Island soil quality assessment and the relationship between soil quality and land-use type/topography

An ecological restoration assessment integrating multi-criteria decision analysis with landscape sensitivity analysis for a hydroelectric power plant project: the Tokat-Niksar case

Due to Turkey's reliance on imported electricity, it has been using hydroelectric power plants (HPPs) to cover some of its electrical energy needs since 2011. However, HPP projects, which do not take landscape sensitivity into account, cause the ecological integrity of the basins and the ecosystem structure to deteriorate. This study presents the Tokat-Niksar HPP project field example in Turkey's Central Black Sea region with its steep slopes, rich forest and creek vegetation, protected endemic plants and wildlife, cultural heritage dating back to 3000 BC agricultural activities, and long-established local culture. The study, in fact, aims to develop a landscape restoration plan that considers the sensitivity of landscapes in the HPP project area. For this purpose, a landscape sensitivity analysis consisting of water, habitat, visibility, erosion functions, and multi-criteria decision analysis (MCDA) determining priority of functions conducted with experts were performed. According to the results, the water function was found to have the highest, and the visibility the lowest priority in the ranking. Consequently, 1st, 2nd, 3rd, and 4th-degree sensitive areas with very high, high, and moderate landscape sensitivity were determined by weighted sum function by considering the priority of each landscape function, and accordingly, a five-stage landscape restoration model was developed including soil protection, areas to be protected, erosion control, vegetation screening, and creek reclamation. This study presents a framework for sustainable landscape restoration solutions in the town by combining landscape sensitivity analysis via MCDA.

Degradation of soil quality by the waste leachate in a Mediterranean semi-arid ecosystem

The assessment of soil quality indices in waste leachate-affected soils is vital to understand the threats of land quality degradation and how to control it. In this respect, a study was conducted on the effects of uncontrolled landfill leachate on soil quality index (SQI) in calcareous agricultural lands using 28 soil variables. Using the total data set (TDS) and minimum data set (MDS) approaches, the SQI was compared between leachate-affected soils (LAS) and control soils by the integrated quality index (IQI) and nemoro quality index (NQI) methods. The results revealed that LAS were significantly enriched by soil salinity-sodicity indices including electrical conductivity (EC), sodium adsorption ratio (SAR), and exchangeable sodium percentage (ESP), fertility indices including total N, available P and K, organic carbon, and cation exchange capacity (CEC), exchangeable cations (Ca, Mg, K, and Na), the available and total fractions of heavy metals (Zn, Cu, Cd, Pb, Ni). After the leachate got its way into the soil, the values of IQI and NQI were dropped ranging 5-16% and 6.5-13% for the TDS approach and 5-15.2% and 7.5-12.2 for the MDS approach, respectively. Clearly, the data showed that soil quality degradation was encouraged and stimulated by the leachate. Among the different models of SQI applied in the present study, IQI determined by MDS was the optimal model to estimate soil quality and predict crop yields given the analysis of the correlations among the SQI models, the correlations between the SQI models and wheat yield, and sensitivity index values.

Variation of soil properties under different landscape positions and land use in Hunkuyi, Northern Guinea savanna of Nigeria

The food insecurity problem in developing countries has been linked to rapid rates of soil loss and decline in fertility in tropical environments which are characterized by insidious topography. This study was conducted to assess the relationship between topographic positions, land use, and soil characteristics. Three slope classes were considered with six pedons; two on each slope position were opened, described, sampled, and analysed for morphological and physicochemical properties. The results showed that the soils were deep to very deep with drainage improving from HK1 soils (very poorly drained) to HK3 (well-drained). The mean sand fraction ranged between 320 and 740 g kg^-1, while bulk density had values between 1.20 and 1.80 M gm^-3. The cation exchange capacity (CEC) of the soils with values from 5.6 to 10.4 cmol (+) kg^-1 was generally lower on the surface than the subsurface soils. The different landscape positions alongside variation in land use substantially influence variations in soil properties of the study area. The influence of topography was noticed for sand values and soil reaction (pH) along the slope, as mean pH values were significantly (P ≤ 0.05) higher for HK1 compared with HK2 and HK3. Intensive cultivation of soils due to rainfed and irrigated land use on middle slope position (HK2) alongside its strong slope gradient resulted in significant variation in total exchangeable bases (TEB) ((P ≤ 0.05), base saturation (P ≤ 0.05), available P ((P ≤ 0.01), and exchangeable Ca and Mg (P ≤ 0.05).