نشریه تحقیقات سامانه ها و مکانیزاسیون کشاورزی
پیاپی 80 (زمستان 1400)

The increase in the area under greenhouse cultivation in Tehran Province is important for the increase in production and for its substantial social importance due to the preservation of agricultural land, especially small farms. In addition, the increase in the number of greenhouses producing summer crops in this province attracts idle capital to the agriculture sector thereby creating jobs. The present research used stratified cluster sampling for selecting the counties of interest having the largest areas under greenhouse cultivation of summer crops in Tehran Province in order to select the producers in each greenhouse size range (taking into consideration the number of producers in it) via random sampling in which a table of random numbers was employed. Fifty-five greenhouses were selected in the province, 22 greenhouses producing only cucumbers, 15 greenhouses producing cucumbers and tomatoes, and 18 greenhouses producing cucumbers and bell peppers. The results of the cost-benefit analysis (CBA) showed that production of greenhouse summer crops was economically justified for greenhouses larger than 3000 m2 in surface area. However, the trend in the profitability of activities was a rising one for greenhouse surface areas of up to 4500 m2 beyond which a falling trend was observed. Finally, it was suggested that the Jihad Agricultural Organization of Tehran Province refuse to issue an establishment license for the production of greenhouse summer crops in areas lower than 1500 square meters and provide the necessary incentives for the production of greenhouse summer crops in Tehran, in areas between 5000 to 7500 square meters.

This research was carried out in Hakim Farabi Agro-Industry Company located in 35 km of Ahvaz-Abadan road in the years 2016 to 2018 by the method of random complete blocks design and was performed in three replications. The comparative treatments included 1- using the subsoil twice D8 bulldozer (conventional operation), 2- Alpego composite tillage, 3- Nardi composite tillage and 4- subsoil using D8 bulldozer + Khorasan forging tractor subsoil.  The results of this study showed that there was no significant difference between different treatments in terms of yield components (quantitative and qualitative indices of sugarcane). Also, different treatments had a significant effect on soil physical properties and performance parameters. In stem height, yield, syrup brix and purity, the highest values related to the second treatment, with 236 cm, 102 t ha-1, 19.95% and 93.85%, respectively, and in the weight average of the diameter of the lumps, specific mass apparent, at depths of 30 to 60, soil resistance at depths of 0-30 cm, fuel consumption and operating time, the lowest values, respectively, related to the third treatment with 38.33 mm, the second treatment with 1.15 g (cm3)-1 The second treatment was 104.96 pascal, the second treatment was 48.33 liters per hectare, and the second treatment was 2.21 hours.

Today, with the expansion of industrial agriculture, the use of new sciences and technologies such as artificial intelligence has a significant role in increasing productivity and smartening of agricultural methods. These methods include estimating seedling density using image processing methods. In addition to helping agricultural land management, this is also effective in assessing the amount of fertilizer and chemicals and determining the storage space required. In this paper, a new method for estimating rapeseed crop density at the two-leaf stage is proposed. To prepare the images, first, images were taken from several random areas of the rapeseed field in the two-leaf stage located in the village of Mohammadabad, Qazvin, using square frames one meter long to meet the usual standards; Then the Gaussian mixed model with the Expectation Maximization algorithm is used to segment the images. In order to improve the segmentation of the images, the k-mean clustering algorithm was used and finally, when the leaves were separated from the other components of the image, morphological operators were used to count the number of products in the images. The number of rapeseed products in the images is also averaged manually and used as reference values to evaluate the performance of the proposed algorithm. The results of the proposed method have a correlation of R=0.96 with the manual counting method and have an accuracy of 96.5%. The results of the proposed method are also compared with two common methods called the Normalized Difference Index (NDI) and the Otsu threshold methods which are based on the color characteristics of the images and used in recent studies, and it is observed that the proposed method works better. Although the images were taken in different environmental conditions and with different light intensities, the error rate of the proposed method for the images used was only less than four percent, which shows the efficiency of the proposed method in estimating canola density. Therefore, the proposed method can be used in estimating canola seedlings in practice in agricultural fields.

Injecting Liquid fertilizers in trees root zone is one of the fertilizing methods that can be implemented either after air injection (aeration) or directly without aeration. This study focused on diffusion pattern of the liquid injected directly or after aeration under the soil in both dry and wet soils. To apply treatments associated with aeration, the compressed air was primarily injected for 3 seconds followed by injecting liquid for a certain time, whereas for direct liquid injection no air was applied into the soil. The applied liquid was made of water and mineral dyes to contrast the soil color. The soil was excavated in the vicinity of injection point and the area of diffused dyed particles was measured in different treatments. The results showed that diffusion rate in wet soil was significantly higher than that of dry soil but aeration before liquid injection had no significant effect on the liquid diffusion rate.  In wet soil, applying the air pressure upheaves the soil layer above the injection point and by cutting the pressure the soil subsides on its original point. The injected liquid flows horizontally into the fractures developed below the upheaved layer. In direct injection in wet soil, the liquid pressure itself was still adequate to upheave the top layer and the liquid flew horizontally below the top layer. In dry soil, on the contrary, due to high shear strength of soil, no upheaving occurred in both injection treatments and the injected liquid was restrained in close vicinity of injection point

Peanuts are harvested in two stages. The first stage involves the complete removal of the plants from the soil and the second stage is the drying and separation of the peanut pod from the plant. This study was conducted in Moghan, in 2020. The purposes of this study were to estimate cost and benefit of harvesting methods and to determine profitability indices with using a special peanut traction combine. The experiment was performed based on a split plot design in the form of randomized complete blocks with four replications. The research was based on whether the imported traction combine is more economical compared to other common methods of peanut harvesting? Three harvest methods in the second stage include: b1- combine harvesting b2 - harvesting with a thresher behind the tractor, b3 - manual harvesting. To find out if the assumption proved, we used partial budgeting technique including net present value (NPV), economic and non-economic test for substitution of harvesters and marginal rate of return (MRR). The results showed that the MRR rate of replacing the application of traction combine with other treatments in the average area harvest conditions is higher than 41.83%. According to the results, it was found that net profit in traction combine harvesting compared to thresher behind the tractor and manual method had a profitability of 6.07 and 8.82 percent, and a cost reduction of 4.86 and 23.43 percent, respectively.

Soil-wheel interaction is very attractive topic for agricultural researchers for its effect on the energy consumption and soil properties especially in agriculture. The purpose of this research is measuring soil-wheel contact area under the effect of independent variables of vertical load on the tire, tire inflation pressure and tire forward speed at controlled condition of soil bin also its prediction using adaptive neuro-fuzzy inference system. The tests were accomplished at two forward speeds (0.386 and 0.879 km/h), three inflation pressures (18, 25 and 32 psi), three vertical loads (150, 300 and 450 kg) plus 3 replications and totally 54 passes. All data analysis was done using Genstat software. Results showed that increase of vertical load on the wheel caused to increase of soil-wheel contact area and increment of inflation pressure caused to decrease of it. Low forward speed had not effect on the soil-wheel contact area. Furthermore, correlation coefficient (R2) of ANFIS models (0.9182) was very more than regression one (0.359). Thus, ANFIS models could predict the soil-wheel contact area with high accuracy using measured input variables included vertical load, tire inflation pressure and forward speed at soil bin.