The last week of June and the start of July have brought unusually dry conditions to much of West Tennessee, and we’re already seeing the effects on the region’s major row crops. Among crops cotton—often considered a heat-loving crop—may appear to be thriving right now, extended heat and limited rainfall can still influence how cotton and other major crops grow and develop as the season progresses.

Why this matters now

Dry weather at this point in the season can quickly shift from “manageable” to “yield-limiting,” especially if high temperature and evaporative demand rates continue and soil water remains low. A widespread, soaking rain in the coming weeks would help stabilize crop conditions and reduce stress during critical growth periods.

What this blog covers

This article focuses on:

• How drought and heat affect crop performance during key growth stages in:

• Corn
• Soybean
• Cotton

• General guidance on irrigation scheduling, including what to consider when deciding when and how much to irrigate
• A brief overview of irrigation scheduling methods, highlighting a few practical approaches growers can use to make more informed decisions

Corn

Water deficit stress in corn becomes much more damaging as the crop reaches tasseling and silking. Yield loss risk peaks at silking, with the next most severe losses typically occurring during the blister stage. During this period, water use remains very high and often stays elevated until the crop moves past the dough stage, so falling behind on moisture can be difficult to correct quickly. You can read more here: https://news.utcrops.com/2022/07/thoughts-on-irrigating-corn-and-soybean-during-2022/

A key concept for understanding irrigation demand is evapotranspiration (ET)—the movement of water from the soil into plant roots, through stems and leaves, and back into the atmosphere. Because ET is influenced by weather conditions and the plant’s growth stage, corn’s water use and sensitivity to water-deficit stress can change significantly over the season (Table 1).

To improve irrigation timing, consider installing soil water sensors within the crop’s rooting zone and monitoring moisture throughout the soil profile. Sensor data can help guide when to initiate irrigation and maintain adequate water availability during critical growth stages. Even with good tools, it’s strongly recommended to scout fields regularly, since soil type and local environmental conditions can cause irrigation needs to vary from field to field. Read more here: https://news.utcrops.com/2022/06/is-it-time-to-irrigate-corn/

Soybean

Irrigating soybeans typically resembles cotton irrigation more than corn irrigation. In most cases, irrigated soybeans outperform dryland soybeans, but it’s important not to overdo it—excess irrigation can reduce yield by increasing the risk of lodging and creating greater disease pressure. Read here: https://news.utcrops.com/2022/07/thoughts-on-irrigating-corn-and-soybean-during-2022/ and https://ipcm.wisc.edu/blog/2022/07/soybean-irrigation-during-reproductive-growth-2/

As soybean plants grow and continue to develop, their transpiration rate increases, causing soil water to be depleted more quickly. Table 2 It shows the estimated water use of soybeans across the different growth stages.

During the mid- to late-reproductive growth stages, which includes pod development (R3 to R4) and seed fill (R5 to R6), soybean is most sensitive to water stress. Read here: https://news.utcrops.com/2025/04/soybean-growth-stages/

Cotton

Cotton irrigation in the humid Southeastern and Mid-South U.S. is complex due to seasonal variations in rainfall and temperature throughout the growing season. Cotton plants are particularly susceptible to drought during the early boll development stages which immediately follow flowering (Table 3).

As the crop develops over the growing season, it adjusts the ET to reflect changes in plant growth and the amount of water use. Table 4 provides a summary of the changes and the daily water loss.

Based on multi-year research on silt loam soils in Western Tennessee, we have consistently found that yields are optimized when irrigation is initiated at early bloom and terminated at 15–20% cracked-boll. You can read more here: https://news.utcrops.com/2020/07/cotton-growth-stages-and-water-requirements/

If you have any questions about this content—or anything else related to cotton, corn, or soybeans in the coming months—please feel free to contact your local county office.