By Nathan Mueller
Soybeans Statewide
USDA is forecasting a record 2016 soybean yield of 59 bushels per acre, the highest August forecast ever. Last year Nebraska set a state record of 58 bushels per acre and the August forecast was 56 bushels per acres. In both years, soybean planting by the end of May was behind average. In 2016 we dealt with more heat waves and dry pockets than in 2015 and I think the major difference in this year’s soybean crop could will be a lack of August rainfall. In 2015, we had great rains during August to finish the soybean crop.
Figure 1. Aug. 18, 2015: No drought or abnormally dry areas were indicated in Nebraska.
Figure 2. Aug. 16, 2016: Approximately 43% of Nebraska was classified in drought, 33% of which was in the lowest category, "Abnormally Dry."
Portions of the state are definitely experiencing drier soil moisture conditions during the first half of August than we had a year ago (Figures 1 and 2). Even with all our irrigated acres, we still have a large rainfed crop and we know that August precipitation is the biggest driver of soybean yield. Insect and disease issues have been fairly low this year. We have had only light foliar feeding from various insects this year, with grasshoppers at higher levels in western and central Nebraska. Soybean aphids are only present at low levels in northeast and east central Nebraska. Scouts will notice some weed issues, especially from marestail, waterhemp, and Palmer amaranth. Scouts will definitely find pockets of outstanding pod counts and estimated yield. There is no doubt that Nebraska will raise a great soybean crop, but it is going to be tough to keep up with the record-breaking soybean crop of 2015.
Corn Statewide
USDA is also forecasting a record 2016 corn yield of 187 bushels per acre, similar to last year’s August forecast. There are two things we need during July for high-yielding corn: moderate temperatures and good soil moisture. We definitely experienced warmer temperatures in July 2016 than we did in 2015 when we set the Nebraska record of 185 bushels per acre. These warmer temperatures are being blamed for some pollination issues and tip back in the irrigated corn crop. Rainfall totals during June and July in areas like south central, southeast, and northeast Nebraska are nowhere near what they were in 2015, and generally, Nebraska rainfall has been more variable in 2016 than in 2015. Scouts will not find the consistency they did last year. Some areas that have had great growing conditions unfortunately dealt with green snap and lodging from early July storms.
USDA NASS Vegetation Map
Figure 3. Ratio of 2016 (August 9 -15, 2016) to 2015 (August 11-17) Normalized Difference Vegetation Index (NDVI). NDVI has been used to evaluate plant nitrogen status, green leaf biomass, and yield. Legend top to bottom: Red <= -25%, brown <= -15%, tan <= -5%, yellow +/-, light green >= +5%, green >=+15%, dark green >=+25%. Gray color represents non-crop areas.
A short ear count will definitely take the top-end yield from some rainfed and irrigated corn fields. We still have time to affect kernel size in the next several weeks, but kernel number is already determined. University of Nebraska corn yield modeling results on August 10 show a strong probability of near normal irrigated corn yields for most locations in Nebraska. However, rainfed corn yields in southeast and northeast Nebraska have a high probability of below normal yields, while those in east central Nebraska have a high probability of above average yields. The USDA Crop Condition Image (NDVI) is also less in 2016 compared to 2015, based on the USDA Vegscape – Vegetation Condition Explorer (Figure 3). It seems very possible that we will fall short of the records yields set in 2015 as pockets of lower than normal corn yields may outweigh the good.