Agriculture Reference
In-Depth Information
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Crop conditions were monitored during 1997-2001 vegetation periods
by comparing dekadal NDVI values with the previous year's values and the
long-term mean values for each administrative unit in Poland. Administra-
tive units were grouped into regions to study regional differences in NDVI
levels. All of the above mentioned materials were used for analyzing crop
development in Poland. For example, figure 13.6 illustrates crop growth
conditions in Poland in 2001 based on analysis of NDVI data.
These NDVI-based outputs were delivered to the Central Statistical
Office for comparative analysis. In addition, research conducted at the
Institute of Geodesy and Cartography found the following indices useful
for monitoring vegetation and drought conditions in Poland:
1. Crop growth index (CGI), the ratio of NDVI to radiation temper-
ature (NDVI/ T s ). This index more precisely reflects the deficits in
soil water content than the NDVI or temperature alone. The lower
the CGI, the worse the vegetation conditions.
2. Soil-adjusted vegetation index, a function of NDVI, taking into
account reflection from soil background (Huete, 1988; chapter 5).
3. Ratio of sensible heat to latent heat (H/LE); the higher the index,
the worse the crop conditions. Figure 13.7 shows spatial variation
of H/LE index for 1998 and 2000.
4. Water deficit index, the ratio of actual to potential latent heat,
LE/LE p (Moran et al., 1994).
[177
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D rought-Mitigating Measures
Efforts to mitigate drought in Poland began in the beginning of 20th cen-
tury in the central part of Poland (Wielkopolska and Kujawy regions),
Figure 13.6 Changes of crop growth conditions in 2001 as compared to normal year expressed
by NDVI ratios.
 
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