Agricultural Engineering

Abstract Introduction: Considering the serious challenges related to the waste of agricultural products and the limitations in the traditional storage and processing methods, the use of new technologies such as drying and tablet production seems necessary. Mushrooms also have antifungal, anti-inflammatory, anti-cancer, antiviral and antibacterial effects. After harvesting, mushrooms have a shorter shelf life than other vegetables due to their high humidity, high respiration rate, lack of cuticle and intense enzymatic activity. They spoil quickly and begin to change color immediately after harvesting. In order to increase their shelf life, edible mushrooms must undergo processing processes, so researchers have investigated various methods for preserving and increasing the shelf life of mushrooms. However, drying is one of the most common methods used for edible mushrooms. Therefore, this research was done with the aim of optimizing the drying and tableting processes for a valuable and perishable product such as edible button mushrooms.

Materials and Methods: Edible button mushrooms were purchased from the local market and after cleaning and washing, they were cut into pieces with a thickness of three millimeters. Then, the samples were placed in the oven for 24 hours to obtain its initial moisture, and finally they were dried by two methods of drying in the shade and drying with a continuous dryer. Then the dried mushrooms were powdered and shaped into smooth round tablets. For this purpose, the tests were defined in the form of a central composite design in Design Expert software version 13. Independent variables (input) to Design Expert software in continuous dryer including temperature (50, 60 and 70 degrees Celsius) and air speed (1.5, 2.5 and 3.5 m/s) and dependent variables for drying included total phenol, antioxidant property and color parameters. Regarding the optimization of the tableting process, independent variables include: pressure (50×105, 60×105, 70×105, 80×105 and 90×105 Pa), stress relaxation time (3, 8, 13, 18 and 22 s) and mold diameter (10, 14, 18, 22 and 26 mm) and the dependent variables included penetration resistance, stress along the diameter and density.

Results and Discussion: According to the findings, the air temperature variable had a greater effect on the response variables than the air velocity variable. According to the results obtained from the optimization, the conditions in which the air temperature was 64.1°C and the air velocity was 2.49 m/s were selected as the optimal conditions with a desirability of 76.3%. The edible button mushroom sample dried in optimal conditions has a total phenol content of 10.7 mg of gallic acid in the weight of the dry sample, antioxidant property of 91.72%, brightness index (L*) 69.73, redness index (a*) was -23.44 and the jaundice index (b*) was 1.80. The shade-dried sample also has a total phenol content of 2.87 mg of gallic acid in the weight of the dry sample, antioxidant property of 91.27%, brightness index (L*) of 72.54, redness index (a*) of 09 -9/ and the yellowness index (b*) was 6.74. According to the total phenol content and antioxidant property in the continuous drying method, this method was more favorable than the shade drying method. Among the factors affecting the mechanical properties of tablets prepared from dried mushroom powder by the continuous method and shade, the die diameter variable was more effective than the other two variables. To optimize the tablet obtained from dried mushroom powder by continuous method, the conditions in which the pressure was equal to 72.74 ×105 Pa, the die diameter was 14 mm, and the stress relaxation time was 8 seconds, with the desirability of 71.8% as a point. Optimum was selected. For shadow-dried mushroom powder tablets, the conditions in which the pressure was equal to 80×105 Pa, the diameter of the mold was 18.70 mm, and the stress relaxation time was 18 seconds were selected as the optimal point with a desirability of 60.1%.

Conclusion: From the comparison of the optimal conditions obtained from the optimization for the two powders dried by the shade and continuous methods, it can be stated that the optimal tablet sample obtained from mushroom powder dried by the continuous method was more desirable than the optimal tablet obtained from mushroom powder dried in the shade.
In general, it can be concluded that drying by continuous method can be a good option to replace drying by traditional method. Because the tablet obtained from mushroom powder dried by the continuous method had a higher density, penetration resistance and stress along the diameter compared to the shadow method.

Abstract Introduction: Biodiesel is a renewable, biodegradable, and nontoxic fuel made from fatty acid methyl esters produced via triglyceride transesterification. This reaction is accelerated by various catalysts, including chemical types (alkali, acid, and solid) and biocatalytic lipase enzymes. Lipase enzymes are particularly favored for their mild reaction conditions, reduced formation of soap byproducts, tolerance toward free fatty acids, ease of product recovery, eco-friendliness, and lower overall energy and raw material demands. However, free enzymes suffer from limited operational stability and high cost, motivating the development of immobilization strategies. Enzyme immobilization enhances the catalyst's reusability, thermal and pH stability, and specific activity, thereby enabling frequent cycles without significant activity loss. The process relies on cost-effective supports with ample surface areas and pore structures to maximize enzyme loading and accessibility. Among these, silica/iron oxide magnetic nanoparticles stand out for their rapid separation capabilities under an external magnetic field, which simplifies downstream processing and reduces wastewater generation. Covalent binding methods, such as glutaraldehyde coupling, are employed to securely attach the enzyme to the support, improving overall performance and preventing enzyme leaching. In this research, we aim to optimize biodiesel production from canola waste cooking oil using response surface methodology and assess the operational stability and reusability of the immobilized lipase under repeated batch cycles.

Materials and Methods: Key reagents—including analytical-grade methanol, tetraethyl orthosilicate (TEOS), ferric and ferrous salts, and glutaraldehyde—along with Burkholderia cepacia lipase (≥50 U/mg), were sourced from Sigma-Aldrich. Superparamagnetic mesoporous silica/iron oxide nanoparticles were synthesized via a two‑step approach: iron oxide core formation by coprecipitation, followed by a sol–gel process using TEOS with CTAB as a pore-directing agent. Resulting particles were calcined to remove surfactants, yielding a stable mesoporous shell. These magnetic nanoparticles were used as supports for enzyme immobilization. Lipase was covalently attached using a glutaraldehyde coupling process in phosphate buffer (pH 7.0) at 4 °C, with protein loadings varied between 10 and 40 mg/g support. Immobilization efficiency and activity recovery were determined by Bradford assay and olive oil hydrolysis assays, respectively. Biodiesel production assays were performed by transesterifying pretreated canola waste cooking oil with the immobilized lipase under gentle stirring. Reaction parameters (lipase concentration, methanol-to-oil ratio, temperature, and time) were systematically varied according to a central composite design, and FAME content was quantified by gas chromatography (GC-FID). All experiments were carried out in triplicate to ensure reproducibility.

Results and Discussion: SPION-silica nanoparticles, averaging 90–110 nm with a uniform mesoporous shell (pore diameter ~8 nm), offered a high surface area (~420 m²/g) for enzyme immobilization and pronounced superparamagnetic behavior (saturation magnetization ~45 emu/g). Upon lipase binding, saturation magnetization decreased to ~40 emu/g, confirming successful enzyme attachment without compromising magnetic responsiveness. Immobilization efficiency reached up to 78%, with an optimal activity recovery of 68.4% attained at 30 mg enzyme/g support and 12 h coupling time. The RSM-based second-order polynomial model exhibited strong predictive power (R² ≈ 0.96, adjusted R² ≈ 0.94), with significant linear and quadratic effects of lipase concentration, reaction time, methanol-to-oil ratio, and temperature (p < 0.01). Interaction terms—particularly between methanol ratio and time—highlighted enzyme inhibition by excess alcohol. Surface response plots revealed that FAME yield increased with enzyme loading (20–40 mg/g) and prolonged reaction time (15–30 h), but declined at methanol/oil ratios above 6:1 and temperatures exceeding 40 °C. Under optimal conditions (36 mg/g lipase, 25 h, 6:1 methanol/oil, 34 °C), the desirability function predicted a maximum biodiesel yield of 92%. Experimentally, three consecutive cycles yielded 92%, 89%, and 84% conversion, indicating only ~8.7% cumulative activity loss after three uses, demonstrating robust reusability for practical applications.

Conclusion: Burkholderia cepacia lipase was successfully immobilized on mesoporous silica/iron oxide magnetic nanoparticles. The immobilized enzyme effectively catalyzed the transesterification of waste cooking oil to produce biodiesel. VSM analysis confirmed that the magnetic properties of the nanoparticles remained largely unchanged after immobilization. Key process variables—immobilized lipase concentration, reaction time, methanol‑to‑oil molar ratio, and temperature—were optimized. A quadratic response surface model, developed using RSM, accurately predicted the biodiesel (FAMEs) yield. The desirability function analysis forecasted a maximum FAMEs content of 92% at optimal conditions. Statistical validation showed the model was both adequate and precise in predicting biodiesel yield. The immobilized lipase demonstrated good reusability, with only an 11% activity loss after three cycles. These findings underscore the potential for scalable, eco-friendly biodiesel production using enzyme‑catalyzed processes. The magnetic recovery of the biocatalyst not only simplifies downstream processing but also contributes to reduced overall production costs. Future work will focus on pilot‑scale trials and the evaluation of long‑term operational stability under continuous‐flow conditions to assess commercial feasibility.

Abstract Introduction: Phosphorus (P) is an essential nutrient for plant growth that affects all biochemical and growth reactions. Compared to other essential elements, this element has low bioavailability for plants, which is due to the precipitation of phosphorus in the form of calcium phosphate in calcareous soils. The amount of phosphorus available in 2.5 million hectares of Iranian arable land (70.2% of irrigated land) is less than 15 mg/kg. Due to the lack of phosphorus (P) in a large area of Iran's agricultural soils and the increasing price of phosphorus fertilizers, it is necessary to recommend phosphorus fertilizers more precisely. Identifying phosphorus-efficient safflower cultivars can help reduce the amount of phosphorus fertilizer consumption. Therefore, this study was conducted to investigate the growth, seed and oil yield and phosphorus efficiency indices in different safflower cultivars. Oilseeds after cereals, provide the most energy in the human diet, and are an important source of protein and vitamins. Safflower (Carthamus tinctorius) ranks eighth in the world in terms of oilseed production after soybean (Glycine max L.), peanut (Arachis hypogaea L.), rapeseed (Brassica napus L.), sunflower (Helianthus annus L.), sesame (Sesamum indicum L.), flax (Linium usitatissimum L.), and castor (Ricinus communis L.).
Materials and Methods: A factorial experiment was carried out in Darab, Isfahan, Dezful, and Kerman regions of Iran in a randomized complete block design with three replications (in 2018 and 2019). The factors included P rates of 0, 10, 20, 30, and 40 kg P ha-1 from Triple superphosphate and safflower cultivars Padideh and Goldasht for Isfahan and Darab and Goldasht and Soffeh for Kerman and Dezful regions. The available P in Isfahan, Darab, Kerman and Dezful soil was 10.2, 11, 7, and 7.18 mg kg-1, respectively. After the end of the rosette period and before flowering (before the two-digit growth code 62), five whole plant samples were randomly prepared from each plot and the plant dry weight (DW), phosphorus concentration and plant phosphorus uptake (product of dry weight multiplied by plant phosphorus concentration) were determined at this stage of growth. Shoot dry weight (DW) and P concentration, grain yield and phosphorus efficiency (PE) of DW and grain, P acquisition efficiency (PACE) and P use efficiency (PUTE) of DW was measured too. Statistical analysis of the results, including analysis of variance and Duncan's multiple range test model (p<0.05), was performed using SAS 9.4 software.
Results and Discussion: Based on the results, the soil texture in Isfahan, Darab and Dezful regions was heavier than Kerman region. Organic carbon in all soils was low and calcium carbonate equivalent was high. The soils were non-saline (slightly saline in Isfahan region), with insufficient potassium in Isfahan, Kerman and Dezful regions, and phosphorus content was moderate in all regions. The experiment revealed significant differences in the response of safflower cultivars to soil and fertilizer phosphorus, particularly in biomass yield and phosphorus efficiency indices. Application of 10 kg P ha-1 in Darab, 20 kg in Dezful, 10 kg in Isfahan, and 30 kg in Kerman increased grain yield by 20%, 78%, 28%, and 237% compared to the control treatment, respectively. The results showed that the main effect of P rate was significant on PUTE of DW (p<0.01), PACE (p<0.05), PE of grain (p<0.05), PE of DW (p<0.01) in Darab, Dezful, Dezful, Isfahan regions, respectively. The main effect of cultivar was also significant on PE of DW (p<0.01) in Darab and PUTE of DW (p<0.01, p<0.05) in Isfahan and Kerman regions, respectively. The P efficiency of DW had a higher correlation with the PACE of DW (R2=0.45**, 0.19*, 0.43**, 0.57**, respectively in Isfahan, Darab, Kerman and Dezful regions) compared to the correlation of PE with PUTE (in all four regions non-significant).
Conclusion: The results of the present study showed that the studied cultivars have different responses to phosphorus application. For safflower crops in warm regions with 10 mg P kg-1 soil, application of 10 kg P ha-1 is recommended, while for soils with 7 mg P kg-1, application of 30 kg P ha-1 is suggested. It seems that safflower can uptake further amounts of P if we use further amounts of fertilizer but can still produce optimum yields with lower phosphorus percentages in aerial parts. A phosphorus concentration of 0.18% is deficient, while 0.23% is sufficient in safflower aerial parts during the stem elongation growth stage.

Abstract Introduction: Pistachio is an important horticultural crop in Iran, extensively grown in arid and semi-arid regions, particularly in Kerman province. The cultivation of pistachios in calcareous soils presents significant challenges, including nutrient deficiencies, high salinity, elevated pH, and low organic matter content, all of which impair effective plant nutrition. Phosphorus stands as the second most important macronutrient after nitrogen in plant nutrition, playing a critical role in diverse metabolic functions essential for growth, development, and stress response. Understanding the dynamics of phosphorus (P) forms, especially non-labile P, in calcareous saline soils is crucial for optimizing P fertilizer use and minimizing adverse environmental impacts. Phosphorus fixation, a persistent issue associated with P fertilizer application, significantly reduces pistachio orchard productivity in eastern Iran. Excessive use of P fertilizers not only contributes to environmental issues such as nutrient imbalances, micronutrient deficiencies, and an increased risk of eutrophication, but also escalates production costs. Effective management of phosphorus fixation could reduce dependence on chemical fertilizers, limit phosphorus leaching into water sources, and alleviate eutrophication risks. This study investigates the vertical distribution of phosphorus forms, with a focus on non-labile P, in response to varying levels of phosphorus fertilizer application in pistachio-cultivated soils, aiming to inform sustainable nutrient management practices.

Materials and Methods: This study was conducted in a pistachio orchard in Kazem-Abad, located 39 km northwest of Kerman province (30°34'23"N, 56°49'44"E). The experiment followed a completely randomized design with three replicates to assess the effects of triple superphosphate (TSP) applied at rates of 200, 400, and 600 kg ha⁻¹, compared to a control treatment (no TSP). Soil samples were collected from four depths (0–10, 10–20, 20–30, and 30–50 cm), air-dried, and passed through a 2 mm sieve. Standard laboratory methods were used to determine the physicochemical properties of the soil. Inorganic phosphorus fractions (Pi fractions) were quantified using a sequential extraction method. Available P (Olsen P), total phosphorus (TP), total organic phosphorus (TPo), and total inorganic phosphorus (TPi) were also measured. Phosphorus concentrations in the extracts were determined using a colorimetric method. Data normality was assessed with the Kolmogorov-Smirnov test, and a Cox-Box transformation was applied when necessary to normalize the data. Analysis of variance (ANOVA) was performed using SAS 9.4 software to evaluate the effects of different phosphorus fertilizer levels on various phosphorus forms. Mean comparisons were conducted using the LSD at a 5% significance level (p < 0.05).

Results and Discussion: The results revealed a significant effect of fertilizer application rates on available phosphorus across all soil depth (p < 0.05). Available phosphorus concentrations increased progressively with higher TSP application rates, with the highest levels observed at 600 kg ha⁻¹. Compared to the control, this rate resulted in an average increase of 50% in total organic phosphorus, 40% in total inorganic phosphorus, and 43% in total phosphorus across the sampled soil layers. The proportions of Pi fractions also increased consistently with higher fertilizer rates across all depths. Non-labile phosphorus was the predominant inorganic P forms in all treatments and depths. Notably, application of 200 kg ha⁻¹ TSP enhanced both labile and moderately labile phosphorus, while higher rates (400 and 600 kg ha⁻¹) significantly increased non-labile phosphorus content. At 600 kg ha⁻¹, non-labile phosphorus concentrations were significantly higher than in the control. Statistical analysis showed significant correlations between available phosphorus, inorganic phosphorus fractions, and total phosphorus, with non-labile phosphorus exhibiting the strongest correlation with available phosphorus (r = 0.59). This suggests that non-labile phosphorus serves as a reservoir, releasing phosphorus to meet plant demands as labile P forms.

Conclusion: The study demonstrates that varying levels of phosphorus fertilizer application significantly influence the distribution of phosphorus forms, with higher application rates increasing the proportion of non-labile phosphorus. These findings highlight the critical role of non-labile phosphorus in sustaining long-term phosphorus availability for pistachio crops, thereby supporting soil fertility in calcareous, arid environments. To prevent excessive phosphorus accumulation and mitigate environmental risks such as eutrophication, careful management of fertilizer application is essential. The results advocate for the use of reduced chemical fertilizer rates and the exploration of stabilized phosphorus sources as sustainable alternatives. Such strategies can lower production costs, enhance soil health, and minimize environmental pollution, contributing to the long-term sustainability of pistachio cultivation in Iran.

Abstract Introduction: Food security relies on access to safe, affordable food and meeting nutritional needs. Rice is a staple crop, feeding over a third of the global population. Simulation models are essential tools for optimizing agricultural systems and forecasting crop performance under various environmental conditionsDeveloped by the FAO, the AquaCrop model evaluates the interplay of soil, water, climate, and management practices, offering user-friendly and robust features for simulating irrigated and rainfed farming systems. Central to such models is simplifying complex biological dynamics to accurately predict yield and biomass while minimizing environmental degradation. By simplifying complex biological processes, AquaCrop enables the accurate prediction of crop yield and biomass. This study uses AquaCrop to simulate the growth and productivity of Hashemi rice across 92 paddy fields in Sowme’eh Sara County. By calibrating and validating the model with site-specific data, this research showcases AquaCrop’s effectiveness in addressing regional challenges and its potential to improve agricultural sustainability through enhanced resource management and informed decision-making.

Materials and Methods: This study was conducted in 92 paddy fields within Sowme’eh Sara County, aiming to assess the AquaCrop model’s reliability for simulating rice yield and biomass under real-world conditions. Soil samples were collected via stratified random sampling from depths of up to 60 cm across different soil layers (surface, compacted plow layer, and subsoil) and analyzed for parameters such as texture (loamy to clayey), organic carbon content, field capacity, wilting point, pH, and electrical conductivity. Meteorological data, including daily temperatures, solar radiation, precipitation, and wind speed, were gathered during the rice growth period to calibrate and validate the model. Farmer surveys documented management practices, including fertilization methods, irrigation strategies (alternate vs. continuous), and pest control techniques. The AquaCrop model was calibrated by adjusting region-specific parameters, such as initial canopy cover, harvest index, and water-use efficiency, using soil, crop, and meteorological data. Validation involved comparing observed yield and biomass data with AquaCrop-simulated results. The model’s performance was evaluated using statistical indices such as normalized root mean square error (nRMSE), root mean square error (RMSE), coefficient of determination (R²), and model efficiency (EF). Finally, sensitivity analysis identified key parameters influencing simulation accuracy, ensuring comprehensive applicability to diverse management scenarios.
Results and Discussion: The observed yield values for grain across the studied paddy fields ranged from 2.54 ton/ha to 5.97 ton/ha, with a mean yield of 3.92 ton/ha. Biomass production varied from 6.20 ton/ha to 12.62 ton/ha, averaging 8.46 ton/ha. The AquaCrop model successfully replicated these trends, achieving R² values of 0.70 for grain yield and 0.66 for biomass, with nRMSE values of 10% and 20%, respectively. Model efficiency indices further confirmed AquaCrop’s reliability, with EF = 0.70 for grain yield and EF = 0.97 for biomass yield. Sensitivity analysis identified several critical parameters influencing simulation accuracy, such as harvest index, initial canopy cover, and saturated hydraulic conductivity. Fine-tuning these inputs enhanced the model’s predictive capabilities. While minor discrepancies were noted in biomass accumulation under specific stress conditions, these results aligned with findings from previous research. The AquaCrop model demonstrated its adaptability for agricultural decision-making by evaluating outcomes under diverse management practices across 92 paddy fields. Simulated results also provided effective strategies for optimizing irrigation water usage, nutrient management, and reducing environmental impacts. The study highlights AquaCrop’s role as a robust decision-support tool capable of offering actionable insights into improving agricultural sustainability. It successfully accommodated variations in soil structure, agroecological settings, and crop rotation practices, underscoring its potential for large-scale applications in heterogeneous farming systems.
Conclusion: The AquaCrop model exhibits high potential for sustainable resource management in agriculture and serves as an advanced and effective tool for the agricultural community. This study demonstrated that AquaCrop is highly accurate and effective in simulating rice grain yield and biomass under real-world farming conditions. With simple input requirements and adaptable algorithms, AquaCrop offers robust solutions for sustainable agricultural resource management. The model proved capable of optimizing irrigation practices and resource inputs like water and nutrients, thereby reducing environmental impact while maintaining productivity. Its application across varied agroecosystems highlights its scalability and relevance to regions facing challenges like water scarcity and climate change. AquaCrop’s role as a proactive tool for agricultural sustainability strongly supports its utility in future farming research and policymaking. Extending this framework to additional crops and geographical areas could further enhance global food security and resource efficiency.

Abstract Introduction: Given the extensive rice cultivation in Gilan province, second cropping after rice is a key strategy for increasing production, farmer income, and economic sustainability. This is particularly important in areas facing challenges like small land parcels and traditional farming methods. Second cropping creates employment opportunities and helps move away from a monoculture system. However, due to the lack of suitable crop introductions and efficient technical solutions, many paddy fields remain fallow after rice harvest. Developing annual forage crops such as triticale can meet the needs of livestock farming at a lower cost. Numerous studies have shown that second cropping (including triticale, rapeseed, and fava beans) offers a positive cost-benefit ratio, increases farmers’ income, and has positive social effects like reduced migration and unemployment. Triticale, due to its high production and nutritional capacity, has good potential for meeting the country’s forage needs. Proper management, provision of technical and financial support, and selecting appropriate crops with optimal agronomic techniques are essential for the success of second cropping. Ultimately, considering the importance of second cropping and the high potential of triticale, evaluating the technical and economic parameters of its mechanized harvesting as a second crop in Gilan’s paddy fields can aid in effective supportive and extension policies.
Materials and Methods: This study was conducted to evaluate the technical and economic indicators of mechanized triticale production, with a focus on the machinery used in tillage, planting, and harvesting stages, under two harvesting methods (wet and dry). The research was carried out over two cropping years (2019–2020) at the Soil and Water Rice Research Station, affiliated with the Rice Research Institute of Iran. To determine the fresh forage yield per unit area, after removing the border effect (including side rows and half a meter from the beginning and end of each plot), harvesting was carried out, and the produce was immediately weighed. To measure the dry forage yield, one kilogram of fresh forage from each treatment was randomly selected, and the samples were dried in an oven at 75°C for 48 hours and then weighed. This study was divided into two main sections: a) Technical Assessments and b) Economic Assessments. To measure technical indicators such as fuel consumption, theoretical and effective field capacity, and the time required for each operation in both dry and wet harvesting systems, the experimental field was divided into two plots of 50x120 meters. The economic analysis of the two harvesting methods was performed using indicators such as the cost per kilogram of product, net profit, benefit-cost ratio, sales return percentage (SRP), and investment return percentage (IRP). In this analysis, if the Gross Margin (GM) is negative, the product is not economically justifiable, and if GM is positive, the production is considered economical. The Sales Return Percentage (SRP) indicates the profit generated per unit of sales revenue, and the Investment Return Percentage (IRP) shows the profit generated per unit of investment.
Results and Discussion: The technical evaluation of mechanized triticale production in Guilan province revealed significant differences in machine performance between wet and dry harvesting methods. Among the machines studied, the fertilizer spreader demonstrated the highest effective field capacity (1 ha/h), lowest operation time (1 hr/ha), and lowest fuel consumption (~11.8 L/ha) during wet harvesting, indicating superior efficiency and energy use. Conversely, the rotivator showed the lowest capacity (0.29 ha/h) and highest fuel consumption (~41.07 L/ha), making it the least efficient operation due to higher soil resistance and repeated passes. In dry harvesting, two machine combinations were compared. The second combination, which replaced the self-propelled reaper with a disc mower, doubled the harvesting capacity (0.6 ha/h vs. 0.24 ha/h) and reduced operation time significantly (1.7 vs. 4.1 hr/ha), though fuel consumption was somewhat higher. The rake and fertilizer spreader consistently showed high efficiency and low fuel consumption in both combinations. Overall, wet harvesting with a forage chopper was approximately 2.7 times faster and consumed 64% less fuel per hectare than dry harvesting. However, dry harvesting, despite higher fuel use and operation time, provides advantages for producing dry forage suitable for long-term storage and transport. Economically, although the wet harvesting method had higher total production costs (~199 million IRR/ha) compared to dry harvesting (~146 million IRR/ha), the gross revenue was equal for both due to the higher yield in wet harvesting (35,000 kg/ha vs. 7,700 kg/ha). Notably, dry harvesting yielded a positive profit (~8.4 million IRR/ha) and return on investment (~5.8%), while wet harvesting resulted in a significant loss (-45.1 million IRR/ha). The primary economic challenge in wet harvesting arises from high fixed costs (e.g., land rent) and variable costs related to handling large volumes of moist product. In conclusion, while wet harvesting is technically more efficient and environmentally flexible, dry harvesting is currently more economically viable under the studied conditions. Selecting machines with higher capacity and efficiency, alongside managing energy consumption, is critical to improving mechanized triticale production.
Conclusion: The study shows that under current agricultural and economic conditions in Gilan Province, the dry harvesting method for triticale is more economically beneficial than the wet harvesting method. Dry harvesting yielded a net profit of over 4.8 million IRR per hectare and an ROI of about 8.5%, while wet harvesting incurred a loss exceeding 45 million IRR per hectare with a negative ROI of –22.7%. High rental costs for paddy fields and increased transportation expenses mainly caused the economic loss in the wet method. Technically, wet harvesting with forage choppers is about 2.7 times faster and consumes over 60% less fuel than dry harvesting, making it preferable in unfavorable weather conditions. Some dry harvesting machinery consumes more time and fuel, but equipment like rakes and manure spreaders reduce fuel consumption and speed up operations. The study recommends future focus on optimizing or replacing less efficient machines used in dry harvesting to improve overall efficiency.

Abstract Introduction: Uniform distribution of rice seeds in seedling trays is a critical factor that significantly influences the growth performance and overall yield of rice crops. Proper seed placement ensures optimal seedling density, reduces competition among plants, and promotes uniform germination and development. However, many farmers, especially in regions where resources are limited, rely on manual or traditional methods for seed sowing due to the high cost and limited availability of automatic seed-sowing machines. These manual methods are often time-consuming, labor-intensive, and prone to uneven seed distribution, which can negatively impact seedling quality. Therefore, there is a pressing need for an affordable, simple, and efficient device that can facilitate quick and precise sowing of rice seeds in seedling trays. This study aims to design, manufacture, and evaluate a handheld mechanical seed-sowing device tailored to meet these requirements.
Materials and Methods: The seed-sowing device was designed using SolidWorks, a three-dimensional CAD software, to ensure precision and functionality in the design phase. The device features two main containers: one for holding rice seeds and another for soil. It incorporates soil and seed distributors, carrying handles for ease of use, and a transmission system comprising gears, a chain, and a chain wheel.

• Body: Constructed from stainless steel alloys 304 and ST37 steel to provide durability, corrosion resistance, and lightweight characteristics.

• Transmission Gears: Manufactured from PTFE (Teflon) to reduce friction and wear, ensuring smooth operation.

• Seed metering: Designed as a grooved roller made from aluminum alloy, chosen for its strength and lightweight properties.

• Soil Distributor: Made from a rigid plastic conveyor, enabling consistent soil delivery.

The device was tested using rice paddy seeds with varying quantities ranging from 70 grams to 180 grams per seedling tray to simulate different sowing densities. The device allows adjustment of soil thickness both below and above the seeds, ranging from 0.5 to 2 centimeters, controlled by an adjustable cover of the seed metering device. This feature aims to optimize seed coverage and protection. Performance evaluation focused on the accuracy of seed quantity placement and consistency of soil coverage. Data were collected and analyzed to determine the correlation between the device’s settings and the actual sowing outcomes.
Results and Discussion: The evaluation demonstrated that the designed device effectively achieves uniform seed distribution within seedling trays, ensuring consistent spacing and reducing seed wastage. Detailed testing revealed that the relationship between the number of seeds dispensed and the recommended sowing quantity showed a high degree of accuracy, with a coefficient of determination (R²) of 0.99, indicating excellent precision in seed placement. This level of accuracy underscores the device’s reliability in achieving targeted plant populations, which is crucial for maximizing crop yield and health. The adjustability of soil thickness proved to be a valuable and user-friendly feature, enabling users to customize seed coverage according to specific agronomic recommendations for different rice varieties and environmental conditions. The device consistently maintained soil thickness within the predefined range, with a maximum observed error of 12% in cases of over-sowing and 15% in under-sowing coverage. These deviations fall well within acceptable limits for practical agricultural applications, reflecting the device’s robustness in real-world conditions. Furthermore, the mechanical design, which included the use of low-friction PTFE gears and a lightweight yet sturdy aluminum seed distributor, significantly contributed to smooth operation, accuracy, and durability under repeated use. The handheld nature of the device enhanced its usability and portability, making it particularly accessible to smallholder farmers, who often lack access to expensive and complex machinery. This user-centered design approach is expected to facilitate widespread adoption in rural farming communities, ultimately improving sowing efficiency and crop establishment. Overall, the device addresses key challenges associated with manual seed sowing by improving speed, accuracy, and uniformity, which are essential for optimizing seedling growth and subsequent crop yield.
Conclusion: This study successfully designed, manufactured, and evaluated a cost-effective, simple, and handheld mechanical seed-sowing device tailored for rice seedling trays. The device demonstrated high precision in seed distribution and adjustable soil coverage, meeting the agronomic requirements for optimal seedling growth. Its affordability and ease of use make it a practical alternative to expensive imported automatic seed-sowing machines, potentially benefiting small-scale farmers by enhancing sowing efficiency and crop establishment. Additionally, the device's lightweight design and ergonomic handle reduce operator fatigue, allowing for prolonged use during busy planting seasons. Its modular components also simplify maintenance and repairs, increasing overall durability and lifespan. The seed-sowing device also supports sustainable agricultural practices by minimizing seed wastage and ensuring uniform germination, thereby contributing to improved resource management. Future work may focus on field trials to assess long-term impacts on seedling vigor and yield, as well as exploring adaptations for other crop types, such as vegetables and legumes, to broaden its applicability across diverse agricultural systems.

Abstract Introduction: Rill erosion is considered one of the most significant forms of water erosion. Most existing erosion models have been developed to estimate soil loss and formulate conservation measures. For this reason, spatial and temporal variations of erosion at small scales, such as rill erosion, are often simplified in these models. In addition to soil and flow characteristics, soil resistance to erosion is also a function of dynamic external environmental variables. Among these, soil moisture is an external environmental characteristic that can influence soil resistance to erosion. However, limited information exists regarding the precise role of soil moisture content on resistance to water erosion. Therefore, this research aimed to investigate the effect of initial soil moisture and flow characteristics on rill erosion in two erosion-prone soils containing more than 40% silt but with different textures.

Materials and Methods: Soil samples with silt loam and silty clay textures, having approximately similar silt content, were collected from the 0-10 cm of two rain-fed farmlands exhibiting signs of rill erosion in Shirkuh village, Rudbar, Gilan Province. Soil samples did not have considerable differences in other properties such as organic matter content, calcium carbonate equivalent, aggregate stability, and other characteristics. Measurements of rill detachment capacity (Dc) for both soils were conducted under simulated runoff conditions with four flow discharge rates (0.546, 0.986, 1.125, and 1.895 m³h-1) and two slope levels (0.061 and 0.121 m/m), totaling eight combinations of flow discharge and slope, at five initial moisture levels (5, 10, 15, 20, and 30% by mass) with three replications.

Results and Discussion: The results of the analysis of variance showed that the effects of soil type, moisture level, and the interaction effects between soil type and moisture level on Dc were significant at p <0.01. Results indicated that in both silty clay and silt loam soils, Dc decreased with increasing soil initial moisture content. The soil detachment capacity in silt loam soil, after a decreasing pattern, increased from 0.015 kg m-²s-1 at 20% moisture to 0.086 kg m-²s-1 at 30% moisture, indicating the existence of a moisture threshold for changes in susceptibility to rill erosion. whereas in silty clay soil, the trend of detachment capacity continued to decrease with increasing initial moisture content. Analysis of rill erodibility factor at different moisture levels also revealed a pattern similar to the changes in detachment capacity. In the drier moisture range, initial moisture may lead to increased soil strength, and consequently, soil loss decreases until reaching a moisture content corresponding to the plastic limit. Reduced aggregate breakdown and increased cohesion due to the presence of water films likely explain the greater soil resistance with increasing initial moisture. However, there may be an optimal moisture content beyond which the trend of increasing soil resistance with initial moisture begins to decrease or at least does not show incremental changes. This soil moisture threshold depends on the characteristics of the soil under study, such as the plastic limit, which can also be influenced by texture, especially the clay content of the soil. Therefore, the difference in clay content between the two soils probably caused their different behaviors at various moisture levels. Based on the Pearson correlation test results, the correlation of rill detachment capacity in both soils showed the highest correlation coefficient with the stream power parameter (r = 0.76 to 0.83 in silty clay soil and r = 0.76 to 0.94 in silt loam soil). In silty clay soil, increased moisture generally leads to higher correlation, whereas in silty loam soil, a more complex pattern is observed, with Dc at 10% moisture showing the strongest correlation for most parameters. Initial soil moisture had a significant impact on the relationship between detachment capacity and flow characteristics, though this effect varied between the two soil types.

Conclusion: This finding indicates that rill erodibility is not a constant value and varies depending on the interaction effects between initial soil moisture and the texture of the studied soil. Therefore, although some soil properties such as soil texture are considered unchangeable factors over specific time periods (e.g., days, months, or even years) affecting erosion, the manner in which time-dependent parameters, such as initial soil water content (referred to here as initial soil moisture), and its interaction with soil texture influence erosion remains a subject of interest. Results of correlation between soil detachment capacity and flow hydraulic and hydrodynamic properties suggests that stream power may be a good predictor for soil detachment. Overall, these findings suggest that the influence of dynamic external factors, such as initial moisture level, should be considered for more accurate soil erosion modeling.