods of simple limitation and Khiddir are more consistent. Since these researches have been for different products and different regions, it has not been possible to evaluate the degree of adaptation of different methods without considering the type of product and its location. On the other hand, the numerical value of the adaptation or conformity of these methods with each other has not been determined. So, regardless of the type of product and location, a basic question that arises is how well do the different land suitability methods fit together, and are the degree of adaptation different for various land suitability classes? Current research seeks to answer this question.

In this study, land suitability classes were determined using numerical simulation, without considering any product and location. In numerical simulation, each of the eight factors involved in determining the suitability classes accounted for a random number from zero to 100, and then based on these simulated numbers the land suitability classes were determined with the four conventional methods and in two forms of the uncorrected land index and the corrected land index. The simulation process for each proportional class, including classes S1(suitable), S2(Moderately suitable), S3(Marginally suitable), N1 (temporary unsuitable), and N2 (permanently unsuitable), was performed one million times. So a total of five million simulations were done. In the next step, the degree of adaptation for each class and each method was calculated based on the Overall Accuracy(OA) formula.

The results showed that the numerical value of the degree of adaptation of different land suitability methods in various classes are very different; Overall, however, the least and most adaptation between the different methods occurs for Class N1 and N2, respectively. After class N2, there is the greatest adaptation between the different methods in class S1. For classes S2 and S3, the degree of adaptation between different methods does not follow a specific trend. Among the various methods, in the case of using the uncorrected index, the simple limitation method was more consistent with the Khiddir method. However, using the corrected land index, the greatest correlation was observed between the simple limitation method and the parametric approach (both Khiddir and Storie method) and in this case there was not much difference between the results of Khiddir method and Storie method. Therefore, the corrected index is superior to the uncorrected index.

Based on the findings of this study, it can be said that the results obtained from the uncorrected land indices may be far from reality, and this issue is much more severe for the Storie method. The use of the uncorrected index causes a large difference between the parametric approach with the two methods of simple limitation and the number and intensity of limitations. Therefore, it is necessary to use corrected indices to determine the suitability classes so that the results of different methods are as close as possible.

Most of the soils in arid and semi-arid regions of Iran contain less than 1 % organic matter, which lead to reduce the quality of some physical properties of the soil, including decreasing the stability of aggregates, destruction the soil structure and reducing saturated hydraulic conductivity. Considering to the importance and role of organic matter and the presence of sodium and potassium in cattle manure and their destructive effects on soil structure, this research was performed to study the effect to investigate the effect cattle manure, sewage sludge and potassium chloride on soil structure stability indices.

In this research, the effects of cattle manure and municipal sewage sludge at three rates (0, 1 and 2 %) and potassium cation (potassium chloride) at three salinity levels (1, 3 and 5 dS/m) and 3 replications as a completely randomized design and factorial arrangement were studied to compare the treatments on soil structure stability indices. Treatments of 1 and 2 % (weight) cattle manure and sewage sludge were applied to soil and treated soil filled in pots (1 kg weight). To saturate the soil, all pots were irrigated with 300 ml of urban water. Then, irrigation was made by KCl solutions and 200 ml of KCl was added to each pot every week for the period of 8 weeks. After then, soil structural stability indices including normalized stability index (NSI), geometric mean diameter of wet aggregates (GMD), and percentage of aggregate destruction (PAD) were measured. The statistical analysis of data was made by JMP8 software and comparison of means based on LSD test at P < 0.001 was performed.

the results of structural stability showed that sewage sludge treatment had a positive effect on aggregate stability, percentage of aggregate destruction and geometric mean diameter of wet aggregates, while manure application due to high concentration of sodium and potassium and their destructive effects on aggregate stability had the negative effect on most structural stability, except for the normalized stability index. In general, geometric mean diameter of wet aggregates in treatment with no organic matter and salinity level of 3 dS/m was the lowest value and it showed the highest value in 1 % of sewage sludge and salinity level of 3 dS/m. Also, amounts of normalized stability index were the highest and lowest values in salinity of 1 dS/m + 1 % of manure, and salinity of 3 dS/m + no organic matter, respectively. Percentage of aggregate destruction significantly decreased at salinity levels less than 3 dS/m when organic matter increased, while it was not significantly changed at salinity of 5 dS/m due to increment of potassium and its destructive effect on soil structure.

Considering the positive effect of organic matter on stability of aggregates in short term, and the cost effectiveness of sewage sludge, it is suggested that the application the sewage sludge on soil structure indices in agricultural lands will be studied during several years.

Improper use of land resources due to increased human food needs has led to the destruction and reduction of arable land. One way to increase production per unit area is to land suitability assessment. Land suitability assessment is the fitness of a type of land for defined use. Assessing spatial variability of land suitability class is necessary to increase production and prevent land degradation. Determining the land suitability class requires measuring soil, topography, moisture and climate properties, which are costly and time consuming. One solution to this problem is to use learning machines and auxiliary data. Learning machines are used to relate various properties with auxiliary variables to assess their spatial and temporal variability. Random forest learning machine is one of the most common and widely used learning machines. The aim of this study is to assess land suitability based on FAO land suitability framework and parametric method for three important irrigated crops of the region, including alfalfa, potato and irrigated wheat, and to predict their land suitability classes using random forest learning machine and auxiliary data.

122 soil profiles were dug, described and sampled in the Ghorveh area of Kurdistan Province (covers 6500 ha). Soil texture, acidity, organic carbon, CaCO3, gypsum, ESP, electrical conductivity and gravel were measured in all soil samples. Moreover, topography and climate data were also recorded. Environmental variables in this research were terrain attributes, land unit components map, and data of ETM+ image. To make a relationship between land suitability class and auxiliary data, random forest (RF) learning machine were applied and using cross validation method and statistic indices including overall accuracy and kappa index was validated.

The results showed that suitability class of the study area has 37, 41 and 57% N2 class, 21, 34 and 27% N1 class and 48, 19 and 16% S3 class for irrigated wheat, alfalfa and potato, respectively. The major limitations of the study area to plant the crops are included high slope, shallow soil depth, high pH and gravel.To predict land suitability class of alfalfa, potato and irrigated wheat, auxiliary variables including MRRTF index, MRVBF index, wetness index, LS factor, elevation and land unit components map were the most important. The results of this study showed that the random forest learning machine for prediction of land suitability class of irrigated wheat with 0.78, and 0.71, alfalfa with 0.75 and 0.70 and potato with 0.79 and 0.72 for overall accuracy and kappa index, respectively, had a suitable accuracy.

Topography is the most important soil forming factor and is effective in distribution of land suitability class. The study area, because of limitation of soil and topography has low to non-suitable suitability to plant these crops and it is suggested proper land improvement operations to increase production and land sustainability management. Random forest learning machine had suitable accuracy for predicting land suitability class. Therefore, it is suggested to map land suitability class learning machine techniques (such as randomized forest) and auxiliary data such as terrain attributes, land unit components map and satellite images were applied.

How to manage nitrogen consumption as one of the most important nutrients and challenges of its application in farms has been noticed by researchers. Due to low soil nitrogen content in the arid and semi-arid regions, as well as the adverse environmental effects of excessive use of nitrogen fertilizers, the role of nitrogen fixing-bacteria is very important. Some research has been done about how to use nitrogen fixing-bacteria and their effects on increasing the yield of various plants. The goal of this study was to investigate the role of nitrogen fixing-bacteria application (Azotobacter and Azospirillum) on the yield and concentration of some macro-nutrients in barley cultivars.

The experiment was conducted as factorial experiment in a completely randomized block design with three replications in research field of Agriculture College and Natural Resources of Darab, Shiraz University during 2017-2018 growing season. Experimental treatments included two barley cultivars (Zehak and Nimroz) and nitrogen source at six levels including control (no fertilizer applied), Azotobacter (Azotobacter chroococcum (seed inoculation alone, Azospirillum (Azospirillum lipoferum) seed inoculation alone, combination of Azotobacter with Azospirillum, combination of Azotobacter with Azospirillum with 100 kg/ha urea nitrogen source, and use of 200 kg urea nitrogen source alone. After harvesting manually, yield and yield components and the amount of nitrogen, phosphorus and potassium nutrients of seed were measured in the laboratory and data analyzed by SAS software.

The results showed that in Nimroz cultivar inoculation of seeds with each of Azotobacter and Azospirillum along with 100 kg urea application increased plant height and spike number per square meter by 9.74 and 18 % compared to control, respectively. Also, application of Azotobacter and Azospirillum with 100 kg urea 1000-kernel weight increased 18%. Increasing of 27.27% in biomass was observed in application of two bacteria together. The combination of Azotobacter and Azospirillum with 100 kg urea increased 40% and 21.33% grain yield of Zehak and Nimroz cultivars compared to control, respectively. Combined Azotobacter and Azospirillum with 100 kg urea treatment resulted in 21.6% increase in grain nitrogen content of barley. Seed inoculation of Zehak with Azospirillum and seed inoculation of Nimrooz with Azotobacter and Azospirillum together increased 9.58% and 30% of seed phosphorus compared to control, respectively. Finally, seed inoculation of Zehak with Azospirillum and seed inoculation of Nimrooz with Azotobacter and Azospirillum increased 42.58% and 61.74% of seed potassium.

The results of the present study showed that the use of nitrogen-fixing bacteria Azotobacter and Azospirillum with 100 kg urea decreased nitrogen fertilizer demand up to 50% and increased 1000- grain weight, nitrogen content and yield of barley.

Drought stress is one of the important challenges of agricultural crop production in the arid and desert region. In order to increase yield, indrouction of drought resistance cultivars, and reduction water consumption, this experiment was conducted to recognize effects of drought stress and planting date on morphophysiological and yield of two varieteds of millet.

Materials and Methods :

The experiments were carried out as a split plots arranged in randomized complete block design with three replications in Zahak Agricultural Research Station in 2015 and 2016. The main factor included planting dates (1, 15 and 30 March and 15 April) and drought stress (50, 65 and 80% of field capacity) were in sub sub plots. Grain yield and traits of plant height, plant height, 1000 seeds weight, dry forage yield, chlorophyll, proline, day to maturity, and day to flowering were determined.

Results :

The results showed that maximum and minmun grain yield was obtained at 50 and 80 percent of filed capacity with average of 1679 and 469 kg hg-1, respectively. Grain yield, day to flowering number, day to maturing number, chlorophyle concentration, dry forage yield, 1000 seed weight, and plant height was affected by cultivars. Maximum grain yields was in Bastan cultivar (1200 kg ha-1). Grain yield, day to flowering number, day to maturing number, chlorophyle concentration, dry forage yield, 1000 seed weight, and plant height was infulunced by interaction effects of planting date, drought stress, and cultivar. Maxium grain yield (2711 kg hg-1), day to maturing (72.2 days), cholorphyle concentration (6.50 mg g-1), dry forage yield (9475.6 kg ha-1), 1000 seed weight (4.55 g ), and planting height (122.5 cm) were for Bastan culrivar in 15 March and 50 percent irrigarion.

According to the obtained results of forage and grain yield, it seems that planting at 15th March play a key role in increasing yield of millet, because of water and temperature suffiencny. The plant at this date had more contribution to transfer the produced phytotsenythetic materials to seeds. Howerver, delay in planting date resulted in late season heat stress at seed filling time and abnormality in photosynthesis to transpiration ratio which it can dercrease the transfer of photosynthetic materials to seeds. It seems that sowing of cultivar of Bastan in comparison with conventional one has resulted in highest resistant to drought stress. We can recommend as resistant cultivar of millet at 15th of March palnting date and 50 percent of field capacity For the Sistan region the relationship between farmers and extension specialists, and researcher can increase yield in drought years. Although Millet is resistant to drought, increasing the soil moisture to 80 percent of field capacity resulted in reducing chlorophyll and yield components. Sowing tin 15 March because of availability of moisture and proper temperature, has significant role in increasing yield. The millet in this date was able to transfer its photosynthetic products to grains; however, delay in sowing as result of hot weather the relative of photosynthesis to transpiration in grain filling period.

Salinity is one of the major constraints prevailing in the environment that affects not only plant growth but also agriculture productivity and soil fertility. Salinity stress causes nutritional and hormonal imbalance, ion toxicity, oxidative and osmotic stress and increase susceptibility of plant to diseases. In this regard, research has shown that salicylic acid causes resistance in plants to environmental stresses, including salinity. Nitrogen also has a direct effect on plant yield due to its significant role in plant establishment and photosynthetic and physiological abilities.

In order to investigate the effects of salicylic acid and nitrogen fertilizer application rates at different salinity levels on growth of wheat cv. Morvarid, an experiment was conducted as a split plot factorial based on a randomized complete block design with four replications in the fields of Mazraeh-E-Nemooneh located in Anbarolum, Aq Qala city, Golestan province. The main factor included three soil salinity levels (3-4 below wheat tolerance threshold (control), 9-11and 13-15 dS/m) and sub factors included two levels of salicylic acid (0 and 1.5 mM) and three levels of nitrogen fertilizer (urea) included 30% N less than soil test recommendation, N based on soil test recommendation and 30% N more than soil test recommendation, respectively. Salicylic acid was foliar applied twice at 2 weeks intervals in the tillering stage. Nitrogen treatments were applied in three stages- before planting and twice as top dressing at the tillering and stem elongation stages. Plant dry weight and height, grain yield, number of spike, number of grains per spike, thousand seed weight and spike length were measured.

The results showed that the effect of different levels of salinity on yield and its components were significant. With increasing the salinity, yield and yield components decreased (p≤0.01). However, yield and yield components increased as N fertilizer consumption increased (p≤0.01). So that the highest grain yield was in the +30% of soil test recommendation treatment (N3), which was significantly different from the other levels. Application of calicylic acid increased all parameters of yield and its components except for number of grains per spike and spike length (p≤0.01). The interactive effect of salinity and nitrogen showed that application of N fertilizer more than the soil test recommendation level up to moderate salinity level (9-11 dS/m) was increased yield and yield components but at high salinity level (13-15 dS/m) reduced these traits. Also, nitrogen application with salicylic acid improved these traits under low and moderate saline conditions, but could not have a significant effect on them at high salinity level.

Therefore, the application of salicylic acid and nitrogen fertilizer management to some extent alleviated the adverse effects of salinity up to moderate salinity levels and improved plant growth and yield by increasing plant tolerance to salinity. At high salinity condition, it is better to reduce the use of nitrogen fertilizer.