The Corn Belt, a region in the Midwestern United States, is renowned for its high agricultural productivity, particularly in corn production. Spanning across states such as Iowa, Illinois, southern Minnesota, and eastern Nebraska, the Corn Belt plays a crucial role in the US economy. Understanding the agricultural patterns in this region is essential for predicting crop yield and managing resources effectively. One widely-used method for monitoring vegetation health and productivity is the Normalized Difference Vegetation Index (NDVI).
- What are the historical patterns of the growing season in the top 4 Corn Belt states as shown by NDVI data?
- When do the growing seasons typically start, peak, and finish?
- Can we identify historical anomalies in the NDVI data?
Extracting Locations from United States CDL
The United States Cropland Data Layer (CDL) is a great resource for extracting information about corn farm locations. To perform our analysis, we first extracted a random sample of 10,000 locations from the GeoTIFF map where corn was grown.
Next, we used the First Order Admin feature from Natural Earth Data to filter the original dataset for only the locations in the key Corn Belt states
These locations, represented by latitude and longitude coordinates, served as the basis for our subsequent data query.
Corn Farm Locations
Next we did a sanity check by plotting the locations to be used in the query:
Querying Data from Streambatch
We utilized the Streambatch API to obtain NDVI (Normalized Difference Vegetation Index) data from Sentinel-2 satellite imagery. NDVI is a key indicator of plant health and growth, making it a valuable metric for analyzing the corn growing season.
The query retrieves NDVI values over a specified time range (`start` and `end`) for the given locations (`space`). We obtained NDVI values for the years 2018 to 2022.
For the analysis, we filtered the dataset to only include data for the months April to November by adding 'year', 'month', and 'day' columns to the dataframe.
Next, we grouped the data by year and month, then computed the mean NDVI for each group. We also created a pivot table from the growing_season_monthly_mean.
We plotted a single heatmap of the monthly average NDVI for all corn farms across the top 4 corn belt states:
NDVI values typically begin to increase starting in June, although 2019 was an overall exception with a much later start to the growing season. Indeed, 2019 was a particularly bad year for US corn, with production at its lowest since 2015. Peak NDVI values range between 0.78-0.81, with peaks typically occurring in either July or August. Similar to 2019, 2022 was also associated with decreased corn production in the US, although it may be necessary to visualize the data at a higher temporal resolution (e.g. weekly) to observe any anomalies that may be present.
Exploring Weekly Average NDVI for the Corn Belt States Individually
To further understand the variations in the corn growing seasons and identify any unique patterns or differences between the top corn-producing states, we decided to take a deeper dive by analyzing the data at both the state level and a weekly temporal resolution. By separating the data by state, we can better understand the specific growing conditions and trends in each of the top corn-producing states.
To achieve this, we added a 'State' column to the dataframe to note which state each corn farm location was in.
Then, we plotted the weekly average NDVI during the growing season for each state individually.
To better understand the timing changes in NDVI values quantitatively, we identified the peak NDVI value and noted the week in which it occurred for each state and year.
Next, we plotted the timing of the peak value for each state, for each year, to visualize the variations in NDVI timing over time.
- The 2019 growing season was delayed across all of the top four Corn Belt states, (sometimes by up to 7 weeks in the case of Illinois), likely impacting overall crop production.
- The 2022 growing season experienced an anomalous event during the last week in August (34th week) that was picked up across Iowa, Illinois, and Minnesota. August 2022 was already the hottest ever recorded for North America, and the anomalous NDVI decreases observed are likely a result of the intense heatwaves that took a toll on crops across the US during the last week of August 2022.
- Among the top four Corn Belt states, Nebraska consistently had lower overall NDVI across all years included in the analysis, suggesting that the growing conditions in Nebraska may be less favorable than those in the other top corn-producing states.
In conclusion, analyzing NDVI data provides valuable insights into the corn growing season, allowing us to identify trends and anomalies in the crop production process. By examining this data on a state-by-state basis, we can better understand regional variations in crop health and growth patterns, which can inform decision-making in agricultural practices and policies.
- Determine how NDVI can be used as a predictor of crop yield to better understand the relationship between NDVI and production.
- Explore the factors contributing to the anomaly in 2022, potentially through weather data or other relevant datasets.
- Expand the analysis to include additional states and a longer time frame to identify broader trends in corn production across the United States.
- Incorporate other satellite-derived datasets, such as precipitation or soil moisture data, to provide a more comprehensive understanding of the factors influencing crop health and productivity.