The earlier and more prevalent arrival of smoke from Canadian wildfires in Ohio, as compared to previous years like 2021. While this phenomenon may create diffuse light conditions, offsetting direct sunlight, it also brings potential harm to crops.
Smoke reduces light availability, which can negatively affect photosynthesis in crops. Reports suggest that a 15% reduction in light intensity does not significantly impact corn yield. However, when sustained shading of 30-50% occurs, yield losses become evident.
The main crops affected, corn, and soybean, may respond differently to reduced sunlight. Soybeans, being C3 plants with CO2 as the primary limiting factor affecting productivity, could be more susceptible to reduced light during their flowering and pod development stages. Corn, a C4 plant with light as the main limiting factor for productivity, may experience more damage during grain fill stages. Farmers are advised to closely monitor soybean fields during flowering and pod development this season.
As the wheat crop approaches harvest season, hazy conditions may hinder grain drying and foster disease development depending on the extent and duration of the haze.
Side Effects Mitigating the Negatives:
Lower Leaf Surface Temperatures: Diffuse light resulting from the smoke can lower leaf surface temperatures. This proves beneficial under water stress or drought conditions, as reduced leaf temperatures lead to less transpiration, thereby lessening water stress injury.
Optimized Photosynthesis: Leaf photosynthesis works best at light intensities ranging from 50-67% of full sunlight. Diffuse light can actually aid photosynthesis compared to full direct light, promoting productivity.
Analyzing Light Availability Trends:
Monitoring data from CFAES weather stations in Northwestern, Western, and Wooster regions reveals that the dry months of May and June have led to an accumulated light integral surpassing the 10-year average up to the early portion of June. While gains in total light have reduced recently, they are still near the 10-year average.
Consideration of Photothermal Quotient (PTQ):
The PTQ, or amount of light available per growing degree day, has been 6-16% greater than normal in June at the mentioned sites. Higher PTQ values mean more photons per GDD, potentially leading to increased productivity. However, lower GDD accumulation this season necessitates close monitoring of crop development during the summer.