Forecasting 2017 Kansas corn yields
Precise and reliable yield forecast tools could play a foundational role in supporting policy formulation and decision-making processes in agriculture. For farmers, reliable yield forecasts might represent a source for considering changes in management practices during the reproductive phase of the field crops.
For this study, the final yield forecast tool was developed by utilizing satellite imagery of current corn growing conditions across the state. The main steps to forecast yields were:
1) Data collection (2009-2016 period)
a) USDA-National Agricultural Statistics Service (NASS) county-level data was collected to determine yield distributions at the district level.
b) MODIS (820-ft x 820-ft pixel size) satellite information with an image every 8 days until the beginning of August
c) CropLand Data Layer or spatial distribution of the different crops throughout the state
2) Building and Validation of Yield Forecasting Models (YFM)
a) For building the models, NDVI (Normalized Difference Vegetation Index) was utilized, collected from corn producing regions within a county.
b) Yields at the county-level were estimated before harvest from satellite information and compared against the final yields reported by USDA-NASS at the county-level.
3) Building and Validation Layer for Corn 2017
Information from the CropLand Data Layer is available for corn in Kansas from 2006 until 2016 – but current corn locations across the state are not available for the 2017 season until next year. Therefore, a complex statistical technique was employed (random forest prediction) to predict corn geo-locations across the state for the current season. Final validation of this map was tested against “known” field locations (collected via field survey analysis), summing up a total of over 500 field locations across the state.
4) Validation of previous years
Forecasted yield at the state-level from previous years (2009-2016) was validated by comparing those yields with the August yield estimation and the final yield from USDA-NASS. The yield forecasted via the satellite model was quite precise in predicting the final yields (e.g., example for 2009, 2012, 2014, and 2015 seasons; Figure 1).
5) 2017 Kansas Corn Yield Forecast
As a last step on the yield estimation, the yield and crop map models previously built were utilized to forecast the 2017 corn yield for Kansas. Satellite information from planting until the beginning of August was aggregated to provide a more reliable yield prediction.
Based on the satellite yield model developed by our team, the state-level yield prediction will be 125 bushels per acre, which is close to both the August and September yield estimations of 133 bushels per acre released by USDA-NASS.
Figure 1. Forecasting corn yields derived from satellite data for the state of Kansas. Infographic developed by Ignacio Ciampitti, Rai Schwalbert, and Luciana Nieto, K-State Research and Extension.
A final prediction will be conducted in the first week of October that incorporates satellite information until the end of September to adjust and update the corn yield forecast value obtained from satellite data through the beginning of August. Stay tuned for the next update on the final 2017 corn yield prediction for the state of Kansas.
Ignacio A. Ciampitti, Crop Production and Cropping Systems Specialist
Rai Schwalbert, KSUCROPS Production, Dr. Ciampitti’s Lab
Luciana Nieto, KSUCROPS Production, Dr. Ciampitti’s Lab