behnam kamkar

Today, the DeNitrification DeComposition (DNDC) is model used to anticipate soil organic carbon (SOC) turnover and crop growth under various field management practices. Gorgan County is an important region for soybean production in Iran.  We aimed to 1) validate the DNDC model for modeling SOC dynamic in croplands under soybean cropping, 2) simulate the total topsoil (0–30 cm) SOC stocks of soybean cropping systems, 3) quantify the spatial distributions of carbon sequestration potential of soybean-grown croplands by Geographic Information System (GIS) techniques. In this research, soil samples were taken from 150 fields at depth of 0–30 cm before soybean cultivation and after crop harvesting. In this research, we used the site simulation type of DNDC model for simulation and denitrification/decomposition procedure. Inputs in the DNDC model included information on survey region, climate, soil, crop properties, and farmland management practices. The soil and crop properties categorized into farming management practices such as fertilization, tillage, grazing or plant cutting, and irrigation. The climatic data were obtained from one meteorological station located within the study area. To continue, crop parameters were provided based on field survey and laboratory work. Also, the soil properties (including texture, bulk density, pH, SOC, soil total N, field capacity, wilting point, hydro-conductivity point, porosity and clay fraction) were obtained from sampling sites distributed in soybean croplands of Gorgan county. Results indicated that the DNDC model can simulate the SOC values for soybean fields. Based on the results, there was correlation between the simulated and measured data for SOC. The average concentration and storage of carbon sequestration were as 3.97 and 1.42 Mg ha-1 for observed situation and in predicted situations obtained as 2.60, and 1.42 Mg ha-1, respectively. The highest content of SOC was related to the east, southeast, and central parts toward the south of the county, which was affected by several factors such as soil bulk density, regional climatic condition, using conservation cropping systems, improved irrigation systems, and fertilization management type. The study provided new information on how improvements in the process-based DNDC model in Iran. Therefore, it can be utilized to determine SOC change and dynamism and carbon sequestration potential on the regional scale.

This study was performed to investigate the effect of nitrogen fertilizer levels and pre-planting of cover crops on some vegetative traits and yield of rice plants.

This was conducted over 2017-2018 and 2018-2019, at the research farm of Sari University of Agricultural Sciences and Natural Resources. The experimental design employed a three-replicated split-plot arrangement within a randomized complete block design. The main plots involved five nitrogen consumption levels (0, 120, 240, 320, and 400 kg ha-1). The sub-plots included four types of pre-planted cover crops (no cover crop, canola, bersim clover, and rye).

Based on the findings, employing berseem clover as a cover crop in pre-sowing resulted in a significantly more favorable rice yield than others. Nitrogen fertilizer at rates of 320- 400 kg ha-1 led to enhanced vegetative traits, yield, and various yield components, including leaf area index and tiller number, ultimately resulting in increased overall yield. Results revealed that planting bersim clover cover crop before planting rice, along with 320 kg ha-1 of urea fertilizer, leads to 41.5% higher yield compared to no fertilizer).).

Bersim clover stood out among the pre-planting cover crops, significantly enhancing many rice traits. Additionally, no significant difference was observed between urea fertilizer levels of 320 and 400 kg ha-1 in several measured traits. Thus, the integrated treatment of bersim clover cover crop and 320 kg ha-1 of urea fertilizer is recommended before planting rice.

The organic carbon in soil is correlated with soil quality and important for evaluating management practices and related structural and functional consequences in land uses. Carbon input to different ecosystems varies with plant type, soil fertility, management practice, and climatic condition. This review evaluates carbon sequestration potentials in various land uses, land use change effects on carbon sequestration and ways to increase the carbon sequestration in these land uses. According to various studies, the protected forest ecosystems and cereal croplands had respectively the highest and lowest carbon sequestration rates compared to other ecosystems. In most of the reviewed cases, land use change reduces vegetation cover and prevents the maintenance of the organic matter in the soil. Heavy soil destruction is based on the alteration of natural ecosystems into agroecosystems and urban land uses. In contrast, forests supply 20 to 100 times more carbon than croplands. Soil organic carbon content in agricultural lands is approximately 15 to 30% lower than natural soils. Finally, it could be concluded that management practices and policy could strongly influence the carbon sequestration process. On the other hand, in all land uses, carbon sequestration potential can be increased by appropriate management activities. Thus, more attention to carbon sequestration for sustainability development and reasonable management is essential in landscape planning and policy support actions.

The germination process is one of the most critical stages of a plant's growth and determines the success of the emergence of a weed in an agroecosystem because it is the first stage in which the weed competes for a niche. Various environmental factors, including temperature and moisture, affect the germination of weed seeds. Modeling techniques are capable of predicting germination, seedling emergence, and establishment of weed species. The ability to predict weed germination in response to environmental conditions is very effective for the development of control programs. The experiment was conducted to determine the cardinal temperature and evaluate the best model for quantifying the response of the germination rate of Western ragweed weed seeds under different water stress conditions.

A factorial experiment was conducted in the form of a completely randomized design in three replications. The investigated factors include temperature with eight levels (5, 10, 15, 20, 25, 30, 35, and 40 C˚) and water potential with six levels (0, -0.3, -0.6, -0.9, -1.2, and -1.5 MPa) on the germination of Western ragweed. In order to quantify the response of Western ragweed germination rate to temperature, three non-linear Dent-like, Beta, and Segmented regression models were used.

The results showed that the effect of temperature, water potential, and their interactions on maximum germination, germination rate, and time required to reach 10, 50, and 90 percent germination were significant. Also, the results showed that by increasing the temperature from 10 to 25 C˚, the percentage and rate of germination increased whereas by increasing water potential, the percentage and rate of germination decreased. In comparing the models, based on RMSE, R2, CV, and coefficients a and b parameters, the Beta model was the most suitable for estimating the temperatures of cardinal Western ragweed. The base, optimum, and ceiling temperatures using the Beta model were 3.88, 25, and 40 C˚, respectively.

The use of the Beta model to quantify the germination response of Western ragweed seeds to different levels of water potential at different temperatures had acceptable results. Therefore, by using the output of these models at different temperatures, it is possible to predict the germination rate at different potentials.

  Intensification of agriculture along with increasing use of chemical pesticides can have significant environmental effects on other non-target organisms as well as various environments such as air, soil and water. Increasing concerns about the negative effects of pesticide resulted some indicators that measure the environmental risk of each pesticide. One of these indicators is the Environmental Impact Quotient (EIQ), which has been used repeatedly to monitor environmental pesticides in a wide range of agricultural and horticultural fields. The purpose of this study is to investigate the environmental effects of pesticides used in wheat fields in Bandar-e-Turkeman county in 2019-2020 year.

To implement the model, information about the name, amount of consumption and times of application of pesticides used by farmers were collected in the form of questionnaires and face-to-face interviews with 59 farmers. The Environmental Impact Quotient (EIQ) of these pesticides was extracted from version 2021 of the Integrated Pest Management (IPM) site. The environmental effect of used pesticides in each wheat field was obtained from the sum of EIQ of pesticides in the amount of consumption and dose of pesticides per hectare. The calculations of this model were done in Excel version 2013.

The result showed that the final EIQ score for all toxins had the highest impact on the ecological section. Imidacloprid (92.88), Carbendazim (86.00), Acetamiprid (71.95), Cyproconazole (67.00) and Deltamethrin (65.15) had the highest toxicity for the ecological section, respectively. Based on the results, Carbendazim was introduced as the most dangerous and the insecticides Acetamiprid and Imidacloprid were the least dangerous toxin for the farm workers. Calculation of environmental impact of pesticides per hectare showed that there was a high numerical variation among surveyed fields. So that the lowest of index related to fields No. 25, 55 and 42 they had about 6.31, 7.01 and 7.02 environmental impact, respectively. In these fields, no pesticides were used during the wheat growing period and only at the time of planting, carboxin fungicide was used for seeds at the rate of 0.45 and 0.50 kg/ha. The fields No. 40, 10, 30 and 35 recorded with EIQ-FUR equal to 41.49, 33.20, 31.20, 30.85 and 30.67, respectively. In these fields, we were observed the highest environmental impact per hectare. In continue, the distribution map of this index in studied fields was produced. The results showed that there is a different variety in terms of pesticide application in fields, therefore target points can be determine to farmers for reduce of pesticide application and field with high environmental impact.

Among the three components of the EIQ index, including risk to farm workers, consumers, and ecology, the numerical values of these three components can vary depending on location. The current values of this index do not take into account differences in the technology of application or use of personal protective equipment. It can be concluded that the EIQ model requires changes in the direction of localization with the study areas, including the number of farm workers, specifying the type of tools and equipment used and separating the type of developed or developing countries. In general, in these fields, the management of pest, the identification and management of weeds diversity can be effective in controlling the amount of pesticide consumption and reduce environmental risks.

We would like to thank Gorgan University of Agricultural Sciences and Natural Resources, wheat farmers and agricultural Jihad management of Bandar-e-Turkeman county for their cooperation in conducting this research.

In recent years, the heightened concentration of greenhouse gases has brought increased attention to the pressing issue of climate change. Therefore, monitoring climatic variables to prevent the adverse effects of climate change is more important than ever. In the pursuit of long-term climatic forecasting and the assessment of their evolving patterns, various international scientific societies have concentrated their efforts on understanding the extent of climate change and devising measures to counter its adverse effects. The development of general circulation models of the atmosphere (GCM) has been a significant stride in this direction. However, GCMs may lack precision in predicting minor changes at a local scale. To address this limitation, the utilization of downscaling models such as SDSM and Lars_WG (that were used here) becomes imperative. These models serve as essential tools for simulating the viability of cultivating agricultural species in the future, especially when considering localized impacts. Because climate change will probably change the conditions for growing canola, as one of the strategic and prominent crops in Iran, studying the effects of this worldwide event on the canola-grown fields in the future is needed. 

In this research, using temperature and precipitation forecasting models along with GIS functions and hierarchical analysis process (AHP), canola suitability classes for 2050 were determined in Mazandaran Province. For this, 37 meteorological and synoptic stations were involved, and climatic data (including temperatures and precipitation) were generated under three RCP scenarios (2.6, 4.5, 8.5). In this study, we utilized two general circulation models (Can-ESM2 and HadGEM2-ES) that had been recommended for application in the study area.

A comparison of the involved models showed that the SDSM model was superior in predicting temperature, while the Lars-WG model performed better in predicting precipitation. The results for the land suitability revealed that the changes in climatic variables in the future would lead to changing the suitability of agricultural lands for growing canola. The examination of temperature change maps in the investigated region revealed that both minimum and maximum temperature variables are poised to rise under climate change scenarios, with a more pronounced increase anticipated in maximum temperatures. The findings indicate that the projected temperature increase in the future will establish more conducive conditions for canola cultivation. Additionally, precipitation patterns exhibit an increase in both RCP 2.6 and 4 scenarios, with a more substantial rise in the RCP 2.6 scenario. Conversely, the RCP 8.5 scenario predicts a decline in precipitation levels. Top of Form
Also, considering the climate change scenarios, the spatial distribution and the area of each suitability class changed slightly, so the high-suitable class will extend under RCP2.6, especially toward the center parts of the study area. Under RCP 8.5 and RCP 4.5 scenarios, not only suitable lands were not considerable, but also the less suitable land extended to the southern and western parts of the study area.

The output of the land suitability maps showed that climate change would change the suitability of the studied agricultural lands in the future. Also, with the implementation of the climate change scenarios, the area and geographical distribution of detected classes will change. In general, in the optimistic scenario, the lands will be more appropriate for canola cultivation and will cover a wider area. In other scenarios, the conditions for canola cultivation in the lands of Mazandaran will be more unsuitable compared to the present, and the decrease in the level of suitability will be more evident in the western and southern lands of the province. Therefore, solutions such as the use of more compatible cultivars and changes in agricultural management in facing new conditions in these areas should be considered. The outcomes of these studies offer practical insights for shaping regional planting strategies, aiding decisions on crop inclusion or exclusion, and informing the overall design of agricultural patterns in the area

Ecosystem services are defined as services provided by the natural environment. These services produce outputs or effects that directly and indirectly impact human well-being, culture, and the global economic system (Feng et al., 2018; Ma et al., 2020). Quantifying the services of agroecosystems is one of the most important strategies to increase attention to these services and provide appropriate solutions to maintain and sustain these services. The development of intensive agriculture has transformed agricultural landscapes into simple, low-coverage single-product systems similar to semi-natural habitats. This change has led to a sharp decline in biodiversity and a reduction in the provision of ecosystem services to agriculture. It has been confirmed that among ecosystem services, pest, and weed control, and pollination have significant impacts on global agricultural production.

In this study, 8 plots were selected from different plots of autumn crops included barley, and triticale. In this study provisioning, supporting, regulating services in the cultivation of barley and triticale fields of Dasht-e Naz, Sari Agricultural Company (Mazandaran province) were evaluated and quantified, during 2019-2020. In this study, some ecosystem services such as insect and weed biodiversity (using Shannon-Weiner, Simpson, Margalf, Uniformity and Menhinick indices), soil microbial respiration, carbon sequestration, organic matter, abundance of earthworms, grain yield, protein content oxygen production, and soil protection (by the stability of aggregates) were evaluated and quantified. Soil samples were taken from a depth of 0-30 cm before barley and triticale planting in November 2019 and after harvest in June 2020 for assessment of rate of microbial respiration, organic matter and carbon sequestration. Also, oxygen production was estimated based on net primary production. A sampling of plant biodiversity and yield of autumn crops was performed based on the W shaped pattern with 0.5×0.5 m2 quadrate. In this study, insects were collected in ways: yellow sticky trap, insect nets, and ground trap. Sampling was done from late March to mid-April 2020. All data were analyzed with SAS version 9.4 and T-test was used to compare the means between cultivars at the 5% probability level.

The results showed that the highest amount of oxygen production was obtained at about 17.66 and 16.57 tons per hectare from 12 and 16 fodder plots for barley and triticale, respectively. In this research, the highest amount of carbon sequestration (2.67 tons per hectare) and the activity of microbial respiration before planting and after harvesting the crop were 91.40 and 45.95 milligrams of CO2 per kilogram of soil per day, respectively andearthworm abundance (13 per square meter) belonged to plot 18. The evaluation of the biodiversity status in insects and weeds showed that the highest Shannon-Weiner diversity index in weeds was 2.65 and 2.89 from plots 12 and 16 of barley and triticale fodder, respectively. Also, in 12 plots of barley and 16 plots of triticale, because the purpose of farming was to produce fodder, herbicides were not used compared to other plots. In another study, it was observed that the highest Shannon-Weiner diversity index was obtained from triticale farms (1.00) and the lowest (0.14) from winter wheat farms(Sawicka et al., 2020). This could increase the Shannon-Weiner index. Also, the Shannon-Weiner index of insect communities was calculated as 2.37 and 2.49 from 19 and 16 plots, for barley and triticale, respectively.4 beneficial insects named Syrphus ribesii, Chrysoperla carnea, Coccinella septempunctata Linnaeus and Apis ellifera mellificawere recorded in the barley and triticale plots studied.

The results of this study showed that crop management and implementation of intensive agricultural systems were effective in providing many ecosystem services of barley and triticale fields. So, these services were affected by various factors, such as cultivar type, crop rotation, and tillage methods. In general, intensive agriculture is associated with climate change and biodiversity loss and alternatively, the reduction of ecosystem services including regulating and provisioning services is inevitable. Therefore, adopting management of agroecosystems associated with natural ecosystems can help to provide more ecosystem services in agroecosystems and maintain their sustainability level.Acknowledgements:We are thankful to Gorgan University of Agricultural Sciences and Natural Resources (GUASNR), the agricultural company of Dasht-e-Naz Sari and Dr. Hamid Sakinin for all his companions and supports.

This research was conducted to study of diversity and weed population structure of wheat agroecosystems of Bandar-e-Torkeman county in 2018-2019 year. Diversity indices such as Shannon-Wiener and Simpson for fields and frequency, relative frequency, relative uniformity and relative density indices for all weed species were calculated and measured in two time stages, before and after chemical treatment with herbicides. Obtained data from diversity indices were moved in the GIS media and weed species maps of wheat fields were prepared. In this study, we were identified 18 species from 9 plant families. The checking of plant species showed that 66.67% and 33.33% were belonged to annual and perennial, also, about 27.77% and 72.23% were narrow-leaved and broad-leaved, respectively. Gramineae species include Avena ludoviciana, Lolium temulentum, Phalaris minor, Alopecurus myosuroides and Polygon monspeliensis, Fabaceae species include Medicago scutellata, Polygonom avicular, Vicia villosa and Oxalis corniculata and Compositea species such as Helianthus annuus and Cirsium arvense, had about 27.77, 22.22 and 11.11 percent of the available plant species, that were recognized as the most important plant families in wheat fields of county, respectively. In this study, weed distribution maps in wheat fields of the county before and after chemical control were prepared in three frequency groups of 50-100, 30-50 and less than 30% and showed an almost uniform distribution of weeds in surveyed region.

Sustainability in agriculture at regional scale is about balancing food security with maintaining environmental health. Therefore, agricultural operations are sustainable when they maintain the health of the environment, the interaction between plant and animal production, social acceptance and economic benefits (Kumaraswamy, 2012). Excessive use of environmental resources and excessive consumption of chemicals in agriculture have caused environmental problems and reduced sustainability (Quintero-Angel & Gonzales-Acevedo, 2018). Therefore, it is necessary to study the patterns of energy consumption and efficient use of energy in agriculture, which is one of the basic principles in sustainable agriculture. Emergy analysis, as suitable tool for this purpose, is used in the various ecosystems (Odum, 2000; Brown & Ulgiati, 2004). Emergy analysis is able to determine the degree of sustainability of connected ecological and economic systems. Emergy indices are effective tools for integrating ecological-economic systems and make it possible to measure and compare all aspects of these ecosystems (Patterson et al., 2017). The purpose of this study was to evaluate sustainability indices for rapeseed (Brassica napus L.) production systems using emergy indices and provide suggestions for sustainable product of the crop in Kalaleh county. 

In this study, production systems of rapeseed were evaluated using emergy sustainability indices in Kalaleh County (Golestan province), during the period of 2018-2019. For this purpose, 50 rapeseed fields were selected as Cochran equation. First, the spatial and temporal boundaries of the system were defined (Odum, 1996; Odum, 2000) and resources were divided into four categories: renewable environmental resources, nonrenewable environmental resources, purchased renewable resources and purchased nonrenewable resources (Amiri et al., 2019). Emergy flow for each input was multiplied by their transformities in joules and grammes (Odum, 2000). Finally, emergy indices such as renewability, emergy yield ratio, emergy self-support ratio, environmental loading ratio and emergy sustainability index were calculated and evaluated in rapeseed production systems. 

Total emergy input for the rapeseed production was estimated as 1.64E+16 sej ha-1 year-1. In rapeseed production, dependence on environmental and nonrenewable inputs was higher than purchased and renewable inputs. Soil erosion emergy was the largest emergy inputs of the total in rapeseed production system with share of 47.31%. Also, fossil fuel emergy was the largest emergy inputs of the purchased with share of 38.41%. In this research, we calculated the transformity equal to 2.59E+05 sej j-1, specific emergy equal to 7.33E+09 sej g-1, emergy renewability equal to 8.16%, emergy yield ratio equal to 2.17 and emergy investment ratio equal to 0.85. Also, emergy self-support ratio, standard environmental loading ratio, modified environmental loading ratio, standard emergy sustainability index, and modified emergy sustainability index were estimated 0.54, 13.81, 11.27, 0.16 and 0.19, respectively. Despite the higher contribution of environmental resources in the rapeseed production system, the high share of soil erosion as a non-renewable input along with the unreasonable consumption of some nonrenewable purchased inputs, such as fossil fuels, led to a decrease in renewability and an increase in environmental load. Based on evaluation of emergy indices, rapeseed ecosystem had the high production efficiency and resource consumption efficiency and it had the great potential to increase economic productivity. However, rapeseed production in Kalaleh county had low environmental and economic sustainability. The implementation of conservation tillage methods and the modernization of machinery can contribute to a reduction in the consumption of nonrenewable and economic inputs in rapeseed production ecosystems. This reduction in input consumption not only alleviates environmental pressure but also enhances sustainability. By prioritizing the use of renewable environmental inputs and minimizing the utilization of nonrenewable and economic inputs, the emergy sustainability index can be improved.

The rapeseed ecosystems exhibited high production efficiency and resource consumption efficiency, along with significant potential for increasing economic productivity. However, despite the substantial contribution of environmental resources in these systems, the prevalence of soil erosion as a significant portion of the total emergy input resulted in a decline in renewability, an escalation in environmental burden, and ultimately a decrease in sustainability. It appears that enhancing management methods to minimize the consumption of nonrenewable and economic resources would be effective in bolstering the environmental and economic sustainability of rapeseed farming ecosystems in Kalaleh county.

Ecosystem services are usually divided into four categories: (a) provision services, (b) regulating services, (C) cultural services and (d) supporting services. Ecosystem services are managed in agroecosystems primarily for food production. But, agricultural ecosystems provide provision, regulating and cultural services for human society. These services respond strongly to human socio-economic needs. Quantifying the various services and functions of agroecosystems is one of the most important effective strategies in order to increase attention pay to these services. Therefore, the purpose of this study was evaluation and quantification of ecosystem services in wheat (Triticum aestivum L.) agroecosystems of Dasht-e-Naz, Sari.

This experiment was performed as an unbalanced completely design in wheat agroecosystems of Dasht-e-Naz, Sari (Mazandaran province), during 2019-2020. In this study, 9 wheat plots with 4 cultivars including Tirgan, Ehsan, Collector and N-92-9 were surveyed and monitored. In this study, some ecosystem services such as insect and weed biodiversity (using Shannon-Weiner, Simpson, Margalf, Uniformity and Menhinick indices), soil microbial respiration, carbon sequestration, organic matter, abundance of earthworms, grain yield, protein content oxygen production, and soil protection (by the stability of aggregates) were evaluated and quantified. Soil samples were taken from a depth of 0-30 cm before wheat planting in November 2019 and after harvest in June 2020 for assessment of rate of microbial respiration, organic matter and carbon sequestration. Also, oxygen production was estimated based on net primary production. Sampling of yield and plant biodiversity was harvested based on W pattern and with quadrate 0.5 × 0.5 m2. All samples were moved to the crop research laboratory of Gorgan University of Agricultural Sciences and Natural Resources and the plant flora was determined by genus and species names.

The results showed that crop management and performance of intensive agricultural system were effective on providing many services of ecosystems in wheat fields of Dasht-e-Naz, Sari. These services are influenced by several factors such as cultivar type, crop rotation, tillage, etc. The results showed that the effect of different cultivars was significant on grain yield and protein percentage. The highest percentage of grain protein as a provision service was obtained from Ehsan cultivar (12.15%) and the lowest content was obtained about 11.42% from N-92-9 cultivar. The highest wheat grain yield and oxygen production were calculated from plots under Collector cultivar. In additional, the highest amount of carbon sequestration (2.33 ton/ha) and microbial respiration rate in before planting and after harvest (76.46 and 38.52 mg CO2 per kg of soil per day, respectively) belonged to plot 15. Also, it was determined that plot 15 was better than other plots from soil protection service view based on the diameter mean weight index (MWD) and the geometric mean diameter index (GMD). In this research, three beneficial insects (biodiversity assessment) were observed such as Coccinella septempunctata Linnaeus and Aphidius matricariae, and Chrysoperla carnea. The highest values of Shannon-Weiner and uniformity indices of weeds were as 2.63 and 0.82 in plots 23 and 15, respectively. Furthermore, Shannon-Weiner and uniformity indices of insect communities were obtained as 2.07 and 0.94 from plot 22, respectively.

 Generally, carbon sequestration, organic matter, microbial respiration, earthworm abundance, aggregate stability index, average weight diameter (MWD) and geometric mean diameter index (GMD) were better in plots 14 and 15 under wheat cultivation  than other plots. The results of this study showed that crop management and implementation of intensive agricultural system were effective in providing many ecosystem services in wheat fields in Dasht-e Naz region of Sari. So that, these services were affected by several factors such as cultivar, crop rotation and tillage methods.
Acknowledgment
The authors gratefully acknowledge the financial support of Gorgan University of Agricultural Sciences and Natural Resources and Dr. Hamid Sakinin for his help.

Carbon sequestration is the ability of plant biomass and the soil to absorb atmospheric carbon dioxide and store it for a long time. Therefore, carbon sequestration occurs when the rate of absorption of carbon dioxide by plants from the atmosphere, is larger than the total soil respiration rate, plant respiration and plant biomass cut (Anderson et al., 2008). Today, agriculture is effective in carbon sequestration through as an important factor in in order to mitigate the effects of climate change. In the past, carbon sequesters are mainly raised in relation to forests. But today, crops production or animal husbandry can also be effective by maintaining plant residues and proper consumption of organic fertilizers obtained in soil in carbon sequestration (Seyedi, 2016). Therefore, this study was conducted in order to evaluation the carbon sequestration potential in canola plant tissues in agroecosystems Sorkhankalateh region, Gorgan county.

This study was conducted to evaluation the carbon sequestration potential in above- ground and below ground tissues of canola (Brassica napus L.) in agricultural lands of Sorkhankalateh region (Gorgan County) during 2021-2022. In this study, 50 canola fields were selected and sampling from the fields based on the W pattern in the four geographical directions of the region. An electric burn furnace method was used to determine the conversion coefficients of carbon sequestration potential in above- ground and below ground tissues (including siliques, seeds, stems, leaves and roots). As well as, the ratio of above- ground to below ground tissues and harvest index were estimated to determine the net primary production based on carbon content in the above ground tissue, below ground and total plant, and the carbon allocation coefficients in each of the canola plant organs. Finally, using the ArcGIS software version 10.3, the amount of carbon sequestration potential in each of the canola organs was presented in the form of a map, and all the data used were analyzed using SAS software version 9.3.Results and DiscussionBased on the findings of this study, the average deposited carbon in total plant tissues in under cultivated fields of Hayola 50 cultivar was equal to 6657.47 kg per hectare and in under cultivated fields of Trapper cultivar equal to 6560.33 kg per hectare. So that the average carbon sequestration potential was obtained in the stem in two Hayola 50 and Trapper cultivars equal to 2012.36 and 1993.97, in seed 1717.20 and 1639.95, in pod 1676.77 and 1608.36, in leaf 602.90 and 615.72, and in root 648.21 and 703.30 kg per hectare, respectively. Also, the shares amount of the allocation coefficient of each of the economic tissues, stem, leaf and silique, root and root secretions were obtained, in two Hayola 50 and Trapper cultivars equal to 21.17 and 20.42, 63.60 and 63.49, 9.22 and 9.74, and 5.99 and 6.33 percent, respectively. In this study, the average total carbon sequestation potential in above- ground and below ground tissues was equal to 6610.86 kg per hectare. The highest and lowest carbon sequestation potential was obtained for stem with 2081.35 kg per hectare and leaf with 759.89 kg per hectare, respectively. Also, in the survey of carbon sequestration in above- ground and below ground tissues in canola fields, it was determined that there was a significant difference in 99% level. The results of carbon sequestration maps showed that there was the highest carbon sequestration rate in the fields located in the west and northwest, and carbon sequestration rate was lower in the fields located in the southern and eastern regions.

Providing future food demand by providing a solution to achieve greater water use efficiency in the water shortage throughout the world, is a major priority in agriculture. Therefore, in arid and semi-arid countries, it is necessary to use methods to improve irrigation management in all maize planting systems. The use of intercropping systems in arid areas where water deficiency poses a serious threat to agricultural sustainability is an effective strategy to reduce the challenge of water scarcity. Deficit irrigation, which means reducing water consumption per unit area, is another way to manage irrigation. Another management strategy to improve production and increase plant tolerance to water scarcity is the use of polyamines as an external source that increases plant tolerance and growth. This study was performed to evaluate the yield of forage maize and pinto bean under deficit irrigation and spermidine foliar application treatments.

An experiment was conducted as split split plots based on a randomized complete block design with three replications. Main plots comprised three irrigation levels ((based on 60 (as control: NI), 80 and 100 mm cumulative evaporation from Class A evaporation pan as deficit irrigation (DI80 and DI100)), subplots included foliar and non-foliar spraying of spermidine and sub-sub-plots consisted five intercropping pattern (maize monoculture (Z), bean monoculture (F), intercropping of 50% maize: 50% bean, (Z %50: F %50), 80% maize: 60% bean (Z %80: F %60) and 80% maize: 40% bean (Z %80: F %40). It was carried out in the research farm of the Campus of Agriculture and Natural Resources of the University of Tehran in the 2009-2010 year.

the result showed that the experimental treatments was significant on maize Fresh and dry forage yield, bean grain and biological yield, bean and maize leaf area index. Due to the higher planting area in bean and maize monoculture treatments, the highest bean grain yield (2.62 t/ha) and fresh yield of maize (66.53 t/ha) were related to monoculture under normal irrigation and spraying treatments, Land Equivalent Ratio (LER) in all intercropping patterns was more than one, indicating their superiority over monoculture treatments that indicated higher ground productivity in intercropping pattern than in monoculture of crops all levels of irrigation. Deficit irrigation up to 80 mm, decreased maize Fresh and dry forage yield, bean grain and biological yield less than 10 percent and spermidine increased all traits values. The lowest bean grain yield (0.56 t/ha) and fresh yield of maize (29.92 t/ha) were obtained from 80%: 40% and 50%: 50% under the lowest irrigation rate and non-foliar spraying, respectively.

the result showed that intercropping pattern and spraying treatments is usefulness. Due to the slight decrease in forage maize yield in 80 mm evaporation and additive intercropping patterns (less than 6 and 20%, respectively, compared to monoculture under normal irrigation and non- foliar spraying), if the goal is to produce forage maize, deficit irrigation up to 80 mm evaporation from the pan and additive intercropping along with spermidine foliar application is recommended for maize and bean cultivation to increase the sustainability and forage production in karaj area.

There are few studies on the effectiveness of this type of management on soil properties of Golestan province as the main agricultural pole in Iran. The purpose of this study is to investigate the effect of limited tillage on improving biological soil quality indicators.

Three types of operations which include No Tillage (NT), Minimum or Occasionally Tillage (OT or MT) and Conventional Tillage (CT) were selected. From each management, 30 samples were taken at depths of 0-30 cm. Microbial respiration, microbial biomass, urease, acid and alkaline phosphatase, dehydrogenase and cellulase activity were measured.

Conservation tillage (ST) which include both MT and NT increased acid and alkaline phosphatase by 1.6 to 2.5 times. The reverse trend was observed for cellulase, which showed a decrease from 37.5% in MT to 25% in NT. Urease and dehydrogenase increased by 14 and 18% in MT and decreased by 5.7 and 10% in NT. Microbial biomass and microbial respiration increased by 1.8 and 2.5 times in MT and in no tillage, operation decreased by 15 and 44%.

The emphasis is on the advice of ST, However, it seems that some points related to the promotion of this method in agricultural lands should be considered.  It seems that MT has a better condition for enzyme activity than NT. Low enzyme activity in NT conditions may reduce the availability of nutrients and thus reduce the yield, then extension experts should be inform the Farmers.

Awareness of the existence of specific weeds in an area can be better decided and planned about their control methods. Otherwise, applying different control methods will not have the desired effect. In this study, in order to identify and prepare maps of weed distribution in canola fields of Sorkhankalateh region of Gorgan county, 50 fields were selected and sampled based on W pattern in two stages. Then, using current formulas, frequency, relative frequency, species uniformity and biodiversity indices were calculated. We were recorded the geographical coordinates and altitude of the sampling location by a GPS, Garmin touch model for each field. The obtained information was processed using Arc GIS software (var. 10.3) and the distribution maps of all weeds in canola fields were prepared. The results showed that 41 weed species (20 species in the pre-spraying stage and 21 species in the post-spraying stage) from 14 plant families were present in surveyed fields of Sorkhankalateh region, which Poaceae, Asteraceae, Fabaceae, Brassicaceae and Polygonaceae were the most important plant family. In the pre-spraying stage, the share of annual, perennial and biennial species was 75, 15 and 10%, and in the post-spraying stage, their share was as 66.66, 23.80 and 9.52, respectively. In terms of growth form, in the pre- and post-spraying stages, 8 and 76.19% species were belonged to dicotyledonous and 20 and 23.80% were as monocotyledonous, respectively. According to the results of biodiversity indices, weeds in the post-spraying stage had more diversity than the pre-spraying stage. Also, the results related to weed distribution maps showed that most of the dominant weeds were distributed in the Eastern and southern parts of the studied region.

Over the past half century, intensive agriculture has increased dramatically, and agricultural landscapes have changed to simple with low cover as single crop systems similar to semi-natural habitats. This trend has led to a sharp decline in biodiversity and a reduction in the provision of ecosystem services to agriculture. It has been confirmed that among ecosystem services, pest and weed control and pollination have significant impacts on global agricultural production. This study aimed to investigate the plant biodiversity of wheat, rapeseed, barley and triticale ecosystems in an agricultural landscape (Dasht-e- Naz Sari).

This experiment was carried ou as unbalanced completely randomized design in an agricultural landscape located in Dasht-e- Naz, Sari (Mazandaran province), during crop year 2019-2020. In this study, 26 farms were selected from different parts of autumn crops (rapeseed, wheat, barley and triticale). Sampling of plant biodiversity was performed based on W pattern with 0.5 × 0.5 m2 quadrate. The samples were transferred to the agronomical research laboratory of Gorgan University of Agricultural Sciences and Natural Resources and the flora was determined by genus and species. Then, bidiversity indices including Shannon-Weiner, Margalef, Menhinick, Simpson, Uniformity and Sorenson were calculated using the related equations. In final, based on the results, biodiversity status in the agricultural landscape was analyzed acorrding to status of landscape components including the type ecosystems, corridor, border, etc.

In this study, 25 plant species from 14 plant families were identified that 10 species belonged to narrow-leaved and 15 species belonged to broad-leaved. Among the identified species, Rapistrum rugosum, Avena ludoviciana, Phalaris minor and Cirsium arvense were the most abundant. The results showed that the plant biodiversity in this landscape was in a favorable condition based on Shannon-Weiner index, so that this index for triticale, barley, rapeseed and wheat plots were 2.64, 2.52 and 2.39 and 2.38, respectively. The amount of Menhinick index for autumn crops of rapeseed, barley, wheat and triticale was as 2.86, 2.85, 2.45 and 2.32, respectively. Also, the highest Simpson index for rapeseed, barley, wheat and triticale plots was equal 0.068, 0.047, 0.070 and 0.052, respectively. Based on our results, the highest similarities according to Sorenson index were related to triticale (1), barley (0.95), wheat (0.95) and rapeseed (0.93), respectively.

In general, the consumption of manure in some plots, the location of streams and barren lands in the margins of the plots and corridor of trees as windbreak, could affect on biodiversity of the surveyed landscape. The results of this study can be useful for comprehensive weed management program and making decision about control or improve ecosystem services through plant biodiversity.Keywords: Agricultural landscape, Biodiversity, Ecosystem Services.

 Food security has been the most important human concern on the planet. Food security and future changes in food prices and crop development undeniably depend on the average yield of crops. Rice is the second largest crop in terms of area under cultivation and provides food for more than half of the world's population. Due to the importance of rice production, it is important to monitor its production on a large scale. Remote sensing and geostatistical methods play an important role in spatial and temporal evaluation of climatic, soil, living factors and management methods. The study of the amount of yield obtained in province of Guilan can provide appropriate information in advancing/pursuing goals such as the study of the amount of yield gap in this region; therefore, this study was conducted to evaluate the yield of rice using two methods of geostatistics and remote sensing approach in 2016 and 2017 in Guilan province.

 In this study, different methods of preparing vegetation map to determine rice yield map were evaluated. To compare methods based on satellite-imagery and geostatistical procedure-models to estimate the rice yield of rice cultivated lands in Guilan province, a study was conducted in the 2016 and 2017. For field operations, 320 fields were surveyed to record grain yield (of total 238,000 hectares of rice-grown fields) during the physiological maturity stage. In this study, 33 statistical procedure-models were used to interpolate the amount of grain yield and then the accuracy of interpolation methods were evaluated using various statistical criteria. Satellite-imagery based methods using Landsat 8 satellite Operational Land Imager (OLI) sensor images related to the dates of June 18, August 9, August 21 in 2016, and July 23, August 8 in 2017 and the images of the Sentinel-2 satellite on June 30 and September 13, 2017, were used. Eight satellite-derived vegetation indices were calculated and the relationship between them and the yield variable was extracted using the regression relationship, and the yield map was prepared and evaluated. By fitting the peak logistics model between yield values and vegetation indices and selecting the superior index, the yield map was prepared with the help of remote sensing and the obtained yield maps were compared with different statistical criteria.

 The results of the evaluation of geostatistical interpolation methods showed the superiority of the ordinary stable kriging procedure-model over other models. In this study, the RVI vegetation index was selected as the superior index to predict actual yield throughout the Guilan Province. Comparison of geostatistical procedure-models and satellite-imagery oriented models based on the determination coefficient of regressed equations and root mean square error (RMSE) to estimate grain yield in Guilan province showed that both procedures had acceptable accuracy, however, due to the ability of remote sensing to distinguish the pointwise optical reflection of phenomena and to predict yield with high spatial resolution, this method achieved higher accuracy in yield estimating.

 Comparison of geostatistical and remote sensing methods in predicting farm yield indicated that the remote sensing method was more accurate. Early harvest forecasting based on the information extracted from this study showed that the use of image / images obtained in June and August and OLI sensor of Landsat-8 satellite in Guilan province can be used as a basis for forecasting the yield of this plant in the coming years. Such studies in Guilan province, by considering the share of Guilan province in the country's rice supply, will play an effective role in managerial decisions regarding rice supply and demand at the macro level. The results also showed that sampling in the study area based on a regular (systematic) spatial pattern can increase the accuracy of geostatistical methods in estimation of regional yield. The results of this project can provide suitable basic information for other studies such as yield gap, the reasons behind it, the relationship between land suitability and the obtained yield and forecasting and estimating yield in different time periods.

Detection of resistance to an herbicide in a putatively resistant accession requires a series of experiments which are capable of illustrating the response of the accession to various herbicide doses. Whole plant bioassay in pots usually takes approx. 2 months to obtain the results, thus, rapid tests were developed to accelerate the process. Although determination of discriminating concentration as well as conduction of rapid test for some ACCase inhibitors has been performed by various researchers, no reports are available in this regard for haloxyfop-R methyl ester herbicide in winter wild oat. Thus, the following study was conducted with the objective of rapid detection of resistance to the mentioned herbicide in this weed using the rapid test.

The experiment was conducted using the seeds of 7 putatively resistant winter wild oat accessions and a susceptible biotype gathered from canola farms of Kalaleh Township located in Golestan province in 2015. Rapid test in petri dishes was conducted as a completely randomized design with three replications, with each petri dish as one replicate. To determine the discriminating concentration, various concentrations of haloxyfop-R methyl ester was applied on the susceptible accession and then, all putative accessions were screened using this concentration. The biotypes of the studied weed were exposed to various doses of the herbicide in the petri dish bioassay to determine the resistance factor. Also, a completely randomized design experiment with three replications was conducted for screening of putative accessions in the greenhouse. Accessions which maintained their survival and dry weight respectively 50 and 80 percent compared to the unsprayed control were selected. A whole plant dose-response bioassay was also done separately for each biotype.

Discriminating concentration of haloxyfop-R methyl ester for winter wild oat was obtained 0.106 mg ai. L-1. According to the results, 5 out of 7 accessions were detected as resistant and underwent the concentration- response assay in petri dishes. Resistant factors of the biotypes in the rapid test ranged from 2783.054 to 3421.414. However, no significant difference was observed among the biotypes. According to the results of the greenhouse, 5 accessions were detected as resistant with resistance factors of 14.19 to 18.54, with no significant difference among the biotypes. There was a positive and significant correlation between the results obtained from the rapid test with the greenhouse assay, which indicates the validity of the Petri dish assay.

The results of the rapid test are in accordance with those of the whole plant assay in pots. Therefore, putative winter wild oat accessions collected from the region may be screened using the obtained concentration of haloxyfop-R methyl ester (0.106 mg ai. L-1) and resistant biotypes may be detected more rapidly compared to greenhouse assays. Due to the swift development of herbicide resistance issue, rapid detection of resistance is essential. Thus, using methods such as rapid test may be very feasible.

Rational fertilizer management is crucial in the efficient use of resources that are basically non-renewable and that can have a great environmental impact when used without scientific basis. The availability of scientifically sound decision-making tools for rational fertilization  is scarce. FertiliCalc-Fertigate software is a program to determine the consumption of NPK fertilizers during the growing season in a cost-effective and sustainable way. Today, the geographic information system is widely used in spatial planning by determining the distribution of phenomena and combining maps and interpreting ecological data in different stages of planning. Also, the potential yield in an area can be estimated using field tests and simulation models. The ORYZA2000 model is one of the efficient models in investigating rice potential yield, which simulates the growth and development of rice plants under favorable conditions, water limitation and nitrogen limitation. In this study, an attempt was made to estimate the potential yield in Guilan province by integrating the ORYZA2000 model and geographic information system. Also, after determining the potential yield, the NPK fertilizer requirement estimated using FertiliCalc-Fertigate software.

This research was conducted to investigate the potential yield of rice in Guilan province using the ORYZA2000 model. After calibrating and validating the model at the field test level, the model was used to evaluate the potential yield of rice in 12 synoptic stations of Guilan province. The processing of Landsat 8 satellite images was used to separate rice fields in Guilan province and the studied area was separated using supervised classification. The estimation of potential yield in Guilan province was done by combining GIS environment and ORYZA2000 model. The amount of radiation for the whole area was calculated from the Points Solar Radiation function in GIS. Then, from the relationship between the amount of radiation received during the rice growing season and the potential yield estimated in the ORYZA2000 model, the potential yield was calculated and generalized to the whole area based on the agricultural land use of Guilan province. Fertilizer requirement of lands was calculated using FertiliCalc-Fertigate 1.0 software. In order to evaluate  the fertilizer requirement at the province level, first, 320 points were randomly selected in the rice cultivation area of the province and the fertilizer requirement of each point was determined based on the required information, including potential yield and soil information. Then the points were interpolated and the study results were presented in the form of fertilizer requirement maps.

The results showed that the amount of radiation in rice fields in the Guilan area, during the growing season, was between 2552 to 6259 MJ/m2 (average 4405 MJ/m2) in 2016 and from 2423 to 5337 MJ/m2 (average 3880 MJ/m2) in 2017. The lowest amount of received radiation was in the central areas of the basin, which can be due to the topographic conditions of the area. Using the regression relationship between radiation during the growing season and potential yield, a potential yield map of rice fields was prepared. Based on the results, potential yield in rice fields of Guilan province was between 4416 to 7038 kg/ha (with an average of 5160 kg/ha) in 2016 and between 4558 to 7180 kg/ha (with an average yield of 5302 kg/ha) in 2017. Based on these results, the combined approach of ORYZA2000 model and GIS has a good ability to simulate potential yield in the study area. Estimation the levels of fertilizer requirements in the rice fields of Gilan province showed that in order to achieve the potential yield, 262 to 274 kg/ha of potassium fertilizer, 116 to 171 kg/ha of nitrogen fertilizer, and 8 to 12 kg/ha of phosphorus fertilizer are needed. Based on the calculated fertilizer requirement, potassium has played the most important role in achieving the potential yield of rice in the province.

It seems that in many areas of Gilan province, the application of NPK levels in an inappropriate amount and time causes a decrease in rice yield. The results of this research can recommend the appropriate fertilizer consumption pattern to farmers through rice experts so as to achieve maximum yield and avoid problems such as phosphorus leaching due to excessive consumption.

Increasing greenhouse gases will have different effects on crop yields, so that the interaction of these effects may increase or decrease yields. Crop simulation models have been used to investigate different levels of crop and environmental managements. The aim of this study was to investigate the AquaCrop model based on past, present and future climate in Rasht city located in Guilan province to achieve maximum water productivity and rice grain yield.

In order to study the changes in rice yield, water balance and productivity in Rasht city located in Gilan province under the past, present and future climate, the AquaCrop model was used. For this purpose, long-term data (over 30 years) were used to evaluate the yield and water balance in rice cultivation in the past and present climate. Also, using LARS-WG6 software, meteorological data for the next 83 years were generated based on the available daily meteorological data. The AquaCrop model was evaluated in the past, present and future climates based on daily data of minimum and maximum temperatures, precipitation and sun hours. The studied treatments included four levels of irrigation including 55, 70, 85 and 100% of water requirement and the planting dates were April 21st, May 11st and May 31st. By examining the effect of different treatment levels based on RCP 4.5 and RCP 8.5 climate change scenarios, the rate of changes in grain yield, evapotranspiration and water productivity based on evapotranspiration in the past, present and future climates were investigated. Also, the best irrigation treatment and planting date were introduced to increase rice yield and reduce water consumption.

The evaluation results showed that the LARS-WG6 model is able to simulate the climatic components including temperature, precipitation and radiation with high accuracy. The results showed that the minimum and maximum temperatures increased during the climate change scenarios and the amount of radiation and precipitation decreased. The result of rice biomass and grain yield under RCP 4.5 and RCP 8.5 showed that the highest grain and biomass yield was obtained in irrigation of 100% of water requirement and planting date on April 21st. The study of water productivity showed that irrigation treatment of 100% of water requirement and planting date of May 31st had an effective role in increasing soil water storage and reducing evapotranspiration from the soil surface. The highest water productivity in grain production based on evapotranspiration was obtained in irrigation of 100% of water requirement and planting date was May 31st.

According to the obtained results, considering the water consumption productivity and yield and problems that will exist in the future including water shortage, it seems that late cultivation of rice in conditions of water shortage is a good solution, but under conditions where there is no water shortage, early cultivation of rice, such as April 21, can increase production. The study of irrigation levels showed that grain production is the most effective factor in increasing water use productivity and the use of low irrigation levels will not play an effective role in increasing water productivity.

Introduction

Method include seedling size and planting date. Since field experiments are usually laborious and costly, the simulation models could be used as a useful tool for investigating such factors. Due to climate change affects the outputs of crop models, the crop growth simulation models should be widely evaluated with empirical data to ensure that simulation of crop growth under a different management strategy or future weather conditions is reliable. 

 In the present study, the effect of direct-seeding and four seedling sizes (13, 16, 19 and 22 leaf area cm2plant-1 and at 200, 250, 300 and 350 °C cumulative temperature) for transplanting method at four planting dates (10 June, 25 June, 14 July, and 27 July) was simulated in Gorgan environmental conditions for 16 years (2000-2015) using SSM-iCrop2 model. In this simulation, it was supposed that the corn should be harvested on 22 November to provide sufficient time for cultivating the next crop. Also, the economic evaluation between the two methods of transplanting and direct-seeding was carried out using a questionnaire from farmers and experts in the field to evaluate the costs of these two methods.

 The simulation results showed that at early planting date (10 June), in transplanting method, the crop matured earlier between 16 to 26 days compared to the direct-seeding, depending on seedling size. In addition, the average yield of 1331 g m-2 and average net irrigation requirement of 435 mm ha-1 were obtained. At this planting date, transplanting had no effect on the yield and net irrigation requirement. In the common sowing date (25 June), the crop matured earlier between 19 to 33 days (early harvest) in the transplanting method compared to direct-seeding, however, the planting method had no effect on the yield and net amount of irrigation. At this planting date, the average yield and water requirement were 1329 g m2 and 416 mm ha-1, respectively. In late planting date (14 July), transplanting with large seedlings (leaf area of 19 and 22 cm2 plant-1) were able to complete their growth period before 22 November. Average yield and irrigation requirement were 1273 g m-2 and 381 mm ha-1, respectively. It should be noted that in late planting date, direct-seeding and transplanting with small seedlings (leaf area of 13 and 16 cm2 plant-1) were not able to complete maturity to 22 November, therefore, this planting date is not recommended. At the last planting date (27 July), all types of cultivation are not recommended as crop growth period are not completed before 22 November.
 Conclusion

 In general, it can be concluded that transplanting method would be only recommended for late planting date with using large transplants (leaf area of 19 and 22 cm2 plant-1). However, transplanting did not significantly decrease the amount of net irrigation requirement at any of the planting dates, and also had higher costs and lower profit.

Understanding the suitability of the lands is very important in terms of the ability to cultivation a particular crop. Having information in this field helps us to act more intelligently in prioritizing land allocation for the cultivation of various crops. Also, adapting the current-grown lands under cultivation of a crop selected by the farmer to the final layer of land suitability can give us an overview of the right or wrong choice of land use. This information will help agricultural policymakers to replace crops when necessary and to replace crops that have been misallocated in disproportionately desirable lands with other crops or to improve their crop management. Therefore, this study was conducted to assess the land suitability of Golestan province agricultural lands for soybean cultivation and the degree of adaptation of current soybean-grown fields to the obtained suitability layers.

This study was carried out in the agricultural lands of Golestan province with an area of 821 thousand hectares. First, the real lands under cultivation of soybean were separated using 1674 land samples taken from different crops and object-based image analysis (OBIA) method. To separate the lands under soybean cultivation in Golestan province, sentinel 2 satellite images with a spatial accuracy of 10 meters related to planting to harvesting time in 2018 were used. Then, the layers of soil, climate, and topography characteristics were provided to investigate land suitability for soybean cultivation. Climatic components including minimum, optimum, maximum temperatures, and rainfall were estimated using long-term statistics of synoptic stations in the province (maximum available statistics). Data of soil texture, nitrogen, organic matter, phosphorus and potassium, soil pH, and salinity were also received from the provincial agricultural and natural resources research center, and from the data, the soil properties map was obtained. The digital land elevation map (DEM) of the province with a spatial resolution of 20 meters was used to extract slope, elevation, and aspect maps. The process of interpolation of climatic and soil layers was performed using ordinary kriging method. The relative importance of each factor was determined through the Analytic Hierarchy Process (AHP). This was done by designing questionnaires based on AHP paired matrices and completing it by agricultural specialists. After extracting the weights from the questionnaires and preparing the classified raster layers, these layers were imported in GIS version 10.3. Combining and overlaying the layers was done by assigning AHP weight to each layer. Finally, a land suitability map was prepared for the cultivation of the soybean in the study area which, in turn, was used to determine the adaptation of current soybean fields with determined suitability classes.

The accuracy of classification by object-oriented method using kappa coefficient and overall Accuracy coefficient (0.87 and 90%, respectively) shows the acceptable accuracy of soybean land separation in this study. In the study of land suitability for soybean cultivation, the results obtained from hierarchical analysis showed that the soil criterion had the greatest effect on the site selection of soybean cultivation with a coefficient of 0.52 with respect to both climate and topography factors. The results showed that most of the fields (about 87% of total) placed in suitable class and 13% placed in a relatively suitable class. In suitable areas for cultivation, despite having the best conditions for factors such as maximum temperature, average temperature, slope, aspect, height, soil texture, soil pH, phosphorus and soil salinity, soybean production is limited by factors such as precipitation (400 to 500 mm per year), minimum temperature (10 to 12 °C), phosphorus (8 to 10, 15 to 20 mg/kg soil). In these areas, maximum yield can be achieved by managing the mentioned factors and applying desirable agricultural management. In relatively suitable areas, limitations of nitrogen deficiency (less than 0.5 mg/kg soil), organic matter (less than 2%), salinity (above 6 dS/m), slope (more than 5%), restriction of soybean cultivation due to heavy soil texture (high percentage of soil clay), potassium (less than 100 mg/kg soil), phosphorus (more than 20 or less than 8 mg/kg soil), precipitation (less than 400 mm per year), minimum temperature (less than 10 °C), slope (more than 8%) and aspect (west and north) caused relatively high land restrictions for soybean cultivation. Compatibility analysis of the current soybean fields with the suitability maps indicated that about 99% of total cultivated lands are located in a suitable class, which demonstrates the proper selection of farm locations by the farmers.

By considering the position of Golestan province in the production and area under soybean cultivation in the country, if it is possible to identify suitable soybean cultivation areas according to the environmental requirements of this product and identify the limitations created by the environment, more yield per area can be achieved, which will improve the agricultural economy and the level of income of the country.

Biomass plays an important role in providing energy and the global carbon cycle and monitoring the biomass is one of the most important issues in the agricultural sector. Using remote sensing techniques is an effective tool for estimating biomass. This reduces field studies and saves time and money. Today, management practices can be improved using remote sensing technology and vegetation indices. The suitability of the weather in Golestan Province for producing most agricultural products has made the province highly diversified in terms of crop and biomass production. For this purpose, in this study, satellite images of Landsat 8 and Sentinel 2 were used to estimate the residue biomass of crops in the watershed of the southwest of Golestan province (Mohammad Abad, Qaresoo, Zaringol, and Gharnabad).

For this, field surveys were carried out to sample the fields at different stages of plant growth, in the winter and spring of 2016. The number of samples for wheat, barley, canola, rice, and soybean was 90, 70, 65, 67, and 80, respectively. The biomass data were also measured from field survey using four quadrates (0. 25m2) and their moisture content was determined by weighting. The Landsat 8 and Sentinel 2 images were downloaded from the USGS site in the early and middle of the growing season for mapping sattelitesatellite-based vegetation indices including, NDVI, SAVI, RVI, DVI, and RDVI. The relation between the indices and obtained biomass was evaluated using regression analysis to produce biomass maps for five crop residues.

The results showed that the NDVI index is the best indicator to estimate the wheat, barley, and rapeseed residue biomass, in April, with a determination coefficient of 0.61, 0.65, and 0.65, respectively, according to the vegetative growth peak, and for the soybean crop in September, according to the peak of vegetative growth with a determination coefficient of 0.65, and the RVI index is the best indicator for estimating rice residue biomass in August in line with peak vegetative growth in the study area. The total amount of wheat, barley, canola, rice, and soybeans residues in the study area was estimated as 751657, 175637, 14979, 42628, and 93712 tons, respectively. The results of this study can be applied to managers and decision-makers of the agricultural sector in the province by identifying the potential for agricultural production and the amount of their residues.

The results of this study showed that the residue biomass of different products can be estimated by using the vegetation indices extracted from satellite images with acceptable accuracy in the study area. In this research, the overlaying for determining the cultivation area of wheat and soybean products was 97.74% and 97.6%, respectively. The precision of this method for peak vegetation periods was higher than the early stages of plant growth. Also, instead of a vegetation index, several vegetation indices were used and the NDVI and RVI index was the best indicator for estimating the residue biomass of different products.

In order to investigate the resistance of short spike canarygrass (Phalaris brachystachys) biotypes to acetyl coenzyme A carboxylase inhibiting herbicides wheat fields of Golestan province, 43 suspected resistance were collected from a different area in 2018. The susceptible biotype was also collected from regions with no chemical control record. The study was carried out in three steps including determination of discriminating concentration for susceptible biotype, screening P. brachystachys biotypes with the discriminating concentrations, and concentration-response experiment for suspected resistant biotypes at Gorgan University of Agricultural Sciences and Natural Resources in 2018. According to the seed bioassay test, the discriminating concentration of sensitive biotype for clodinafop propargyl, diclofop methyl, haloxyfop-r-methyl, cycloxydim and pinoxaden were 0.02, 1.36, 0.03, 0.06 and 0.08 mg a.i.L-1, respectively. In the screening test using the discriminating concentration, 36 (84%), 36 (84%), 19 (44%), 23 (53%), 21 (48%) out of 43 biotypes were identified as suspected resistant to clodinafop propargyl, diclofop methyl, haloxyfop-R-methyl, cycloxydim and pinoxaden, respectively. In general, the results showed that the studied biotypes had different patterns in terms of resistance to different groups of ACCase-inhibiting herbicides. The results of the concentration-response test also showed that among 43 suspected resistance suspected of resistance, 19 biotypes were resistant to all five herbicides.

In order to investigate the soybean competitive ability (DPX cultivar) under interference condition different densities of Asian spider flower (0, 3, 5, 10, 15, 20, 30, 45 plant/m-2); an experiment was conducted based on randomized complete blocks design with three replications in 2015–2016 growing season in Kalaleh, Golestan province. Different densities of Asian spider flower had a significant effect on biological yield, economic yield, 100 grain weight and pods per plant of soybean. The highest grain and biological yields of soybean were 374.9 and 734.30 g/m2, respectively which observed in weed-free treatment. However, these traits declined nonlinearly as weed density increased, so that in 45 plant/m-2interference treatment, economic and biological yields reached 172 and 344.38 g/m2, respectively.

Introduction:

Climate change and global warming are the most important challenges in sustainable development, which is due to increased concentration of greenhouse gases in the atmosphere. Carbon dioxide is a major component of greenhouse gases. In order to reduce atmospheric carbon dioxide and to create a balance in the content of greenhouse gases, atmospheric carbon must be absorbed in organic forms (Dieleman et al., 2015; Lichtfouse, 2009). For this aim, a study was done in agricultural lands of Gorgan in order to estimate the carbon sequestration potential of soybean plant (Glycine max L.).

This research was carried out in 150 soybean fields of Gorgan township and sampled by quadrate 0.5Í0.5 m2 as random method, during 2016-2017. The soybean shoot and root organs were individually harvested and transferred to the laboratory. An electric burn furnace method was used to determine the carbon sequestration potential in soybean organs (including pods, seeds, stems, leaves and roots). Also, the amount of shoot to root and harvest index were estimated to determine the net primary production based on carbon content in the above ground organ, below ground organ and total plant, and the carbon allocation coefficients in each soybean organ. Then, using different interpolation methods, the spatial distribution of carbon sequestration of the plant organs was investigated in ArcGIS software. All data were analyzed by SPSS software.

The results showed that Kriging method was the best model for carbon interpolation and distribution of carbon sequestration potential in agricultural lands of Gorgan township. The amount of stored carbon was obtained as 579.64 kg.ha-1 in leaves, 744.81 kg.ha-1 in stem, 881.16 kg.ha-1 in seeds, 340.16 kg.ha-1 in pods and 540.21 kg.ha-1 in root. Also, according to harvest index (32%) and grain yield (3461.13 kg.ha-1), other indexes were calculates as the ratio of shoot to root about 4.30, the total net primary carbon production 6734.8 kg.ha-1, above-ground net primary carbon production 4867.2 kg.ha-1 and below-ground net primary carbon production about 1867.63 kg.ha-1. Also, the shares of the allocation coefficients of economic organs, stems, leaves, root and root secretions were 0.23, 0.49, 0.61 and 0.12, respectively. The zoning results showed that the total stored carbon potential in soybean plant was highest in the eastern, north and southeastern regions of the surveyed area, and the central, western and southwestern parts of this township had the lowest stored carbon potential. Also, the amount of carbon sequestration potential (total above ground and below ground organs) was as 3085.98 kg.ha-1 in this study.

 The highest proportion of carbon was allocated to the shoot organs, and the carbon of root exudates was also lower than other plant organs. In this study, it has been found that the potential of carbon sequestration was different in soybean plant organs and some variable such as agronomical management, soil and climatic condition can affect on its contents.AcknowledgementsWe are thankful to Gorgan University of Agricultural Sciences and Natural Resources (GUASNR), Agriculture Services Centers of Gorgan and soybean farmers for all their companions and supports.