فهرست مطالب سیدعلی غفاری نژاد

Organic matter is one of the important indicators of soil quality. Organic matter increases water retention in the soil and helps to transport water and air in the soil. Organic matter increases crop growth and provides nutrients needed by plants and soil microorganisms. The amount of soil organic matter in nature depends on factors such as climate, soil properties, and agricultural management, especially in the plowing stage. This is although in many cultivated and undisturbed soils, the amount of soil organic matter reaches a constant value after some time and becomes balanced.On the other hand, most regions of Iran the arid and semi-arid and have low organic matter. The chemical composition of organic matter is approximately 50% of carbon, 5.0 % of nitrogen, 0.5% of phosphorus, 0.5% of sulfur, 39% of oxygen, and 5.0% of hydrogen, and these values change from one soil to another. The management of compost and plant waste is one of the most essential aspects of soil fertility management in the direction of sustainable agriculture. The research results showed that organic matter and carbohydrates are two factors related to the stability of soil structure. Considering the role and effect of using organic fertilizers (from animal sources and urban waste compost) on the physical characteristics of the soil, it is necessary to improve the productivity of soil and water, changes in the physical characteristics of the soil in different crop management (rotation) in fixed plots and in several years to be reviewed and evaluated consecutively.

This research has been done to investigate the effect of applying organic manure from animal sources and urban waste compost in different and conventional crop rotations in fixed plots and also to investigate the changes in the physical characteristics of the soil due to the application of the following treatments in Alborz Province (at the research station of the Soil and Water Research Institute, Karaj) was implemented from November 2016. After planting wheat in 2016 and harvesting it in 2017, the land alternated with fallow. Wheat was planted again in the fall of 1997 and corn was planted in July 1998. In the fall of 1998, wheat was planted again and then the land was alternated with fallow. This research was conducted in the form of randomized complete blocks in five treatments and three replications in plots with an area of 200 square meters. The treatments include 1- no planting (T1), 2- control without fertilizer use (T2), 3- application of nitrogen, phosphorus, and potassium chemical fertilizers based on soil test (T3), 4- annual application of 20 ton/h of animal manure (T4) and annual application 20 ton/h of compost (T5). By taking soil samples from the surface layer, the physical characteristics of the soil, including field capacity, permanent wilting point, bulk density, final infiltration of soil, and aggregate stability of soil were measured in different treatments. Soil physical characteristics were measured after harvesting each product from a depth of 0-30 cm in three replicates. By removing the soil surface layer, the aggregate stability was determined by the wet sieve method.

Treatments T1, T2, and T3 did not show significant changes in field capacity. The mean values of the field capacity of these treatments T1, T2, and T3 are about 17.8% and the treatment using animal manure (18.1%) and compost (18.3%) increases the field capacity by about 1.0 and 2.0 %, respectively, compared to the average treatments without the use of organic fertilizers. The values of bulk density changes in the treatments for the desired periods are not significant and it indicates that there is no specific trend in each period due to the changes in soil surface conditions for the treatments. The values of changes in the soil aggregate stability values have become significant only in the treatments of organic fertilizer consumption (from animal sources and compost) in the desired periods. The soil aggregate stability index in the treatment of using compost and manure increased by 27 and 18%, respectively, compared to the average of treatments without fertilizer use (1.1 mm), which indicates the role of organic fertilizer use in increasing the aggregate stability. The average final infiltration rate in the treatments without using fertilizer is about 28.1 mm h-1 and the average rate of final infiltration in the treatments using manure and compost is about 32.7 and 33.3 mm h-1, respectively. The average rate of final infiltration in the treatments using manure and compost has increased by about 16 and 19%, respectively, compared to the average of other treatments.

According to the obtained results and the changes in the physical characteristics of the soil affected by the use of manure and compost in the cultivation periods, the role of the use of these materials in improving the physical characteristics of the soil is generally evident. The average bulk density of treatments T1 to T5 was equal to 1.47, 1.52, 1.54, 1.54, and 1.54 g cm-³, respectively, indicating a relative increase in bulk density in organic fertilizer treatments. The soil aggregate stability index in the treatment of using compost and manure increased by 27 and 18%, respectively, compared to the average of treatments without fertilizer use, which indicates the role of organic fertilizer use in increasing the aggregate stability. The average final infiltration rate in manure and compost treatments has increased by about 16 and 19%, respectively, compared to the average of other treatments, which indicates the effect of manure and compost application in increasing the final soil infiltration rate. Because for each crop rotation, the soil is subjected to tillage operations, therefore destruction of the surface layer of the soil (with more organic matter) and as a result intensifying the activity of microorganisms, from the effect of organic matter on the characteristics, the physical properties of the soil are reduced and it even causes that no special trend can be seen in the physical characteristics of the soil during the cultivation periods. Therefore, it is necessary to use a set of management strategies to improve the amount of organic matter or the physical characteristics of the soil.

This study was conducted to evaluate the relationship between leaf iron and some easily-available soil properties in citrus orchards in the southern region of Kerman province by artificial neural network modeling and stepwise regression. For this purpose, 40 orchards were selected from the study area and the physical and chemical properties of soil and iron in the plant leaves were measured. Using artificial neural network in different models with different data from soil properties as input and leaf iron as output, the ability of these models to predict leaf iron concentration was evaluated. The results showed artificial neural network with variables of organic carbon, pH, clay, phosphorus, TNV and electrical conductivity with explanation coefficient of 0.86 and 0.81 and root mean square error (RMSE) of 14.60 and 20.13 mg.kg-1 for data Training and testing were the best models in estimating leaf iron. Comparison of regression and neural network models in the test data showed that the neural network had a higher accuracy with an explanation coefficient of 0.81 than stepwise regression with an explanation coefficient of 0.2. The amount of RMSE in the neural network also improved and increased from 27.72 mg.kg-1 in the stepwise regression model to 20.13 mg.kg-1 in the neural network. Artificial neural networks have been able to predict the iron in plant leaves based on the easily-available properties of the soil, so that by choosing organic carbon as the input of the first model to the best model by selecting organic carbon, pH, clay, phosphorus, TNV and electrical conductivity, model accuracy increased.

Plant growth and production models are great tools to study variation of irrigation and fertilizer application and those impact on plant performance. Due to the fact that applying different scenarios of fertility and irrigation in field conditions is time consuming and costly, the use of plant models is a good solution for simulating and estimating the crop yield in different conditions. The accuracy of the results obtained from the simulation models depends on the accuracy of the data required by the model and if the input data is measured and determined accurately, the model will be applicable in different conditions after calibration and validation. Due to the great effect of using different types of chemical and organic fertilizers on plant growth and yield, it is necessary to compare and evaluate changes in wheat yield using chemical and organic fertilizers in order to improve soil and water productivity. Considering the different management scenarios of fertilizer use in DSSAT application model and the role of fertility in plant performance and also that the efficiency of this model in simulating plant performance in different management scenarios of chemical and organic fertilizer application is not clear, so in this regard the efficiency of DSSAT application model In order to simulate wheat grain yield in different application of fertilizer (chemical-organic) in order to increase yield and recommendations were studied and evaluated.

This research was carried out in the research farm of Karaj Soil and Water Research Institute at 35 and 50 north latitude and 55 and 30 degrees east longitude. In terms of climate, this region is one of the hot and dry Mediterranean climates with hot and dry summers and cold winters. 4 fertilizer application treatments in a randomized complete block design in 3 replications including control, without fertilizer application (T0), application of chemical fertilizers (nitrogen, phosphorus and potassium) based on soil test (T1), application of 20 tons per hectare of waste compost with fertilizer application Chemical nitrogen at 75% and phosphorus and potassium at 50% recommended based on soil test (T2), application of 20 tons of waste compost fertilizer (T3) were considered. In this regard, 4 plots with an area of ​​200 square meters were selected and after tillage operations including plowing,  disc and land preparation, wheat was cultivated. The aim of this research was to investigate the efficiency of the DSSAT model in simulating wheat yield under different management conditions of chemical and organic fertilizer application.

Results showed that measured and simulated wheat grain yield in the control treatment (without fertilizer application) were 2.3 and 2 tons per hectare, respectively, and the corresponding measured and simulated values in chemical fertilizer application (NPK fertilizer application based on soil test) were 3.9 and 4.2 tons per hectare respectively. In terms of compost application at a rate of 20 tons per hectare, the average simulated and measured grain yield was about 3.1 and 2.9 tons per hectare, respectively. Flowering and ripening phonological time of wheat were 192 and 227 days after sowing, respectively, which is in close agreement with the simulated values, which are 190 and 230 days, respectively. RMSE, NRMSE, EF and d of DSSAT model for grain yield were 0.38, 0.13, 0.57 and 0.93, respectively, which indicates the high and appropriate performance of DSSAT(CERES) model in simulating wheat grain yield in different conditions of fertility managements based on application of chemical and organic fertilizers.

Due to the fact that applying different scenarios of fertility and irrigation in field conditions is time consuming and costly, so the use of plant models is a good solution for simulating and estimating the crop yield in different conditions. The results of the statistical indices showed that the appropriate performance of DSSAT model in simulating wheat grain yield in different conditions.

Tomato is one of the most important crops in Bushehr Province and its out-of-season cultivation has doubled its importance. Achieving optimal performance is possible by balancing the nutrients. Nutritional indicators are used to diagnose nutritional disorders and the subsequent optimal use of chemical fertilizers. This research was conducted by selecting 79 tomato farms from different parts of the province with different yields in two years (2018-2020). Soil samples of selected fields were taken from a depth of 0 to 30 cm and leaf samples were taken at the beginning of fruiting. The average yield of each field was measured at the end of harvest and laboratory analysis of samples was performed by standard methods. The experimental data were fitted with compositional nutrient diagnosis model (CND). The studied farms were divided into two groups, low and high yields, with a cut-off yield of 86.7 tons per hectare, based on the highest yield and calculations according to the CND method. Reference numbers of leaf nutrient concentrations were calculated as 2.79±0.202, 0.460±0.174, 2.62±0.143, 2.57±0.195, 2.08±0.225, -2.20±0.134, -3.10±0.134, -3.74±0.200, -4.34±0.250, and -3.25±0.173 for N, P, K, Ca, Mg, Fe, Mn, Zn, Cu, and B, respectively. Also, the optimal leaf nutrient concentrations range for 86.7 tons per hectare of yield were N: 3.38±0.94, P: 0.324±0.074, K: 2.77±0.397, Ca: 2.63±0.423, Mg: 1.64±0.394 percent, and for Fe: 221±24.6, Mn: 90.9±14.8, Zn: 48.3±11.1, Cu: 27.3±8.40, and B: 79.3±17.5 mg.kg-1. Potassium, N, and Zn deficiency as well as excess amount of Mg, Ca, and Mn were identified as the imbalanced nutrients in tomato production in Bushehr Province. This can be due to the calcareous nature of the soil and unbalanced use of chemical fertilizers.

Iran is one of the most important countries in citrus (oranges) production. Citrus fruits are grown in different soils with a wide range of physical, chemical and fertility properties in the country, although some restrictions in the cultivated lands cause yield loss. In this regard, the present study was conducted to investigate the effect of physical, chemical and soil fertility characteristics on citrus yield in important areas under cultivation, the regression relationships of characteristics with yield, and the rating of soil and land parameters.

The 138 oranges orchards (118 orchards for rating and 20 orchards for validation) were selected in Fars, Mazanderan, Kerman and Guilan provinces. In each garden, a questionnaire was completed, a soil pedon was studied and soil samples were taken to carry out the appropriate physicochemical analyses. The selected soil and land characteristics were soil salinity (EC), exchangeable sodium percentage (ESP), pH, gypsum content, soil calcium carbonate (TNV), organic carbon (OC), clay, sand, silt, gravel, and soil available phosphorus and potassium contents. From the whole obtained data, 20 data were considered for validation purpose and the remaining data were used for modeling based on stepwise multivariate and simple regression methods. In these equations, the relationship between yield, as dependent variable, with soil and land characteristics, as independent variables, was investigated. Finally, land characteristics rating was obtained by the FAO method and the proposed crop requirements table was evaluated using the validation dataset.

The results of descriptive statistics analysis showed that the variance values for available potassium, sand, clay, gravel and TNV were high and for pH and OC and gypsum were negligible. Therefore, most soil properties have a wide range of variation which could be related to the fact that oranges are grown in a wide range of soil types. The value of TNV varied between 10 and 33.3%. The presence of carbonate in soil reduces the availability of macro- and micronutrient elements in direct and indirect manners. The average of EC in the studied orchards was 5.4 dS.m-1. Minimum, maximum and average of ESP were 1.7, 28 and 10.7, respectively. The lowest and highest salinity and sodicity were observed in Mazandaran and Kerman soils, respectively. Maximum, minimum and average percentage of gypsum were 12, 0.36 and 3.54%, respectively. The highest amount of gypsum was observed in Bam and Shahdad regions of Kerman province and the lowest gypsum content was observed in Mazandaran and Guilan provinces. The soil pH varied from 6.63 to 8.8 with the average of 7.8. The soil OC values were between 0.05 and 3.53% and its average was 0.89%, showing the fact that the most studied soils were poor in organic matters. The average of soil available phosphorus and potassium in the studied orchards for citrus was less than the critical level. The average, minimum and maximum of available potassium were 224, 100 and 360 mg.kg-1, respectively. The mean, minimum and maximum amounts of available phosphorus were 21.6, 8 and 45.9 mg.kg-1, respectively. According to the multivariate regression model, among soil properties, EC, ESP, TNV, gypsum, gravel, available phosphorus and potassium were selected by the model. The determination coefficient of the model was 0.95, indicating that these properties have the greatest effect on citrus yield. Simple regression equations demonstrated that TNV, gypsum, EC, ESP, sand, clay, gravel, available potassium and phosphorous had the highest correlation (R2 > 0.6); and soil OC and pH had the lowest correlation (R2<0.2) with yield. The equations also revealed that soil EC, ESP, gypsum, TNV and gravel percentage had the greatest effect in yield loss, and soil organic carbon, absorbed phosphorus and potassium had the greatest effect on increasing citrus yield. As stated in equations, reported permissible and critical thresholds for effective soil properties on citrus yield, were 2.4 dS.m-1 for EC, 5 for ESP, 1.5% for gypsum, 20% for TNV, 22 mg.kg-1 for available phosphorus, 280 mg.kg-1 for available potassium, 110 cm for soil depth, and >2 m for groundwater level. Finally, evaluating the proposed crop requirements table with validation dataset fitted between citrus yield and soil index, resulted in the determination coefficient value of 0.79, denoting the acceptable accuracy of proposed table.

Overall results showed that the main land limiting characteristics for orange production were soil salinity and sodicity, high amount of soil calcium carbonate and gypsum. Among unsuitable physical and fertility properties of soil, salinity and sodicity are the most effective factors affecting yield reduction. Consequently, proper management practices such as introducing cultivars compatible with these soil conditions, soil remediation and leaching operations to reduce soil salinity and sodicity are necessary. Furthermore, in most areas under orange cultivation such as Fars and Kerman provinces, the soil calcium carbonate content is more than the critical level for plant growth. In addition, the averages of soil available phosphorus and potassium were less than the critical levels, which should be considered for nutrient management of orchards. The proposed table of crop requirements seems to be accurate enough to conduct land suitability studies for orange varieties, especially cultivars grown in the north and south of the country.

The global food crisis due to the plunging production and rising prices in recent years, particularly in 2008, calls for solutions to ensure food security in most developing countries. The situation is worsened by the rising demands for food and water as consequences of the population explosion and cropland decline in these countries. By 2050, the world population is projected to rise to 9.2 billion and Iran will be one of the top 20 most populated countries in the world. According to a FAO report, agricultural production must be increased by about 70% during the years running up to 2050 in order to meet the projected food requirements. Finally, study has shown that more than 60% of the present population in Asia (particularly in South and South-West Asia) and a quarter of the African population suffer from malnutrition. The present paper explores the literature on sustainable land management and some of its components such as conservation agriculture, proper crop rotation, and proper management of soil organic content as the cornerstones of agricultural production toward food security.

Improved product quality, sustainable cultivation systems, and reduced production costs are among the objectives of modern agriculture despite the global and local climate changes that have faced crops with a variety of stresses. Biostimulants seem to be capable of helping plants in their struggle against these stresses toward the goals of modern agriculture. These compounds include humic substances, seaweed extracts, amino acids, microbial inoculants, and minerals such as useful elements and inorganic salts including phosphates and antiperspirants. While application of biostimulants has witnessed a dramatic increase in the world and in Iran over the past few years, it must be noticed that they might have different effects on different species and even on different varieties of a given plant species. Their application for agricultural and horticultural purposes must, therefore, be duly modified in accordance with local and regional research findings. It is the objective of this paper to provide a better understanding of plant biostimulants based on scientific findings and practical experience in agriculture and horticulture. It will be shown that plant biostimulants are capable of improving crop production, enhancing plant resistance to abiotic stresses, and elevating crop quality. Future research in this area should aim at the determination of the mechanism(s) underlying the activities of such materials since a better understanding of their activities and effects will be necessary for achieving sustainable agricultural production systems.

The importantroleof soil fertility in food production warrants long-term monitoring to track changes in soil properties. Long-term soil tests are field trials conducted onpermanent plots that are regularly sampled to quantify soil changes over time scales of decades. This article intends to introducelong-term soil fertility testsusing permanent plots aimed atcollecting information on the effects of long-term soil fertility management practices on soil properties. Efforts are also made to develop a general methodologyfor future research. Mosttests on permanent plots in the past mainly focused on soil carbon concentrations over long-term periods to find that continuous applicationof organic matter toarable land led not only to improved soil physical and chemical properties but also toits enhanced biological activity.This is while organic modifiers, especially when improperly applied,may reportedly contributeto environmental pollution. So far few long-term soil tests have been conducted in Iran,most of which havemainly determinedthe residual effects of fertilizers containing single nutrient elements such asphosphorus, zinc, orpotassium. This lack of consistent tests and the scant information thus far obtained necessitate planningfor drastic and targetedtestson Iranian soils.Evaluation of long-term experiments revealed that it will be necessary to employsuch variedland management practicesof livestock manuring, proper crop rotation, and avoidance of severe tillage to enhancecarbon sequestration in soils. Finally, it was observed that the use of chemical fertilizers combined with organic and biological agentsis favorable to increased agricultural production and enhanced sustainable soil fertility.

Due to the importance of sesame as an oil crop, in order to investigate the effects of different levels and application time of nitrogen (N) on quantitative and qualitative yield of this crop, an experiment was conducted in two successive years from July 2009, on JL-13 variety in Jiroft. Experimental design was factorial with Completely Randomized Block Design (CRBD) with three replications. Treatments were 5 levels of nitrogen (0, 25, 50, 75, 100 kg N ha-1) as urea and split application of N (two splits: before planting and before flowering; and 3 splits: before planting before flowering before seed pods). Every plot contained four planting rows (five meters length). Spacing between two rows and plants were 50 and 10 cm, respectively. Two central rows were cut for yield and yield components determination. N absorption and nitrogen agronomic efficiency were also measured. Results showed that the effect of N splitting on yield, yield components, and oil content of sesame was not significant. Nitrogen application increased seed yield, yield component, and N agronomic efficiency significantly. Application of 75 kg N ha-1 resulted in the highest seed and oil yield, i.e. 1137 and 602 kg ha-1, respectively. Thus, under the condition of this experiment, application of 75 kg N ha-1 in two splits is recommendable.

The potential of Jiroft region has resulted in progressive development of greenhouse culture. In sustainable agricultural systems, organic manures have special role in increasing yield and soil fertility. To investigate the quantitative and qualitative responses of greenhouse cucumber to sources and levels of organic manures and their effect on some soil properties in Jiroft region, a factorial experiment was conducted, based on completely randomized blocks design, with four organic manure levels (10, 20, 30 and 40 ton/ha), four organic manure sources (municipal solid waste compost, cattle, poultry, and sheep) and three replications. One month after the start of fruit harvest, leaf sampling was performed and concentration of nutrient elements was analyzed. Soil samples were taken from each plot after the fruit harvest and bulk density, electrical conductivity, organic carbon and concentration of available nutrients were determined. Results showed that concentration of nitrogen, potassium, zinc and copper in leaves was not significantly affected by sources and levels of organic manures. Poultry manure significantly increased leaf-phosphorous concentration compared to other manure sources. The highest concentration of iron was observed in sheep manure and compost treatments and the highest concentration of manganese was observed in compost treatment. Based on the yield results, using 20 ton/ha of poultry manure is recommendable for production of greenhouse cucumber in the Jiroft region.

To investigate the effects of different methods of seed bed preparation on yield of greenhouse cucumber, a two-year long experiment was conducted as a randomized complete block design with four replications in Jiroft from 2004. Different methods of seed bed preparation were as follows: 1) ridge with 20 cm height and 50 cm width and 2 plant rows with 40 cm distance, 2) furrow with 20 cm depth and 50 cm width and 2 plant rows inside, with 40 cm distance, and 3) planting on flat area with 40 cm distance. The results showed that the effect of planting bed on yield of greenhouse cucumber was significant. Furrow and flat area increased yield significantly, compared to the ridge treatment. Analysis of yield components such as plant height, number of pickling fruits, number of leaves, photosynthetic area and number of flowers showed that they are all correlated with fruit yield. The number of pickling fruits was significantly more in furrow and flat area than in ridge treatment. The height of cucumber plants on flat bed was significantly higher than that of the other treatments. The number of leaves and photosynthetic area of plants on flat bed were significantly greater than those in the other treatments. The least dead plants due to fungi disease were observed in ridge treatment. In view of yield and its components under the condition of this experiment, it can be concluded that flat area and furrow treatments are better than ridge treatment.

Date palm bunch wilting and drying disorder has been the most important problem of Iran palm producers in recent years. Reduction of relative humidity and increased air temperatures are known as the major causes of this disorder. Calcium decreases plants injuries due to environmental stress, though its movent in plants is slow. Increase in cell sap concentration with calcium injection can increase cell resistance when temperature increases suddenly, thereby preventing fruit injury. In order to investigate the effect of calcium salts trunk injection on this disorder, an experiment was conducted since 2003, using four replicatios of a randomized complete block design with 7 treatments: Check, injection of saturated solution of calcium sulfate, %1 solution of calcium nitrate and chloride in two times (second half of Feb and Apr). Every plot contained one tree in two garden that had been infected with this disorder in recent years. A hydraulic pump was used to inject the solution into tree trunks. Results showed three different groups of disorder injury. The first group consisted of the check (76.3% injury), calcium chloride, and sulfate treatments, indicating that these two salts had no significant effect on reduction of disorder injury. The second group was injection of calcium nitrate in the second half of Feb that had significantly decreased disorder injury in contrast to the first group (48.5 %). The least disorder injury was observed in the two-stage injection of calcium nitrate (38.5%).Correlation of mean leaf calcium concentration and disorder injury was significant in one of the experimental sites (R=-0.88**).Calcium concentration of bunch and leaf increased significantly with high pressure injection method, indicating that, in similar conditions, this method can be used to provide nutrients to the palm trees.

In order to investigate mineral manganese forms and their relations with plant responses, 22 soil samples from Fars province (0-20 cm) were in a greenhouse experiment filled in 3 liter pots, and soybean (Glycine max (L.) merr.,CV.Williams) was grown for 7 weeks. Chemical forms of manganese were determined in soils by warden and Reisenauer sequential extraction method (readily soluble, weakly adsorbed, carbonate bound and oxide bound extracted with Ca(No3)2, Ca DTPA +Na2B4O7, HNO3 and NH2OH. HCl, respectively) after harvesting the plants. Results showed that the amount of Mn in different forms was in the following order: Carbonatic Mn >Mn Oxides >Weakly adsorbed Mn > Soluble Mn. Regression equations between soil properties and Mn forms showed a significant correlation between calcium carbonate equivalent and carbonate bound Mn. Significant correlation between Carbonate bound Mn and concentration of Mn in the aerial part of soybean showed that this fraction plays an important role in plant nutrition.