Why crop history is important to analyze NDVI and Variability

The Crop History is very important to evaluate the history and variability of the fields, when processing and interpreting NDVI maps, Producitivity maps, or other layers derived from remote sensing processing.

This information includes the following, for each of the last crop seasons:

If there was any extraordinary event, such as hail, drought, floods, etc.
The crop planted in each field, with planting and harvesting date.

To send crop history data you may download this Crop History Template, or if you have similar information, send your available crop history table.

Note:

By similar information is meant summary crop history by field, please do not send detailed information of planting and other operations

Knowing this history has a direct impact on the quality of the generated information based on remote sensing, and the later decisions, since it allows to select images when they are more relevant.

The following examples illustrate this point:

Dry and Wet Years

Knowing periods of extreme weather is very important, to interpret NDVI maps, and for selecting the images that will be used to process Productivity maps.

For instance, these images illustrate extreme rain conditions during the years 2001-2009:


We can observe in this image from year 2001 (represented with Landsat bands combination 4-3-5) that it was extremely wet, with green colors in the low flooded areas.	The same area in year 2009 was hit by a severe drought, we can not see areas with humidity.

Planting date

Knowing the planting date allows to know more exactly which image dates can be used, taking into account the different stages and evolution of the crops. There will be different reflectance which are shown in the NDVI analysis according to each crop stage.

The following sequence illustrates different NDVI for different crop stages