Remote sensing as a tool for monitoring plasticulture in agricultural landscapes

Abstract

Agricultural landscapes are changing their appearance with the increasing use of man‐made plastic materials in covered agriculture (plasticulture) all around the world. As these affect the landscape visually, increase pollution and decrease local biodiversity, better monitoring and planning of their uses and areas are needed. Using a field spectrometer we studied the spectral properties of a sample of polyethylene sheets and various nets used in Israel. We detected three major absorption features around 1218 nm, 1732 nm and 2313 nm. These were not affected by settling dust, whitewashing or by the underlying surface, but were not apparent in black coloured polyethylene sheets or nets. A hyperspectral AISA‐ES image with a spatial resolution of 1 m achieved a detection accuracy of above 90% for bright sheets and nets but of only 70% for the black nets. The best spectral feature for plastic mapping was found to be that around 1732 nm as it does not coincide with spectral features of other minerals, soils, vegetation or atmospheric attenuation. As most of the greenhouses patches in Israel are smaller than 3200 m², the optimal spatial resolution of a sensor for mapping them should be equal or better than 8–16 m. As a result of their low spectral and spatial resolution, Landsat images proved inadequate for mapping greenhouses, and strengthen the need of hyperspectral technology for that end.

Acknowledgements

We would like to thank Alexandra Chudnovski and Tal Feingersh from the Department of Geography and the Human Environment at Tel Aviv University for their help in performing the ASD measurements. We also thank Alex Zilberman from the Survey of Israel for GIS layers of greenhouses in Israel, Adi Ben‐Nun from the GIS Centre of the Hebrew University of Jerusalem for the use of GIS layers of Soviet and Israeli topographic maps, and Ayelet Heller and Guy Nizry from the GIS unit of the Society for the Protection of Nature in Israel for helping us with GIS layers of built areas in Israel. Warm thanks also to Yehezkel Nefrin from Netiv ha Asara, and to Neta and Zuf Or from Ein Yahav, for sharing with us some of their hands‐on knowledge regarding plasticulture in Israel. This study was funded by The Fund for Promoting Landscape and Environment Values in the Agricultural Areas of Israel (Nekudat Hen) (http://www.lsea.org.il/site/homepage.asp).