Extraction of agricultural phenological parameters of Sri Lanka using MODIS, NDVI time series data

Abstract

Management of crops is an essential part in the food production procedure. Having a thorough knowledge of growth stages of each crop is of paramount importance in this respect. Phenology (transplanting, panicle formation, flowering etc) is the study of cyclic and seasonal natural phenomena that are controlled by environmental and climatic factors. Monitoring the crop condition manually in the field is difficult and time consuming. Therefore recently, several methods have been introduced by using satellite derived vegetation indices. Extraction of phenological parameters is helpful for the purposes like irrigation management, nutrient management, health management, yield prediction and crop type mapping. Easily extracted parameters will be the important data base for agricultural researchers. This research is an attempt to extract paddy phenological parameters of Sri Lanka by using 16 years’ (2000 to 2015) Time series MODIS Normalised Difference Vegetation Index (NDVI), which is highly sensitive for the green vegetation and the data were analysed using SPIRITS and TIMESAT software’s. Periodicity converter in SPIRITS and Savitzky Golay filtering in TIMESAT and SPIRITS are helpful in smoothing the time series which are perturbed by noise due to missing values and Clouds. Phenology is considered as a sensitive climate change indicator but, it is very essential to have a comprehensive familiarity about the method of water supply that the study area is irrigated or rain fed so as to eliminate the wrong interpretation. As results, average of long time series of NDVI profile for a few agro ecological zones of Sri Lanka with extracted seven parameters (Start of the season, End of the season, Length of the season, Booting date, Base value, Maximum NDVI during the Season, Amplitude) and generated phenological parameter maps are presented here. The crop phenology is a very important element of agricultural monitoring, to ensure the security of the food crop production.