نشریه تحقیقات سامانه ها و مکانیزاسیون کشاورزی
پیاپی 77 (بهار 1400)

In this research, horizontal, vertical and side forces on a single bentleg plow (SBLP) and a double bentleg plow (DBLP) at four forward speeds of 1.8, 2.3, 2.9 and 3.5 kmh-1 and at the constant depth of 40 cm was evaluated. The experiment was arranged in the randomized complete block design with four replications. In each experiment, three perpendicular soil forces were measured and recorded. Results showed that increasing forward speed from 1.8 to 3.5 kmh-1 resulted in increasing horizontal, vertical and side forces by 14, 3.5 and 1% for SBLP and 13, 1.2 and 11.5% for DBLP, respectively. Other results indicated that horizontal force for DBLP was more than twice of that for SBLP. The vertical force was lower for SBLP but it was not more than half that of DBLP and the side force for DBLP was very less than that for SBLP. Generally, using the DBLP increases tine penetration and decreases side force which leads to balanced operation of the subsoiler and tractor and therefore recommended.

Currently, the available crop and garden sprayers do not have the ability to spray palm trees at high altitudes. In this study, an air blast sprayer was optimized for high palm trees and its performance was evaluated and compared with the performance of trailed and wheelbarrow lance sprayers. In order to evaluate the sprayers in the region, eight important traits were considered. The results of this study showed that the optimum air blast sprayer quality was better than that of the trailed and wheelbarrow lance sprayers, such a way that the spray quality coefficient was 1.81 versus 3.3 and 3.84 for trailed and wheelbarrow lance sprayers. The presence of poison on the ground, in turbine sprayer was seventy-five percent less compared to the trailed and wheelbarrow lance sprayers. The amount of solvent in turbine sprayer is about 50% lower than that of tow lance sprayers. Spraying capacity was 54 trees per hour without the need for the worker for turbine sprayer and for trailed and wheelbarrow sprayers were 30 and 27 trees per hour with 1 worker. According to the results of this study, it is better to use an optimized turbine sprayer for spraying palm trees with different heights.

Greenhouse cultures include energy-related economic activities in the agricultural sector. Due to the problems in the production, transmission and distribution systems of electricity in conventional systems, development of CHP systems were so attractive in recent years. In this research after determining of advantages and disadvantage of CHP systems for using in greenhouse cultures, technical, economic and environmental assessments of these systems were evaluated. Finally, the role of government policies and supports were investigated. For technical, economic and environmental feasibility of using these systems in the greenhouse, the technical use of the system in the greenhouse, the amount of net present value (NPV), investment income components, cost components of capital, the amount of stored energy and carbon dioxide emissions were calculated. The results showed that because of the low number of technical personnel for installation, maintenance and repair of the system, it would be out of order if a problem occurred. Economically, it can be economically feasible to use government-sponsored sales of electricity to the national grid and the use of free-tariff gas. This reflects the role of government policies and facilities in the economic development of these projects.

Minimum tillage and no tillage methods not only increase soil fertility but also reduce energy consumption and production costs. This study was performed to determine the energy indices in corn production under different tillage systems (conventional tillage, minimum tillage by disk, minimum tillage by chisel packer, and no tillage) in corn farms of Orzuiyeh region, Kerman province in 2017. For this purpose, questionnaires were filled by farmers and the necessary data were collected through interviews with them. In this study, energy efficiency, net energy gain, energy productivity, energy intensity and water use efficiency indices were calculated and analyzed. Results of this study showed that the maximum energy efficiency (1.81 MJ / ha) and maximum net energy gain (51402 MJ / ha) were achieved in minimum tillage by disk treatment. Energy productivity index was equal to 0.155, 0.155, 0.123 and 0.105 kg / ha for conventional tillage, minimum tillage by disk, minimum tillage by chisel packer and no tillage respectively. Maximum energy intensity (9 MJ/kg) was found in conventional tillage and minimum energy intensity (8.1 MJ/kg) was calculated in minimum tillage by disk treatment. Maximum water use efficiency (0.85 kg/m3) was found in the treatment of minimum tillage by disk. The results of this study also indicated that in corn cultivation in Orzuiyeh region, the maximum amount of energy consumptions occur in water supply, fertilizer application, machinery equipment and fuel  respectively. Modification of irrigation methods, optimation of fertilizer consumption and using minimum tillage methods may improve energy ratio and increase farmer’s income in corn production in Orzuiyeh region.

In no-tillage, the coulters are the best way to cross the plant residues, which, along with the furrow openers, prepare the soil for seed placement. So four available tiller models in front of a mechanical row crop planter were installed and a two factor randomized complete block design using strip plots with four coulters (sweep, nail, narrow chisel and T inverted) as factor A and the three factors related to the speed of tractor (4.8, 7.2 and 9.4 km.h-1) as factor B were performed. The planter units were adjusted on 50 cm distance between rows. The sweep model with 24.4 and 7.3 cm had the highest width and depth of disturbed soil. T inverted tiller at the specified depth with the least amount of standard deviation got the highest uniformity of seed distribution on the row that was 80.4% and did not change depth of seeding by speed increasing but increased the distance between two seeds. Also, the highest quality of feed index (42.7%) and the lowest multiple index (46.8%) were related to this treatment and its miss index (10.5%) has been around other tillers. Although T inverted tiller in the forward speed of 4.8 km h-1 has better performance in terms of planting indices, but the nail tiller is more suitable because of simplicity and performance as well as its low cost compared to other tested tillers and it passes through plant residues more easily.

The area in which conservation tillage is used, and also the area in which cultivation of dry seeding method of rice is used, both, due to their advantages, are increasing. This study was done in two years (2014-2016) in Khuzestan province to compare different conservation tillage methods. The experiments were based on split plot with randomized complete blocks design with two factors and three replications under dry seeding of rice. The main factor included different methods of tillage and sub-factor included different seed rates. The main factor treatments were: strip-till-drill, twice disk + grain drill, and no tillage (direct planting) and the sub-factor treatments were: 50, 75 and 100 kg.ha-1 of seed rates. The analysis of variance of technical parameters showed significant difference in all indices. Comparison of data showed that  twice disk with 31.6 L.ha-1, no tillage with 1.62 ha.h-1 and twice disk with 1.5 million Rials per hectare had the highest value in fuel consumption, field capacity and costs per hectar, respectively, and strip-till-drill with 8.6 L.ha-1, twice disk with 0.48 ha.h-1 and strip-till-drill with 1.1 million Rials per hectare had the lowest value in those indices. Analysis of variance in two years of agronomic traits showed that tillage methods had significant effects only on 1000 grain weight and harvest index, and no effects on other indices. Among tillage methods, strip-till-drill with 3490 kg.ha-1 and twice disk with 3344 kg.ha-1 had the highest and lowest yield, respectively.

Nowadays, tillage and related topics are of great importance to researchers and farmers. One of these issues is the draft force, which is influenced by many factors. Knowing the approximate amount of this force helps, for example, to use suitable machines and tools on the farm. The purpose of this study was to use the results of shear vane and cone penetration tests to provide a model for predicting the draft force of chisel plow without measuring soil physical and mechanical parameters. For this purpose, four farms were seleced and cone index and shear van test were performed on each farm. Also, draft force of chisel plow was obtained in each farm considering the variables of forward speed (3, 5, 7 and 9 km.h-1) and tillage depth (15, 20, 25 and 30 cm). The experiments were performed based on a split plot experiment and on a completely randomized block design with three replications. The results showed that with increasing the penetration depth from 15 to 30 cm, shear strength of soil and cone index increased by 36.62% to 48.21% and 23.60% to 38.86%, respectively. With increasing forward speed and tillage depth, the draft force increased by about 30.16% and 25.32%, respectively. With increasing soil moisture, the amount of draft force decreased by 47.83%. Also, with increasing cone index and shear strength of soil, the draft force of chisel plow increased. According to the relationship between the mentioned variables with draft force, a model with response surface methodology and historical data design was obtained. In this model, draft force was considered as a dependent variable and forward speed, tillage depth, cone index and soil shear strength were considered as independent variables. The coefficient of determination (R2), root mean square error (RMSE) and mean relative deviation modulus (MRDM) for this model were 0.97, 0.49 kN and 2.34%, respectively, indicating high accuracy of the model for predicting draft force.