JWSS - Journal of Water and Soil Science

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Cultivating rangeland to be shifted to crop land farms commonly causes soil degradation and runoff generation. This study was conducted to evaluate the cultivation effects on runoff generation and soil quality. The experiment was performed in a rangeland and a 40-year cultivated land located at two slope positions (back slope and shoulder) of a hillside in Dorahan, Chaharmahal & Bakhtiari Province. A 60±5 mm.hr^-1 rainfall intensity was simulated by a rainulator. Organic matter, mean weighted diameter, saturated hydraulic conductivity, collected runoff and sediments were measured. The differences between the means were tested using T-test. Results showed 35, 53 and 8% increases in the organic matter, mean weighted diameter, and saturated hydraulic conductivity in back slope, respectively. The increases in these parameters in shoulder position were 39, 60 and 33%. The values for runoff and sediments in back slope were 3 and 8 times greater than in other similar positions while the values in the shoulder position were 11 and 55 times greater than the same values in other positions.

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Improper management of watershed land utilization has many ill effects on the available resources. Land use optimization is one of the proper strategies to achieve sustainable development and to reduce resource dissipation. Focusing on Brimvand watershed in Kermanshah province which comprises an area of 9572 ha, the present study was conducted to find out the most suitable land allocation to different land uses viz. garden, irrigated farming, dry farming and rangeland to achieve soil erosion minimization and benefit maximization. The soil erosion, net benefit and standard land capability maps were supposed as the inputs of the objective functions and to defined constraints. The multi-objective linear problem was then solved using simplex method with the help of ADBASE software package and ultimately the optimal solution was gained. Additionally, the results of the study revealed that the amount of soil erosion could reduce by 7.78% whereas the benefit increases at the rate of 118.62%, in case of implementation of optimal solution. The above mentioned optimization led to dry farming decrease and garden increase over that area. The results of sensitivity analysis also showed that objective functions were strongly susceptible to the variation of maximum constraint of irrigated farming and garden areas.

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Improper use of natural resources, especially soil, causes its degradation and severe soil erosion. Water erosion is an important factor causing soil degradation. Land use change of pasture would result in severe soil erosion mainly due to the reduction of vegetation cover and also surface soil disturbance. The objectives of this study were to estimate the amount of sediment, runoff and nutrient loss in four different land uses including a pasture with good vegetation cover (> 20%), a pasture with poor vegetation cover (< 10%), a currently being used dryland farm and a degraded dryland farm which is not used. Soil samples were taken from the depth of 0–10 cm in a completely randomized design with four replications. A rainfall simulator was run for two hours to estimate the amount of sediment, runoff and nutrient loss. Organic matter, total N, available P and distribution of particles size in soil and sediment were measured. The results showed that a very high degradation has occurred in the area mostly due to water erosion created as a result of overgrazing in pasture, susceptibility of geological formations and more importantly, the change of land use pasture to inefficient dryland farming. Maximum and minimum runoff was observed in the abandoned dry landfarm and pasture with good vegetation cover, respectively. Maximum sediment content was observed in dryland farm. Sediment content in dryland farm, abandoned dry landfarm and pasture with poor vegetation cover were 54.5, 21 and 10.4 times more than that in the pasture with good vegetation cover, respectively. Enrichment ratio (ER) of soil particles in sediment was highest for fine silt (2-5µm), followed by clay. A minimum of ER was obtained for sand fraction. Percentages of organic matter, total N and available P in sediment were higher in the first hour as compared to the second one. This is mainly due to the fact that fine particles are removed at the beginnings of the rainfall event. Total removal of these chemical factors was highest in dryland, intermediate in pasture with poor vegetation cover and abandoned dryland and lowest in pasture with good vegetation cover. In general, cultivation and disturbance of the pasture in the area land have caused a great decrease in soil quality and made the surface very sensitive to erosion.

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To investigate the degree of forest degradation and the effect of land use change on selected soil quality attributes in loess-derived landforms, samples were taken from different land uses including forest, rangeland, degradated rangeland and farmland in Pasang watershed located in the Galikesh area of Golestan province (37°16'N, 55°30'E). The annual average temperature and mean precipitation of study area were 15°C and 730 mm respectively. Organic matter, pH, EC, CaCO₃ and nutrients (N, P, K) as chemical indicators, hydraulic conductivity, bulk density and porosity as physical indicators and soil respiration as biological indicator were measured. The results showed that the amount of organic matter decreased three percent when it was turned from forest to farmland, and increased two percent from farmland to rangeland. The amount of CaCO₃ in surface layer of deforested area was more than in the forest soils. The amount of soil N in forest and soil P and K in rangeland were higher than in other land uses. Bulk density and porosity in forest and MWD in rangeland were higher than in other land uses because of the decrease in organic matter due to farming activities. Soil respiration in forest was highest as compared to in other land uses. Difference of enzymes activities (L-asparaginase and Dehydrogenase) compared to microbial respiration indicates that enzymes activity is related to specific biological processes while soil microbial respiration basically depends on the general activity of soil microbial population. It could be concluded that amount of organic matter, soil N, bulk density, porosity, MWD, soil respiration and enzymes activities are suitable indicators for soil quality evaluation in this area.

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  Applying of intensive cultivation especially in marginal and sensitive regions, after conversion of rangelands to cropland farms, commonly causes reduction in soil quality, and thus an increase in soil degradation, erosion and runoff. This study was conducted to evaluate the land use change effects on some soil physical and chemical properties such as mean weight diameter (MWD), soil organic matter (SOM), bulk density (BD) and saturated electrical conductivity (ECe). For the experiment, soil samples were collected from 8 regions (rangeland and cultivated range) from west and southwest of Isfahan. Samples were taken from two soil layers 0-15 and 15-30 cm. Results showed that after conversion of range to cultivated lands, in some regions, SOM content was increased about 39% but in some regions decreased about 26%. This is due to the initial conditions of the regions. The ECe also increased by 41% due to this conversion. However, no changes were observed to the MWD, BD and pH in different treatments. Although there were little change to the physical and chemical properties of soil as a result of this conversion, those properties which were changed, could have a degradation effect and lower the soil quality.

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The forms and dynamics of soil phosphorus can be greatly affected by land use changes, which often involve changes in vegetation cover, biomass production and nutrient cycling in the ecosystem. Present research evaluates the impact of land use change on the amount of total organic and inorganic P, labile, moderately labile and nonlabile P pools in semiarid soils of central Zagros. Samples were collected from surface soils (0-10 cm) of i) of moderately degraded pasture (20-25% plant cover), ii) highly degraded pasture (5-10 % plant cover), and iii) cultivated field (10 years) in Soolegan sub watershed and i) moderately degraded pasture (25-30 % plant cover) and ii) highly degraded pasture (5-10 % plant cover) in Sadat Abad sub-watershed. Significantly (P<0.05) low amounts of total organic P were found following cultivation (23.9%) and overgrazing (18.2 and 40.8 %) in Soolegan and Sadat Abad, respectively. The largest depletion of labile organic P (NaHCO3-Po) (72.3%) and moderately labile organic P (H2SO4-Po plus NaOH-Pi) (24.3%) were observed in cultivated rainfed land in Soolegan. Overgrazing led to decrease in labile organic P (42.1 and 64.4%), moderately labile organic P (13.9 and 35.7%) and nonlabile organic P (NaOH-Po) including moderately resistant and resistant organic P (12.9 and 44.4%) in Soolegan and Sadat Abad, respectively. Our results showed that degradation of natural plant cover cause to depletion in the soil P pools. Decreasing the amounts of moderately resistant and resistant P pools led to a decline in soil productivity and fertility.

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To investigate land use changes, Qale Shahrokh basin (15098.1 ha area) was selected. Satellite images of Landsat sensors (MSS, TM and ETM+) were used. After improvement and different enhancement analysis of images such as FCC, PCA, the study area was checked using GPS and topographic maps (1:50000) and other information. Land use units were determined using classified random sampling method. Maps accuracy was assessed after performing different classifications. Final land use maps of 1354, 1369, 1381 years were produced using a hybrid method with fine accuracy. Trend of land use changes was investigated during the study periods. Results showed that during the first period (1354), most area of land use was rangeland with sparse vegetation cover (%41.6) and least area was irrigated farming (1.5%). Also, during the second period (1354-1369) most area of land use was rangeland with sparse vegetation cover (%43.4) and least area was irrigated farming (4.1%). During the third period (1369-1381), the maximum area of land use was dry farming (%35.6) and minimum of area was irrigated farming (7%). Maximum land use change was related to rangeland with medium vegetation cover. They were changed into dry farming and rangeland with sparse vegetation cover during 1354 to 1369. During 1369 to 1381, maximum land use changes occurred on poor rangeland with sparse vegetation cover and rangeland with medium vegetation cover was changed into irrigated and dry farming.

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Monitoring Land Use and Land Cover Changes have a significant role in environmental programming and management. Satellite data is an essential tool for detecting and analyzing environmental changes. Many change detection techniques have been developed which have advantages or disadvantages. Change Vector Analysis (CVA) technique is one such a method. This method is based on radiometric changes between two dates of satellite imagery. Main advantage of this method is that it provides direction and magnitude image of change. The aim of this study was to describe change vector analysis technique and it applies to detect land cover change in Isfahan area during an 11-year period. The data used for this study were two images Landsat: TM 05 June 1987 and 03 June 1998. Correction radiometric was not carried out because of the similar sensor and acquisition time of the remote sensing data. After geometric correction, the study area was selected from Landsat images. Change vector technique was applied to analyze magnitude and direction of change. The change map showed Kappa and overall accuracy coefficient of 63.19% and 74.4%, respectively. The results showed that the changed land cover was 3340 ha during this period. Overall, the results show that 1325 hectares (especially agricultural lands) have been converted into urban areas, agricultural areas were increased up to1385 hectares, and 435 hectares of agricultural areas were converted to other land use over the period of study. This study showed that CVA is a robust approach for detecting and characterizing radiometric change in multi-spectral remote sensing data sets.

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An increase in the emission of greenhouse gases such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) from the soil surface to the atmosphere has been of worldwide concern over the last several decades. Carbon dioxide is recognized as a significant contributor to global warming and climatic change, accounting for 60% of total greenhouse effect. The aim of this research was to determinate the emission of greenhouse gases from different land under agricultural uses. Four types of agricultural land farm, including wheat field, canola field, citrus garden and fallow land were selected to investigate the fate of CO2 in these fields. Gas chromatography technique and close chamber method were used to analyze soil gas samples. Total carbon losses from soil in form of greenhouse gases was 4.47, 3.72, 3.38 and 1.89 Mg C ha-1 yr-1 for wheat field, canola field, citrus garden and fallow land, respectively. Total additional carbon to soil from biomass for wheat field and canola field was 4.1 and 4.6 Mg C ha-1 yr-1, respectively. ECB (ecosystem carbon budget) = ∑ C input - ∑ C output. For wheat field and canola field ECB was -0.37 and +0.88, respectively. This indicated that in wheat field carbon was lost and in canola field carbon was sequestrated. Under citrus garden due to changes in soil organic carbon form previous year has showed that carbon was sequestrated.

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In order to study the effects of different land uses on soil development, a loess hillslope was selected in Agh-Su area, eastern Golestan Province. Six profiles in four land uses including pasture, Quercuse natural forest, Cupressus artificial forest and a cultivated land, were dug and studied. Samples from different horizons were collected for physico-chemical and microscopic analyses. Important physical and chemical attributes such as bulk density (Bd), mean weight diameter (MWD), Organic carbon (SOC), cation exchange capacity (CEC), soil calcium carbonate (CCE) and available P were compared in land uses. Organic matter, CEC and MWD were significantly lower in the cultivated land use. Organic matter content in the forest and pasture area was considerably higher than that of cultivated land use. Soil profile development studies revealed that forest soils were highly developed. Quercus natural forest soils were classified as Calcic Argixerolls. Unlike cultivated soils which showed the minimum development and were classified as Typic Calcixerepts, formation of argillic horizon with dominant speckled b-fabric in the natural forest indicated the high landscape stability. Crystallitic b-fabric of horizons showed the absence of enough leaching of carbonate and the subsequent migration of clay particles. Intense erosion of the surface horizons of cultivated land use resulted in the outcropping of the subsurface carbonate rich horizon preventing soil development. The soils of pasture and Cuprecuse soils had mollic epipedon and were classified as Typic Calcixerolls with moderate development. Micromorphological properties of soils can help consider changes in pedogenic processes occurring under different land covers.

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As the first event in soil erosion, rain splash erosion causes movement of soil fragments. Splash is an important process in interrill erosion. The amount of soil particles detached from the surface is associated with soil and rain characteristics and may be affected by rainfall erosivity and soil erodibility. Therefore, in this study, splash erosion rate and its relation with some soil properties were studied. 120 soil samples were collected from three adjacent land uses including forest, rangeland and agriculture in two depths of 0-10 and10-20 cm in Kasilian Watershed. Soil samples were investigated under the experimental condition using splash cup and rainfall simulator. Results showed no significant differences between splash erosion in different land uses. Cultivated and rangeland soils were found to show a significantly lower organic matter (OM) by 59.93% and 33.62% in depth (0-10cm) and 33.33% and 25.59% in depth (10-20cm), respectively. We also found significance positive correlation between percent of silt and splash erosion rate in agriculture (r=0.69, p=0.018) and significance negative correlation between soil organic matter and splash erosion rate in rangeland (r=0.767, p=0.001) and significance positive correlation between K-USLE and splash erosion rate in agriculture (r=0.00, p=0.758).

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LISS IV sensor's data from IRS-P6 satellite was used to produce land use map of eastern region of Isfahan, the studied part of which has an area of 22121 hectares. Its three band data, namely band 2 (Green), band 3 (Red) and band 4 (Near infra red) of LISS-IV sensor images with 5.8 m ground resolution were georeferenced by nearest neighbor method and first-order polynomial model to the DEM map of 1:25000, where the RMSE was equal to 0.3 pixel. To analyze the satellite data, various image processing methods such as supervised and unsupervised classification methods, principal component analysis, NDVI vegetation index and filtering were applied to the satellite data. Finally, the land use map was produced with hybrid method. The final map detected 6 land uses very clearly, which are: Agricultural lands, barren lands, disturbed lands, cultivated Haloxylon amodendron, roads, residential areas and industrial locations. The kappa of land use map is 0.89 and the overall precision is 0.92. The barren lands have a very poor natural vegetation and are considered as natural deserts. Disturbed lands have been formed because of brick kiln activities, and the vegetation cover of these areas has disappeared completely The LISS IV data has a high ability to detect the various studied land-uses especially to digitize the roads. They can be used to update the 1:25000 topographic maps, as well.

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Climate situation changes over a year cause changes in some soil characteristics and soil sensitivity to erosion. Investigation of these changes and how they impact on erosion can be of particular importance. This study investigated changes in Sediment Productivity and soil factors affecting these changes in Tiregan rangeland located in Daregaz city in Khorasan Razavi province. In this study, using the position of the upper and lower hillside of eastern and western aspects, the sampling with rain simulator was performed. Characteristic features of sediment yield including runoff threshold, runoff volume, sediment and turbidity were measured. Soil samples were taken from each sample rain simulation and features of the initial moisture content, bulk density, electrical conductivity, pH and organic matter were measured. Sample was collected with the same intensity and duration of the instrument with fixed locations, and was repeated in four seasons. In order to obtain the position and orientation of each of the parameters in the data obtained at different seasons, the combined analysis of variance test was used. The effect of each of these parameters and the difference between them were evaluated using the Tukey test, and the graphs in 2007 Excel software were plotted. The results showed that all the parameters of sediment yield during the year have significantly changed. The maximum amount of sediment production rates occurred in autumn and was gradually reduced. Its decreasing in both winter and spring can be attributed to vegetation in the area.

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Study of land use effects on soil quality indicators leads to sustainable management and preventing progressive land degradation. The TM (1987) and ETM+ (2000 and 2005) data were used to study land use change effects in Mahan-Joopar area on soil quality indicators. Fifty random soil samples from 0-30 cm depth of each land use were taken using provided maps. Organic matter, microbial respiration potential, bulk density, pH, EC, and soil texture were investigated as soil quality indicators. Eight land uses including fruit orchards, woodlands, pistachio orchards, cultivated, barren, bare land, fallowed, and haloxylone land were detected. Results showed overall accuracies of 89.4, 95.2, and 91.7 % with kappa coefficients of 85, 92, and 88% for maps provided in 1987, 2000, and 2005, respectively. Generally, the investigated quality indicators showed that woodlands, fruit orchards, cultivated land, and pistachio orchards enhanced soil quality better than other land uses.

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The quantity and variability of soil organic carbon (SOC) is one of the most important indices to determine the effect of land use changes on the soil quality. Regarding long-term changes from rangeland to dry farming in the Roin area of North Khorasan, the objectives of this study were to investigate the effect of long-term land use changes on the SOC in different slope faces and use SOC as an index to make a proper decision about the future of land use in this area. 140 soil samples were taken from 0-15 cm soil depth of back slope position of north-, south-, west- and east-facing slopes of rangeland, dry farming, alfalfa dry farming and garden in 7 points. 14 soil samples were taken from irrigated farming, too. The results showed that garden and irrigation farming with averages of 2.03 and 0.78% have the maximum and minimum SOC content. The average of SOC content in rangeland was 1.40% that decreased by land use change to 1.04 and 1.27% in dry farming and alfalfa dry farming, respectively. SOC content in southern slope aspects showed a significant difference compared to other slope aspects. The most SOC content occurred in east aspects. It seems that after long-term land use changes, the SOC content have equilibrated to environmental and land use conditions. The average SOC content in different slope aspects except south one changed from 1.4% in rangeland to 1.11% in dry farming and 1.32% in alfalfa dry farming, which are a suitable value for semiarid regions. In conclusion, to protect land from degradation and considering this fact that dry farming is the main income of the people in the study area, it is recommended to stop dry farming on south aspects and continue on east, north and west aspects with conservation practices.

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Paddy soils provide the staple diet for nearly half of the world's population. The formation of the Anthrosols is induced by tilling the wet soil (puddling), flooding and drainage regimes associated with the development of a plow pan and specific redoximorphic features. The aim of this study was to evaluate the effects of long-term rice cultivation on physico-chemical properties and clay mineralogy of soils of three rice farms and compare the results with adjacent virgin lands in Yasouj region. Paddy soils exhibited larger contents of clay, organic carbon, saturation percentage, cation exchangeable capacity, cation exchange activity classes, electrical conductivity and lower content of calcium carbonate equivalent compared to non-paddy soils. This land use showed higher proportions of Feo, Fet and lower content of Fed. No such differences were noticed with the type of clay minerals in both land uses. Paddy soils contained greater amount of smectite, particularly in the surface horizons. Smectite in paddy soils exhibited lower layer charge and higher degree of crystallinity compared to non-paddy soils. Transformation of illite and chlorite to expandable minerals is a possible mechanism for lower amounts of these minerals in paddy soils.

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Change in land use and tillage practices has great influence on soil physical and chemical properties. The present study has focused on the effects of converting undisturbed soil to agricultural lands. Chemical and physical soil properties, infiltration, cation exchange capacity (CEC), electrical conductivity, pH, bulk density, porosity, sodium, potassium, total Ca + Mg, organic matter percentage, sodium adsorption ratio (SAR) and lime percentage were measured using standard frequently used methods. Fifty soil samples from agriculture land and other 50 soil samples from undisturbed land were collected from 0 – 30 cm depth and different statistical analysis were performed. Agriculture land is Cultivated for more than 20 years. The results showed that change in land use from undisturbed to disturbed soil did not significantly changed soil organic matter content. Also, soil electrical conductivity showed a huge increase whereas pH showed non-significant changes due to land use change. Unlike pH, SAR, organic matter percentage and lime percentage, some other soil parameters showed significant decrease in quality through land use change. Correlation coefficients of the effective factors were calculated to explain the main reason for lowering soil quality. The results showed that sodium in EC bulk density in porosity and CEC sodium and Ca+Mg in SAR EC in soil infiltration and Ca+Mg in organic matter showed the most correlation.

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Organic carbon pools and carbon lability directly affect soil biological, physical and chemical characteristics. Besides, capacity of self-organization of soil is related to the organic carbon pools. Sand size fraction (> 50 µm) organic matter is more labile than silt+clay size fraction organic matter. Assessment of this organic carbon variation can be a suitable index to determine soil quality. The aim of present study was to evaluate the impact of land use change on particle size fractions of organic carbon and carbon pool index. In September 2010, soil samples were collected from the three major land use types including wetlands around the lake, wetlands converted to wheat, and alfalfa cultivations. Soil samples were collected from the 0-30, 30-60 and 60-90-cm depths in each of land use. According to the results of particle size fractionation of organic carbon in 0-30-cm layer, the highest and lowest amounts of sand size fraction organic carbon were obtained in wetland (67.01 g.C.kg-1soil) and wheat land use (24.57 g.C.kg-1soil), respectively. Land use change from wetland to alfalfa and wheat caused a decrease of silt+clay size fraction organic carbon in 0-30-cm by 48.39 and 45.14 t.C.h^-1, respectively. In the 30-60-cm layer of cultivated land, soil organic carbon storage in silt+clay size particle was more than sand size fraction organic carbon. Results showed that carbon pool index in alfalfa, and wheat land was decreased by 50 and 60% compared to wetland, respectively. And carbon management index in alfalfa and wheat was declined by 44.90% and 66.70%, respectively.

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Improper use of rangelands may lead to their destruction. Therefore, the conversion of these degraded rangelands to agricultural lands and other land uses may improve their soil quality. The purpose of the present study was to evaluate the impact of cultivation in the degraded rangelands on some soil characteristics in Safashahr region of Fars province. Four land uses including the rangeland with sparse vegetation (degraded rangeland), the rangeland converted to agricultural land over 17 years, the agricultural land converted to apple orchard for 4 years and also to an apple orchard for 40 years were selected. Samples were randomly taken from each land use at two depths (0-20 and 20-50 cm) with five replications. The results revealed that land use change significantly increased organic matter and MWD in both soil depths. Bulk density and water dispersible clay increased in agricultural land and new orchard while a decrease was observed for old apple orchard. It is suggested the traditional farming to be replaced with new cultivation methods like minimum tillage and no tillage. Overgrazing of the rangelands must also be avoided.

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Reduction of quality and soil productivity due to organic carbon losses is one of the most important consequences of land use changes, that creates irreparable effects on the soil. To evaluate the land use effect on the amount of soil organic carbon in Vertisols, Sartip Abad series with extent of 1850 hectare in south of Bilehvar area in Kermanshah province was studied by using the completely randomized block design in factorial experiment with 10 repeats in farmland and grassland, some soil physical and chemical properties in two Lands compared with each other. The results showed that the soil organic carbon in surface horizons of grassland has been more than farmland and accordingly increase the amount of sequestrated carbon in grassland. No significant differences were found in the amount of soil organic carbon in lower horizons of two lands. Due to land use change from grassland to farmland, noticeably increase in Bulk density, Nitrogen, Acidity, soil Electrical Conductivity and decrease the organic carbon percent and the soil organic material. Pedutorbation, clay amount (higher of 50%), numerous small subsoil, and stable structure are the important factors in saving the organic carbon of vertisols that can reduce the effects of land use changes on organic carbon amount. Generally, it can be conclude that: the land use changes not only can create the severe damage on soil physical and chemical properties but with the carbon losses and more release of greenhouse gases exacerbate the pollution of environment which endangers the life in a earth planet.