JOURNAL OF AGRICULTURAL ENGINEERING RESEARCH
Year:2013 | Volume:14 | Issue:1|Papers Count:10

This research was conducted at Torogh Agricultural Research Station in Khorasan-e Razavi province to determine the impact of irrigation cutoff at different growth stages and percentage of water use on the yield and water use efficiency (WUE) of wheat cultivars using sprinkler irrigation. The study was done from 2006-2008. The experimental design was a randomized complete block design with a strip split plot layout and three replications. The three vertical plots were for irrigation (70%, 85%, 100% of plant requirement), the three horizontal plots were for irrigation cutoff point (full irrigation, irrigation cutoff at stem elongation, cutoff at pollination) Three wheat cultivars (Alvand, Toos, Gaskozhen) were the subplots. The yield means at 70%, 85% and 100% water consumption were, respectively, 3182, 4639, and 4748 kg/ha. Water consumption of 85% and 100% fell into statistical group A. The highest value for WUE was 1.849 kg/m3 at 85%, followed 1/389 kg/m3 for 70%, and 1.618 kg/m3 for 100%. The irrigation cutoff treatment showed significant differences (P£ 0.05) for grain yield and WUE. Full irrigation showed the highest grain yield (4557 kg/ha) and irrigation cutoff at stem elongation and cutoff at pollination actually decreased yield to 4195 and 3817 kg/ha, respectively. Full irrigation and irrigation cutoff at stem elongation fell into statistical group A. Cutoff at stem elongation had the highest WUE (1.778 kg/m3). Combined analysis showed that wheat cultivar had a significant effect on grain yield and WUE. Alvand cultivar had the highest yield (4447 kg/ha) and WUE (1.718 kg/m3). The results showed that, where water shortage was not an issue, full irrigation produced the best results. In areas of water shortage, 85% irrigation using the cutoff at stem elongation method is recommended for the best results in yield, water consumption and WUE.

Study of the spatial variability of infiltration characteristics is essential to estimating infiltration parameters on a local scale. The objectives of the present study were to scale the parameters of a Philip two-term model for infiltration and survey the variability of infiltration characteristics geostatistically using wastewater in the Bajgah catchment. Infiltration was measured at 30 points in a random pattern over the study area using double rings. Infiltration characteristics in the area showed a low basic infiltration rate for most sites (0.001-0.178 cm/min-1). The Philip infiltration model, the best model to describe infiltration characteristics, was fitted to the data. The parameters (sorptivity, hydraulic conductivity) showed wide variation across the sites. The sorptivity-based scaling factor (aS) and the hydraulic-based scaling factor (aA) were computed and the observed infiltration data were scaled based on these values. Results showed that scaling achieved using aA was better than that obtained using aS. The optimum scaling factors (aopt) were determined using the least squares method (Solver option) and scaling was repeated using aopt. Scaling factors based on the arithmetic, geometric and harmonic means of aS and aA were also computed. It was found that aopt and aA scaled the infiltration data more effectively (with lowest sum of squares error) than the other scaling factors. The results showed that the study area has high spatial variability. A map of aA developed using ArcGIS software showed that aA increased from the center to the surrounding areas as soil clay content decreased.

Food preservation has always been a concern for mankind. Different methods have been developed to preserve food for long periods, such as cold storage, plastic covers, and modified atmosphere This study examined the physicochemical and biological effects of a modified atmosphere on packaged Romaine lettuce at three levels (G1: 40% oxygen, 15% carbon dioxide, 45% nitrogen; G2: 70% oxygen, 15% carbon dioxide, 15% nitrogen; G3: 100% oxygen). The lettuce was packaged in 40 mm (P1) or 50 mm (P2) thick polyethylene at 4°C and stored for 16 days. The least polluted sample was G3 using P2, as assessed by the total number of microorganisms, mold and yeast. This sample was also in the best condition, as measured by pH and color. The highest percentage of weight loss was for G3 and P1; it also showed the greatest decrease in the percentage of soluble solid materials. The results showed that G3 and P1 was the best combination to preserve packaged Romaine lettuce. This combination was effective for two weeks of preservation.

Malting is a complex biotechnological process that includes steeping, germination and kilning of cereal grains under controlled temperature and humidity. This research investigated the effects of steeping (24, 36, 48 h) and germination time (3, 5, 7 days) on the quantitative and qualitative characteristics (hot water extract, malt extract color, soluble nitrogen, Kolbach index, total soluble solids, cold water extract) of malt extract obtained from barley (line EBYT88-17). Statistical analysis and process optimization were carried out using response surface methodology. Results showed that increasing steeping over a long germination period increased the the yield of hot water extract. Malt extract color increased as steeping and germination time increased and malt extract soluble nitrogen content varied from 0.081% to 0.46%. The results of process optimization showed that 47.99 h steeping and 6.89 day germination produced malt extract with the highest hot and cold water extracts and total soluble solids.

This research was conducted to determine the effect of hot water, ethanol and acetic acid vapor treatments on the characteristics of stored peaches (var elberta). Benomyl fungicide was applied to the control groups for all phases of study. In the first phase, the effect of hot water (immersion in 45, 50, 55 °C water for 1, 3, 5 min) on the quantitative (weight loss), qualitative (total soluble solids, flesh firmness, postharvest decay, acidity, vitamin C) and organoleptic (texture, aroma, total acceptance) characteristics of peaches over 45 days of storage (temp: 0±1°C and RH: 90 95%) were studied. Benomyl fungicide was applied at 1000 ppm for 0.5 min to the control peaches. The results showed that treating fruit with hot water 50°C for 1 min and 45°C for 3 min had the same effect as fungicide on fruit quality. In the second phase, the effect of hot ethanol solutions (2.5%, 5%, 10%, 20% at 40 or 50 °C) was compared with the control group over 45 days storage. The results showed that treating fruits with 10% ethanol solution at 50°C and 20% ethanol solution at 40°C both had the same effect as using benomyl fungicide. The third phase studied the effect of acetic acid fumigation (1.35%, 2%, 2.7%, 4%, 5.30% for 1 h). The results showed that peaches treated with 2.7% and 4% acetic acid solutions preserved the quantitative, qualitative and organoleptic characteristics of fruits in a condition similar to the fungicide control group.

In a direct injection sprayer (DI), the delay time to change the concentration of chemicals in the spray tip can have a substantial effect on sprayer performance. Delay time is the most important variable in evaluating the performance of a DI system in real time herbicide application. The flow of solution from the injection point to the nozzles was mathematically modeled to quantitatively evaluate the effect of tube volume and carrier flow rate on dynamic specifications, such as delay time. Plug-Flow and Well-Mixed models were used to model solution flow in DI systems. A DI system was designed and built to allow comparison between the mathematical model and tests results. ANOVA (Duncan test) at a 5% confidence level was used to determine the effect of change of the parameters on the delay time. A factorial completely randomized block design and SPSS 15 software were used for statistical analysis of the data. Comparison of the mathematical model with the test results showed that, for time response, the Well-Mixed model had a more appropriate response time than did the Plug-Flow model. The Well-Mixed model is suggested for predicting the dynamic behavior of a DI system. Both models produced stable state values that were slightly different from test results.

In this study, a numerical simulation was developed for flow in a pilot plant spray dryer with a cooling air jacket using the CFD method. A k-ɛ standard model was used to simulate turbulence. Air flow patterns and temperature variation in the chamber and cooling air jacket were estimated and suitable insulation calculated for the ceiling of the chamber. To verify the numerical results, velocity in the dryer was measured using a portable hot wire anemometer. Temperature variation was measured using transmitters installed at varying heights in the chamber. The numerical results showed that flow pattern consisted of a high velocity core extending toward the end of dryer. A circular flow around the circumference of the flow created vortices and caused particles to turn back toward the top of the dryer. The maximum temperature was at the core of the air flow and temperature decreased from the core toward the dryer wall. The flow path line in the cooling air jacket showed that the air layers were in smooth and harmonic motion around one another that produced little variation in axial velocity in this zone; however, at the junction of the cylindrical and conical parts of dryer jacket, some flow deviation occurred toward the wall. Adequate insulation for the ceiling was chosen according to the ratio of heat conductivity to the thickness of the insulator (K/L).

Most areas of Khuzestan province in Iran are extremely uneven and a traditional leveler is not adequate for precision leveling of provincial farms. Uneven soil surface in a field affects seed germination, yield, and water consumption. This experiment was conducted in 2010-2011. A t-test based on the unpaired observations experimental method compared a laser leveler (LL) and conventional leveler (CL) by leveling index (LI), total operation time, water consumption, and yield. The two test fields of differing roughness were located north of the city of Ahvaz. Results showed a 1.4 cm LI for LL for both fields, while, for the CL method, LI was 3.5 cm for field one and 2.7 cm for field two. The time needed for leveling with LL (3.7 h/ha) was 2.2 times more than that for CL. There were significant differences between LL and CL for mean of seed germination and grain yield. LL produced the highest seed germination and grain yield. LL grain yield was 29% greater than CL and LL water use efficiency was 67% greater. LL water consumption was about 33% less than for CL. On the other hand, fields with low roughness could be efficiently leveled using CL without the need for laser technology.