KSÜ. Fen ve Mühendislik Dergisi, 9(1), 2006 KSU. Journal of Science and Engineering 9(1), 2006 69 A Review of Remote Sensing and Vegetation Indices in Precision Farming Çağatay TANRIVERDİ KSÜ, Ziraat Fakültesi, Tarımsal Yapılar ve Sulama Bölümü, Kahramanmaraş ABSTRACT: Precision farming is a technique to establish a better agricultural management. Global positioning systems (GPS), geographic information systems (GIS), remote sensing (RS) and variable rate application (VRA) are the major components of precision farming. RS has the potential of playing a determinant role as a spatial information source. One of the main reasons is that the conventional methods of data collection are difficult, time- consuming, mainly in large irrigated agricultural fields. Moreover, using RS system, reflectance data could be collected to calculate vegetation indices. In this paper, major known vegetation indices (estimated vegetation cover) are summarized and compared with measured vegetation cover. In addition, precision farming as a key to accomplish a better agricultural management was discussed in details. Keywords: Precision farming, remote sensing, vegetation indices Hassas Tarımda Uzaktan Algılama ve Bitki İndekslerinin Bir Derlemesi ÖZET: Hassas tarım daha iyi bir zirai yönetim kurmak için bir tekniktir. Küresel konumlama sistemi, coğrafi bilgi sistemleri, uzaktan algılama ve değişken oran uygulamaları hassas tarımın belli başlı öğeleridir. Uzaktan algılama, bir yersel bilgi kaynağı olarak belirleyici bir potansiyel role sahiptir. Bunun en önemli nedeni de özellikle geniş sulanmış tarım alanlarında geleneksel veri toplama zorluğu ve zaman kaybıdır. Bunun dışında uzaktan algılama sistemi kullanılarak, yansıma verileri bitki indekslerini hesaplamak için toplanabilir. Bu makalede başlıca en çok bilinen bitki indeksleri özetlenmiş ve ölçme yöntemi ile belirlenen bitki örtüsüyle karşılaştırılmıştır. Ayrıca daha iyi bir zirai yönetimi saptamak için hassas tarımın önemi detaylarıyla tartışılmıştır. Anahtar Kelimeler: Hassas tarım, uzaktan algılama, bitki indeksi INTRODUCTION Precision farming (site specific management, site specific farming, prescription farming, variable rate application technology) is an information and technology based agricultural management system to identify, analyze, and manage site-soil spatial and temporal variability within fields for optimum profitability, sustainability, and protection of the environment. This implies the concept of using information about variability in site and climatic characteristics to manage specific sites in a field by using management practices. The main components of precision farming are global positioning systems (GPS), geographic information systems (GIS), remote sensing (RS), and variable rate application (VRA). In the past decade, the spatial variability of soil and crop properties evaluating one or a combination of these precision-farming components has been widely researched. Under the assumption that the field is homogeneous, the field is managed as a whole, without reference to the spatial variability of its production components. If the field is not homogeneous, agricultural inputs should be changed on a spatial basis; therefore, agricultural management is important and necessary to determine more accurate information of fields. Thus, precision farming is a technique to establish a better agricultural management. PRECISION FARMING The objectives of precision farming are to increase crop production and reduce environmental impacts of agricultural chemicals by adjusting agricultural inputs (fertilizer, seeds and pesticide) to the particular situations within each side of a field (Mermer et al., 2000). A farming method that determines the different needs of specific areas in the field is known as precision farming. This impression is an alternative to conventional farming, where needs are determined for the entire field. In conventional farming, needs such as irrigation, fertilization, pesticide or herbicide applications, are determined for an entire field. Unfortunately, conventional farming method ignores the spatial variability in the field (Diker and Ünlü, 1999). Precision farming is an old idea that has been given new life by the advent of technologies based on global positioning systems (GPS). These GPS based technologies are used to customize soil and crop management to match states at each part in a field to precision farming (Lowenberg-DeBoer et al., 2002). Dawson and Johnston (1997) state that an early essay by Mercer and Hall (1911) presented a detailed field yield map. Until recently, such maps were extremely labor intensive to prepare because of lack of advanced technologies. In more recent times, the appropriation of precision farming has been stimulated by the development of new technologies and an immense need for enhanced use of agricultural inputs. The ability to automate data collection, and to process and implement such data has been extremely increased by new technology. Although precision farming of fields may be justified due to the existence of in-field spatial variability such that crop yields differ under a single