Overview of the Crop condition assessment program

The Agriculture Division of Statistics Canada has a mandate to collect census and survey information regarding all forms of agriculture in Canada, and provide it in an expeditious manner to clients, often government policy makers. Long ago Statistics Canada realized that new technologies such as satellite remote sensing and geographic information systems (GIS) could reduce costs and provide valuable information in support of its operations.

The Crop Condition Assessment Program (CCAP), developed and maintained by the Remote sensing and geospatial applications Section (RSGA) within the Agriculture Division, is a prime example of such an application project that has provided substantial benefit to Statistics Canada subscribers. The CCAP combines remote sensing, GIS, and the Internet to provide timely and reliable information on crop and pasture/rangeland conditions. The application covers the whole Canadian agriculture area and the northern half of the United States.

Severe droughts, increasing competition among grain exporters, and the instability of grain markets have underscored the importance of having accurate and timely information on crop conditions and potential yield. CCAP is able to supply the user community with frequent updates over a large geographic area. The National Oceanic and Atmospheric Administration (NOAA) series of satellites carrying the Advanced Very High Resolution Radiometer (AVHRR) records images of the entire earth's surface twice a day. Although designed for atmospheric observations and weather forecasting, there are two AVHRR spectral bands (red and infrared) that have proven to be extremely useful for vegetation monitoring.

NOAA satellite data for this project are collected daily during the growing season at the satellite receiving station in Prince Albert, Saskatchewan. The data are transferred to the Manitoba Remote Sensing Centre (MRSC), where they are input, pre-processed, geocoded, and resampled. A composite of processed images covering the latest seven-day period is produced to remove as much of the cloud effects as possible, which substantially improves the quantitative analysis capability for vegetation condition monitoring. These products are then immediately transferred electronically to Statistics Canada where additional value-added processing, required for monitoring and measuring vegetation change, is completed. Once done, the application is updated on the internet, usually on the same day the data is received.

RSGA built an interactive mapping interface that allows users to view, via the Web, value-added satellite images and map products as well as statistical and graphical data. CCAP image products show vegetation conditions on a pixel by pixel basis while map products illustrate the predominant vegetation condition by Census Agricultural Region (CAR), Census Division (CD) or Census Consolidated Subdivision (CCS), or within Townships or US counties.

Users from federal and provincial governments, grain marketing agencies, and crop insurance companies view RSGA’s value-added products on the Internet in less than 24 hours after the last satellite overpass, a substantial improvement compared to a decade ago when processing and distribution took five days.

Depending on their particular requirements, using the GIS interface, users can either view cropland and/or pasture/rangeland areas of interest, together or as separate classes. This type of analysis allows users to quickly assess the conditions. Water bodies, rivers, roads, and major cities and provincial, all the boundaries may be overlaid on the image to aid in area location.

A detailed, quantitative analysis is accomplished by RSGA to calculate the mean Normalized Difference Vegetation Index (NDVI) value on a weekly basis for crop and pasture/rangeland masks and for each CAR, CD, CCS, Townships and Counties. The NDVI emphasizes differences between stressed and unstressed vegetation, providing an indication of plant health. Mean NDVI data by the boundaries can be plotted, viewed, compared, and analyzed with any other year in the statistical archive. The tabular and/or graphical data can either be electronically exported into reports or presentations.

Coupling CCAP with the capability to accurately and reliably forecast spring wheat production for western Canada, well in advance of Statistics Canada’s first survey information on spring wheat yield based on farmer observations, gives users a very useful tool for making management decisions. Users require the most up-to-date information possible on how much, and where, week-to-week conditions have either deteriorated, remained unchanged, or improved.

A close working association with users has been paramount to the successful development of the CCAP.