مجله تحقیقات آب و خاک ایران
سال پنجاه و یکم شماره 7 (پیاپی 55، مهر 1399)

This study aimed to investigate the efficiency of different chitosan composites on lettuce plant and mobility reduction of cadmium in the soil. For this purpose, a pot factorial experiment was conducted in greenhouse conditions using a completely randomized design.The proposed factors were soil cadmium levels (0, 8, 25 and 75 mg/kg) and types of adsorbent (chitosan, biochar, zeolite, nanomagnetite and composites of chitosan-biochar, chitosan- zeolite,chitosan- magnetite and control). Each adsorbent was applied to the soil at the rate of 0.5% W/W. The results showed that the shoot height, the shoot and root dry weight and the concentrations of phosphorus, potassium, iron and zinc in the shoot of lettuce decreased but the cadmium concentration of leaf increased as the concentration of soil total cadmium increased. The results also showed increasing the amount of adsorbents to the soil decreased the toxic effects of cadmium by adsorpting the part of soluble cadmium. As, by application of 0.5% W/W of chitosan-magnetite composite, the concentration of cadmium in the shoot of lettuce decreased about 24.22 mg/kg as compared to the control treatment. But the shoot height and the shoot dry weight increased by 29.57 and 43.6% respectively, and the concentration of phosphorus, potassium, iron and zinc increased by 72.22, 98.78, 267.77 and 128.10% respectively, as compared to the control treatment.

Among the microorganisms, mycorrhizal fungi are involved in providing phosphorus, zinc, copper and water to the plant. Also, growth hormones by increasing rhyzogenesis and thus the nutrient uptake of rootstocks enhances plant growth. In order to investigate the effects of plant growth hormones and mycorrhizal fungi on the yield of potato plant, Agria cultivar, a factorial experiment with a randomized complete block design was performed under greenhouse conditions. The proposed factors were four types of growth hormone (control, gibberellic acid, indole acetic acid and naphthalene acetic acid) and four types of mycorrhizal fungi which are used for inoculation of the potato plant (control, Funneliformis Mosseae, Rhizophagus intraradices and a mixture of Funneliformis Mosseae + Rhizophagus intraradices). Each factor was consisted of three replications. Plant growth hormones were sprayed with a concentration of 25 mg/l and 10 g of the medium containing mycorrhizal fungi was applied to each planting box. The results showed that the highest amount of the leaf chlorophyll index and potato tuber length were obtained from the treatment containing Funneliformis Mosseae fungus with the simultaneous use of naphthalene acetic acid growth hormone, which were 1.20 and 5.45 cm, respectively. The highest percentage of dry matter, stem diameter and fresh weight of the potato tuber were obtained from the treatment containing a mixture of Funneliformis Mosseae and Rhizophagus intraradices fungi and without application of growth hormone, which were 19.69%, 12.93 mm and 98.87 g, respectively. The maximum diameter of potato tuber was obtained by using the gibberellic acid growth hormone without mycorrhizal fungi application, which was 12.46 cm. The highest density of potato tuber was obtained from the treatment containing Funneliformis mosseae fungus and gibberellic acid growth hormone, which was 1.50 g/cm3. In general, the results of this study showed that the application of gibberellic acid growth hormone and a mixture of Rhizophagus Rhizophagus intraradices and Funneliformis Mosseae fungi as inoculant created the highest potato yield.

Accurate water measurement is one of the key factors for reduction of agricultural water consumption, distribution integrity and delivery management in irrigation networks. In recent years, there has been a significant advance in flow measurement devices, but the usage of these devices is limited due to the high cost, special maintenance conditions and the need for skill expertise. Water structure used in this study is a new form of flow measurement flume that installed along the channel and has cylindrical and conical shape walls. The crest matches the channel's floor thus in this measuring structure, the control section happens only by transversal constriction. The new flumes are simple in shape and easily applicable in irrigation networks and they have not sedimentation problem. The amount of energy loss and consequently the upstream backwater in this structure is low. This structure controls the flow by creating critical flow in constriction section and will be able to measure flow discharge. In this study, the flow characteristics through the cylindrical and conical flumes have been studied theoretically and experimentally, and several equations have been developed for flow discharge estimation in rectangular open channels.

Evaluation of soil erosion control factors is important regarding the application of management practices. In this study, the effects of non-structural management practices including revision of crop cover (RC) and exclosure (EX) were simulated using WEPP model in ​​Emamzadeh Abdullah watershed of Baghmalek, located in the northeast of Khuzestan Province. Optimization of physical and hydraulic parameters affecting erosion including soil texture and components of the Van Genuchten equation was performed using response surface methodology (RSM), random forest (RF), support vector machine (SVM) and artificial neural network (ANN). Also, the soil erosion rate before and after management practices was defined as the first response (R1) and the second response (R2), respectively. Optimization results by Orange software including random forest methods, support vector machine and artificial neural network showed that the random forest method with MSE, RMSE and R2 equal to 0.991, 0.995 and 0.963 respectively, for the first response and equal to 0.095, 0.307 and 0.974 respectively, for the second response is the most proper method. Also, optimization by response surface method is the most appropriate method with MSE, RMSE and R2 equal to 28.7, 5.37 and 0.999 respectively, for the first response and equal to 4.16, 2.03 and 0.998 respectively, for the second response. Generally, using optimization techniques is a convenient method for evaluating management practices and finally selecting the best one for critical areas. Appropriate management practices based on optimal conditions leading to water and soil loss reduction.

One of the best methods for managing coal wastes to prevent their accumulation in nature and reduce environmental pollution is their application as the sorbents of pollutants. The objective of this study was to investigate the capability and behavior of the coal wastes in three forms of pristine powder (cp), nanoparticles (cnp) and FeCl3 modified nanoparticles (mcnp) for phosphorous (P) sorption from aqueous solution. Characterization of the sorbents was carried out using XRD, SEM-EDS and FTIR analyses. Equilibrium sorption experiments were done in batch systems and the effects of pH, initial P concentration and contact time were studied. The results showed that the P sorption process was pH dependent and the maximum P sorption occurred at 2-6 pH ranges. The maximum P removal efficiency of the sorbents obtained in the range of 0-50 mg/L of initial P concentration and it was increased with time and reached equilibrium after 2 hours. The P removal efficiencies of the sorbents were determined to be 3.3, 18 and 78.8 % for cp, cnp and mcnp, respectively. The pseudo-first and pseudo-second order kinetic models and Langmuir isotherm described the P sorption data well. The maximum P sorption capacities were calculated to be 0.37, 3.97 and 30.39 mg/g for cp, cnp and mcnp, respectively. Results revealed that the modified coal wastes have the potential to use as cost-effective and environmental-friendly sorbents.

The aim of this study was to evaluate and compare the double horizontal screens with four types of stilling basin (I, II, III and IV) at vertical drop downstream in terms of energy dissipation. A total of 140 different experiments were performed on a vertical drop equipped with double horizontal screens (with 40 and 50% porosity) at relative spaces of 0.25, 0.33 and 0.5 between the screens, and two drop height of 20 and 25 cm. The results showed that the relative spacing and porosity of the double horizontal screen do not have a significant effect on the residual energy and the relative depth of downstream, however, the length of drop stilling basin is decreased with increasing the relative spacing and porosity of screen. In compared to the stilling basins, the use of double horizontal screens reduced the length of drop stilling basin and the residual energy and relative depth of downstream is reduced by more than 35 and 49%, respectively.

Measuring the soil water retention curve in the laboratory is time consuming and costly. For this purpose, researchers have developed some methods to reduce measurements. One of these methods is scaling. The objective of this study is to scaling the soil moisture retention curve using Brooks-Corey model for all textural classes. This method requires a reference curve and the moisture content in a specified suction. In this method the scaling factor is the logarithm of water content in a specified suction (e.g.) in the reference soil to the logarithm of water content in the same suction of the proposed soil. The scaling factor obtained by the proposed method was evaluated with the scaling factor obtained by the statistical optimization method. In this study, 11 different soil texture classes data provided by Rawls et al. were used. The results showed that the scaling factor obtained based on the water content of ,  and  is close to the optimum scaling factor. The mean value of the sum of squares error for the proposed and optimization methods were 0.047 and 0.045, respectively. The mean value of the geometric mean error for the proposed and optimization methods were 1.024 and 1.047, respectively. The results showed that the reference curve is optional and each soil can be used as the reference curve. In the case of De-scaling, the soil water retention curve obtained by the proposed method was fitted very well to the one obtained from Brooks-Corey model.

Soil pollution due to heavy metals subsidence from cement industry has harmful effects on soil, plant and human health. The objective of this study was to investigate the effects of Sepahan cement factory on heavy metals contamination in the soils of Dizicheh area of Isfahan province. In order to do this study, 52 soil samples were collected from different land uses including: agricultural lands, gardens and green space. Total concentration of zinc (Zn), manganese (Mn), iron (Fe), cadmium (Cd), lead (Pb), nickel (Ni), chromium (Cr) and cobalt (Co) in samples were measured. Contamination factor (CF) was used to determine soil contamination with heavy metals. The distribution map of contamination factor was plotted using inverse distance weighting (IDW) method. The results showed that the heavy metals concentration in the studied area was lower than the permissible limit provided by the Iran Department of Environment, while the amount of contamination factors indicated the degree of contamination of heavy metals in the studied area. Also, the highest contamination factor values of heavy metals except Cd were in the average contamination category (1<CF<3). The highest value of mean contamination factor in the studied region was obtained for Cd in green space land use (5.88) and with high contamination category. Spatial distribution of heavy metal’s contamination factors indicated high contamination factor’s values especially Pb and Cd around cement factory (green space land use).

This study was conducted to investigate the effect of salinity and drought stress on water uptake reduction by maize. In order to exert this stresses, the pots were divided into two compartments including salinity and drought stresses. For two seasons, greenhouse experiments were conducted in a randomized design with four replicates in 2017. Water uptake by maize was measured daily in saline compartment of pots under constant matric potential of -100 cm, in different salinity levels of irrigation water (0, 1.7, 3.36, 6.33 and 8.35 dS m-1). The osmotic potential in pots was kept constant after the treatment initiation. The matric and osmotic potentials were quantified based on equal water uptake by roots in salinity and drought compartments of pots. In spring, the ratio of matric to osmotic potential was 0.28, 0.5, 0.47 and 0.46 in corresponding drought treatments (D1, D2, D3, D4)  and salinity treatments (S1, S2, S3, S4). For autumn, these ratios were 0.25, 0.32, 0.32 and 0.33 in corresponding drought treatments (D1, D2, D3, D4) and salinity treatments (S1, S2, S3, S4). Water uptake reduction by one unit decrease of matric potential was found to be more than the one caused by one unit decrease of osmotic potential. Osmotic potential had more effect than the matric potential on reducing root mass under the same water use conditions. These results indicated that the assumption of matric and osmotic potentials to be additive or multiplicative is not valid. The results of this study can be used to accurately manage irrigation water under salinity and drought stresses.

The performance of four erodibility indices' equations including K-USLE, K-Vaezi, K-EPIC and K-Dg were evaluated by measuring soil loss at four dryfarming soil samples in the Rainfall and Erosion Simulation Laboratory of Soil Conservation and Watershed Management Research Institute. For each soil sample, several experiments (33, 64 and 110 mm/h rainfall intensities, RI, at 12% slope and 64 mm/h RI at 6%, 12% and 25% slopes) were conducted for 30 min in two replicates and the soil loss were measured. In addition, the volume of rills was measured at the end of each experiment. The observed erodibility (K-Obs.) was obtained by dividing the soil loss to RLSCP factors product of USLE in each treatment which showed a high scatter. The 110 mm/h RI on 12% slope was selected as the reference treatment due to complete developed rill erosion network. Then, the estimated K value was compared to it. The results indicate an underestimation of K-Vaezi (and a negative value in one case) and an overestimation of the other three indices. The lowest difference is for K-Dg with 3-5 times overestimation. In the Next step, for each treatment, a ratio was calculated by dividing the K-Obs. of each pair soils and compared with the corresponding ratios of estimated erodibility indices using t-student statistic. The results of ratios analysis showed that the K-Dg and K-EPIC indices had better agreement with K-Obs. at 5% probability level. As a conclusion, it is recommended to use K-Dg by applying a reduction coefficient for similar soils.

Utilizing adjacent piers is one of the cost reduction factors in bridge construction. The impact of turbulent flow around piers on each other, piers distance and the amount of scouring in the adjacent piers are of great importance. In this research, it is tried to present a convenient and efficient combination of adjacent piers in order to reduce the amount of scour by analyzing the placement of these piers in two different shapes and various distances from each other and its impact on the amount of local scouring and the bed erosion pattern. Numerical simulation is done by FLOW3D software. Designed models for two cylindrical and combined shapes of piers in two specific placements, side by side and tandem, and in 6 different distance between the two piers for each state, totally 26 simulation models were simulated and investigated. It is found that the scouring depth increases significantly by decreasing distance between piers which creates a wider obstacle against the flow and water jet between the piers. The flow depth is decreased by increasing this distance and the adjacent piers have no impact on the amount and pattern of scouring in S=4D and higher distances away from each other and the most suitable distance was obtained at S=2.75D. In the tandem cases, it was found that the piers distance does not have any impact on the amount of scouring at the upstream and just the middle part experiences quantitative changes in the bed level; this impact is low by decreasing the distance and obvious by increasing the distance. All the mentioned items are correct in the combined pier, but the amount of scouring shows reduction.

Information about the spatial distribution of soil quality is one of the most ‎significant issues in recognition, planning, management and optimal ‎exploitation of soil resources in each area. In the this study, the characteristics of soil ‎‎surface (0-30 Cm) were measured in 95 fields in the Nazar Abad region in Alborz ‎province and the factors influencing soil quality were selected using ‎principal component analysis (PCA) method. In addition, the weighted additive soil quality index (SQIw), the additive soil quality index (SQIa) and the Nemero soil quality index (NQI) were determined using total data set (TDS) and minimum data set (MDS). Spatial variability of these soil quality indices were analyzed using geostatistics technique and their spatial distribution were determined using the Ordinary kriging method‎. Based on the results and among the soil quality indices, the SQIw obtained from the MDS, had a higher accuracy in the area with R2 of 0.89, mean absolute error (MAE) of 0.11 and normalized root mean squares error (NRMSE) of 0.1. The exponential variogram model (R2 = 0.95) indicated that the SQIw and SQIa indices using MDS had the best fitness, whereas, the spherical model (R2= 0.90) was strongly fitted to the NQI index obtained from MDS. Furthermore, the effective range of spatial variability for SQIa, SQIw and NQI indices was 8, 10 and 11.5 kilometers, respectively. Soil quality of the fields in the area was strongly related to the soil particles size distribution, especially sand and clay percentages with coefficients of 0.90 and 0.85, respectively. Soil quality value in the area decreased considerably from west to east. This study revealed that the geostatistics technique can be used for spatial analysis of soil quality indices in the area and spatial distribution maps of these indices can be effectively used to plan the sustainable soil management strategies in the fields.

The purpose of this study is to present a weighting factor for considering limitation of salinity on plant water uptake (ωsi) for the concept of Integral Water Capacity (IWC). The experiment was conducted under greenhouse conditions and included corn planting in two soil types, three salinity levels (1.5, 4, and 8 dS m-1), and three replications. After the plants were fully established, all pots were continuously irrigated with a specific salinity. The transpiration values were obtained from the weight differences of pots considering water mass balance components at different times. Cumulative transpiration was calculated at each time step and they were plotted against the drainage water salinity at the same time. Then, using the numerical derivative of the cumulative transpiration curves, the transpiration intensity curve was calculated. By fitting a logarithmic model and their relativization, the effect of salinity constraint on the transpiration was calculated and a new salinity weighting coefficient was proposed. The results of ωsi showed that the relative water uptake decreased logarithmically with increasing salinity and the salinity tolerance of corn varied in soils with different properties and a constant value cannot be reported as salinity tolerance.

Leakage of hydrocarbon organic fluids into the soil usually causes a reduction in its bearing capacity and performance. Cementation is one of the most effective and suitable solutions to improve the geotechnical parameters of contaminated clays. In this study, the effect of Portland cement (3, 6 and 9%) and lime (10, 20 and 30%) on improvement of kaolinite clay contaminated with anthracene (0.06, 0.09 and 0.12%) was investigated by performing an experimental study. For this purpose, the samples were prepared as mixtures of clean or anthracene-contaminated clay with different cement and lime contents for a curing time of 7 days. Then, unconfined compressive strength (UCS) tests were conducted on the samples. The results showed the strength reduction of anthracene-contaminated kaolinite clay compared to the clean soil. The reduction in the unconfined strength was about 46% with an increase in degree of contamination up to 0.12%. Adding Portland cement and lime to the clean and contaminated soil increased the compressive strength. As, the addition of 3% Portland cement or 10% lime to clay contaminated with 0.12% anthracene increased UCS up to 4 times. Thus, according to the results of soil improvement, the strength of soil-cement mixture containing 3% Portland cement is approximately equal to that of soil-lime containing 10% lime. Both the Portland cement and lime were capable of improving the strength of anthracene-contaminated soil. However, the rate of improvement by cement was more than that of lime. The main reason was due to the reduction of double layer thickness which causes flocculation of particles and tendency of clay structure to behave like granular soils.

Because of the key role of the agricultural sector in achievement of food security, increasing climatic variations due to global change and the dependence of agricultural yields to climatic conditions, it is essential to study the long-term relationship between climatic conditions and agricultural yields in order to coordinate agricultural activities with climate change trend. In this study, a screener algorithm considering the climatic conditions of the region has been developed to rank the most suitable agricultural products with the climatic conditions of Soumar plain in Kermanshah province. For this purpose, the sensitivity of the defined agroecosystem to climatic conditions of the region was calculated using the Shannon-Wiener index. Then, using Multiple Linear Regression method and SPSS software, regression models were developed between climatic data and crop yield data. In the next step, the accuracy of the developed models was confirmed considering the conditions of using linear regression for all models. Afterward, the weight of effective climatic parameters was determined using pairwise comparison methods. According to the results, the minimum monthly temperature parameter with weight of 0.169 and the average monthly wind speed parameter with weight of 0.032 were considered the most and the least effective climatic parameters, respectively. Finally, crops ranking in the study area was completed using TOPSIS method and calculating Ci index which shows the score of each crop. According to the results, bean, barley and canola with the Ci of 0.601, 0.537 and 0.564 and tobacco, tomato and fodder corn with the Ci of 0.376, 0.513 and 0.518 show the most and the least compatibility with the climate conditions of the region, respectively.

In order to evaluate the salinity tolerance indices and to select the ideal genotype among several new cultivars and lines of safflower, a factorial experiment was conducted in a completely randomized design with three replicates in Darab Agricultural and Natural Resources Research Station. The first factor, with two salinity levels of irrigation water consisted of 0.98 (as control) and 7.8 dS.m-1, and the second factor with eight safflower genotypes included Goldasht, Parnian, Golmehr, Isfahan, Padideh and three promising lines Mec14., Mec235 and Mec248. For evaluation of salinity tolerance of cultivars and lines, some indices including stress sensitivity (SSI), harmonic mean (HM), tolerance index (TOL), stress tolerance index (STI), geometric mean productivity (GMP), index average productivity (MP), yield index (YI), yield stability index (YSI) and finally the ideal genotype selection index (SIIG) technique were used. Based on the results, MP, GMP, HM, YI and STI indices had the highest correlation with grain yield under control and salinity conditions, thus they were recognized as the most suitable indices for determining salinity tolerance. According to these indices, Mec248 line was introduced as the best genotypes in this experiment. On the other hand, based on ideal genotype selection index (SIIG), Parnian genotype with the highest value (0.683) was introduced as the most tolerant genotype to salinity stress. Therefore, this genotype is recommended for planting in similar southern areas that have salinity problems.

Floods are one of the most important natural hazards causing many serious destruction and fatalities, especially in Iran. Despite recognizing the high number of fatalities due to floods, especially in recent years, there is not an acceptable/reliable model for mortality estimation.  The few presented models, that are intrinsicly valuable, are not enough for achieving the goals. The regional model presented in this paper employs hydraulic properties of floods and geometric characteristics of rivers for mortality estimation while considering the effect of available evacuation time in flood-prone areas. Based on the presented algorithm, the product of two hydraulic parameters: depth and flow velocity, presented in a raster format, are required for mortality simulation.  An exponential function was developed based on the relationship between the depth, velocity, and the number of observed fatalities in the corresponding floods. The model, employing the length and slope of the main channel as the two geomorphologic parameters of the river directly related to the flow hydraulics, is capable of considering the available time for the people at risk to evacuate the region. Finally, the developed model’s efficacy and accuracy were confirmed by comparing the results of the model with historical records and with that of the global/regional models.

The present study was conducted to investigate the effects of rice husk biomass (RH) and its biochar (RHBC) on some chemical properties and enzymatic activities involved in carbon and phosphorus cycling of a calcareous sandy soil (control, U) after two (M2), four (M4), eight (M8), and twelve (M12) months incubation. For this purpose, a factorial experiment with a randomized complete block design and four replications and two treatments (RH and RHBC) was performed. Three levels of organic amendments (L1= 1.25%, L2= 2.5% and L3= 5%) were added to the soil. The results showed that the amount of soil organic carbon (SOC) was significantly (p < 0.001) affected by the types of organic amendments, their application rate and incubation time. The highest and the lowest values of SOC were observed in RHBCL3M2 and RHL1M12 treatments with 96.3% and 73.2% increase as compared to the control treatment, respectively. The trend of changes in SOC and TN was similar and decreased with incubation time. The highest and the lowest activity of β-glucosidase were corresponded to the treatments of RHL3M12 (1.6 μgPNP.gr-1h-1) and RHBCL1M2 (0.6 μgPNP.gr-1h-1), respectively. The RHBCL3M8 and RHL1M2 treatments exhibited the highest (590.6 mg Glu.g-13h-1) and the lowest (109.6 mg Glu.g-13h-1) invertase enzyme activity, respectively. So that, the highest enzyme activity was observed in 8th month of incubation. The highest activity of alkaline and acid phosphatases activities were found in RHL3M12 treatment which were 78.1% and 81.7% higher than that in control treatment, respectively. In general, the addition of good quality biochars to the soil could be a very good source for compensation of soil organic carbon deficiency and thereby improving chemical and biochemical properties and soil health, because of its higher carbon content than its biomass. Therefore, based on the effects of rice biomass and its biochar on the increasing of SOC content as well as enzymatic activities, these organic amendments are suggested to improve the quality of sandy soils.

Climate change through increased water demand, especially in agricultural sector, is the main challenge facing water resources management. Wheat is one of the staple and strategic crop throughout the world, particularly in Iran. In this study, historical observations from 1985-2005 were used to simulate the effects of climate change on the winter wheat water requirement across Gorgan plain. SDSM4.2 and CanESM2 models were used to downscale winter wheat water requirement under three concentration pathway scenarios; RCP2.6, RCP4.5, and RCP8.5 in four periods (2020-2039, 2040-2059, 2060-2070, and 2080-2099). The Hargreaves-Samani (HS) model with less input variables in comparison with FAO-Penman-Monteith (PMF-56), was used for downscaling water requirement. The results of RCP2.6 scenario showed that the maximum and minimum annual water requirement of winter wheat are 403 and 286 mm in 2040-2059 and 2020-2039 periods, respectively. These values for RCP4.5 scenario were predicted to be 361 and 336 mm in 2020-2039 and 2040-2059 periods, respectively. For RCP8.5 scenario, they were predicted to be 336 and 199 mm in 2020-2039 and 2060-2079 periods, respectively. The growing period will be reduced in all three proposed scenarios and the reduction rate in RCP8.5 scenario is more than that in RCP4.5 scenario. According to the results, climate change is generally expected to reduce agricultural water consumption in Gorgan plain by reducing the cumulative winter wheat water requirement.

Accelerated soil erosion is the most important degradation factor of soil and water resources. Typically, soil erosion involves the detachment and transport of soil particles by rainfall, shallow surface flow or the interaction of these two factors. Therefore, understanding the motion threshold of sediment particles and temporal variation of sediment concentration in flow-induced can provide a detailed cognition of the processes inducing soil erosion and sediment transport and their eventual interactions. It is also important for increasing the accuracy of soil erosion models. In this study, the particle motion threshold and temporal variation of sediment were studied for a sandy sample at three slopes; 3.1, 5.9, 8.9% and-dunder three flow discharges of 4.78, 7.12 and 9.05 (×10-5 m2 s-1). This study was carried out in the laboratory conditions using a flume with 240 cm long by 40 cm width. The results showed that the Shields curve is not suitable for this study to determine the motion threshold. The threshold stream power of particle motion was determined 0.035 W m-2. Also, with increasing slope and consequently increasing stream power up to 0.05 W m-2, the erosion intensity increased and soil erosion changed from sheet erosion to rill erosion. The results indicate that the formation and development of rill erosion would be the main factor for soil loss and sediment production in hillslopes. Therefore, prevention of rill formation by strip croping, terracing and terrace farming is an effective strategy for soil conservation.