مجله کشاورزی بوم شناختی
سال هشتم شماره 1 (1397)

In the last century, agroecosystems have been considered as production units despite their range of functions. The variety of methods used to maximize production have had a negative impact on the dimensions and functions of the agroecosystem (Alkorta et al., 2004). Industrial agriculture methods have resulted in a series of negative environmental effects such as contamination of surface drainage and groundwater with pesticides and highly-soluble chemical fertilizers, soil compaction by excessive use of machinery, reduction in biodiversity, overexploitation of natural resources, and high rates of carbon emission due to direct or indirect consumption of petroleum. In different parts of the world, especially in developed countries, the expansion of agricultural lands and the intensification of production methods reach their socioeconomic and environmental limitations. Therefore sustainable agriculture with its holistic principles have a key role in finding solutions for these challenges. The correct management of soil, water and fertilizer is critical for sustainable agriculture, because such management can increase food production and enhance the quality of the environment. Evaluation of different aspects of agroecosystem health (i.e. structural, functional, and organizational) is an acceptable method for monitoring and comparing systems (Xu and Mage, 2001). The current study has been performed to determine the trend of changes in agroecosystem health in the three northern provinces of Iran.
The current survey was conducted in order to compare the health status of agroecosystems in three important Northern provinces of Iran (Gilan, Mazandaran and Golestan) during the period of 2002-11. The required data and information was obtained from a formal statistical database. Different indicators selected and calculated based on their scientific definitions (Mohammadi et al., 2016; Vafabakhsh et al., 2007) and for each year the total numerical value for health conditions was calculated using different indicators. Because of the different nature of selected indicators and also their wide range, in order to facilitate a comparison of all the calculated indicators normalized using the appropriate equations.
Based on results in all of the studied years, the highest value of structural health calculated was for Mazandaran Province and the lowest value was for Gilan Province. In all three provinces, the trend of changes in structural health during the study period was incremental. It seems that in Mazandaran, the higher values for some of the calculated indicators such as area pressurized irrigation, machinery applications, cropping intensity, and agronomic diversity improved the structural health compared to other provinces under study. The same results were also observed for functional health and in all years of study except 2004, the highest values of functional health calculated for Mazandaran agro-ecosystems. The main reasons for better conditions of functional health in Mazandaran were higher values of different indicators such as yield of irrigated and dryland cereals, yield of pulses and kitchen garden plants, production costs and nitrogen use efficiency. The organizational health status was somewhat different. During the first six years the organizational health in Golestan was higher, while in the rest of the years Mazandaran had better organizational health status than the other two provinces. The higher organizational health in Golestan was due to the higher value of different indicators such as dryland cropping intensity, dryland area/irrigated land area, application of chemical fertilizers and application of chemical pesticides.
Based on the results during the years of study, the total agroecosystem health in Mazandaran was higher than in the two other provinces. Golestan ranked second and Gilan third. The structural and organizational health of agroecosystems in Mazandaran had a more effective role in its higher health. Agroecosystems of Gilan were weakest in all three criteria. In Golestan, the organizational health of agroecosystems was better than functional and structural health.

Weed management or any management in agriculture has to be considered in terms of the impact on the ecosystem of the soil (Yang et al., 2007). The combination of mulch and any management that affects soil is one of the most important factors affecting the chemical, physical and biological properties of soil (Luo et al., 2015; Wright et al., 2005). The aim of this study is to evaluate the effects of various methods of potato weed management on the biological properties of the soil.
The experiment carried out was a randomized complete block design with three replications in 2016 at two agricultural research stations, Alarogh and Samian, in Ardabil Province in Iran. Treatments included: 1) trifluralin herbicide, 2) metribuzin herbicide, 3) use of a cultivator, 4) wheat straw mulch, 5) canola straw mulch, 6) black plastic mulch, 7) transparent plastic mulch, 8) weed infested (control), and 9) weed control (control). Soil sampling was carried out in two stages. The first sampling was 30 days after application of the treatments and the second sampling was 60 days after. Microbial biomass carbon, soil organic carbon and soil respiration were measured. At the end of the growing season, the potato tuber yield was measured.
The treatments applied in the study caused significant differences in the rates of microbial biomass carbon, soil organic carbon, basal respiration, and induced respiration. The highest rate of microbial biomass carbon was observed with wheat straw and canola straw mulch at the first and the second soil samples. The lowest amounts of microbial biomass in the first sampling were from the trifluralin and metribuzin treatments. In the second stage, the use of a cultivator could significantly reduce the microbial biomass compared to the treatment of plant straw mulch. The wheat and canola mulch treatments had the highest rate of organic carbon in the two stages compared to other treatments. In other words, these treatments increased the organic carbon rate of the soil. The lowest organic carbon rate in both the first and second soil sampling occurred with the transparent plastic mulch. The highest basal respirations for the first sampling were with the canola straw, wheat straw, and black plastic mulches. The lowest basal respiration at the first soil sampling, however, occurred with the trifluralin herbicide. Furthermore, the highest basal respiration rates at the second sampling were with the wheat straw mulch, canola straw mulch, and metribuzin herbicide. Nevertheless, the highest rates of induced respiration were induced with the wheat straw and canola straw mulches. The lowest rate came with the cultivator use at the second sampling. The highest tuber yield was observed with weed control and plant mulch and the lowest yield was observed with weed control and transparent plastic mulch.
To manage weeds, it was determined that applying plant straw mulch treatments to cover the soil surface had more positive effects on the biological characteristics measured compared to the other methods employed in the experiment. The use of plant straw, black polyethylene mulch and a cultivator to manage weeds could lead to lower potato yield. Using mulch, especially plant straw, compared with herbicides, in addition to lowering costs, would adequately control weeds.

Agronomic approaches to weed management are effective, low-cost, environmentally-friendly options without adverse effects on human health. These approaches should be emphasized to develop a sustainable agriculture (Zimdahl, 2007). A living cover crop can affect weed competition by competing for growth resources and the residue of cover crops may affect weed growth and competition with their allopathic potential (Karbalaei-Khiavi et al., 2016). Fenugreek plants, with their shallow root system, ability of nitrogen-fixing as well as allopathic potential, were chosen as a cover crop to study the effects of various densities of fenugreek on growth and weed competition.
An experiment was conducted in a randomized complete block design with six treatments and three replications at the experimental station of Torbat-e Jam University in 2016. The treatments included the seeding of 0, 10, 20, 30 and 40 fenugreek plants per square meter as a cover crop and a control treatment. The destructive sampling was taken to determine the dry matter production in sunflower, fenugreek and weed from 60 cm of rows. After examining the residuals for normality, analysis of variance was done using SAS software.
The highest and lowest weed dry matter were obtained from the densities of 0 and 20 fenugreek plants per square meter, respectively. The results showed that the planting of fenugreek, regardless of its density, at the same time as the sunflower planting reduced growth of competing weeds by at least 50%. This reduction can also be increased by up to 78% by establishing the appropriate density of fenugreek. The highest and lowest leaf area, dry matter production and seed yield in the sunflowers was obtained from densities of 20 and 40 cover crop plants per m-2, respectively. The presence of cover crops in all densities, except for 20 fenugreek plants per m-2, significantly reduced sunflower yield compared with the control. Regression analysis also showed that the response of sunflower growth and yield to increased cover crop density follows a quadratic trend. The sunflower growth and yield was reduced at lower and higher densities of cover crop compared to its optimum density. The role of cover crop densities higher than the optimum level, however, was greater than the lower one in reducing competing weeds. Thus, the establishment of a suitable plant density of fenugreek would occupy an existing vacant niche, reduce available growth resources, and ultimately reduce the growth of competing weeds (Mohammadi et al., 2015).
Due to the reduction of competing weeds in the presence of fenugreek and the economic value of fenugreek production, this plant can be used as an effective cover crop in sunflower fields as an option in a comprehensive weed management system.

The yield of agricultural crops is one parameter closely correlated to weather features. The ENSO phenomenon is a climate parameter that affects weather, climate and agricultural production. Iran is one of the top producers of grapes in the world. With the large area of cultivation and high grape production, this product can be exported. In addition to grape yield importance, the effects of ENSO on agriculture that has been confirmed by researchers, and the lack of similar studies on the grape plant especially in Iran, the purpose of this investigation is to evaluate the effects of ENSO in El Nino and La Nina phases on grape yield.
In this study, for evaluation of the effect of ENSO phenomenon on grape yield, irrigated and rain-fed grape cluster weight information as a yield of 27 different provinces during 1999 to 2015 was used. For assessment, the effect of ENSO, the information of nine different indices of ENSO including SOI¡ PNA¡ NOI¡ NINO 3.4¡ NINO 1¡ NINO 3¡ NINO 4¡ MEI and TNI were provided. Pearson correlation coefficient was used for the determined relation between ENSO indexes and yield amount in SPSS software. Finally, the zoning maps with considering irrigated and rain-fed grape yield in El Nino and La Nina phases were drowned.
The results showed that NINO 1 index in April was the most effective of the ENSO indices on irrigated grape yield and PNA index in August had the highest correlation with rain-fed grape yield. Comparing the correlation between ENSO and grape yield indicated that the effect of ENSO on irrigated grape yield was more than the rain-fed yield (.633 against -0.534). The comparison of average grape yield in each of El Nino and La Nina phases showed that La Nina phase led to an increase of 24.5% in irrigated grape yield. The average yield for irrigated grape in La Nina was 11,822 kg/ha, and in El Nino was 9,490 kg/ha. While the average rain-fed grape yield during La Nina was 2,401 kg/ha, and during El Nino was 3,552 kg/ha, which indicated increasing rain-fed grape yield during El Nino to La Nina with a value of 47.9%. These results were in line with the studies of Zareabyaneh and Bayatvarkeshi (2012), Yousefi and Hajjam (2012), Khorshiddoust and Ghavidel Rahimi (2006) and Moron and Plaut (2003).
In total, the effects of the ENSO phenomenon on irrigated and rain-fed grape yield in the country was confirmed. The effect of ENSO on agriculture productions, however, depends on the type of plant, kind of cultivation and study area. It can be expected that the results of the ENSO effect on each agricultural plant are not generalized. Moreover, further study of each crop in each region is needed.

This study investigates land use suitability to find sustainable production areas in arid and semi-arid regions. Crops perform best in locations where climatic conditions meet their growing requirements. Factors such as elevation, slope percentage, slope aspect, soil type, vegetation cover and other climatic features affecting growth are crucial in identifying the most suitable areas for crops. The trend of land suitability classification includes evaluating particular areas in terms of their aptness for a specific use (Seyedi Shahivandi et al., 2013). The suitability of farms in western Iran were evaluated for rain-fed wheat, while the climate parameters were studied in accordance with the eco-physiological needs of wheat. Finally, the areas were classified into suitable, semi-suitable and non-suitable regions (Kamali, 1996).In this study, geographic information systems (GIS) and the Analytical Hierarchy Process (AHP) were applied to evaluate the feasibility of the agricultural lands of Ilam Province for cultivation of irrigated wheat (Triticum aestivum L.).
In this research, climatic parameters including temperature and rainfall were collected from seven synoptic stations of the region. Also compiled were data on important factors in zoning and environmental parameters including elevation, slope percentage, slope aspect, distance from river, soil texture, organic matter, the probability of the occurrence of appropriate temperatures during planting stage, the probability of the occurrence of the maximum temperature of 25°C during flowering, and the probability of the occurrence of temperatures of 30°C during the grain stage. First, the climatic data were extracted and environmental variables were obtained, then the maps related to these parameters were drawn. Furthermore, the weight of each factor was calculated using AHP with the layers integrated into the GIS environment. Kriging and IDW methods were applied for interpolation of environmental variables. Accordingly, a prospective map of irrigated wheat cultivation of the region was obtained. Lands were zoned into five classes: highly suitable, suitable, semi-suitable, non-suitable and highly non-suitable. Non-suitable lands seem to have extreme limitations and include those which should be used by farmers either rarely or never.
The results of AHP analysis showed that among the factors affecting land suitability, appropriate temperature during planting stage (0.31) had the highest weight and elevation (0.009) had the lowest weight. In the AHP model, the inconsistency ratio is about 0.0346. This showed that the comparisons of factors were absolutely consistent (Bertolini et al., 2006), and the relative weights were adapted for applying land suitability analysis in our study area.The results indicated that about 34.74% of lands were very suitable and 34.74% were suitable. 13.91% of lands had average capabilities of cultivation (semi-suitability). 16.04% of the lands were poor and 8.04% were very poor for irrigated wheat cultivation. The conclusion was that the role of each climatic and land parameter varies in different parts of the region. Moreover, it is possible to determine suitable regions for irrigated wheat using GIS and AHP method.
In this research, the most effective factors determining the suitability of land for wheat were the appropriate temperature during sowing, the probability of the occurrence of the maximum temperature of 25° C during flowering, elevation and slope percentage. The results of this research confirmed the capability of GIS in zoning.

In recent decades, erosion control, especially in rural pastures, has become one of the most important factors in retaining natural resources and increasing production. Increasing plant diversity increases the yield of forage, improves the sustainability of yield and reduces nutrient loss in the soil (Berendse et al, 2015). Diverse grasslands have more productive power. Some researchers point out that production and sustainability of ecosystems are not necessarily dependent on diversity, but also on the presence of key species and functional species (Guretzky et al., 2005). One way to prevent erosion is to create vegetation (Zuazo et al., 2008). This investigation has been conducted in order to survey the effects of planting 4 pasture plants with compositions of 1, 2, 3 and 4 plants.
This experiment was conducted in the year 1395 in the area near Lake Urumia. The experiment was conducted in a randomized complete block design with 16 treatments in each replicate and a total of 48 test plots in three replications. The studied treatments were Arrhenatherum elatius, Agropyron trichophorum, Bromus inermis, Festuca arundinacea and combinations of two, three and four of these species. Measurements were taken in the second year of the experiment. Statistical analysis was performed using MSTAT-C software. Duncan's test was used at a 5% probability level to compare the means. Excel charts were used to draw graphs.
Based on the results of this investigation, incorporating pasture plants in 3 and 4 compositions decreased erosion and runoff. Compositions with only 1 or 2 plants had less effect on erosion control. There were no significant differences between different plant compositions’ effect on hay yield, but the overall treatment of adding new plants did increase hay yield. All treatments of plant compositions affected the light interception rate by canopy. Based on results, the plantings increased the percentage of green area and the soil biological index, but decreased the contents of phosphorous, potash, and nitrogen and sodium. The highest nitrogen and phosphorus contents were observed in the 4*3*2*1 treatment and the highest potash was observed in the 3*2*1 and 4*2*1. The highest soil biological content was observed in the 4*3*2*1 treatment that was equivalent to a 73% increase in relation to biomass, canopy and soil nutrient. Similar results have been observed in the research of Idris et al. (2012) and Talaei et al. (2011).
Considering the results, it seems that the planting of pasture plants, and especially the triaxial and quadruple planting of pasture plants, in addition to increasing the yield of fodder, also leads to good erosion control because of the improvements to soil characteristics.

Lentils are one of the most important legumes in agricultural systems. Unfortunately, they compete poorly with weeds due to morphological characteristics. Weed control is therefore necessary to prevent yield loss. Yield is not generally affected by single-species weed interference but the presence of several different weeds leads to reduced crop yields (Song et al., 2017). Therefore, the study of multi-species weed interference provides useful information at the field level. Regarding the material mentioned in this study, the interference of multi-species weeds with lentil in natural field conditions was investigated.
This experiment was conducted on one of the lentil fields of the Agricultural and Natural Resources Campus of Razi University in Kermanshah. Sampling was systematically carried out in two stages in a network of regular points with 7-meter spacing using a 1-square meter quadrate. The geographic coordinates of each sampling point were recorded using a GPS device. The first stage of non-degraded sampling was done at the the pre-flowering stage of lentil and recorded density, height and the percentage of weed canopy and lentil canopy. The second stage of sampling was carried out precisely at the same points of the first sampling. The recorded variable in this stage included dry weight, weed density, and lentil yield. Relationship between weed density, canopy percentage and height with lentil yield were investigated using regression function.
The results showed that the regression relationships between weed density, canopy percentage and height with the lentil yield were significant (p≤0.01) and the function was able to express the variations of the dependent variable affected by independent variables. According to the model, lentil yield was significantly affected by weed density and canopy percentage (p≤0.01). Thus lentil yield decreased with increasing weed density and canopy percentage with decreasing coefficients of 0.62 and 0.67T respectively. Weed height did not show a significant effect on yield. Correlation coefficients between weed density and lentil yield indicated that there were significant negative correlations between three weeds of high density including Chenopodium album, Polygonum aviculare and Sinapis arvensis with lentil. In a study about the relationship between weeds and autumn wheat, researchers also reported that just three species of the seven weed species in the field had a negative effect on wheat yield (Noroozi et al., 2003). Mean comparison of lentil yield affected by different levels of weed canopy indicated that the effect of the weed canopy on lentil yield was significant. The highest yield was observed when the weed canopy was 0-10% and the lowest when the weed canopy was 60-70%. Investigating the relationship between weed canopy percentages and lentil yield showed that there were significant negative correlations between the four weeds including Sinapis arvensis, Picnomon acarna, Cerastium perfoliatum, and Convolvolus stachydifolium with yield. In general, the different levels of weed canopy percentage had a significant effect on lentil yield. The yield showed a decreasing trend with increasing weed canopy percentage. Research has also shown that plants are affected by increasing canopy levels of adjacent plants (Cressman et al., 2011).
The results of the study indicated the significant effect of weeds on lentil yield, so that increasing the density, weed density, and canopy can reduce yield. The results also showed that weeds can have negative or positive effects on crops. Among weeds registered in the field, only a few weed species had a significant negative effect on lentil yield.

Due to water shortages in Iran, it is not possible to increase areas of cultivation to supply the increasing demand for wheat (Nassiri Mahallati and Koocheki, 2009). There is a significant gap between the actual and potential yield (Koocheki et al., 2016). Specifying the potential and impact of each limiting factor in yield is important in determining alternative management strategies to reduce the gap (Varvani et al., 2016). This study was performed to evaluate the wheat yield potential and gap, and the relative contribution of climatic and management variables in Kerman Province.
For this study, meteorological and managerial information was extracted for all the regions of Kerman Province. Various wheat yield and growth parameters were simulated by CERES-Wheat model. The model was calibrated and validated using the extracted data from the designed experiments and previously conducted research from various regions of Kerman. Multiple regression was used to determine the relative contribution of each of the climatic and managerial factors on the yield potential and gap.
The results showed that CERES-Wheat model indicated an acceptable accuracy for simulating wheat growth and yield in Kerman. The 10-year average of wheat yield in Kerman ranged between 2 - 4.6 t/ha-1. The results of regression analysis showed that the relationship between water, N and P with actual yield was positive, and the highest R2 (0.97) was related to the amount of water consumed. Therefore the highest actual yield of wheat was assigned to the areas that consumed the greatest value of input. The potential yield was simulated at 6.6 - 8.2 t/ha-1 for different regions of the province. The analysis of regression confirmed that temperature is the most important factor affecting potential yield in the area and showed an inverse relationship with this parameter. The range of yield gap for different regions of the province varied from 2.33 t/ha-1 in Kahnuj to 4.84 t/ha-1 in Baft. In most parts of the province, water was the most important limiting factor for wheat yields, which included more than 50% of the yield gap in dry-climate regions. Replacing conventional cultivars with the high-yielding cultivars of Mihan for lower temperature regions and Chamran 2 for tropical regions had a significant role in improving actual yield and subsequently reducing the yield gap of these areas. The range of fertilizer contribution in yield gap was between 1.34 and 0.21 t/ha-1.
In general, the results illustrated that there is a remarkable gap between the actual and potential wheat yield in most regions of Kerman. Irrigation is the most important factor affecting the gap. It seems that the gap can be mitigated by identifying the limiting factors and appropriate management of water, fertilizer and cultivar.

Humic acid is a natural organic compound that results from the decay of organic soil matter. It is used to increase yield and product quality (Motagh and Nejad, 2014). It is the most active compound of soil and organic matter that increases plant growth and thereby yield (Nikbakh et al., 2008). The organic matter in humic compounds possibly contains material that would serve as a substrate for the production of physiologically active compounds (Zandonadi et al., 2013). This research was conducted with the aim of reducing the use of chemical fertilizers especially nitrogen and also extending strawberry cultivation in different climatic conditions.
In order to evaluate the effects of humic acid and nitrogen fertilizer on the biochemical and physiological properties of strawberry, a split-split-plot experiment in a randomized complete block design with three replications was carried out with foliar and soil applications of humic acid treatments, each with four levels (control, 2, 4 and 6 kg per hectare) and nitrogen fertilizer with three levels (50, 100 and 150 kg per hectare). In this study, levels of nitrogen were arranged in main plots and sub-plots and humic acid application c in sub-sub plots. Proline content, soluble sugars, starch, protein content, phenols in roots, cell membrane permeability, osmotic potential, and relative water content of leaves were measured.
Results and The results showed that biochemical interactions among nitrogen fertilizer, application method and the concentration of humic acid have significant effects. There were no treatments that did not affect the membrane integrity while relative water content and osmotic potential were influenced by the nitrogen and humic acid concentrations. Nitrogen and humic acid had a positive impact on traits. The treatments consisting of 100 kg of nitrogen and 2 kg of humic acid had the highest value for means of assessed traits. Application of humic acid to the soil showed a positive impact on biochemical traits compared to the spraying method. Increasing the solublity and release of nutrients by humic substances, the result is more absorption of the material by the roots and it was observed to be one of the main factors for the positive effects of humic acid on the amount of compounds in the root of the plant (Kauser and Azam, 1985º, Pinton et al., 1999.(
Integrated application of humic acid with nitrogen fertilizer, improved nitrogen uptake and use efficiency. The best results were obtained with an application of 100 kg nitrogen per hectare. It was also observed that a better result was obtained from the use of humic acid in the soil compared to the foliar spraying method. The application of 2 kg/ha-1 of humic acid and 100 kg of nitrogen per hectare is suitable for suitable strawberry yield and quality and increased resistance to various unfavorable environmental conditions.