© by PSP Volume 20 – No 2. 2011 Fresenius Environmental Bulletin 310 SPATIAL VARIABILITY OF Fe, Mn, Zn AND Cu IN SOILS OF BÜYÜK MENDERES DELTA IN WESTERN TURKEY Ercan Yeşilırmak 1 *, Levent Atatanır 2 , Alper Yorulmaz 2 , Gönül Aydın 2 and Cafer Turgut 3 1 Department of Agricultural Structures and Irrigation, Faculty of Agriculture, Adnan Menderes University, Aydın, Turkey 2 Department of Soil Science and Plant Nutrition, Faculty of Agriculture, Adnan Menderes University, Aydın, Turkey 3 Department of Plant Protection, Faculty of Agriculture, Adnan Menderes University, Aydın, Turkey ABSTRACT The purpose of this study was to investigate the spa- tial distribution of micronutrients (Fe, Mn, Zn and Cu) in soils of Büyük Menderes Delta, Western Turkey. Soil sam- ples were taken at 0-30 cm and 30-60 cm depths on grid nodes (1 by 1 km), 59 samples (in total) for each depth. Spherical model is best fitted to the experimental models for Fe at two depths, Mn at 0-30 cm depth, Zn at 30-60 cm depth and Cu at 0-30 cm depth, while the experimental semivariograms for Mn at 30-60 cm depth, Zn at 0-30 cm depth and Cu at 30-60 cm depth showed pure nugget effect model. Then, point kriging was employed to get soil mi- cronutrient values at unsampled locations. Spatial distribu- tion maps of each micronutrient attained in this study are considered to be beneficial for refining agricultural man- agement practices. KEYWORDS: Micronutrient, Büyük Menderes Delta, geostatis- tics, spatial variability, Turkey 1. INTRODUCTION The availability of micronutrients in the soil can strongly affect the production and quality of crops [1]. Soils vary widely in their micronutrient contents and their ability to supply sufficient micronutrients for optimal crop growth [1]. Surveys and maps illustrating the geographic distribution of soil micronutrient availability would pro- vide guidance for proper management of nutrients in soils, and are necessary for a better understanding of the nature and extent of micronutrient deficiencies and toxicities in plants, livestock and humans [2]. In Turkey, many local and regional studies were con- ducted to determine the micronutrient status of soils. The most comprehensive one was conducted by the General Directorate of Rural Services to determine micronutrient *Corresponding author status of soils in Turkey [3]. Besides, some local studies were conducted to delineate the micronutrient status of soils in various regions of Turkey, for example in Karadeniz [4], Marmara [5, 6], Aegean [7] and Eastern Anatolia [8]. Büyük Menderes River, located in Western Turkey, is an important river system which includes wetland areas, such as Lake Işıklı, Lake Bafa and the delta of Büyük Menderes River. Büyük Menderes Delta which covers an area of 16,690 ha was incorporated into Dilek Penin- sula National Park in 1994. This area hosts many endan- gered and endemic species, and is protected through in- ternational conventions. However, agricultural activities are carried out in the Delta, and the required irrigation water is supplied mostly from nearby drainage canals. Büyük Menderes River and its tributaries have long been considered as receiving water body for disposal of indus- trial and municipal wastewaters [9]. Not only pollutants but also (micro)nutrients carried by irrigation return flows con- tribute to soils in the Delta. Understanding of the spatial variabilities and distribution patterns of soil micronutrients and detecting areas where micronutrient fertilization or soil remediation are required are essential for a proper agricul- tural management. Therefore, this study was carried out to assess the spatial distribution of Fe, Mn, Zn and Cu in soils of Büyük Menderes Delta located in Western Turkey using geostatistical approach which is widely applied for delineating the spatial distribution of soil heavy metals [10-12]. 2. MATERIAL AND METHODS Büyük Menderes Basin and Büyük Menderes Delta are located in the western part of Turkey (Fig. 1). Büyük Menderes River, with a length of 584 km, drains an area of about 24,873 km 2 which corresponds to 3.2 % of Tur- key [13]. It rises near Dinar county of Afyon province and discharges into Aegean Sea within the boundaries of Aydın province, creating the delta [13]. Typical Mediter- ranean climate is dominant in the Delta, with dry and hot summers as well as wet and mild winters. Annual average temperature is 17.1 °C, and mean annual rainfall is about 608 mm at the nearest meteorological station in Kuşadası.