Relationship between natural enviroment conditions and land use i̇n the West Büyük Menderes watershea Basin

TOPRAKSU Organization has classified the lands in our country into capability classification on the basis of the land capability classification system used by the Soil Conversation Service of the USA. This classification system has already been used and laying a foundation for the studies related to soil and land. But, it can' t be said that the criteria taken into consideration, the methods and materials used in this classification system don't suit much to the conditions of our country. That is, it is understood that the effects of the climatic elements and the main material coming to the surface because of the erosion of the soil in the rugged and mountainous areas on the soil formation and classification capability distinction of the land hasn't been sufficiently appraised and this classification system is much more related to agricultural land. (Atalay and Gökçe Gündüzoğlu, 2015, 9). The aim of this study is to classify the lands capability classes by taking the main material-soil property, the conditions of geomorphology and topography, the properties related to climatic elements and natural environment conditions formed by vegetation into consideration, to reveal the ideal forms of their use, to offer solutions to problems arising from present land use. For this purpose,the data related to temperature, vapor pressure, evaporation, relative humidity and precipitation have been provided from the General Directorate of Meteorology Affairs. In order to determine the physical and chemical properties of soil types, laboratory analysis results of soil samples taken from the field were used. Data on the characteristics of the lands were obtained from the Ministry of Food, Agriculture and Livestock, and CORINE database of 2018, Landsat satellite images of 2020 and field observations were used for the current land use status. Mixed research method has been used in the study Our study area is located in the Aegean part of the Aegean Region, the west of the Büyük Menderes (Big Meander) Basin, between 37º2ʹ - 38º1ʹ north latitudes, 27º - 28º 1ʹ east longitudes. In determining the boundaries of the site, the main material in different lithology, soil types and topography conditions such as elevation, slope, aspect and how the differences in climatic elements affect the quantity and quality of the land, its ability classes and usage patterns have been taken into consideration. There lie Aydın Mountains in the north of the study area and the Dilek Peninsula Mountains, which are the southwest extension of these mountains, and the Menteşe Mountains in the South. Aydın, Germencik, Koçarlı and Söke plains take place among these mountains, which are horsts by formation, and also Karpuzlu, Turgut and Milas plains take place in Menteşe Mountainous area. From the southern and northern slopes of the mountains to the base of the plain, there are neogene sandy, clayey deposits, Plio-Quaternary conglomerate, sandy-clay deposits, and accumulation cones and fans. Didim Plateau is located in the southwest of Söke Plain. In mountainous areas, limeless brown forest soils in sandy and sandy loam texture were formed on the gneiss, quartzite, quartzite schist and granite and also Red Mediterranean soils with clayey texture were formed between cracks and layers on marble and limestones. There are medium and coarse textured colluvial soils on the southern skirts of the Aydın and Dilek Peninsula mountains, on the slopes of the mountains surrounding the Karpuzlu, Turgut and Milas plains, and there are medium and fine textured colluvial soils on the margins of the plains. In addition, in the Neogene land extending from the south of Yeniköy and Balat to the Aegean Sea, there are rendzina soils with a clayey loam structure, there are alluvial soils formed by sediments in the size of sand, mile and clay containing muscovite scales on the bases of the plains, and also hydromorphicluvial soils on the sea coast and on the shores of Lake Bafa. Mediterranean climate characteristics are observed in our study area. The temperature is high and the vegetation period covers the whole year. The first frost occurs in the last week of December, and the last frost occurs in the second week of February. Half of the total annual precipitation occurs in winter, and the rest in spring and autumn. The summer period is dry with low relative humidity and high evaporation. In our study area, the lower Mediterranean forest belt consisting of red pines, including maquis appear at the altitudes of 1000 m-1200 m, and the Mediterranean mountain belt forests consisting of oak, larch, juniper and partly pine pine appear on this belt. There are aquatic plants in wetlands, and salt-tolerant herbaceous species in salty areas. Soil thickness, drainage status of the land, wetness, flooding, salinity, alkalinity and usage density of the land have been taken as a basis in the capability classification for the lands suitable for cultivated agriculture which are generally located in the plains, Physiographic location, degree of slope, effective soil depth, stony, rocky, productivity status depending on the physical and chemical properties of the parent material, vegetation type and distribution density have been taken as a basis in the ability classification of the lands in mountainous rough areas. Accordingly, 35,3 % of the whole research area is formed up by agricultural land, and 64,7 % is formed by non-agricultural land, and it has been determined by the capability classification conducted by TOPRAKSU Organization that agricultural lands form 33,3 % and non-agricultural lands form 66,7 %. In other words, when the land capability classification done by TOPRAKSU Organization and the land capability classification done regarding natural environment conditions are compared, a change of 2 % has been determined in lands both suitable for agriculture and not suitable for agriculture.While there occurs an increase of 2% in farmlands, there is a decrease of 2% in non-agricultural lands. The biggest change occurs in lands of capability class-II with an increase of 9,6%, and the least change occurs in lands of capability class-IV with an increase of 0,7%. In non-agricultural lands, the biggest change occurs in lands of capability class IV with a decrease of 7,9%, and the least change occurs in lands of capability class-VIII with an increse of 0,7%. When the aspects of changes are scrutinised, the biggest change is 28,6 % with the lands of capability class-II that were formerly capability class-III, the second biggest change is 13,5 % with the lands of capability class-VII that were formerly capability class-VI, the third biggest change is 9 % with the lands of capability class-II that were formerly capability class-I. When the natural environment conditions of the research area indicated above are regarded, the lands where there are no soil problems in the plains in our study area, with good productivity, where more than two crops are harvested a year, are rated as. capability class I, lands where the wetness problem can be solved by drainage and crops are harvested twice a year are rated as capability class II, lands where drainage insufficiency is observed and moderate salinity and alkalinity problems are experienced are rated as capability class III, lands where there is poor drainage, wetness, salinity and alkalinity problems but where agricultural activities are conducted by temporarily overtaking these problems by washing these lands are rated as capability class IV. According to the land capability classification done by TOPRAKSU Organization, the lands of capability class-II have been assessed as capability class-III, and the lands of capability class-IV have been assessed as capability class-VI according to natural environment conditions. In these lands, while cotton is cultivated mostly, wheat and corn are partly cultivated as well. The use of washing operation and the flood method for the lands where there are alkalinty and salinity problems will increase salinity rate in the long term. For this reason, priority should be given to the cultivation of plants with low water demand, more comprehensive, long-term effective action plans for reducing salinity and alkalinity should be prepared and carried out without delay. Pasture areas with salt-resistant herbaceous species close to the sea have been rated as capability class V lands. These areas where there is a risk of wind erosion should not be exposed to overgrazing. Lands with sparse saline plants are rated as capability class VI, marshy areas covered with aquatic plants are rated as capability class VIII. Regulating swampy areas and taking them under protection is of great importance for the continuity of wildlife. In the land capability classification done by TOPRAKSU Organization, the pasture grounds with salt resistant vegetation have been assessed as lands of capability class-VI, and the marsh areas covered by aquatic vegetation have been assessed as lands of capability class-VII. The lands with medium and fine textured deep soil and medium deep colluvial soil on the edges of plains have been assessed as lands of capability class-III and IV, and the lands in hillsides with coarse textured colluvial soil have been assessed as capability class-V. Olive cultivation is generally carried out in these lands where physiological depth is high and fertility is low. The cultivation of deep-rooted fruits such as figs and vines should be expanded and soil fertility should be increased. The parts of the slopes that are opened to olive cultivation or covered with vegetation have been rated as capability class VII, cliffs and the bare parts of the slopes with no vegetation are rated as capability class VIII. In the land capability classification done by TOPRAKSU Organization, the lands in hillsides with coarse textured colluvial soil have mostly been assessed as capability class-VI, and bleak areas with no vegetation have been assessed as capability class-VII. Enough measures should be taken to conserve water and soil on slopy lands where olive cultivation is carried out. Bleak areas that are appropriate can be used to benefit from solar energy. Flat or nearly flat lands at high sections are rated as capability class IV, forest and pasture areas with low slope, covered with vegetation are rated as a capability class VI. More emphasis should be placed on planting stone pines in these lands where sandy and sandy loam textured limeless brown forest soils are common. Keywords: Büyük Menderes (Big Meander) Basin, land capability classes, land us