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Production
Estimates and Crop Assessment Division |
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Production
Estimates and Crop Assessment Division |
August 12, 2002
The drought plaguing the Western United States expanded into South Dakota during May and June 2002. Low available soil moisture and above-normal temperatures have caused spring wheat, summer crops, pastures, and hay crop conditions to deteriorate during June 2002. South Dakota is too dry across three-fourths of the state. Spring grain, summer crop, and pasture conditions from here on out depend on which way the weather turns. If dryness continues, crop conditions and yields will continue to worsen. Analysis of satellite imagery and weather data indicate that crops will deteriorate further, unless rainfall increases soon. The June satellite imagery shows the area of very poor condition in western South Dakota and wildfires that have already broken out in the Black Hills.
Current year winter wheat escaped most of the unfavorable growing conditions, and was a fairly good crop compared to the disastrous 2001 crop, a crop hurt by poor fall 2000 establishment and above-normal winter-kill. However, 2002 winter wheat did deteriorate in the final crop stages, from the moisture critical "grain-filling" stage to maturity, due to lack of moisture and high temperatures. As of June 1, 2002, the National Agricultural Statistics Service (NASS) forecasts that South Dakota will produce 35.7 million bushels of wheat with an average yield of 34 bushels/acre, on 1.05 million harvested acres. During May 2002, NASS forecast South Dakota winter wheat yields at 40 bushels/acre. During 2001, South Dakota only produced 11.8 million bushels of winter wheat, harvesting only 370,000 acres, abandoning over 60 percent of the crop, and yielding only 32 bushels/harvested acre. To further illustrate how crop conditions have plummeted, on June 2, 2002, NASS reported that 25 percent of South Dakota's winter wheat crop was in very-poor to poor condition. On June 30, NASS reported 76 percent of the winter wheat crop as very-poor to poor. Spring wheat conditions have also deteriorated. On June 2, 2002, NASS reported that 10 percent of the state's spring wheat crop was rated as very-poor or poor. On July 1, 2002, conditions worsened, with 68 percent of the spring wheat crop meeting a very-poor to poor rating. Figures 1 and 2 are five-year average winter wheat and spring wheat production maps for the Northern Plains, which include South Dakota. Figure 3 is a South Dakota corn condition graph, illustrating the percent of the state's corn crop that is in the very-poor to poor condition this year compared to 2001 and 2000. As of July 1, 2002, NASS reported that 23 percent of South Dakota's corn crop was rated as very-poor or poor, typically only 5 percent or less of the crop meets these ratings. Range and pasture conditions have also deteriorated each week since late May 2002. As of July 1, 2002, 65 percent of South Dakota's range and pasture land were rated as very-poor or poor. During the last two years, as of July 1, less than 5 percent of these areas were rated so low. Figure 4 is a graph of comparing percent of range land and pastures that rate very-poor to poor, for 2002, 2001, and 2000.
Comparison of vegetation for this growing season with recent years indicates
that South Dakota has much less vigorous vegetation this June compared to June
2001. Figure 5
shows vegetation index maps of South Dakota, comparing vegetation vigor during
June 16-30, 2002 with June 16-30, 2001. Vegetation index graphs are included
for each of South Dakota's nine crop reporting districts or growing regions.
These graphs show growing conditions across the state and compare
well with precipitation time series which were monitored also by crop reporting
districts. Through July 1, 2002, precipitation for 2002 is slightly above
the last 3 years in the Northeast and East Central crop reporting
districts. Vegetation index comparison graphs, as well as visual analysis of
satellite imagery, indicate that crop conditions are similar to last year.
Throughout the rest of the state, precipitation and vegetation index comparison
indicate that as of July 1, 2002, conditions are poorer than last year and in recent
years. The three western districts are in the worst condition, with the
Northwest Crop District deviating the most from recent years in vegetation.
Figure 6 is a comparison of two Landsat scenes from a portion of Brown County, South Dakota. Compared here are Landsat scenes from June 16, 2001 and June 11, 2002. It is quite evident that the James River, its tributaries, and the area around Aberdeen, South Dakota, are much drier this year than they were last year. Last year, excessive wetness interfered with spring grain and summer crop planting. Aberdeen and Brown County are in the North Central Crop District. The dark blue and black areas are standing water, the orange is vigorous vegetation, and the green-to-yellow shades are emerging crops. As well as having much more moisture last year, there are many more bright orange or vigorous fields on last year's image.
Figure 7 is a Landsat image comparison from June 25, 2001 and June 20, 2002 for a portion of Brookings County. Brookings County is in the East Central Crop District. Vegetation and rainfall were similar during the last two years. Natural vegetation, winter grains, and alfalfa fields, orange on both scenes, indicate that conditions are close to equal as of these dates. Also, the "yellow cast" fields are establishing summer crops. They too are about equal. There is more "standing water" on the 2001 scene, the dark blue and black areas, especially along the river. There was much more reserve moisture last year, this could pose a problem for this year's summer crops, if rains don't come soon.
Figure 8 is a Landsat image comparison from June 8, 2001 and June 11, 2002 for a portion of Brule County, just southeast of Chamberlain, South Dakota. Winter grains on the 2002 scene range from maroon in color, just past flowing and starting to "turn color", to starting to "dry down" and turn gold. Many of the fields are better than last year, but judging from the natural vegetation and the number of less healthy or "gray" fields on the 2002 scene, condition are declining this year and more rainfall is needed to carry normal summer crops and pastures.
