Mapping Wheat Growing Areas of Turkey by Integrating Multi-Temporal NDVI Data and Official Crop Statistics

Wheat is the most widely cultivated crop in the world providing critical food source of most countries. It exceeds most of the grain crops in acreage and production because of its ability to grow in wide range of climatic and geographic conditions. Timely and reliable information on wheat acreages is essential for government services in order to formulate their policies for planning of agricultural production and monitoring their food supply. Traditionally, agricultural statistics is considered as the main source of such information. Unfortunately, existing statistical data of wheat acreages of Turkey, mostly dependent on farmers’ declarations, does not provide spatial information of where this crop specifically is grown. Satellite remote sensing technology can enable the acquisition of such information indirectly with the use of ancillary data of crop statistics. This study aims to determine wheat cultivation areas of Turkey as percentage per unit area in a crop map by integrating time series satellite NDVI imagery with the official crop statistics through regression analysis. The regression results indicated that satellite data explained 95.8% of the variability in official wheat crop statistics and actual wheat cropping areas were significantly related to NDVI-based wheat classes. Validation of the produced wheat map showed that there was good agreement between actual wheat fractions and estimated NDVI-based wheat fractions explaining approximately 69% (Adj. R2) of the total variability between them. This study suggests use of the methodology employed here to governing bodies that need to identify and to map current wheat cropping areas