JWSS - Journal of Water and Soil Science

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The effects of three levels of soil moisture content (8-10, 10-12 and 12-14% d.b.) and three levels of plowing depth (15, 20 and 25 cm) on draft, specific draft and drawbar power requirement of a 7-shank chisel plow in a clay loam soil were investigated. The experimental design was a randomized complete block design with a 3×4 factorial. The effect of plowing depth on all of the parameters mentioned was highly significant. Implement draft and drawbar power requirement both increased with plowing depth, whereas a decreasing trend of specific draft with depth was observed. Soil moisture content had no significant effect on draft and specific draft of chisel plow in the range of moisture contents studied, though both parameters were minimized at 10-12% m.c. At this moisture level, the drawbar power requirement showed a significant reduction comparing with the other two moisture levels. This indicated that the soil was close to its optimum friability at this moisture content. Soil penetrometer readings, taken before and after plowing, indicated the existence of a hardpan from about 8 to 20 cm below the surface which was broken by chisel tines, but another hard layer formed under the plowing depth by the chisel points. Comparison of the results from the present study with those from the previously published works on chisel plow draft at similar plowing depths showed that the values obtained for draft and specific draft were acceptably close to those previous investigators. Also, a comparison with the findings of Loghavi and Moradi on moldboard plow draft under similar conditions confirmed the reports of previous investigators to the effect that a chisel plow requires approximately one-half of the draft of a moldboard plow with the same working width and depth.

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One of the most vital problems in the storage and utilization of surface waters for drinking, flood control, hydropower, and agricultural purposes is that of sedimentation in reservoirs and subsequent decline of dam lifetime. The useful lifetime of a dam is defined as the time necessary for approximately 80% of the volume of its initial capacity to be filled by sediments washed in by water. It is a function of the volume of the incoming sediments, specific weight of sediments, and reservoir trap efficiency. Trap efficiency depends on sediment characteristics, life, shape, and rule curves of the reservoir as well as on the capacity-inflow ratio. It is the purpose of the present study to calculate sediment trap efficiency of small dams and also to determine the relationship(s) among the effective parameters in the Chaharmahal and Bakhtiary region. For our purposes, 14 small earth dams (with heights of less than 15 m and capacities of about 1 MCM) were selected around Shahrekord and Borougen. Since no data were available on the erosion and sedimentation for these dams, the MPSIAC empirical model was used to estimate the incoming sediment to the dams' reservoirs. The model considers nine factors effective on erosion and sediment production in each watershed. These factors were analyzed for the watershed of each dam under study and the annual sediment yield was calculated. The amount of sediments retained in the reservoirs as a result of the working life of the dams was estimated by reservoir surveying. The trap efficiency was calculated for all the reservoirs under study. The results obtained revealed that the trap efficiencies for these small dams ranged from 10.4 to 68.9%. New curves were developed and suggested for the trap efficiency of small dams based on these results.

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Optimum rice population densities and the response of rice yield and yield components to population densities and planting pattern are important factors helping rice producers and researchers to achieve maximum productivity. For this reason, a randomized complete block design experiment was conducted during the summer of 1995 at Isfahan University of Technology Research Farm located at Lavark, Najafabad. Zayandeh-rood cultivar was transplanted with three seedlings per hill at row spacing of 15, 25 and 35 cm and hill spacing of 10, 15 and 20 cm under flooded conditions. Row spacing influenced the plant height significantly at heading and anthesis stages. Wider row spacing, enhanced days to 50% heading and anthesis and consequently grain filling duration and ripening stage coincided with unfavorable conditions at the end of the season, which decreased the percentage of maturity. Although number of tillers per unit area increased, tillers per plant decreased as row spacing was reduced. Narrow row spacing limited vegetative growth after anthesis and thereby growth rate of panicle increased. With reduction of row spacing, without any change in the percentage of full grains per panicle and grain weight, number of panicle per unit area increased but number of grains per panicle decreased. At greater row spacing, grain yield per unit area decreased although grain yield per plant and harvest index increased. Although, effects of hill spacing were similar to those of row spacing, hill spacing usually did not influence plant characters, yield components and grain yield significantly. Stepwise regression and path-coefficient analysis revealed that number of panicle per unit area is the most important yield components. It also showed that indirect effects of panicle per unit area on yield through its association with grain per panicle prevented real effects of grain per panicle on yield. Fifteen × 15 cm spacing produced maximum yield which is probably recommendable for rice production in Isfahan.

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Effect of different times and levels of nitrogen fertilizer application on growth and grain yield of spring wheat cultivar “Ghods” was studied during 1993-1994 growing season at Karkadj, Agricultural Experiment Station, College of Agriculture, University of Tabriz, using a split plot design with three replications. Main plots were assigned to five levels of N fertilizers (0, 40, 80, 120 and 160 kg/ha) and subplots to five times of applications [all of N fertilizer at planting (T^₀) 1/2 at planting + 1/2 during tillering stage (T₁), 1/2 at planting + 1/2 during heading stage (T₂), 1/3 at planting + 1/3 during tillering and 1/3 at heading stages (T₃) and 1/4 at planting + 1/4 at tillering + 1/4 at stem elongation and 1/4 at heading (T₄)]. Results showed that different levels of N applications affected grain yield and biological yield significantly, while the effect of split application and also N levels × times of application interaction on these two traits were non-significant. Growth stages of wheat were not significantly affected by different N Levels and times of application. Dry matter accumulation, leaf area index, and crop growth rate, in response to growing degree days during growing season, increased when higher levels of N fertilizer were applied. Leaf area index and crop growth rate initially increased up to anthesis and then decreased. Crop growth rate decreased to zero level at soft dough stage and then became negative. Variations in relative growth rate and net assimilation rate, in relation to growing degree days, decreased when different levels of N fertilizer were applied at early part of growing season it was maximum while at later growth stages decreased and finally became negative, Times of N application and level × time interaction during growing season did not affect the growth indices significantly.

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To determine the effects of field slope, emitter discharge, irrigation water volume and soil texture on soil moisture profile and soil surface wetted shape from a point source, field data were collected on three different soil types, three emitter discharges (4, 8, and 12 lph), four slopes (0, 2, 5, and 10%), and five irrigation water volumes (10, 20, 30, 40, and 50 liters) with three replications. The results showed that the surface-wetted area increases as the emitter discharge increases. The surface-wetted area decreased with a corresponding increase in emitter discharge in experimental fields with light-textured soils. In experimental fields with heavy textured soils and slopes greater than 5%, the changes in surface-wetted area due to the emitter discharge increases, were higher compared to slopes of less than 5%. Since, a higher emitter discharge would result in higher surface-wetted area, the results showed that for an equal volume of irrigation water, the soil moisture profile was deeper for lower emitter discharge. In general, the volume of wetted zone was higher for greater emitter discharges. It was found that as the volume of irrigation water increased, the volume of wetted zone would increase correspondingly. This effect is more prominent than that of emitter discharge. In general, the depth of wetting front was lower and the wetted surface area was greater for heavy textured soils as compared to the light textured soils. The wetted-surface area and the shape of wetting front in the direction of slope were affected by the soil infiltration, emitter discharge and volume of irrigation water where these effects were more critical in higher sloping lands.

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Feeding high levels of barley to laying hens is accompanied with dirty eggs, decreasing the feed intake and egg size. To improve the diet with barley for layers, different chemicals including a commercial enzyme effective on barley (Fin Feed), cupric sulfate pentahydrate, sodium bicarbonate, magnesium sulfate and oxytetracycline antibiotic were supplemented to experimental barley based diets. It was found that the commercial enzyme had a significant effect on layer performance. Other treatments didn't have any considerable effects on their performances. Enzyme supplementation significantly (P < 0.05) improved feed intake, production rate and daily egg mass production of laying hens. No significant difference were observed in laying performance of mature birds fed with barley-based diet or soybean corn diet.

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This study aims to evaluate the present management of border irrigation systems applied to wheat, alfalfa and sugar-beet farms in Boyer-Ahmad and Gachsaran cities in Kohgiloyeh and Boyer-Ahmad Province. Experimental farms included 8 alfalfa farms, 5 wheat farms and 5 sugar-beet farms. The experiments were conducted at different growth stages of plants and customary borders with prevalent dimensions, slopes, and management practices. The relationship between management allowable deficit, moisture deficit before irrigation, and infiltrated depth indicated that in most cases either “deficit irrigation” or “stress irrigation” had been applied. This type of irrigation has positive effects on water use but negative effects on supply of required soil moisture for plants. In the first to third irrigations, measured application efficiencies ranged from 40.8% to 100%, 52.2% to 100%, and 61.1% to 100%, respectively. Graphs of advance, recession, and ideal recession showed the effects of border slope and length on inflow cut time and uniformity of water distribution. Water infiltration curves showed the amount of deficit irrigation. The results showed that weak irrigation management is the result of three parameters: lack of knowledge on the part of farmers about soil moisture conditions and correct time for irrigation, weak irrigation scheduling, as well as an imbalance between available water supply and irrigation requirements which leads to wasting water and reduced irrigation efficiency.

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This research was conducted over a period of one year from the beginning of spring until mid autumn in 1996, during the bloom of all flowering plants in the region, when pollinator bees were collected with insect veil. Some of them were preserved in 80% ethylalcohol and some were dried, coded, kept in insect box and transferred to the laboratory for identification. The collected insects were identified to 7 families and 19 genera as follows 37 species from among them were identified to species level and 40 species were identified to genus level:

 1- Colletidae: Colletes (Colletes sp.)

2- Andrenidae: Andrena (A. thoracica, A. labialis, A. apicata, A. personata, A. erytrogaster, A. kalmiae, Andrena sp.), Melitturga (M. clavicornis, M. sp.)

3- Halictidae: Halictus (H. brunescens, H. senilis, H. squamosus, H. asperulus, H. resurgens), Lasioglossum (L. discum, L. epipygial, L. nigripes, L. villosulum, L. pygmaeum), Nomia (Nomia sp.).

4- Melittidae: Melitta (M. leporina)

5- Megachilidae: Megachile (M. rotundata, M. maritima, M. concina, M. frigida), Chalicodoma (C. georgica, C. rubripes, Chalicodoma sp.), Osmia (O. cornifrons, O. taurus, O. uncinata), Anthidium (A. florentinum, Anthidium sp.)

6- Anthophoridae: Anthophora (Anthophora sp.), Amegilla (A. quadrifasciata, A. albigena, Amegilla sp.), Eucera (E. nitidiventris), Tetralonia (Tetralonia sp.), Xylocopa (X. iranica, X. valga, X. pubescens, Xylocopa sp.), Proxylocopa (P. nitidiventris, P. rufa, Proxylocopa sp.)

7- Apidae: Apis (A. mellifera), Bombus (Bombus sp.)

 A key to the separate genera level and a complete key to the genera level for the Apoidea is produced and presented for each of the above named families collected in the north of Fars province.

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In order to study the genetic variation among local varieties of onion in Iran, an experiment was conducted in the Research Center, Faculty of Agriculture, Tabriz University. Sixteen populations were evaluated for agronomic characteristics and also total seed proteins via SDS-PAGE. Cluster analysis and principal component analysis were used to group the onion populations under study.

 Analysis of variance showed significant differences among varieties for leaf color, leaf length, texture tightness, onion yield per plant, and number of edible layers. No significant differences were observed for the number of twin onions, bulb diameter, and onion dry weight. Hamadan (98-148), Arak (98-95, 98-96, 98-97, 98-103), and Zanjan (98-223) populations acquired the highest onion yield per plant. The significant differences between populations for the majority of characteristics proved the existence of genetic variation in the Iranian onion germplasm. The results from cluster analysis for agronomic characteristics were the same as those from the cluster analysis for the onion yield per plant. The 16 populations were divided into 4 groups. Cluster analysis for the electrophoresis banding pattern resulted in two groups, which was not similar to the dendrogram of agronomic traits. Using principal component analysis, the first principal components determined 97.57% of the total variation. Onion yield per plant was the most important trait in the first principal component and onion dry weight was the second trait in the rank.

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In this research, the hydraulic behavior of furrow irrigation was investigated under cut-back, Walker-Skogerboe and conventional methods at the three experimental farms of Lavark, Shervedan, and Isfahan University of Technology for three irrigation events. In each farm, data were collected for each of the above methods with at least three replications including furrow shape, furrow length, furrow slope, soil texture, advance and furrow inflow and outflow.

 The parameters of Kostiakov-Lewis infiltration function were determined using the volume balance method. The deep percolation ratio, runoff ratio and application efficiency were then computed.

The results showed that deep percolation ratio was higher in the cut-back method as compared to the Walker-Skogerboe method (18.6% as compared to 13.7%) and the runoff ratio was less in the cut-back method as compared to those in the Walker-Skogerboe and conventional methods (12.4% as compared to 16 and 20.6%, respectively). The effect of the two parameters of deep percolation ratio and runoff ratio caused, in general, the application efficiency to be less in the conventional method than those in the cut-back and Walker-Skogerboe methods (42.7% as compared to 69 and 70%, respectively). In general, the cut-back method had a higher application efficiency in heavy texture soils as compared to light texture soils (73.9% as compared to 51.2%).

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In order to compare the effect of drip and furrow irrigation methods with different quantities of water (50%, 75%, and 100% of the amount of water evaporated from class A pan evaporation during irrigation intervals) on yield and quality of tomato, an experiment was conducted on a silty loam soil in Mashhad Agricultural Research Station. The experimental design was a factorial trial with completely randomized blocks and. four replications.

The results showed that the highest yield (51 t/ha) was obtained from the treatment of drip irrigation with 100% water application. This amount was 4.5 tons higher than the yield from furrow irrigation treatment. Deficit irrigation by 25 and 50 percent decreased total yield by 34.7% and 67.95% in the drip irrigation method and by 27.57% and 64.29% in the furrow irrigation, respectively. Water use efficiency in drip irrigation was two times higher than that in the furrow treatment. Quality and chemical composition of the fruits were not significantly different in the two irrigation methods. Increasing the water deficit, however, increased the amount of soluble solids of the fruits.

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Bridge abutments are usually located in the floodplain zone of rivers where velocity and shear stress are not uniformly distributed. The influence of channel geometry and lateral momentum transfer in compound flow field on the scouring phenomenon has not been fully investigated and understood yet. The impact of lateral momentum transfer on the local scour at abutments terminating in the floodplain of a compound channel is presented in this paper.

It is shown that, by accounting for lateral momentum transfer at small floodplain/main channel depth ratios (λ_a/H<0.3), estimates of maximum local scour depth are increased by up to 30%. Therefore, ignoring the influence of the lateral momentum transfer, in such circumstances, might result in unrealistic estimation of the scour depth. To draw a more general conclusion, more data are required to assess the influence of different parameters affecting the phenomenon in compound flow conditions.

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An experiment was conducted in order to study the possibility of compensatory growth by changing dietary nutrients concentration in the female Arian broiler chicks using a completely randomized design by means of standard and diluted diets. By standard diet is meant diet recommended by Arian’s guide catalogue and by diluted diet is meant the diet used in Iran broiler farms. However, both diets contain the same nutrient/energy ratios. Chicks in the seven treatments received in their starter, grower and finisher stages standard and standard and standard, standard and diluted and diluted, diluted and standard and diluted, diluted and diluted and standard, diluted and standard and standard, diluted and diluted and diluted, standard and standard and diluted respectively. Furthermore each treatment contained three replicants and each replicant contained 30 chicks. This experiment was conducted in autumn using 630 female Arian broiler chicks for eight weeks.

 It was concluded that weight gain of chicks receiving standard diets during all stages of their growing period was the same as the chicks receiving diluted diet during their starter period and standard diets during grower and finisher periods. Feed consumption and feed conversion ratio of these treatments were statistically lower than other treatment groups. Furthermore, production index and percentage of mortality was better than other treatment groups. Likewise, viscera% and abdominal fat% remained significantly constant in all treatment groups. But the cost of feed per unit of live body weight was lower in the treatment receiving diluted diets in all three stages of their growing period.

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Flood is one of the catastrophic events that has attracted the hydrologists’ attention. In this research one of the important flood indices, i.e. maximum-daily mean-discharge, was determined for several western Iran watersheds, namely, in the catchments of Gamasiab, Qarasou, Saimare, Kashkan, Sezar and Abshineh. Daily data were prepared from stream-gauging stations and a 30-year concurrent period was selected.

 Flood frequency analysis was performed using HYFA and TR computer programs and optimum distributions were chosen by goodness of fit tests. Extreme flow values having different return periods of 2, 5, 10, 25, 50, 100, 500 and 1000 years were calculated. Modeling was done with regional analysis using multiple regression technique between maximum-daily mean-discharge and physiographic characteristics of the basins. The most important parameter for the selection of the model was the adjusted coefficient of determination while significant level, standard error and observed discharger vs. computed discharge plot acted as controlling parameters. Finally, different models with different parameters were selected from power, exponential, linear and logarithmic forms. The results showed the power model to be the best among the four types. The main channel length, drainage density and time of concentration were the most effective parameters on flow. After analyzing the errors, it appeared that increasing the return period would cause an increase in the model error. At 1000-year return period, the error reached 32.2%.

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The main sources of cadmium in soil-plant continuum in amounts that might present a hazard are liquid and solid wastes of sewage sludge, farm manures and fertilizers. In the southwest of Iran (Khuzestan Province) over 50,000 ha of land is under sugarcane (Saccarum officinarum) cultivation and more than 80,000 ha will be under sugarcane by the end of the year 2000. In these sugarcane fields, about 400 kg ha^-1 diamonium phosphate (DAP) and 400 kg ha^-1 urea are applied annually. There is no data available to show the fertilizers impact on soil, water and plant contaminations in Iran with respect to cadmium. The objective of this research was to compare the extractable cadmium of virgin soils with that of soils under sugarcane.

 Four sugarcane growing stations viz. Haft-tapeh, Karoon, Shoeibieh and Ghazali with cultivation histories of 36, 20, 2 and 1 year, respectively, were selected. In each site, along a transect soil samples from 0-30 cm of both furrows and ridges of cultivated soils and of virgin soils were collected. Electrical conductivity (EC), pH, clay and organic carbon contents, CI and Cd of 101 soil samples were measured according to standard methods. Results showed that increasing either EC or CI increased Cd concentration with its maximum in virgin soils and its minimum in furrows.

 Results also indicated a slight decrease in the Cd content of cultivated soils.

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Two experiments were conducted to investigate the effect of dietary energy levels on the performance of Arian broiler chicks. Trial 1 was performed in summer and trial 2 in fall. Both experiments were accomplished in 5×2 factorial designs, involving 5 levels of dietary metabolizable energy and two sexes. Each of the 10 resulting treatments was replicated 4 and 3 times in trials 1 and 2, respectively. The metabolizable energy contents in diets number 1 to 5 were 2800, 2900, 3000, 3100 and 3200 Kcal/kg for starter (0-4 weeks) period and 2900, 3000, 3100, 3200 and 3300 Kcal/kg for grower (4-7 weeks) period, respectively. The ratios of energy to each nutrient were the same for all diets in each stage of the experiments.

In both experiments, body weight gain and feed conversion ratio improved significantly (P<0.01) when diets with higher levels of energy were consumed. Feed intake was affected (P<0.01) by the dietary energy content only in summer (trial 1) resulting from the reduced intake of chicks fed with the lowest energy level. Abdominal fat percentage was decreased (P<0.01) in chicks fed with the lowest energy diet in summer. In both experiments, the cost of the feed per unit of live body weight was reduced (P<0.01) in accordance with the reduction in diet density. As expected, body weight gain, feed conversion ratio, abdominal fat and cost of the feed per unit of live body weight for male chicks were significantly better than the same values for females (P<0.01).

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To determine the relationships between yield and its components, and to find the direct and indirect effects of yield-related traits on soybean yield, 240 genotypes were grown in the Research Station, College of Agriculture, Karaj, Iran, in 1997-98 using an augmented design. The study of correlation analysis showed that number of seeds per plant and seed yield per plant had the highest significant correlation coefficient (r=0.92). Other significant correlation coefficients were found between biomass per plant and yield (r=0.86) and between number of pods per plant and yield (r=0.67). Results of stepwise regression analysis revealed that number of seeds per plant, seed weight, and number of seeds per pod were the three major traits affecting seed yield in soybean. However, path analysis showed that only two of the three above-mentioned traits, namely, number of seeds per plant and seed weight, are quite important for soybean selection programs. Stepwise regression analysis was used again, omitting number of seeds per plant, which showed that number of pods per plant, seed weight, plant height and number of days to 90% maturity, are important contributors to yield. Path analysis, this time, revealed that the correlation effects to plant height and number of days to 90% maturity on yield is due to the indirect effects exerted through other traits. It is concluded that three traits, namely, number of seeds per plant, seed weight and number of pods per plant have notable effects on soybean seed yield.

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Cooperative have always been considered institutions capable of solving major problems in the process of development in different countries. These institutions has evolved along with theories of development from government dependent organization to independent, people centered with the objective of being equal-opportunity systems for all members in order to be responsive to current goals of development. The aim of the present research was to determine the level of success in mechanized companies in Fars Province (12 Mechanized Companies, 24 Rural Cooperatives and 8 Production Cooperatives) in achieving development goals through a survey research.

The findings indicated that production cooperatives were more successful in promoting farmers' income and participation of members in community activities, increasing equity and farmers' work related welfare while mechanized companies had more achievements in flexibility and participation of members in making decisions regarding farming activities and in terms of payment to farmers. In other words, production cooperatives have been more successful in achieving development goals (increasing income, participation, and work related welfare and decreasing inequity). Mechanized companies rank a position in the middle of the success scale, but rural cooperatives had the lowest success level in achieving development goals.

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The quality of Iranian breads has intensively decreased during recent years due to socio-economic factors and poor quality of flour. The purpose of this study is to investigate the effects of mono- and diglycerides and ascorbic acid as improvers on Iranian bread (Taftoon) quality. Three wheat type flours (Ghods, Mahdavi and Roshan wheat varieties produced in Isfahan region) were used. The effects of ascorbic acid at three levels (20, 40 and 60 ppm flour basis) and esters of mono- and diglycerides at three levels (0.5, 1.0 and 1.5 percent) on the dough baking and bread quality were measured. The Taftoon bread was baked in a semi-traditional oven.

 Loaves of bread were scored after baking and also on the first and second days of storage at room temperature. Analysis of variances indicated that ascorbic acid and mono- and diglycerides have significant effects on the improvement of the rheological properties of dough. However, ascorbic acid had higher effects than mono- and diglycerides. The results of the tests showed that dough resistance to mixing and tensile stress increased with addition of the improvers. Both improvers used in this experiment have an anti-stabling effect on bread. However, the ascorbic acid effect is much less than that of mono- and diglyceride. The low concentration of 0.5 percent of mono- and diglyceride and 60 ppm of ascorbic acid with flours of moderate protein contents (10-11%) resulted in good quality Taftoon bread with good organoleptic and tearing qualities after two days.

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A field study was conducted at the College of Agriculture, Ferdowsi University of Mashhad, to investigate the effect of irrigation with treated municipal wastewater on the yield and quality of lettuce and some soil characteristics. Five irrigation treatments were applied to a clay loam soil, classified as fine loamy mixed mesic Calcixerollic Xerochrepts, in a randomized block design with 5 replications. The treatments consisted of T1 (Irrigation with treated wastewater over all growing season), T2 (Alternate irrigation with treated wastewater and well water), T3 (Irrigation with well water and application of cattle manure), T4 (Irrigation with well water plus fertilizer N and P), and T5 (Irrigation with well water only as control). Chemical analysis of well water proved to be a suitable source for agriculture.

The results showed that the yield was higher in T1, T2, T3 and T4 as compared to the control treatment. Maximum fresh and dry yields were obtained from T3 & T1 and T1 & T3, respectively. Plant tissue analysis showed an increase in macronutrients (N, P, K) and heavy metal concentrations in shoots and roots of lettuce in the first four treatments as compared to the control. In T1, iron concentration was maximum while that of cadmium was minimum. Furthermore, microbial contamination was considerably higher in T1 and T2. Soil analysis indicated that in plots treated with wastewater, electrical conductivity, total nitrogen, available phosphorus, soluble boron and heavy metal concentration increased. However, their values were all below international standards. More experiments seem to be necessary in this regard.