نشریه مهندسی زراعی
سال چهل و پنجم شماره 4 (زمستان 1401)

Increasing concerns about global warming and climate change have led to special attention to soil and its capability in carbon sequestration in recent years. About 540,000 hectares of soils in Golestan province are under agronomic activities and so far no studies have been conducted on soil organic carbon changes and its interactions with climate change. The total organic carbon in soils is approximately twice the amount of carbon atmosphere, so changes in soil carbon have significant effects on climate change. On the other hand, factors such as climate change or changes in land use and management affect soil organic carbon changes. As soil temperature increases, the rate of organic carbon decomposition will increase, which potentially increases the average release of soil carbon dioxide emission into the atmosphere. Therefore, finding low-cost and rapid methods for estimating soil organic carbon in large ranges and predicting its changes in the future has became a necessity.
Modeling is a tool that can be used to evaluate the feasibility of various land management techniques, and with the help of the results, the best methods can be selected and researched. In the field of soil organic carbon studies, the RothC model is one of the most widely used models, which is of great interest to researchers due to its simplicity and availability of inputs. Climatic changes are also investigated using the output of general circulation models (GCMs) under greenhouse gas emissions scenarios. These data are used after exponential microscale, in which Lars-WG statistical method has been used in this research.

The purpose of this study is to investigate the status of soil organic carbon storage in agricultural lands of Golestan province and the effect of climate change on soil organic carbon storage in the coming decades. Therefore, in order to conduct this research along the northeast_southwest of the province were selected 3 points in 3 arid climates, semi-arid and Moist climate. In selected points, soil samples were collected by digging 3 profiles and several augers and soil organic carbon, soil texture and soil apparent specific weight were measured (year 2018). The Roth C model has been used to investigate changes in soil organic carbon storage in the future. Roth C model has been used to investigate future changes in soil organic carbon storage. In order to validate the Roth C model, the results of previous studies (1997 and 2004) were used. Also, the climatic data used in this project were extracted from the statistics of 1371 to 1398 weather stations of Chat, Kalaleh and Ramyan and using the output of general circulation models (GCMs), scaled by Lars WG6 model and precipitation and temperature data were predicted of future decades.

The study of temperature changes showed that by 2040, based on scenario 4.5, the temperature will increase between 0.6 and 0.8 and based on scenario 8.5 between 0.6 and 1.3 °C. Also, by 2080, based on scenario 4.5, the temperature increase was predicted between 1.5 and 2.3 and based on scenario 8.5 between 2.2 and 3.2 °C. Climate change in different regions can reduce, increase or no change in precipitation. According to the forecast of the third report of the InterGovernmental Panel on Climate Change, precipitation will increase in winter and decrease in the summer. Based on the findings of this study, the amount of precipitation in the studied stations will increase in the future (in 2040 and 2080) based on two scenarios of 4.5 and 8.5. The results of prediction of soil organic carbon storage show that in 2040 based on scenario 4.5 the amount of soil organic carbon storage in agricultural land use will decrease between 0.5 and 5.3 tons per hectare. Also, based on scenario 8.5, the reduction of soil organic carbon storage in these lands was predicted between 0.8 and 6 tons per hectare. Based on these results, the greatest reduction in soil organic carbon storage was predicted in the humid and rainy areas of the province in 2040. According to this research, in the three investigated stations, in 2080, based on scenario 4.5, the amount of soil organic carbon storage in agricultural land use will decrease between 1.5 and 13.1 tons per hectare. However, in this year, based on MIROC5 and MPI-ESM-MR climate models in Sufian station, we will see an increasement in soil organic carbon storage between 0.6 and 3.9 tons per hectare. Also, according the scenario 8.5, in 2080, the reduction of soil organic carbon in these lands is predicted between 0.5 and 10.5. According to these results, the greatest reduction in soil organic carbon storage in 2080 was calculated in wet and rainy areas (Ramian station).

According to the obtained results, the Rothamsted model has been able to simulate the dynamics of soil organic carbon storage in the study area with appropriate accuracy. The output of the four climate models showed that future temperature changes will increase in 2040 and 2080 based on scenarios 4.5 and 8.5. these findings are consistent with the results of most climate studies that have predicted temperature enhancement in the future decades. According to the findings of the current research, the amount of precipitation in the studied stations will increase in the future (in 2040 and 2080) based on two scenarios of 4.5 and 8.5. The results of Roth C model simulations for predicting soil organic carbon storage showed that soil organic carbon storage will decrease in 2040 and 2080 in both climatic scenarios. According to these results, with increasing of temperature, the rate of decomposition of soil organic carbon increases. Increasing the rate of decomposition in agricultural land use due to the lack of surface vegetation in periods of the year causes the waste of soil organic carbon in the form of CO2 in the upper layers of the soil. Some studies have shown that low vegetation cover (agricultural compared to rangeland) areas will be severely affected by climate change and will lead to soil organic carbon waste in these areas.

Soils at the earth crust could be considered as the result of interaction among five soil-forming factors. The strength and weakness of each of these factors causes formation of different soils with different properties and horizons. Previous studies have reported that Iranian agricultural soils show different levels of zinc deficiency. Although the literature review confirms many studies in this regard, the number of studies compared the distribution of the chemical forms of micronutrients and especially zinc after the application of chemical fertilizers in the soils of Khuzestan especially in the common diagnostic horizons of these soils, is limited. Therefore, the purposes of this study were two-fold: (1) to measure and determine the chemical forms of zinc in selected diagnostic horizons (Mollic, Calcic and Salic) of Khuzestan Province, (2) to identify the contribution of some physical and chemical properties of these soils on availability of zinc.

In order to carry out this research, Mollic and Calcic diagnostic horizons were collected from the Karun 3 watershed in the east of Khuzestan province, with thermic and mesic temperature and xeric moisture regimes. However, Salic diagnostic horizon was sampled from the route between Ahvaz to Abadan in the southwest of the province, with hyperthermic temperature regime and an aridic moisture regime. After being transferred to the laboratory, the samples were first air-dried, and after passing through a 2-mm sieve and before carrying out the fractionation and speciation experiments, their physical and chemical characteristics including electrical conductivity (EC), pH, particle size distribution, organic C content, calcium carbonate equivalent, cation exchange capacity (CEC), specific surface area (SSA), and total and DTPA extractable Zn were determined employing common standard procedures (Table 2). Different forms of zinc in the solid phase of the Mollic, Calcic, and Salic soils were extracted using the method described by Tessier et al. (1979). In brief, 5 components including water soluble, exchangeable, carbonates, iron and manganese oxide, organic and residual forms were determined. The concentration of zinc in the extracts obtained from different stages of successive soil extraction was determined using an atomic absorption device. In order to estimate the accuracy of the extraction method described above, the recovery percentage was calculated. To do this, one gram of a certified soil from the state of Montana (ANIST 2711A) was used and the recovery percentage of zinc in our study was 94.5%. In order to determine the chemical forms of zinc in the solution phase of the soils, 100 g of each soil sample was saturated with double distilled water, and then extracted using a vacuum pump and Buchner funnel. The extracts were passed through filter paper and centrifuged at 2500 rpm for 8 minutes, then the values of pH, electrical conductivity, dissolved organic carbon, and dissolved cations and were determined using common laboratory methods described earlier (Table 1). These parameters were considered as input in Visual MINTEQ software to predict zinc species in soil solution (all free and complexed organic and mineral species). The data analysis was conducted considering a factorial design based on a completely randomized design through SAS software (v9.1). The comparison of means was also done using the Tukey’s test at the 5% probability level. Graphs were also drawn using Origin software (v2018).

Considering the critical level of zinc deficiency in the soil (1 mg/kg), all the soils are deficient in terms of available zinc. The studied soils are among alkaline and calcareous soils, but they did not show any differences from each other in terms of soil texture. It is noteworthy that the mollic horizon has a greater cation exchange capacity and specific surface area than the other two soils due to the higher amount of organic matter and the greater abundance of clay contents. The results of zinc fractionation in the studied soils showed that organic, carbonate and oxide forms in the Mollic and Calcic horizons, and carbonate, oxide and exchangable forms in the Salic horizon were the dominant forms of Zn which affects its supply to the plants. The results also showed that Zn2+, Zn(OH)2(aq), Zn-DOM (aq), and Zn (OH)+ species were the dominant species of Zn in soil solution of all diagnostic horizons. The result of Zn mobility factor calculations with the addition of 10 mg/kg Zn(SO4)2 showed lower values of mobility factor in the mollic diagnostic horizon than those of the calcic and salic.

Spatial and temporal variations of soil characteristics occur in large and small scales. Investigating the variability of soil parameters is considered as one of the requirements for proper management of fertilizer resources in a sustainable agricultural system. Studying of these variation is very time-consuming and costly especially in large scales. In order to the fast and reliable determination of the soil properties, various interpolation techniques have been developed and applied. The most widely used interpolation technique is the different Kriging types. The copula function is one of the new interpolation techniques that are recently used in sciences such as hydrology. Thus, the aim of this research was to evaluate the spatial variation of some soil chemical properties using the copula function and comparisons with geostatistics techniques.

Sampling by regular networking was done in an area of 484 ha located in 10 km far from the west of Baft city, located in Kerman province, central Iran (latitude of 29° 15′ N and longitude of 56° 29′ E). In the studied area, three agricultural, pasture and industrial sites are located nearby. The common crops of the region are wheat, barley, alfalfa, legumes and orchards of walnuts, pomegranates, almonds and grapes. The average height of the studied area is 2270 meters above sea level, the average annual temperature of the area is 16 degrees Celsius, and the average annual precipitation of the area is 247 mm. The soil used for the experiment was collected from 0 to 20 cm depth of the field. 121 soil samples were air-dried and, some physical and chemical properties were measured. In order to fit the Copula function to the data, first the appropriate marginal distribution function should be fitted to the data. For this purpose, three tests were used: Kolmogorov-Smirnov, Anderson-Darling and Chi-Square. The mentioned tests were carried out in the EasyFit 5.5 statistical software. By fitting the best marginal distribution function, the cumulative value of the marginal distribution function is calculated for each data. After calculating the above values, detailed functions can be fitted to the data. Finally, the accuracy of each interpolation method was evaluated according to the root mean square Error (RMSE), coefficient of determination (R2), mean absolute error (MAE) and mean biass error (MBE) indices.

In all types of geostatistical methods, the first step in interpolation is to fit the semivaiogram to the measured data, so after normalizing the data and validating the models, the appropriate model was selected for fitting the semivaiogram. Among the measured parameters, Pava and Kava semivaiogram followed spherical model and the interpolation of the above variables was done on the basis of this model. Copula analysis showed that the available phosphorous and potassium variables followed from the Wakeby and gamma distribution function, respectively. Also, based on the Pearson correlation coefficient, the correlation between pairs of points was less than 2000 m and the distance more than 2000 m was known as an independent distance. Based on the validation criteria for Pava parameter, Median copula function, Average copula function, IDW, Ordinary Kriging, Disjunctive Kriging, Universal Kriging and Simple Kriging have better estimates, respectively, and in the same way, the best interpolator for Kava parameter Median copula function, Average copula function, Ordinary Kriging, Universal Kriging, Disjunctive Kriging, Simple Kriging and IDW were determined, respectively. The estimation performance based on the coefficient of determination (R2) showed that value of this coefficient for copula function for available phosphorous and potassium were 5% and 4% greater than conventional geostatistics techniques. Also, the error of estimation was less for copula function indicating the better performance of copula to estimate the mentioned soil properties

This study was performed to investigate the Feasibility study of Copula function in predicting some soil nutrients and comprising this method with widely used methods of geostatistics. Our results demonstrated that the copula function method is more capable than the classical geostatistical methods in estimating soil properties due to the non-dependence of this method on the normality of the data distribution and outlier data. Therefore, with the help of this method, having a reliable and high-quality data bank of soil characteristics, acceptable maps of other soil characteristics can be presented at various scales.

Nitrogen (N), an essential nutrient for growth and development of plants, is added to agricultural fields to boost crop yields. Major concern in modern agriculture to account for maximum nutrient use efficiency, improve the soil fertility and prevent groundwater pollution. Environmental and economic challenges due to nitrogen application in agricultural have increased regard to nitrogen use efficiency (NUE). Improving the nitrogen use efficiency, which is the fraction of the applied fertilizer nitrogen taken up by a plant for its physiological and growth purposes, is one of the strategies for reducing N loss in agriculture. With the continued escalating costs of inorganic fertilizers, NUE in field crops should be enhanced to reduce production costs. Therefore, it is essential that appropriate N fertilizer management practices are adopted to optimize the use of applied N in cropping systems. NUE and better plant growth are related to soil’s physico-chemical traits. In this context, the application of soil amendments, such as zeolie, has great importance for the reclamation of soil properties and improve plant growth. Natural zeolites are naturally occurring, hydrated aluminosilicates with and being considered as good soil amendment for minimizes N losses and increase NUE. Therefore the objective of this study was investigating the effect of different levels of clinoptilolite zeolite and nitrogen fertilizer on the efficiency of nitrogen use, growth and yield of maize (Zea mays L.) in field conditions.

This study carried out in field condition as a split-plot arrangement based on randomized complete blocks and in three replications, at the University of Kurdistan research farm in Dehgolan. The experimental treatments include the application of clinoptilolite zeolite at four levels (0, 5, 10 and 15 ton ha-1) as the main plot and the application of nitrogen at five levels (0, 50, 100, 150 and 200 kg N ha-1) as the sub-plot. Urea fertilizer was used to supply the required nitrogen.
Maize cultivation (KSC 260 cultivar) was done in 2021. At the end of cultivation season, harvest was done from each plot, and some plant growth traits (leaf area, cob length and cob diameter), leaf N concentration, yield components (grain number in cob, raw number in cob and grain weight in cob), and grain yield were measured. In addition, the NUE was calculated. In order to investigate the effect of zeolite on soil nitrogen status, soil samples were collected from plots after harvest, and cation exchange capacity (CEC), and total soil nitrogen (TN) were measured. Analysis of variance (ANOVA) was performed using SAS program version 9.4 (SAS Institute, Cary, NC). Significant differences of the mean values (P <0 .05 for F-test) were determined by Duncans’s Multiple Range test.

The results showed that as a result of the application of 10 and 15 ton zeolite ha-1, the soil cation exchange capacity the soil total nitrogen concentration, leaf nitrogen concentration, leaf area index ,cob length, grain yield and nitrogen use efficiency increased significantly. The results showed that the highest leaf N concentration, plant growth indices, grain yield and yield omponents was observed in the treatments of co-application of 150 and 200 kg N ha-1 with 10 and 15 ton ha-1 of zeolite. There was no significant difference between the grain yields in these treatments. The results also indicated that Moreover, nitrogen use efficiency decreased with increasing nitrogen application levels. The nitrogen use efficiency (NUE) in the 150 kg N ha-1 treatment was significantly higher than 200 kg N ha-1 treatment. The results demonstrated that there was no significant difference between two nitrogen fertilizer levels (150 and 200 kg N ha-1) positive effects on grain yield. The improved maize growth and enhanced grain yield induced by zeolite amendment were related to the increase in soil CEC, soil N status, N uptake in plant, as well as probably improved soil nutrient availability and physicochemical propertis. Leaf N concentration (56.6), leaf area index (56.5%), cob length (21.5%), leaf nitrogen concentration (56.6%), grain weight in cob (61.8%), grain number in cob (41.6%) and grain yield (38.6%) in the plant were significantly higher than control treatment.

It could be concluded that application of potassium sulfate fertilizer results In general, it can be concluded that the combined use of zeolite (at the level of 10 ton ha-1) and nitrogen (150 kg ha-1) can be a suitable solution for improving corn yield and increasing the nitrogen use efficiency (NUE).

Hydrocarbons derived from petroleum and gas have gained increased attention as the most important fossil resources of energy as well as crude material for petrochemical industries. However, environmental issues such as pollution due to extraction, exploitation and transportation of these materials has raised concerns as an environmental warning. In recent years, utilization of biochar (via biomass burning) has been regarded as a soil refiner to reduce or eliminate pollution, especially in in situ studies. Biochar is a product rich in carbon, which is produced during the pyrolysis of various types of woods, fertilizers, leaves, straws as well as agricultural wastes under abiotic conditions. It seems that biochar can be suggested as a suitable compound to manage biomass wastes as well as to enhance soil fertility. Thus, kinetic behavior of biochar in reduction of gasoil pollution of soil, its changes of this pollutant over time and changes in the microbial activity in this time period were investigated.

The soil polluted with gasoil was collected from the vicinity of the gasoil tanker located in Shiraz refinery. The soil had been polluted for years due to the leakage of gasoil. Then, after the measurement of the initial total petroleum hydrocarbon content and physical and chemical properties (soil texture via hydrometry, electrical conductivity in the saturated paste, available phosphorous using the Olsen method, total nitrogen using the Kjehdahl method, pH of soil in the saturated paste, soil carbon using the Walkey and Black method) of the polluted soil, 700 gram soil samples containing wheat straw biochar at one and two mm sizes and 20, 40, 60, 80 and 100 g kg-1 weight doses were prepared as split-split-plot experiment based on a completely randomized design with three replicates. The samples were then rested in a 50% constant humidity for four weeks at 28 ± 2 °C, and were aerated two times a week. Finally, the results of the changes in the total petroleum hydrocarbon and microbial activity over time were recorded. A three- parameter sigmoidal function was fitted to the data related to the total petroleum hydrocarbon and microbial activity over time. Analysis of variance was carried out using the SAS software v. 9.0. The leas significant difference method (LSD) was used to compare the means. The changes in the total petroleum hydrocarbons and microbial activity were analyzed using the SigmaPlot software v. 12.5. Microsoft Excel v. 2013 and SigmaPlot v. 12.5 were used to draw the figures.

According to the results of the present study, the application of biochar had a significant effect on the reduction of gasoil pollution of the soil. The results related to determination of the kinetic model for the reduction of pollution during the biochar application process showed that the kinetic of reduction in total petroleum hydrocarbon was of first order equation; so that in the first 28 days of the experiment, the rate of total petroleum hydrocarbon degradation was increasing, whereas it decreased 35 days after the beginning of the experiment. Biodegradation constant (k) was higher for the soil treated with the refiner and these soils had a lower half-life compared with the polluted control. The rate of reduction in half-life and Biodegradation constant rate increased with increasing refiner weight. On the contrary, half-life increased and Biodegradation constant decreased with increasing refiner size. The results indicated a significant difference in the traits as a result of applying various sizes and weights of refiner. Weekly monitoring of the pollution degradation and bioremediation performance in all refiner sizes and weights showed that the lowest time to 50% pollutant removal was obtained in 100g kg-1 and 1 mm size treatment. Investigation of the respiration under the mentioned conditions showed that the lower sizes and higher weights of biochar led to improved hydrocarbon degradation. Also, according to the results, biological efficiency (E%) of biochar was calculated 40.05 at the end of the 60 day period.

According to the present study, biochar refiner has a great potential for utilization as a cheap and relatively new strategy to eradicate or reduce soil hydrocarbon pollution. This method is compatible with the in situ bioremediation in the soils polluted with petroleum and other petroleum derivate compounds, due to being less costly and posing less hydrocarbon threat to the environment. It is also a suitable tool to devise bioremediation strategies.

The decrease in yield and quality levels of button mushrooms during the cultivation period is one of the important challenges of the mushroom production industry, due to the reduction of substrate nutrients and the accumulation of undesirable compounds. One of the solutions to prevent the decrease in yield and qualitative characteristics of edible mushrooms during different flushes is to enrich compost with nutrient supplements.

In order to investigate the effect of supplementary nutrition at different times on the yield indicators of button mushroom, a factorial experiment based on completely randomized design was conducted. Experimental treatments included four concentrations (C) of supplementary nutrition (0 (C1), 20 (C2), 40 (C3) and 60 (C4) g/L) (combination of two phases, the liquid phase includes micro and macro elements and amino acids, and the solid phase includes sucrose and dextrin) and two application times (one day after harvesting the first flush (T1) and the beginning of the second flush and the formation of pin (T2).

The findings of this research indicated the highest number of button mushroom was observed in C3T2 treatment by 215.89, which demonstrated a 20.35% increase compared to C1T2 treatment. The lowest single mushroom weight was measured in the first time of foliar spraying in C1T1 treatment and the highest single mushroom weight was obtained in the second time of foliar spraying in C3T2 and C2T2 treatments, respectively. The maximum length of the mushroom base was obtained in C2T2 treatment by 1.36 cm. Along with the increase in the concentration of nutritional solutions; the diameter of the cap showed a significant increase at T1 time, while at T2 time, this value showed a decreasing trend after the treatment of 20 g/L of nutrient solution. In addition, no significant difference was observed between the cap diameter of mushrooms treated with 20 and 40 g/L in treatments of C2T2 and C3T2, and the maximum cap diameter of mushrooms in these treatments was 3.73 and 3.67 cm, respectively. Enrichment of button mushroom compost by nutritional supplements can prevent severe yield reduction during different flushes.
The number of mushrooms produced in two different times was not significant. It showed that the effect of using time of supplemental nutrition was more effective on the rapid growth of the formed pins than growth of new pins. The formation of pins and the number of mushrooms were under the influence of the amount of inoculation and used spawn in the compost. The positive results obtained from the foliar application of the nutrients showed that its compounds, including sucrose and dextrose and highly consumed elements such as nitrogen, phosphorus, potassium and amino acids, have played an important role on the number, single weight of mushrooms and the cap diameter of mushroom.
The use of nutrient solution in C3T2 treatment compared to C1T2 increased nitrogen percentage by 66.43%, protein by 66.22%, tissue firmness by 71.44% and biological efficiency of substrate by 66.32%, respectively. Pervious study showed that, the effect of different concentrations of three amino acids asparagine, glutamine and glycine on some quality indicators and performance components of white button mushroom was investigated and the results indicated that asparagine 150 ppm improved the yield and increased the protein content. High NPK content in mushroom substrates significantly shortens the rate of mycelium propagation and increases oyster mushroom growth. One of the basic criteria for a good mushroom substrate is the carbohydrate and nitrogen content to support mushroom growth.
Also, using a concentration of 40 g/L of nutrient solution at the time of emergence of the second pin, in comparison with C1T2 treatment, increased the yield of the second flush by 64.15%, the yield of the third flush by 71.17%, the yield of all flushes by 26.79% and the total yield of composted by 26.76%, respectively. Carbon, with its structural role and presence in most organic compounds and providing energy for metabolic reactions, plays a significant role in the growth of button mushrooms. On the other hand, button mushrooms are able to use amino acids as a source of nitrogen. Therefore, it seems that the use of the above compounds in the nutrient solution used in this research has been able to produce favorable results both quantitatively and qualitatively in the studied button mushrooms. On the other hand, it seems that the presence of widely used elements such as phosphorus and potassium in the nutrients used in this research and the positive role of these elements in the production of nucleic acid, adenosine triphosphate, membrane phospholipids and enzyme reactions has been able to play a key role in increasing the quantitative and qualitative properties of button mushrooms.

The use of 40 g/L concentration of nutritional supplement at the time of the appearance of the second flush by affecting the percentage of dry matter, protein and tissue firmness increased the quality level of button mushrooms and enhanced quantitative level by improving yield indicators such as the number of mushrooms, single weight of mushroom, total yield of flushes and percentage of total yield of compost.