JOURNAL OF AGRICULTURAL ENGINEERING RESEARCH
Year:2007 | Volume:8 | Issue:2|Papers Count:19

Among different land degradation processes, soil erosion is a serious threat to the soil and water resources in Iran. Soil physical and chemical properties have an important role in runoff and sediment. The purpose of this study was to investigate the effect of some of these agents on sediment yield, runoff generation and sediment concentration, under interrill erosion process at the field. The experiments were done on Golabad soils, with annual precipitation of 170 mm. A portable rainfall simulator was used in 9 homogenous sites of the watershed with 3 replications (overall 27 plots). Rain intensity of 35 mm hr–1 for 40 minutes was run on 1m2 plots. Runoff and sediment samples were collected from each plot. Some of soil physical and chemical properties consisted of texture, gravel content in two positions, moisture content, pH, EC, CaCo3 and organic matter were determined. The results indicated that increasing clay content, sediment yield and its concentration increased while, sand fraction decreased runoff and sediment. Surface gravel had an important role in erosion control. Increasing surface and embedded gravel, runoff rate increased and decreased, respectively. Besides, due to surface gravel, sediment yield increased. There were positive and significant relations between moisture content at 0.03 and 1.5 MPa with sediment yield and its concentration. Among chemical properties, pH was entered into the regression model. Also, due to crusting, lime increased erosion. It was concluded that particle size distribution is the main factor which controls sediment yield, runoff generation and sediment concentration under interrill erosion processes in this arid soils.

The shortage of fresh water and growing competition for clear water makes less water available for agriculture production. The great chalange for the coming decades will be the task of increasing food  production with less water, particularly in countries  with limited water and land resources. Therefore, increasing of irrigation efficienciy and decreasing of water losses are important factores in agricultural development. Evaluation of different irrigation management and their performance is essential for improving of irrigation water application. In this research, on-farm furrow irrigation efficiencies under different management and different crops such as sugarbeet and corn were measured in some parts of Moghan region. After selection of the irrigation plots (for two selected crops) and measurment of water discharge, runoff rates, soil moisture befor and after irrigation, rooting depth and wetted soil depth, different irrigation efficiencies were determined. The results showed that irrigation efficiencies vary extremely with respect to farmers management, length and slope of plots, physical characteristics of soils, crop and other factors. The minimum irrigation application efficiency for corn was about 6.9% and the maximum of that was 93.4% and on average was 45%. The average irrigation application efficiency for corn under governmental management was 24.9% and the average of that for corn under farmers management was 65.3%. Also the minimum irrigation application efficiency for sugarbeet was about 7.8% and the maximum of that was 84.5% and on average was 49.2%. The average irrigation application efficiency for sugarbeet under governmental management was 62.7% and the average of that for sugarbeet in farmers management was 35.6%. The study showed that losses to deep drainage were substantial and improvement of  irrigation  management can reduce water losses.

In order to study the possibility of reduced tillage methods in Wheat planting after Potato, a field experiment was conducted on a sandy clay loam soil in the Tajarak Agricultural Research Station located in 70km Northeast of Hamedan. A randomized complete block design experiment with 8 tillage treatments (consisted of 1. Moldboard plowing + Twice disking + Leveler 2. Chisel plowing + Once disking + Leveler 3. Six bottoms plow + Once disking + Leveler 4. Once disking + Leveler 5. Sweeping + Leveler 6. Six bottoms plow + Leveler 7. Chisel plowing + Leveler 8. Leveler) was performed in 3 replication during 2 years (2001-2 and 2002-3). In this study, the machine parameters of forward speed, tractor drive wheel slip, working depth, field efficiency and theoretical and effective field capacity, as well as crop parameters of grain, straw yield and harvesting index, were measured or calculated. It was noted the method of disking + leveler after potato harvesting was for wheat planting. However if sweep used after harvesting potato, only leveler can be suggested as the most suitable method.

In big cities, considerable amounts of fresh water are allocated to the municipal and industrial usages, and no sufficient water is available for agricultural purposes. As a result, in recent years, utilizing treated municipal wastewater for other purposes and especially for irrigation has brought the attention of many researchers and scientists. In this study, the effects of the treated municipal wastewater of Ahwaz on some of the hydraulic characteristics of soil including saturated hydraulic conductivity (Ks), specific water retention (Sr), and final infiltration rate of the soil (If) at various depths (0-13, 13-26, and 26-40cm) and various irrigation periods (1, 2, 4, and 6 months) were investigated. The irrigation waters used were effluent from Ahwaz Municipal Wastewater Treatment Plant (AMWTP) and Karoon River Water (KRW). The study performed on the lands near the Ahwaz Municipal Wastewater Treatment Plant with a completely randomized factorial design and three replications under no plant culture. The experimental plots were 2.5m × 2.5m in size with a sandy loam texture. After 1, 2, 4, and 6 months irrigation with the AMWTP and KRW, the hydraulic characteristics of the experimental plots at the specified depths of soil were measured and/or calculated. The results of the study showed that irrigation with the AMWTP significantly (P<0.05) increased the final infiltration rate and the saturated hydraulic conductivity (Ks) of soil compared to the KRW. Also, with increasing the irrigation period from 2 to 4 months, the AMWTP increased more the hydraulic properties of the soil, which could be due to better environmental conditions for the growth of micro-organisms in the Spring season. The results also indicated that with increasing the soil depth, the increasing effect of the AMWTP on the hydraulic properties of the soil decreased.

In order to evaluate the physico-chemical properties of new potato varieties and to introduce proper varieties for processing, this study was carried out using Randomized Complete Block Design (RCBD) with three replications for two years in Karaj. Seventeen varieties i.e. Jelli, Slani, Burren, Banba, Colombus, Sante, Agria, Akira, Aida, Arkola, Almera, Daisy, Cyclon, Lady Clayer, Lady Rozeta, Melodi, and Lady Florina were investigated. Dry matter and specific gravity (two weeks after harvest), sugar reduction (two weeks after harvest and two months after storage at 7oC and 85-90 % R.H.) and sensory parameters such as overall acceptability, color and crispiness (two weeks after harvest) were examined. Results revealed that the measured properties were significantly different. Changes in level of sugar reduction during storage were significantly different for the above varieties. The highest variation was related to the varieties containing lower level of sugar reduction at harvesting time. Lady Rozeta, Lady Clayer, Daisy, and Akira varieties had higher levels of dry matter while Akira had the highest specific gravity. Specific gravity was significantly correlated with dry matter and texture hardness of potatoes, but the level of reducing sugar was correlated inversely with specific gravity. The results of sensory analysis of chips indicated that Agria, Cyclon, Akira, Colombus and Jelli had the most overall acceptability respectively. Correlations between overall acceptability with the color and crispiness of chips were significantly positive. Overall acceptability showed stronger correlation with crispiness than that of for color. According to the findings of this research, it can be recommended that Jelli, Colombus, Agria varieties are suitable for french fries, Sante is appropriate for chips and Akira, Burren, Banba are good for other applications.

In order to investigate the effects of single irrigation amounts at different stages of rapeseed growth on yield and the improvement of water use efficiency and water productivity indices, this experiment was conducted as split plot arranged in a randomized complete block design (RCBD) with three replications during 2002-2003 for rainfed spring rapeseed variety (PF.7015.91= Sarigol) at Maragheh Agricultural Research Station of DARI. The treatments included four levels of single irrigation amounts (rainfed, 30, 60 and 90mm of water use) at three growth stages (stem elongation, flowering and filling stage). The analysis of variance showed that, during two seasons of the study, there were significant effects due to single irrigation amounts, growth stages and their interactions. Results showed that the optimum level of single irrigation for increase and yield stability of rapeseed was 60mm water use at flowering stage which produced 1071kg.grain.ha-1. The WPI+P, WPI and WUE for this treatment were 4.79, 8.09 and 2.46kg.mm-1, respectively.

Crust breaking of saffron is an important operation at the first stage of growth that should be accuratly operated as in this period sprouts of saffron rise up to near the soil surface. After primary irrigation, farmers soften the soil surface by means of different cultivation implements, which enables saffron flowers arise from subsurfarce. This research was conducted to compare tillage implements with no crust breaking method for three-times irrigations (early, on time, late) technically and economically. In this research, therefore, three-time irrigations were selected as three expriments and horizontal factors were: a) no crust breaking b) animal plow c) manual crust breaking using a local tool (Chahar shakh) d) rotivator with special blades. This research performed at the farm of Saffron and Medical Plants Research Station planted three years ago. It was concluded that for the early irrigation experiment tillage implements did not have significant effect on yield at the first year, but manual crust breaking and no crust breaking had significant difference at the second year. Regarding the effect of time of irrigation manual crust breaking and rotivator factors produced saffron yield higher than no crust breaking and animal plow factors with significant difference. At the late irrigation experiment, the highest yield was related to both no crust breaking and manual crust breaking factors and there were significant differences between no crust breaking and manual crust breaking factors and also between rotivator and animal plow factors. Economical evaluation showed that using rotivator would be the best method for early and on time irrigation, and the suitable method for late irrigation was no crust breaking.

Soaking of watermelon seed helps to germinate faster (especially in dry farming) and increases with the weeds. In this case seeds absorb considerable amount water and may also germinate. Because of some specifications of the seeds during germination, there should be a proper mechanism for seed metering and distribution. Four different types of mechanisms which were supposed to be useful in this regards were designed and compared in this research. Different mechanisms were planned on the basis of helping the seed to fall down through a pipe by water movement. On the other hand, using water can help the seed to hold more moisture and protect it against mechanical damages. Horizontal seed plates were used for all the mechanisms. Seed plates were provided in two types of internal holes and side holes which by a water injection (weight/pressure) and three speed levels of 1.5, 3 and 4.5 (km /hr) were tested for 50 cm space of hill sowing. Different mechanisms were tested and evaluated for planting of watermelon seeds. A factorial experiment in the form of complete randomized design was used with three replications. Percentage of hills with two or three or four seeds (ACP), performance index (PI), damage percentage (D) and volume of water (V) in each hill were determined in this experiment. Results showed that the type of seed plate, water injection, forward speed and interactions between injection method and speed on PI, V and ACP were significant. Interacted effect of injection method and speed was significant on PI while type of seed plates and speed had no significant effect on other parameters. Interaction effect of three mentioned parameters was only significant regarding the volume of water and seeds mechanical damages were found not to be significant in all the cases.

This field experiment was conducted in order to investigate drainage and nitrogen fertilizer effects on grain yield and oil percentage of rapeseed. The split-plot method in a randomized block design (RCBD) with variety of Hyola 308 in three replications was employed in the paddy field at the north of Iran (Rasht - Rice Research Institute of Iran). Treatments were included three drainage levels (without drain, surface drain with 2m spacing and average depth of 15cm, surface drain with 4m spacing and average depth of 15cm vertical ditches of 1m spacing and average depth of 7cm) and four nitrogen fertilizer levels (0, 150, 200 and 250kgN/ha that split as 1/3, 1/3, 1/3). The results indicated that, drainage increased grain yield, oil percentage, nitrogen uptake, nitrogen recovery efficiency. Agronomy efficiency 94.33-97.82%, 2.47-3.88%, 96.55-103.50%, 88.01-125.30% and 104.69-167.18% respectively, but reduces protein percentage 4.21-9.76%. Also, nitrogen fertilizer increases grain yield, protein percentage and nitrogen uptake 199.08-239.60%, 5.31-7.60% and 233.26-292.44% respectively but reduces oil percentage, nitrogen recovery efficiency and agronomy efficiency 0.74-3.35%, 10.24-24.77% and 11.39-21.84% respectively. In general considering all phenomena involved in the paddy fields (environmental problems, soil condition, operational suitability, costs, ...) surface drain with 4m spacing along with nitrogen fertilizer of at least 150kgN/ha can be suggested.

The objective of this research was the prediction of head rice yield (HRY) in fixed bed dryer by using artificial neural network approach. Several parameters affect on operation of fixed bed dryers that were considered as input variables for artificial neural network. These variables were: air relative humidity, air temperature, inlet air velocity, bed depth, initial moisture content, final moisture content and inlet air temperature. In total, 375 drying experiments were accomplished for creating of training and testing patterns by a laboratory dryer. Samples were separated from various depths of dryer and then dehulling and polishing operations were done by laboratory apparatues. HRY was measured for all the depths and average of them was considered as HRY for each experiment. Feed forward neural network and cascade forward neural network with Levenberg-Marquardt and Bayesians regulation back propagation algorithm were used for training of presented patterns. Results showed that the feed forward back propagation algorithm with topology of 7-7-7-1 and Levenberg-Marquardt training algorithm and similar activation functions for all of the layers (Sigmoid Tangent) predicted the HRY with coefficient of determination 0.9655 and mean absolute error 0.019 at different conditions of fixed bed paddy drying method. Results showed that the input air temperature and final moisture content had the strongest effect on HRY.