Ukraine: Estimated Wheat Yield Based on Satellite-Derived Vegetative Indices

The USDA estimates Ukraine wheat production for 2008/09 at 21.0 million tons, up 50 percent from last year. The winter wheat crop has benefited from excellent weather throughout the growing season and the estimated yield of 3.09 tons per hectare is among the highest of the past fifteen years. The current USDA yield estimate is based chiefly on the analysis of satellite imagery: satellite-derived vegetative indices such as the normalized-difference vegetation index (NDVI) have proven to be a reasonably reliable indicator of wheat yield in both Ukraine and the neighboring winter-wheat region of southern Russia. Higher NDVI typically indicate greater vegetative biomass or, in the case of cropland, higher potential yield.

For winter wheat, the NDVI begins to increase after the crop breaks dormancy and resumes vegetative growth in the early spring, and reaches the maximum value when the plants reach the flowering stage in mid- to late May.  Methods for NDVI-based yield analysis vary by region; in the case of Ukraine winter wheat, the maximum NDVI provides the most reliable estimate of potential yield.

Note that aggregate oblast-level NDVI typically continues to increase even after winter wheat reaches its maximum value in late May.  This is due to the emergence and development of the early spring grains (chiefly barley) and the summer crops (corn, sunflowers, and sugar beets). The NDVI continues to build until the summer crops reach their maximum values in July.

The vegetative indices for 2008/09 winter wheat indicate excellent crop conditions and high potential yield throughout the main production regions of central, southern, and eastern Ukraine. The NDVI-based forecast for 2008/09 wheat yield was determined by plotting historical yields against the corresponding maximum NDVI for each oblast (the first-order administrative territory, similar to a U.S. state). The potential 2008 wheat yield for each oblast- was then estimated based on regression analysis of the current-year NDVI.

Eleven oblasts in eastern and southern Ukraine account for nearly 70 percent of the country's winter wheat production. These oblasts are also marked by a reasonably high correlation between NDVI and wheat yield.

(Click on the map below to view NDVI graphs.)

Estimated wheat production was calculated by applying the NDVI-derived yield to the oblast-level sown area reported by the Ministry of Agriculture. The total Ukraine wheat-production estimate of 21.0 million tons includes 0.7 million tons of spring wheat.

The harvest of winter wheat (which accounts for about 95 percent of total wheat area) typically begins in southern Ukraine in late June or early July and is largely complete by early August.

Current USDA area and production estimates for grains and other agricultural commodities are available on IPAD’s Agricultural Production page, or at PSD Online.