In the Remote Sensing Centre crop growth conditions are monitored with the use of models based on NOAA/AVHRR satellite data. Condition of vegetation is presented for agricultural areas spatially.
For determining areas threaneted with drought index of identification of agricultural drought - DISS is applied (Drought Identification Satelite System). The index is strictly related to rainfall and air temperature since start of vegetation season. Models are based on radiation temperature derived for each 1 sq. km area (NOAA pixel) and for every 10-day period within vegetation season. Using satellite indices, which characterize plant phenology and their water requirements in particular phases of crop development, drought intensity and its impact on yield reduction is determined. The monitoring is conducted since autumn sowing through spring crop development till harvest.
In current year crop growth conditions were not favourable. After non-snowy winter high fluctuations of temperature and lack of rainfall occured in April at the beginning of vegetation period. May was very wet, but from the beginning of June severe drought appeared. The area of agricultural crops affected with drought reached over 70 %, while long-term drought covered 50 % of agricultural land (state on July 5). Starting from the second ten-day period of July gradual improvement of plant moisture was observed for crops being still under development. However, central-western region of Poland (wielkopolskie and lubuskie voivodships) still remains within zone of deficit of rainfall, which is needed for proper plant development.
Moisture conditions of agricultural crops in 2019
The maps presented below demonstrate various moisture conditions of crop development based on Temperature Condition Index (TCI), marked with various colours:
- heavily threatened with drought - red
- threatened with drought - orange
- average conditions - light green
- good conditions - dark green
In addition, dark blue denotes areas with excessive plant moisture, which in combination with low air temperature at the start of vegetation season can cause ground frosts. The maps are produced since the beginning of May.
In climatic conditions of Poland droughts cause large damages of crops, in turn inducing significant decrease of yields. The drought is the result of disruption of water balance. The disruption is caused by atmospheric drought due to lack of rainfall, soil drought caused by excessive drying of soil and hydrological drought, which causes lowering of water table. In the course of last fifty years the most severe droughts appeared in 1951, 1953, 1959, 1963, 1964, 1969, 1971, 1976, 1982, 1988, 1990 and the extreme drought in 1992, which caused yield reduction of winter crops up to 15% and spring crops up to 20%. In 21st century the droughts were noticed in 2000, 2003, 2006, 2015 and 2016.
In Remote Sensing Centre various types of satellite data with different resolutins are used in order to create the comprehensive Agricultural Drought Monitoring System for particular areas, plots, administrative units etc.
Maps of agricultural drought prepared since 20 years by the Remote Sensing Centre deliver information on ubfavourable conditions of crop development caused by drought situation. Drought information in country scale can be compared with crop condition at particular plots. The image above presents condition of maize in 2016 and 2018 (NDVI index) comparing it with drought maps for the same periods.