A one-way moldboard plow turns over soil in only one direction. Problems created by this type of tillage in Iran include compaction of boundary regions, decreased efficiency of irrigation and disruption of bed leveling, requiring the use of bed-leveling equipment every few years. To overcome these problems, ...
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A one-way moldboard plow turns over soil in only one direction. Problems created by this type of tillage in Iran include compaction of boundary regions, decreased efficiency of irrigation and disruption of bed leveling, requiring the use of bed-leveling equipment every few years. To overcome these problems, the use of a two-way plow with two harrows which turns over the soil to both the left and right sides is recommended by specialists. However, the weight and expense of these two-way plows along with the limited power of tractors available in Iran rules out this method for most farmers. The two-way three-harrow square plow was designed to solve the problems of conventional two-way plows. In this study, the performance of the two-way three-harrow square plow was compared to the conventional one-way three-harrow moldboard plow. The tests were conducted according to the RNAM test code and the recommendations of Smith et al. at the training and research farm of the Abureyhan campus of the University of Tehran. The results showed that the bulk density of the soil after tillage by the two-way plow is significantly lower than for the one-way plow and soil evenness created by the two-way plow is more desirable than for the one-way plow. The difference between plow uniformity was not significant for the two types of plow. The mean soil clod diameters were 31.96 mm and 39.86 mm for the two-way and one-way plows, respectively. The draft and tractor wheel slippage of the two-way plow were significantly greater than for the one way plow. It was generally concluded that the performances of the square plow and one-way plow are similar, thus recommending the used of the two-way plow.
This study was conducted to evaluate the impact of deficit irrigation and growth stages on yield and yield components of potatoes and water use efficiency. A field experiment was conducted at Shahrekord Agricultural Research Station over three years of crop seasons using a randomized complete block design ...
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This study was conducted to evaluate the impact of deficit irrigation and growth stages on yield and yield components of potatoes and water use efficiency. A field experiment was conducted at Shahrekord Agricultural Research Station over three years of crop seasons using a randomized complete block design with three replications. Plots were assigned to five levels of deficit irrigation treatments, E0 (full irrigation), E1 (85%), E2 (70%), E3 (55%) and E4 (30%) for actual evapotranspiration of potatoes, and three growth stages, T1, T2 and T3. Results of the combined analysis of variance showed that biological yield, tuber yield, yield components, water use efficiency and other traits in the growth stages were significantly affected by deficit irrigation treatments. Under E1, E2, E3 and E4 treatments, yield decreased by 5.1%, 8.9%, 13.12% and 25.5%, respectively, when compared to E0. Susceptibility at developmental stages of the potato to deficit irrigation differed. The T1 stage was the most critical stage under water stress conditions. Water use decreased compared to E0 by 17.5% in stage T1, 11.1% in stage T3 and 10.08% in stage T2.
Soil hydraulic properties are key soil physical characteristics that are required to conduct soil and water related studies such as irrigation and drainage. In this study, three indirect methods: inverse modeling, pedo-transfer function, and the semi-physical method of Arya et al., were compared in a ...
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Soil hydraulic properties are key soil physical characteristics that are required to conduct soil and water related studies such as irrigation and drainage. In this study, three indirect methods: inverse modeling, pedo-transfer function, and the semi-physical method of Arya et al., were compared in a sandy loam soil to estimate soil moisture retention and unsaturated hydraulic conductivity curves. Subsequently, they were applied to simulate soil moisture in irrigated furrows. In the indirect methods, soil hydraulic properties were estimated from easily measured soil data. Using the neural network-based pedo-transfer function of ROSETTA code, soil hydraulic parameters were obtained from soil textural fractions (percentage of sand, silt and clay), bulk density, and two water retention points as input. In the inverse method, the most sensitive soil hydraulic properties were estimated using the Levenberg-Marquardt optimization algorithm in combination with the HYDRUS-2D numerical code. In the semi-physical method, both soil retention and unsaturated hydraulic conductivity curves were predicted from a particle size distribution curve. The predicted soil hydraulic properties were applied to simulate soil moisture below the irrigated furrows during two subsequent irrigations. The results showed that the inverse modeling and Arya et al. methods predicated the soil water content well in the experimental furrows while the pedo-transfer function of ROSETTA overestimated soil water content.
In this study, the effect of the speed of the mill-rotor during the whitening process was evaluated for the milling properties of two varieties of rice in Fars province. A split plot design with five replications and the Duncan test were used for statistical analysis. Two varieties of paddy rice, Amol-3 ...
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In this study, the effect of the speed of the mill-rotor during the whitening process was evaluated for the milling properties of two varieties of rice in Fars province. A split plot design with five replications and the Duncan test were used for statistical analysis. Two varieties of paddy rice, Amol-3 and Kamfiruzi, and five mill-rotor speeds, 550, 600, 650, 700 and 750 rpm, were selected as main plot and sub-plot, respectively. The samples were milled at different speeds and the milling-output parameters of percentage of breakage and cracking, break strength and whiteness degree of rice kernels was measured. The results showed that the speeds of 600 and 600-650 rpm are the most proper mill-rotor speeds for the Kamfiruzi and Amol-3 varieties, respectively. Furthermore, the percentage of breakage and degree whiteness of the Amol-3 rice was 6.36% and 3.46%, respectively, more than for the Kamfiruzi variety. The percentage of cracking and break strength were 13.31% and 17.22 kgf more in the Kamfiruzi variety compared to the Amol-3 variety.
Stand establishment in crusting soil is one of the main concerns in the production of crops with delicate seedlings such as cotton, onions and rape seed. Crust breaking, maintaining soil moisture and adding chemical and organic amendments to soil are different methods to weaken soil strength and allow ...
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Stand establishment in crusting soil is one of the main concerns in the production of crops with delicate seedlings such as cotton, onions and rape seed. Crust breaking, maintaining soil moisture and adding chemical and organic amendments to soil are different methods to weaken soil strength and allow the shoots to emerge. These methods are not always successful because they depend on factors such as the skill and timing required for crust breaking, shortage of water in arid regions and slow increase of soil organic content. The development of natural desiccation cracks along the planting lines is a new technique that can create a route by which seedlings can emerge. In this study, a pneumatic row crop planter was modified to provide physical conditions conducive to the development of longitudinal cracks along planting lines. The modifications included a v-shaped pre-opener attached to the front of the main opener and a conical wheel that replaced the original flat wheel of the machine, causing machine to leave a shallow furrow on the planting lines. This allowed the formation of longitudinal cracks over 96% of the planting line, which brought about an emergence rate of 72% for cotton seedlings in well-prepared soil. This technique in row planting was then compared the emergence of cotton seedlings using the conventional method (seed broadcasting and crust breaking) on large plots in the Isfahan region. Results revealed that, by using 1/10 the seed used currently in the broadcasting method, a desirable stand establishment can be achieved without crust breaking or further thinning. This results in a more uniform stand distribution and 2,100,000 rials per hectare saving for growers in planting stage alone.
Soil compaction is an important aspect of agriculture and different methods are available to measure this parameter. One method is called the cone index; measuring the force required per unit area for penetration of a standard steel cone into the ground. Cone penetrometers are used for cone index measurement. ...
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Soil compaction is an important aspect of agriculture and different methods are available to measure this parameter. One method is called the cone index; measuring the force required per unit area for penetration of a standard steel cone into the ground. Cone penetrometers are used for cone index measurement. In this study, a tractor mounted, hydraulically-operated penetrometer was designed, built and evaluated. The penetrometer consisted of a frame, hydraulic driving unit, force transducer, depth measuring unit and data acquisition system. The entire penetrometer unit was mounted on the frame and held in place by the three-point hitch on a category III tractor. The hydraulic driving unit provided a constant penetration rate of 3 cm/s, in accordance with the ASAE S313.3 standard. A cantilever beam strain-gauge load cell measured the penetration force applied to the cone shaft and a photodiode sensor measured the penetration depth. A microcontroller-based data acquisition system was designed and developed to record and save the penetration data. Evaluations were conducted by comparing the data of the tractor- mounted penetrometer and that of a commercial hand-pushed penetrometer (Eijkelkamp). Analysis found no significant difference at the 95% confidence level. The penetrometer performance was found to be reliable and the unit’s mechanical and electronic parts worked without malfunction.
The proper and quantitative recognition of the scale of turbulence in regard to issues such as sediment transport is of major importance. Different experimental techniques can be used to determining the scale of turbulence, but the accuracy of these techniques is open to question. In this paper, after ...
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The proper and quantitative recognition of the scale of turbulence in regard to issues such as sediment transport is of major importance. Different experimental techniques can be used to determining the scale of turbulence, but the accuracy of these techniques is open to question. In this paper, after a review of the Taylor method, the restrictions and advantages of velocity measurement techniques such as hot wire anemometry (HWA), laser doppler velocimetry (LDV) and particle image velocimetry (PIV) are described. Correlation coefficients were applied to determine the scale of turbulence using these techniques. The results showed that the main restrictions of the HWA technique were its intrusiveness and the sensitivity of the sensor. The LDV technique was restricted to measuring correlation coefficients in small distances and for just one velocity component. The results showed that the PIV technique has restrictions in its framing rate, saving image, image resolution and laser pulsing frequencies. However, considering the large spatial domain of PIV and its non-intrusive measurements and especially the continuous development of its capabilities, PIV is an appropriate technique for determination of the scale of the flow of turbulence.
Pectin is used as gelatinizing agent in food industry. In this study pectin was extracted from five commercial sugar beet varieties namely: Doroty, Rasul, 7112, Br1 and Ic using pre-hydrolysis technique. Experiments were conducted using factorial design to verify the effect of temperature, time, percentage ...
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Pectin is used as gelatinizing agent in food industry. In this study pectin was extracted from five commercial sugar beet varieties namely: Doroty, Rasul, 7112, Br1 and Ic using pre-hydrolysis technique. Experiments were conducted using factorial design to verify the effect of temperature, time, percentage of HCl and water requirements on the extraction rate of pectin. The qualitative factors of pectins extracted were compared with high methoxyl (HM) and low methoxyl (LM) pectins as control. Most suitable hydrolysis was maintained using the mixture of 2.5 parts of dried pulp and 5% HCl (v/v) at the temperature of 45ºC and time of 48 hours. The most favorable results were obtained by addition of 450 ml H2O during extraction. Also qualitative analysis of pre-hydrolysed pectin was resulted in 14.96% extraction efficiency, 58.63% estrification value, 63.92% galactronic acid and 14.95% amide substitution value. The estrification degree of pectin obtained by pre-hydrolysis technique was 10% higher and 10% lower than those for the pectins obtained by acid extraction technique and commercial extraction method, respectively. Amide substitution degree using pre-hydrolysis technique was 6.5% and 7.5% higher than those for the acid and commercial extraction, respectively. Since, pre-hydrolysis technique of pectin extraction gained better results as compared to other methods, therefore, it can be concluded that the pre-hydrolysis technique is better than extraction by acid method. Moreover, cultivars 7112 and Rasul had significantly higher pectin content than cultivars Ic and Br1. Considering that the presence of pectin during the sugar-making process is not desirable for the processing of sugar, it is of great importance to decrease the pectin content of sugar beet during breeding programs.
