Leveling Our Expectations with a Drier Start to the Season

BY Dairyland Seed Agronomy Team

Receiving timely and adequate moisture to initiate maximum emergence, early vigor, and adequate nutrient uptake strongly falls upon the blessing of timely rain. The current drier conditions have influenced emergence and early vegetative growth for our 2023 crop in many areas, so it’s important to reflect on water’s four primary roles within the crop.

Evaporative cooling to maintain plant temperature
Carrier for nutrient and sugar transport
Hydraulic force for cell growth, development, and expansion
Source of hydrogen for sugars, starches, and plant cell components

Since we covered the germination moisture needs of both corn and soybeans in the May 17 agronomy update (links below), we will cover the basic knowns after emergence in this offering.

Corn: https://www.dairylandseed.com/articles/corn-germination-and-emergence/

Soybeans: https://www.dairylandseed.com/articles/soybean-germination-and-early-growth-refresher/

Corn, in almost every case in our Dairyland Seed footprint, is somewhere between planted and the V6 stage of growth. A restriction in activity of any of these four water processes reduces corn growth and grain yield. Simplistically, moisture stress post-germination through early vegetative stages reduces root mass and soil exploration, stem and leaf expansion resulting in suppressed root systems and lesser leaf area and plant height in general. Being moisture limited also requires the plant to work harder to acquire the water and nutrients needed to sustain its momentum. Moisture stress yield losses from VE-V12 are estimated to be 1-3 bushel of yield loss per day of stress based on past research. Realistically, after emergence, we are at the least sensitive vegetative stages for water stress resulting in yield loss. We all know the telltale sign of pale curled corn leaves rolling in the summer heat, maybe we are not quite there yet.

Beans in our footprint range from planted to approaching V5. Moisture stress during early vegetative growth for beans after germination may shorten plants and result in smaller leaves due to a lack of water, nutrient availability, and uptake. In response to dryness, soybean root growth increases during drier conditions because plant carbohydrates are shifted to improve root growth. Another factor is the potential of compromised nodulation due to dryness; however, as adequate moisture is experienced, nodulation and symbiotic fixation should resume. Moisture stress early in season can initiate early flowering in some instances, so if you’re approaching V5 and lack of moisture stress is prevalent, keep your eyes open for some early flowering. I could find no information on yield loss at this stage for beans, so let’s pray for some rain and keep this 2023 crop progressing appropriately.

Sources:

https://crops.extension.iastate.edu/cropnews/2017/07/influence-drought-corn-and-soybean