The land productivity dynamics trend as a tool for land degradation assessment in a dryland ecosystem.

The aim of this study was to produce a land productivity dynamic map of a degraded catchment located in dryland ecosystem via a land degradation assessment using three indicators, namely land use, land productivity, and soil organic carbon density. The study was conducted in the Mogan Catchment, Turkey, between 2000 and 2010. The study embraced the current trend for assessing ecosystem services over wide areas. For this purpose, satellite images were used to determine changes in land use and vegetation density. In addition, a total of 834 soil samples were collected from the surface soil in 2000 and 2010 to assess the soil organic carbon density. In more than 37% of the catchment area of approx. 37,100 ha, land productivity had declined, while about 43% of the catchment showed early signs of decline. Analysis of long-term changes and the conversion of levels of vegetative or standing biomass into land productivity dynamics (LPD) is only the first step. Current land management practices are contributing to serious, widespread land degradation, with only a very small area of the catchment showing a stable or increasing LPD for the period from 2000 to 2010. The implementation of land management policies and practices in order to achieve sustainable land management are urgently required.

Spatial and temporal variation of moisture content in the soil profiles of two different agricultural fields of semi-arid region.

Modeling spatio-temporal variation of soil moisture with depth in the soil profile plays an important role for semi-arid crop production from an agro-hydrological perspective. This study was performed in Guvenc Catchment. Two soil series that were called Tabyabayir (TaS) and Kervanpinari (KeS) and classified as Leptosol and Vertisol Soil Groups were used in this research. The TeS has a much shallower (0-34 cm) than the KeS (0-134 cm). At every sampling time, a total of geo-referenced 100 soil moisture samples were taken based on horizon depths. The results indicated that soil moisture content changed spatially and temporally with soil texture and profile depth significantly. In addition, land use was to be important factor when soil was shallow. When the soil conditions were towards to dry, higher values for the coefficient of variation (CV) were observed for TaS (58 and 43% for A and C horizons, respectively); however, the profile CV values were rather stable at the KeS. Spatial variability range of TaS was always higher at both dry and wet soil conditions when compared to that of KeS. Excessive drying of soil prevented to describe any spatial model for surface horizon, additionally resulting in a high nugget variance in the subsurface horizon for the TaS. On the contrary to TaS, distribution maps were formed all horizons for the KeS at any measurement times. These maps, depicting both dry and wet soil conditions through the profile depth, are highly expected to reduce the uncertainty associated with spatially and temporally determining the hydraulic responses of the catchment soils.

Sustainable natural resource management and environmental assessment in the Salt Lake (Tuz Golu) Specially Protected Area.

The Salt Lake Specially Protected Area is a unique ecosystem for both agricultural activities and natural life in Turkey. In the present study, an attempt was made to develop a conceptual land use strategy and methodology, taking into account ecological factors for regional development in the Salt Lake Specially Protected Area. A detailed Geographic Information System (GIS) analysis was done to create a comprehensive database including land use, land suitability, and environmental factors (soil, climate, water quality, fertilizing status, and heavy metal and pesticide pollution). The results of the land suitability survey for agricultural use showed that, while 62.6% of the study area soils were classified as best and relatively good, about 15% were classified as problematic and restricted lands, only 22.2% of the study area soils were not suitable for agricultural uses. However, this is not enough to derive maximum benefit with minimum degradation. Therefore, environmental factors and ecological conditions were combined to support this aim and to protect the ecosystem. Excessive irrigation practices, fertilizer and pesticide application, and incorrect management practices all accelerate salinization and degradation. In addition to this, it was found that a multi-layer GIS analysis made it easy to develop a framework for optimum land use and could increase the production yield preserving the environmental conditions. Finally, alternative management and crop patterns were undertaken to sustain this unique ecosystem, considering water, soil, climate, land use characteristics, and to provide guidance for planners or decision makers.

Land quality assessment and sustainable land use in Salt Lake (Tuz Gölü) specially protected area.

Land quality assessment is of great important for decisions on sustainable land uses and the conservation of ecosystems of high biodiversity value. The main objective of this study was to determine properties of land quality of specially protected area of the Salt Lake using CORINE land quality assessment methodology and to propose a revision for this model. In addition to field study and laboratory analysis, digital soil map, digital elevation model, satellite image and climatic data were used and analyzed with remote sensing and geographic information systems techniques to generate actual land quality map and to form database for study area. Results show that 42.1% of the study area has high quality, 28.7% was classified as moderate quality and 4.0% was determined as low quality. On the other hand, some places classified as moderate quality, were not accurately classified. These places should be low land quality due to content of high salt concentration. Therefore, to resolve this insufficient situation, some soil parameters such as chemical properties should be collaborated with this model. In this case, moderate land quality level of the study area decreased from 28.7 to 12.3%, whereas 4.0% of low quality land of the study area increased to 20.8%. In addition, this research was also carried out to provide guidance for planner or decision makers about specially protected area of the Salt Lake.

Soil erosion assessment using geographical information system (GIS) and remote sensing (RS) study from Ankara-Guvenc Basin, Turkey.

The objective of this research was to assess vulnerable soil erosion risk with qualitative approach using GIS in Ankara-Guvenc Basin. The study area is located about 44 km north of Ankara and covers 17.5 km2. The selected theme layers of this model include topographic factor, soil factors (depth, texture, impermeable horizon) and land use. Slope layer and land use-land cover data were prepared by using DEM and Landsat-TM satellite image. According to land use classification, the most common land use type and land cover are rangeland (50.5%) then, rainfed (36.4%), week forest land (3.2%), irrigated land (0.7%) and other various lands (rock out crop and lake) (9.2%). Each land characteristic is also considered as a thematic layer in geographical information systems (GIS) process. After combination of the layers, soil erosion risk map was produced. The results showed that 44.4% of the study area is at high soil erosion risk, whereas 42% of the study area is insignificantly and slightly susceptible to erosion risk. In addition, it was found that only 12.6% of the total area is moderately susceptible to erosion risk. Furthermore, conservation land management measures were also suggested for moderate, high and very high erosion risk areas in Ankara-Guvenc Basin.

A pollution fate and transport model application in a semi-arid region: Is some number better than no number?

Fate and transport models are powerful tools that aid authorities in making unbiased decisions for developing sustainable management strategies. Application of pollution fate and transport models in semi-arid regions has been challenging because of unique hydrological characteristics and limited data availability. Significant temporal and spatial variability in rainfall events, complex interactions between soil, vegetation and topography, and limited water quality and hydrological data due to insufficient monitoring network make it a difficult task to develop reliable models in semi-arid regions. The performances of these models govern the final use of the outcomes such as policy implementation, screening, economical analysis, etc. In this study, a deterministic distributed fate and transport model, SWAT, is applied in Lake Mogan Watershed, a semi-arid region dominated by dry agricultural practices, to estimate nutrient loads and to develop the water budget of the watershed. To minimize the discrepancy due to limited availability of historical water quality data extensive efforts were placed in collecting site-specific data for model inputs such as soil properties, agricultural practice information and land use. Moreover, calibration parameter ranges suggested in the literature are utilized during calibration in order to obtain more realistic representation of Lake Mogan Watershed in the model. Model performance is evaluated using comparisons of the measured data with 95%CI for the simulated data and comparison of unit pollution load estimations with those provided in the literature for similar catchments, in addition to commonly used evaluation criteria such as Nash-Sutcliffe simulation efficiency, coefficient of determination and percent bias. These evaluations demonstrated that even though the model prediction power is not high according to the commonly used model performance criteria, the calibrated model may provide useful information in the comparison of the effects of different management practices on diffuse pollution and water quality in Lake Mogan Watershed.

Effects of beer factory sludge on soil properties and growth of sugar beet (Beta vulgaris saccharifera L.).

The possible use of beer factory sludge (BFS) for an agricultural purpose was investigated with sugar beet (Beta vulgaris saccharifera L.). BFS was air dried and sieved through a 4 mm mesh before application to a soil (Typic Xerofluvent). Afterwards, the BFS was mixed with soil at a rate 0, 10, 20, 40, 80 and 160 tonnes ha(-1). The mixtures were than put into pots and kept in the greenhouse for an incubation of five months. During the incubation, pH, the electrical conductivity, the organic matter content, NH4+-N and NO3--N content were regularly measured. At the end of the incubation period, sugar beet seeds were sown into the same pots. After a growing period of six-months the sugar beet plants were harvested, and yield and quality parameters were determined. BFS increased leaf and root yield. However, the effect of BFS on leaf growth was more pronounced than on root growth. The highest sugar content, refined sugar content and refined sugar yield were obtained with the application rate of 10 tonnes BFS per hectare. Ten tonnes of BSF per hectare was the most suitable on the basis of root quality parameters and root yield. However BFS should be applied to the soil six or seven months in advance due to the high level of nitrogen released through mineralization.