We are nearing the hottest, wettest, and stormiest months of the year, which always brings up plenty of interesting weather topics. As is typical with summer weather, local precipitation patterns and your “luck” will ultimately determine how the weather influences the success of your crop.

Right now, the big summer weather story is the global transition from the three-year La Niña (Figure 1) to potential El Niño conditions in the next few months (Figure 2). The speed and timing of the transition will play a role in when El Niño might impact the U.S., but the transition will definitely influence global weather patterns. Typically, an El Niño benefits some of the key crop growing areas, due to the changing jet stream pattern potentially bringing in more moisture and somewhat lower summer temperatures. The Midwest Regional Climate Center analyzed historical crop yields in the Midwest during a developing El Niño1 and found above-average yields for corn and soybeans (using a detrended 5-year average from 2010-2014). This yield increase was generally attributed to cooler and wetter Julys during those years. However, there are always exceptions.

In other news, there is also moisture in places where moisture hasn’t been in quite a while. The Western U.S. through the Central Plains has received above-normal precipitation over the recent months, and this will surely play a role going forward. This precipitation will provide an added source of moisture for future weather systems, as well as enhanced soil moisture and surface water sources for irrigation.

Figure 1. Historical Nino 3.4 (Central Pacific region near equator) Sea Surface Temperature Anomaly from 1982-present.

Figure 2. Official ENSO (El Nino Oscillation) Forecast from NOAA Climate Prediction Center.

Extended Summer Outlook from NOAA

The extended summer outlook from the NOAA Climate Prediction Center (CPC) through September does appear to show some influence of the developing El Niño. The CPC gives higher odds for warmer-than-normal temperatures in the West, the South, and along the East Coast, while giving equal chances for above- or below-normal temperatures in the Midwest. (Figure 3). The precipitation outlook puts a target over the Central Plains for higher odds of above-normal precipitation, with near- to below-normal precipitation for the rest of the country (Figure 4). The biggest risk is focused on the Southwest U.S. and how the potential for above-normal temperatures could increase water stress on crops, especially if there is also below-normal precipitation. This also adds risk for drought stress on those dry areas in the Corn Belt. On a positive note, the Plains region has seen a slight increase in soil moisture recently and will now put less pressure on water resources after multiple years in a drought.

Figure 3. The Three-Month Seasonal Temperature Outlook for June, July, and August from the NOAA Climate Prediction Center.

Figure 4. The Three-Month Seasonal Precipitation Outlook for June, July, and August from the NOAA Climate Prediction Center.

The shorter-term outlooks through the month of July (Figure 5) show a slightly different pattern, with higher chances for above-normal precipitation in the East Central Rockies through June and transition to the Northern Rockies and Northern Plains through June. The temperature pattern shows higher odds for above-normal temperatures in the Northern U.S. and below-normal temperatures in the Southwest through June and transition to warmer than normal for most areas east of the Rockies through July. We will see drought conditions persist—at least in the short term in some locations—due to the extreme lack of soil moisture and high atmospheric demand this time of the year.

Figure 5. Monthly Temperature and Precipitation Outlooks for June from the NOAA Climate Prediction Center.

Soil Moisture Status

As I write this article, there are serious, long-term soil moisture deficits through the Plains and all the way through the Corn Belt (Figure 6). However, there has been some improvement in soil moisture across much of the Plains region west of the 100th meridian. Nearly the opposite has happened east of that line. The U.S. Seasonal Drought Outlook (Figure 7) shows this improvement in the Plains and the expectation of some short-term drought development in parts of the Corn Belt and Great Lakes.

Figure 6. Soil moisture anomaly compared to normal and the seasonal soil moisture anomaly change for the U.S. Map from the NOAA Climate Prediction Center.

Figure 7. U.S. Seasonal Drought Outlook through August 31, 2023. Map from the NOAA Climate Prediction Center.

Focus on Soil for Weather Management

The summer months are full of short-term “make-or-break” periods where extreme and dominant weather patterns can derail an entire crop season. Weather events—such as flash droughts and floods, or even hailstorms and derechos—are often unpredictable. However, there are some practices that limit your risk exposure, and many of these practices have to do with cover crops and reduced tillage. I’ll be the first to admit that a baseball-sized hail stone doesn’t care if you grew cover crops last fall or what the organic matter content of your soil is, but cover crops are often the first thing planted on the field after hail to protect the field from erosion, nitrogen leaching, and weed growth. (2) In addition, cover crops can help increase the soil organic matter content to hold extra moisture for crops to use during flash droughts. (3) Crop fields with the highest-quality soil and a protected surface are often the fields that perform the best during periods of extreme weather.

Key Takeaways to Deal with Extreme Weather:

• Surface residue can be your friend. Use the previous cash crop or cover crop residue to conserve valuable soil moisture and reduce soil temperature during high heat events. (4)
• Focus on building healthy soil for enhanced resilience to future weather extremes.
• To reduce the risk of losses, have an “agile” nutrient management plan which includes in-season monitoring.5 For example, too much precipitation may leach nitrates, while too little precipitation could prevent nutrient uptake. Poorly timed rain can prevent surface-applied fertilizer from moving down the profile. (6,7)

Sources:

1 Midwest Climate: El Nino 2015-2016. Midwest Regional Climate Center. Retrieved from: https://mrcc.purdue.edu/mw_climate/elNino/impacts.jsp 2 Are cover crops for me? – UNL CropWatch, Hail Know. Retrieved from: https://cropwatch.unl.edu/hail-know/infographic-cover-crops 3 Clark, A. September 2019. Cover crops for sustainable crop rotations. SARE Bulletin. Retrieved from: https://www.sare.org/wp-content/uploads/Cover-Crops-for-Sustainable-Crop-Rotations.pdf 4 McVay, K. October 2003. The value of crop residue. Kansas State University Department of Agronomy. MF-2604. Retrieved from: MF2604 The Value of Crop Residue (ksu.edu) 5 Nafchi, A. June 1, 2023. Monitoring corn nutrient deficiencies: The traditionals and precision ag approach. South Dakota State University Extension. Retrieved from: Monitoring Corn Nutrient Deficiencies: The Traditional and Precision Ag Approach (sdstate.edu) 6 Lu, C., Zhang, J., Tian, H, Crumpton, W., Helmers, M., Cai, W., Hopkins, C., and Lohrenz, S. 2020. Increased extreme precipitation challenges nitrogen load management to the Gulf of Mexico. Communications Earth and Environment. Nature. Retrieved from: Increased extreme precipitation challenges nitrogen load management to the Gulf of Mexico | Communications Earth & Environment (nature.com) 7 Quinn, D. June 21, 2022. Heat stress and drought considerations for corn. Purdue University. June 21, 2022. Retrieved from: Heat Stress And Drought Considerations For Corn | Purdue University Pest&Crop newsletter

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