JOURNAL OF AGRICULTURAL ENGINEERING RESEARCH
Year:2009 | Volume:10 | Issue:3|Papers Count:8

The friction properties of granular materials play an important role in the determination of specifications for designing hoppers, transporting passages, dryers, silos and machines through which grain flows. In this study, the angle of repose and internal friction coefficient were determined for three common wheat varieties (Sardary, Gaspard and Saysoter) at four moisture contents (12, 15, 18, 21 w.b.%). Four contact surfaces (black, mild, aluminum and galvanized sheets) were used to measure the angle of repose. The tests were done in five replications. Analysis of variance was used to analyze the data and Duncan’s multiple range test was used to compare the effect of the means (P<5%). The results showed that the effects of moisture content, variety and contact surface were significant for the angle of repose. The effects of grain moisture content and variety were significant for the internal friction coefficient (P<1%). When moisture content of the grain increased, the angle of repose and internal friction coefficient increased significantly. Only where grain moisture level changed from 18 to 21% w.b. the internal friction coefficient did not change significantly. The highest and lowest internal friction coefficients belonged to the Sardary and Saysoter varieties, respectively. The highest and lowest the angles of repose belonged to the Gaspard and Sardary varieties, respectively.

The models ORYZA2000, SWAP and WOFOST simulate the growth and development of rice under conditions of potential production and water limitation. The models were evaluated against a data set of field experiments. The study was laid out in RCBD with three replications for one traditional landrace, Hashemi, carried out in 2005 at the Rice Research Institute of Iran in Rasht. The irrigation managements were: I1 (continuous irrigation); I2, I3, and I4 (irrigation at 1, 3 and 5 days, respectively, after disappearance of ponded water) and I5 and I6 (irrigation at 5 and 8 day intervals, respectively). In this paper, simulated and measured leaf area index (LAI), biomass panicles, total aboveground biomass and yield by adjusted coefficient of correlation (R2), and absolute and normalized root mean square errors (RMSE) were compared. On average, RMSE total aboveground biomass was 653 kg/ha for ORYZA2000, 458 kg/ha for WOFOST and 589 kg/ha for SWAP. RMSE biomass panicles biomass was 375 kg/ha for ORYZA2000, 284 kg/ha for WOFOST and 335 kg/ha for SWAP. RMSE LAI was 0.41(-) for ORYZA2000, 0.53(-) for WOFOST and 0.5(-) for SWAP. ORYZA2000, in contrast to WOFOST and SWAP, simulated the yield of rice well.

This paper presents a method for generating a digital management map to apply Cyanazine pre-emergence herbicide. The main objective was to develop a precision method to generate management maps for the variable rate application of herbicide to reduce the amount of herbicide applied and its adverse impact on the environment. First, local and UTM coordinates of a field were determined using Total Station and four static GPS receivers. Data processing was performed using a PC with Compass software. A 14.8 m grid was created using Land software and laid out on the field. Grid point sampling was done at the center of each cell at a depth of 20 cm and analyzed in a laboratory. The laboratory results showed that the range of, maximum, and minimum soil organic matter content (OMC) was 0.82, 1.25 and 0.43, respectively. OMC had a normal distribution with an average of 0.86% and a standard deviation of 0.18%. Soil texture varied between loam, sandy loam and loamy sand. The Kriging interpolation method was then used to determine the make-up at other points in the grid. By considering manufacturer recommendations for herbicide application based on OMC and soil texture, four zones were determined for herbicide application rates of 1.4, 1.7, 2.9 and 3.5 l/ha. A digital map was then generated and used to determine that the total required herbicide was 1.61 l/ha. It was determined from the map that herbicide application could be decreased up to 13% using an application rate of 1.6 l/ha instead of 2.9 l/ha over 67.9% of the field area. The map can be utilized to determine desired input for an electronic controller of a VRA boom sprayer.

As a native fermented dairy drink, doogh is an important industrial product in Iran. However, its characteristics have not been completely evaluated. This study evaluated the flow behavior, particle size distribution and stability of non-fat doogh as affected by the row material employed (fresh skim milk or skim milk powder) and the total solids (TS) content of the final drink. The viscosity of samples produced using fresh skim milk was 1.73±0.24 cPs. Those produced using skim milk powder exhibited higher viscosity resulting from bigger particle size. Increasing the TS content caused the viscosity of the doogh to increase, but the volume of the separated serum was reduced. Flow behavior became non-Newtonian at higher TS contents. Evaluations indicated that the colloidal particles existing in doogh were distributed among a wide range of sizes. Different particle shapes with complex structures were observed.

Applying a suitable tillage method is vital to chickpea production in dryland conditions. Hence, eight tillage methods were studied using strip plots in a randomized complete block design with three replications over three years at the Dryland Agricultural Research Institute in Maragheh, Iran. The amounts of rainfall in the three years of the study were 202, 264 and 203 mm, respectively, which was much lower than the long-term average rainfall of 350 mm. The main plots included two primary tillage in autumn (moldboard and chisel plow) and subplots comprised four secondary methods before sowing (disk harrow, leveler, rotary hoe and conventional broadcasting + disk harrow). The characteristics studied were planting depth, distance of the first pod from the ground, number of branches, pods and seeds per plant, plant height, hundred kernel weight and grain yield, as well as weed weight at two stages. The results of the combined analysis showed that primary tillage had a significant effect on the number of pods and seeds per plant and grain yield. The chisel plow, with 436 kg/ha on average, was better than the moldboard plough. Secondary tillage had a significant effect on the number of branches, pods and seeds per plant, grain yield and weed weight in the first stage. The rotary hoe had the maximum grain yield (431 kg/ha on average), however, the difference was not significant compared with the disk harrow. It can be concluded that the application of the chisel plough + rotary hoe or disk harrow can increase crop yield more than the conventional method in chickpea production.

The Colorado beetle, Leptinotarsa decemlineata (Say), is the major defoliating and exotic insect pest of potato plants and has caused serious problems in the East Azerbaijan and Ardabil regions of Iran since emerging in the absence of natural native enemies. In the development of a suitable control strategy based on integrated pest management, it is important to recognize control methods that decrease insecticide use. This study was conducted to collect Colorado beetle adults and larvae mechanically from a field area using pneumatic equipment generating moving airstreams. In some regions, small-scale farming, conventional planting and irrigation methods have resulted in reduced efficiency for existing tractor-mounted and manual pneumatic equipment because of the damage to plants by the movement of the wheels in the field. In this study, a portable and convenient pneumatic insect control machine was designed and constructed. The machine had a blowing unit to dislodge insects from the plants and a collecting unit placed opposite to one another other and positioned on the two sides of the row of potato plants. Airstreams were produced by the centrifugal pump of an atomizer sprayer. To evaluate the machine, tests were conducted on a potato farm. These were based on a complete block design with two airstream velocities (35 and 45m/s) with four replications. In each test, the number of beetles dislodged and collected by the machine was measured. Results indicated that an airflow velocity of 45 m/s was more effective than 35m/s in dislodging collecting adult insects from plants with rates of 44% and 21.2%, respectively, in one pass.

The Manning roughness coefficient is an important parameter in the design and evaluation of furrow irrigation. Despite its importance, estimation of this parameter for surface irrigation is very difficult, particularly in furrow irrigation. In this study, an EVALUE model was used to estimate the Manning roughness coefficient in furrow irrigation. The model was based on volume balance and developed to estimate the Manning roughness coefficient in surface irrigation. EVALUE also estimates both infiltration parameters of the modified Kostiakov branch function. The main input for EVALUE is depth of flow along the furrow at different times. Evaluation of this model was carried out by comparing simulated advance and resection phases using SIRMOD software based on the estimated parameters and the measured data. The estimated values of the Manning roughness coefficient ranged from 0.02 to 0.102. This model was able to simulate the resection phase, which was more sensitive to the Manning roughness coefficient, closely.