نشریه مهندسی زراعی
سال چهل و ششم شماره 2 (تابستان 1402)

Plant growth and crop productivity may be adversely affected under unfavorable environmental conditions, such as a lack of organic matter in the soil. To counteract the negative impacts of these challenges, a unique strategy is required. The paucity of organic inputs, which is common in conventional agricultural production, can lead to soil degradation, erosion, and loss of soil organic matter, which are unfortunate consequences. Soil organic amendments have been shown to have beneficial effects on crop production and a wide range of soil properties in agricultural systems. However, the limited availability of phosphorus (P) in soil can significantly restrict crop growth and productivity, particularly in maize crops. Adequate P supply has been found to enhance early maturity, crop quality, and yield. However, the prolonged use of chemical fertilizers such as NPK has been found to have adverse effects on soil fertility and crop quality. As a result, the combined application of organic and chemical fertilizers has been proposed as an effective approach compared to the single application of organic or chemical fertilizer alone. Therefore, this study aimed to assess the potential benefits of using compost and Triple Super Phosphate fertilizer (TSP) application on the chemical and biological properties of soil, as well as the properties of forage maize (cv. SC704), in loess soil.

A factorial experiment was conducted using a completely randomized design with three replications. A total of 36 samples were performed in two separate cultivated and incubated experiments. A pot experiment was conducted to invwstigate the effects of simple and enriched compost, containing urea and Streptomyces, and varying amounts of TSP fertilizer (0, 10, 40, and 100 mg/kg), on soil properties and maize plant growth. In addition, an incubation experiment was conducted to measure the effects of the same treatments on soil microbial biomass and activity. The effect of treatments were analyzed as factorial under a completely randomized design. The biomass of maize plants was measured at the time of harvesting (the time from planting to harvesting of forage maize was 80 days). Some parameters such as available phosphorus, substrate-induced respiration, microbial biomass carbon, and some enzyme activity (acid phosphatase, alkaline phosphatase, catalase and urease) were measured in soil.

The findings of this study indicated that the application of compost and TSP fertilizer had significant effects on plant biomass. Specifically, compost application led to an increase in microbial biomass carbon and enzymes activity (acid phosphatase, alkaline phosphatase, catalase and urease) in the soil, ultimately promoting plant growth. Moreover, the combined application of compost and TSP fertilizer increased the availability of phosphorus, substrate-induced respiration, and microbial biomass carbon in the soil. Based on the findings, the combined application of TSP and compost resulted in further increases in substrate-induced respiration (63-168%), microbial biomass carbon (72-167%), available phosphorus (29-103%), and enzyme activity (acid phosphatase (4-21), alkaline phosphatase (14-34%), catalase (13-32%), and urease(54-159%)) compared to the application of each amendment alone. This suggests that the addition of both TSP and compost promotes the availability of easily accessible nutrients for microbial growth and soil enzymes (acid phosphatase, alkaline phosphatase, catalase and urease) activity. The highest amount of available phosphorus, microbial biomass carbon, substrate-induced respiration, catalase activity and urease activity in cultivated soil (23%, 270%, 93%, 68%, 1.8%, respectively) and incubated soil (18%, 243%, 90%, 53%, 1.2%, respectively) were observed in C2P3 treatment. The results also indicated that the enriched compost+TSP treatment led to the highest substrate-induced respiration and microbial biomass carbon, followed by simple compost+TSP, enriched compost only, simple compost only, TSP fertilizer only, and the control. The increase in enzyme activity (P<0.01, r=0.90), and available phosphorus (P<0.01, r=0.60) in the soil positively influenced plant growth. Specifically, the simultaneous application of compost and TSP had a greater effect on maize plant biomass. The highest root biomass (2.80 g), stem biomass (10.4 g), and leaf biomass (2.27 g) were observed in the enriched compost and 100 mg kg-1 TSP treatment, which differed significantly from the other treatments.

The results of this study demonstrated that the addition of compost and TSP to loess soils can promote microbial biomass carbon, substrate-induced respiration, enzyme activity (acid phosphatase, alkaline phosphatase, catalase, and urease), available phosphorus, and maize plant growth. Moreover, the use of compost can protect soil microbial and enzymatic activities in loess soils. Thus, the simultaneous application of enriched compost with TSP can reduce the use of chemical fertilizers and their negative environmental impacts.

The number of environmental variables used in digital soil mapping has increased rapidly, which has made it a challenge to select and focus on the most important covariates. No environmental covariates have the same predictability in modeling, and some covariates may introduce noise that reduces the predictive power of the models used. On the other hand, it is beneficial to identify all environmental variables to obtain spatial information that can improve predictions. In this regard, the feature selection algorithms help reduce the dimensions of the predictive model by identifying the associated covariates. Therefore, this study aims to investigate different feature selection algorithms in the selection of auxiliary variables and evaluation their effect on the predictive model.

The area under study is a part of Darab city in the southeast of Fars province with an area of about 31000 hectares. In the study area 140 profiles were determined and excavated according to the diversity of geomorphological units and thus the type of soils. After excavating the profiles and checking the morphological characteristics of each soil profile, a sufficient amount of soil samples were collected from the genetic horizons and transported to the laboratory for further analysis. Some of the physical and chemical parameters of soils were tested using accepted techniques after air drying and passing through a 2 mm sieve. Finally, all profiles up to the great group level were classified using the U.S. Soil Taxonomy based on the data collected from field observations and the outcomes of laboratory analysis. Environmental variables include the parameters derived from the Digital Elevation Model, Landsat 8 images, geology and geomorphology maps of the study area. All parameters were derived using ArcGIS, SAGAGIS and ENVI softwares. In the present study, four different feature selection techniques including Variance Inflation Factor (VIF), Principal Component Analysis (PCA), Boruta and Recursive Feature Elimination (RFE), were used to identify an optimal set of covariates for predicting spatial classification of soil classes at the great group level. In addition, a Random Forest model (RF) with 10-fold cross-validation and the 5-repeat method, was used to compare different feature selection strategies in soil class mapping. The comparison of different feature selection techniques in estimating soil classes, was based on the evaluation criteria of accuracy and Kappa coefficient between observed and predicted values.

The results showed that the prediction accuracy increased by using variables selected with different feature selection methods compared to using all variables in the model. In addition, the improvement in predictive performance is different between the four types of feature selection. The VIF and PCA methods had the highest and lowest accuracy index and Kappa coefficient, respectively. The Boruta method, with the lowest number of variables, improved the model's performance after the VIF method. However, the Kappa coefficient showed poor agreement between predicted and observed values for all approaches. The imbalance of soil classes could be a reason for decreasing the accuracy index and Kappa coefficient. However, the random forest model, with and without feature selection methods, identified all soil great groups in the study area. Therefore, it can be concluded that the Random Forest algorithm is a very powerful technique for spatial prediction of soil classes in the study area. Although the performance of the model varied using different feature selection algorithms, the predicted soil maps had similar spatial patterns. Based on the prediction of model with the variables selected by the VIF, the resulting map indicates that Ustorthents soils are mainly located in high altitude regions with steep slopes. Haplustepts, Calciustepts, and Calciusterts great groups have developed in places with low to medium slopes. Haplosalids have developed downstream of the salt dome. Great groups of Ustifluvents were discovered in fluvial sedimentary plains. Endoaquepts were found in the floodplains, which had the smallest area on the predicted map.

Overall, the findings indicate that the feature selection methods can utilize significant dependencies among relevant covariates to predict soil classes and to improve modeling accuracy. In the current study, the environmental factors, obtained from the Digital Elevation Model, were selected as key variables, showing the importance of topography and morphology in the classification of soil types in the area. Although the selected variables improved the performance of the model, the prediction of soil classes was random. This could be attributed to the imbalance of soil classes.

Nickel (Ni) is a fundamental micronutrient in plants but hampers plant growth and metabolism at elevated levels in the soil. Ni toxicity to plants is manifested mainly by the decrease in germination efficiency, the inhibition of growth and root branching, damage to the photosynthetic apparatus, and the induction of oxidative stress. In recent years, the use of arbuscular mycorrhiza (AM) has gained importance for its role in enabling plants to tolerate Ni toxicity. However, information about their effectiveness in alleviating Ni stress is scanty. The process of element transport in plants may be assumed to be different among heavy metal concentrations in the substrate. Consequently, whether AM fungi enhance the metal transport to shoots (phytoextraction) or immobilize them in the roots (phytostabilization) mainly depends on metal concentration in the substrate. Moreover, Ni has been reported to compete with other micronutrients for absorption sites, which would trigger different changes of elements concentrations. The aim of this study was to investigate the role of AM fungus in alleviating Ni stress and its possible function in plant nutrition.

In this study, the effects of mycorrhizal inoculation of corn plants with Claroideoglomus etunicatum on alleviation of Ni impact on plant were evaluated. Some growth characteristics of the plant, phosphorus content, micronutrients (iron, zinc, and copper), concentration of nickel in shoot and root, and Bradford reactive soil glomalin (BRSG) were assessed. Accordingly, a two-factor experiment (AM inoculation × Ni levels) in completely randomized design was done. The factors included the different concentrations of nickel (control (Ni0), 50 (Ni50), 100 (Ni100) and 250 (Ni250) mg kg-1), and the levels of fungal application (control without inoculation (NM) and inoculated with C. etunicatum (AM)). Plants were grown in the greenhouse for 90 days and then the growth parameters were recorded. The concentration of phosphorus was measured spectrophotometrically and the concentration of iron, zinc, copper, and nickel in digested plant samples was determined by ICP-OES. Bio-concentration factor and translocation factor were also calculated. The colorimetric method was used to quantify Bradford-reactive soil glomalin. The Bradford protein assay was utilized to determine the concentration of easily extractable and total Bradford-reactive soil glomalin using bovine serum albumin (BSA) as a standard.

Increasing the nickel concentration in soil decreased the dry weight of root and shoot, and this decrease was significant in both inoculated and non-inoculated plants at Ni250 treatment (p≤0.05). Plants inoculated with AM fungus showed significantly higher height and dry weight of shoots than plants without inoculation (p≤0.05), but the effect of mycorrhizal inoculation on the dry weight of roots was not statistically significant. The effect of nickel on the colonization percentage of roots and easily extractable Bradford-reactive soil glomalin (EE-BRSG) was significant. EE-BRSG was higher at all levels of nickel in inoculated plants than in non-inoculated ones. Moreover, with the increase of nickel concentration in soil up to 100 mg Kg-1, total Bradford reactive soil glomalin (T-BRSG) increased. The concentration of phosphorus in the shoots and roots of inoculated plants was higher than in non-inoculated plants. Mycorrhizal inoculation significantly increased the concentration of zinc and copper in the aerial part. Moreover, nickel treatment did not show a statistically significant effect on the concentration of copper in the aerial part and iron in the roots. Inoculation with AM fungus showed a significant impact on the nickel concentration of the shoots and roots, and the concentration of nickel in the roots of inoculated plants at Ni250 level was significantly higher than plants without inoculation by 29% (p<0.05). Mycorrhizal plants had lower nickel concentrations in the aerial part at Ni100 and Ni250 by 30% and 33% respectively, compared to the NM plants. The translocation factors in inoculated plants at Ni100 and Ni250 levels were significantly lower than that in non-inoculated plants, which indicates the role of fungi in preventing the transfer of nickel to the aerial parts and its accumulation in the roots. Moreover, inoculated plants in the Ni100 and Ni250 treatments showed a significantly lower bio-concentration factor by 36% and 22%, respectively, compared to non-inoculated plants.

The results showed that AM colonization can help to reduce the toxicity of nickel by increasing plant growth and uptake of phosphorus, zinc and copper. AM colonization had a prominent impact in preventing the nickel transfer to the aerial parts and its accumulation in the roots. It seems that AM fungi can be used for phytostabilization of heavy metals in soils.

Soil classification categorizes soils into different classes on the basis of their distinguishing characteristics and provides a structured conceptual framework for describing and understanding soil properties. There are two soil classification schemes that are generally regarded as having worldwide application, the Soil Taxonomy (ST) and the World Reference Base (WRB) which are also popular in Iran. These systems of classification consider diagnostic horizons and factors of soil formation as the basis of classification. The aim of this study was to determine the classification of soils of tobacco farms in the Talesh County of Guilan Province based on ST (2022) and WRB (2022) according to the soil diagnostic characteristics, then comparing two systems for soils of tobacco farms to determine the ability of better description of soils by these two systems of soil classification.

Talesh County is considered to be the most important tobacco production areas in Guilan Province and IRAN. The most extensive area of tobacco cultivation in Guilan Province is located in this County and in Jokundan and Mountain districts. The study area has a humid climate with cold winter and hot summer. The mean annual temperature is between 15.6 and 17.2 degrees Celsius and the annual rainfall is between 786 and 1370 mm. Based on the map of moisture and temperature regimes of Iran  and with the help of jNSM software, the moisture and temperature regimes were determined as Udic and the Thermic respectively. In the study area twenty pedons (eight pedons for Mountain and twelve pedons for Jokandan) were described and the morphological characteristics of the pedons layers were studied in the field according to the Soil Survey Manual. Then, the soil of each horizon was collected, air-dried, and sieved by passing through a 2 mm sieve before analyzing the properties of the soil. Soil pH, Electrical Conductivity, Texture, Organic Carbon, Calcium Carbonate Equivalent, Cation Exchange Capacity and Base Saturation were determined in all the samples according to Methods of Soil Analysis. Soils were then classified according to classification criteria of ST (2022) and WRB (2022) systems. For showing changes of tobacco farms soils, eleven pedons were selected as representative pedons and the reference between ST (2022) and WRB (2022) was established for tobacco soils at the level of the subgroup or secondary classification unit.

The results revealed that according to ST (2022), representative pedons of Mountain district were classified as Entisols, Inceptisols and Mollisols orders while, Jokandan had Entisols, Inceptisols, Mollisols and Vertisols pedons. WRB (2022) Reference Soil Groups (RSGs) for Mountain was Regosols, Umbrisols and Phaeozems and for Jokandan district were Fluvisols, Cambisols, Phaeozems and Vertisols. At lower levels of classification, ST (2022) uses climatic data as soil moisture regime whereas WRB (2022) does not use. Therefore, the suborders or great groups of all soils were separated based on the Udic moisture regime. Finally, representative pedons were classified as Typic Udorthents, Mollic Udifluvents, Oxyaquic Udifluvents, Typic Humudepts, Dystric Eutrudepts, Typic Hapludolls, Fluventic Hapludolls, Aquic Argiudolls, Typic Argiudolls and Aquic Hapluderts at great group level.
In regard to the WRB (2022), in the secondary levels, each section had its own series of principal and supplementary qualifications. Among those, the principal qualifications were mainly Eutric, Cambic and so on, and the supplementary qualifications were mainly Clayic, Loamic, Siltic, Humic and so on.

It was found that when compared with ST (2022), the WRB (2022) had stronger abilities to distinguish soil properties for tobacco cultivation which was mainly reflected in the following aspects: 1- The climate-related soil moisture regimes were generally used to classify the suborders in ST (2022). It was found that the soil moisture status of all pedons was Udic, as well as the fixed format of naming soils in ST (2022), Therefore, divisions were limited in the suborders, 2- The flexibility of WRB with the utilization of multiple qualifiers brings out more sensitivity in reflecting soil characteristics in the soil name if compared with Soil Taxonomy. Also, the emphasis put on soil morphology compared with laboratory data makes the system suitable for application in areas with rather modest facilities, 3- The existence of the Mollic or Umbric horizon in pedons is well defined by WRB (2022), while this issue is ambiguous in ST (2022), 4- WRB (2022) have not fixed naming formats, the number of secondary levels qualifiers of the WRB system could be increased or decreased with the number of diagnostic characteristics of the soil pedons. 5- Nomenculture is very complicated in both systems, nevertheless, it is inevitable to transfer information to non- specialist users in a more simpler language, in WRB (2022) this information can be extracted more easily from the soil name.

One of the important proceedings in propagation process of plants is improving the speed of rooting and shortening this propagation period. Today, use of natural materials as an alternative for chemical fertilizer is concerned with successful rooting of cuttings in ornamental plants that in some cases have perceived well and effective influence of these biofertilizer compared with chemicals. Zamioculcas zamiifolia is a valuable ornamental indoor plant. The production of this plant in short time is commercially important. An important stage in the process of accelerating this plant production is to improve the rooting and shortening its growth stage. Therefore, the simultaneous effect of mycorrhizal biofertilizer and biochar on Zamioculcas zamiifolia propagation was studied in this research.

This study was performed in the greenhouse in the faculty of agriculture and environmental science of Arak University with controlled conditions of 25 ◦C temperature, 70% humidity and 10,000 lux of light. Treatments were included biochar 5% + arbuscular mycorrhizal biofertilizer 6%, biochar 10% + arbuscular mycorrhizal biofertilizer 6%, biochar 5% + arbuscular mycorrhizal biofertilizer 12%, and biochar 10% + arbuscular mycorrhizal biofertilizer 12%, and control (without biochar and arbuscular mycorrhizal biofertilizer). The arbuscular mycorrhizal biofertilizer was mixture of Clarodeoglomus etunicatum, Rhizophagus irregularis, Funneliformis mosseae. The experiment was performed as a completely randomized design (CRD) at three replicates. The pots were containing cocopeat + perlite (1:1) and different treatments of arbuscular mycorrhiza biofertilizer and biochar. Morphological and physiological traits such as off-shoot number, Leafy cuttings color, Leaf width, Leaf length, Shoot length, root number, root length, rhizome diameter, chlorophyll a, b and total chlorophyll content, fresh weight (FW) of roots and shoots, the dry weight (DW) of roots and shoots, Saturation weight, relative water content (RWC), biomass, electrolyte leakage and arbuscular mycorrhizal root colonization were measured after 9 months.

Biochar and arbuscular mycorrhiza biofertilizer application in propagation medium increased off-shoot growth of Zamioculcas zamiifolia. The results showed that the highest roots number was obtained in the treatments of arbuscular mycorrhiza biofertilizer 12% + biochar 10% which was followed by arbuscular mycorrhiza biofertilizer 6% + biochar 5%. The maximum root length was observed by arbuscular mycorrhiza biofertilizer 12% + biochar 5% treatment. The root colonization had a positive correlation with the number of off-shoot, leaf size, shoot FW and leaf chlorophyll content. The application of biochar 10% + arbuscular mycorrhiza biofertilizer 6% treatment caused an increase in the height of the shoot about 3.3 times more than the control. The highest rhizome diameter was observed in biochar 10% + arbuscular mycorrhiza biofertilizer 6% treatment. The maximum off-shoot number was measured in the treatment of biochar 10% + arbuscular mycorrhizal biofertilizer 6% treatment which was 1.8 times more than control. No signs of colonization were observed in the control, but the roots colonization in the arbuscular mycorrhiza biofertilization treatment 12% was 1.6 times more that in the arbuscular mycorrhiza biofertilizer 6%. Increasing the amount of biochar and arbuscular mycorrhiza application in the propagation medium enhanced arbuscular mycorrhiza roots colonization of Zamioculcas zamiifolia. A significant positive correlation was observed between the number of off-shoot and the total biomass (r=0.95). A high positive correlation was observed between the fresh weight of shoot and the saturated weight (r=0.95). There was a significant positive correlation between saturated weight with total chlorophyll (r=0.97) and total biomass (r=0.96). The relationship between total chlorophyll and biomass was a significant positive (r=0.95). There was a significant positive correlation between the root colonization and chlorophyll a (r=0.83). A significant negative correlation was detected between dry weight of shoot and dry weight of root (r=0.94) and dry weight of root with relative water content (r=0.95).

Generally, in the most of studied traits, the use of biochar and arbuscular mycorrhiza biofertilizer in the culture medium improved the off-shoot growth and rooting characteristics of Zamioculcas zamiifolia compared to the control. Shortening the propagation period of this slow growth and luxury plant is significant aspects in the production of this ornamental plant that reduce production costs and make the product more cost-effective. The use of biochar 10% + arbuscular mycorrhiza biofertilizer 6% in culture medium is recommended to improve the quantitative and qualitative properties through the propagation of this ornamental houseplant.

In Iran, salinity is a pervasive and limiting Factor of agricultural sustainable production. Plants in saline conditions are exposed to limited absorption of nutrients, water and toxicity of some elements and subsequently, their yield will be affected by salinity. Moreover, dust storms in arid and semi-arid climates are one of the most important environmental and pollution problems, as they directly and indirectly reduced the quality and quantity of agricultural products. Dust occurrence frequency in the country, especially in the western and southwestern regions increased in the last decades. Hence, increased dust occurrence frequency and intensity during the growth period of agricultural crops is one of the most substantial risks in agricultural sustainable production in Khuzestan province. Thus, the aim of the study was to investigate the effects of dust occurrence and farm management practices applied to reduce the effects of this stress on wheat yield indices as a strategic agricultural product in Khuzestan province.

This study was carried out in Khuzestan province in a calcareous and saline soil with clay loam texture under wheat cultivation (Barat cultivar) as a split plat experiment in a randomized complete blocks design with three replications. Two agricultural farm managements included 1) the custom of the farmer (traditional farming) and 2) nutrition management (soil test, soil balanced and complementary nutrition) based on plant phenological growth stages. In each farm management operation, four leaf washing treatments including 1) without leaf washing, 2) leaf washing after the occurrence of dust phenomenon in the tillering stage, 3) leaf washing after the occurrence of dust phenomenon in the booting stage and 4) leaf washing after the occurrence of dust phenomenon in both the tillering and booting stages, in plots with an area of 20 m2 were applied in three replicates. At the end of the growth season, wheat yield indices involved thousand kernel weight, number of grains per spike, biomass weight, grain yield and the number of tillers per square meter in different treatments were determined. SAS v.9.1 statistical software and Duncan's multiple range test were used to compare the means of the studied treatments.

The results showed that the highest wheat grain yield was observed in the treatment of balanced nutrition management and leaf washing after dust occurrence at two wheat growth stages (5180 kg ha-1), while the least wheat grain yield was in the traditional management and no leaf washing treatment (2830 kg ha-1). The interactions of farm management practices and different leaf washing treatments on biomass, grain yield, harvest index, thousand kernel weight and number of tillers per square meter were significant (p< 0.01). In the traditional management of the farmer, using the plant leaves washing at only one wheat growth stage after the occurrence of dust caused about 30% increase in wheat grain yield on average (24 and 35% increase in grain yield as a result of leaf washing after dust, respectively, in the tillering and booting stages). While in the traditional management and leaf washing at both two stages of wheat growth, it increased the wheat grain yield by 43%. In addition, the results showed that by using balanced nutrition management without leaf washing, wheat grain yield and harvest index increased by 10 and 9%, respectively. Application of balanced nutrition and leaf washing after the dust occurrence at both two wheat growth stages (tillering and booting) caused 32, 59, 21 and 11% increase in biomass, grain yield, harvest index and thousand kernel weight of wheat.

Based on the results of this research, it was found that the use of different management operations in the farms, such as balanced nutrition of the crop based on the plant growth phenological stages and the leaves washing after the occurrence of dust, can significantly reduce the damage of wheat yield caused by the occurrence of dust. However, it should be noted that despite the positive and significant effect of washing the plant leaf surface after the occurrence of dust phenomenon on reducing wheat yield damage, the time of leaves washing application is very important. Because if immediately after washing the leaf surface of the plant, the dust phenomenon occurs again, the wetness of the plant leaf surface causes more dust particles to deposit on it and the damage caused by dust on wheat yield indices increases.
All right reserved.