Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Waldrep K., Tagert M.L., McCoy J., Harrison M.

Iron deficiency chlorosis (IDC) of soybeans is a frequent problem in certain areas of the United States, including the Blackland Prairie regions of Mississippi. Previous research has found that the severity of IDC in soybeans can be related to pH, temperature, CaCO₃ content, and moisture in the soil. However, even with these contributing factors identified, variety selection for tolerance has been the primary strategy for alleviating the effects of IDC. This study began in 2019 and focuses on a cropping system approach to manage the effects of IDC and thus increase grain yield in dryland soybeans. The project was established as a split-plot design, with seven different cropping systems as the main plots and six soybean varieties as the subplots. Little field-scale research has been conducted to understand the effect of soil moisture on IDC symptoms. This project evaluates the relationship between soil water tension and IDC severity across the seven cropping systems. Visual ratings and chlorophyll readings were recorded weekly (weather permitting) to evaluate IDC symptomology, and soil water tension was measured continuously throughout the growing season. Soil water tension was measured using Watermark granular matrix sensors installed at 30.5- and 61-cm depths—one set in a tolerant variety subplot and one set in a susceptible variety subplot. The sensors were connected to Watermark 200SS dataloggers and set to record each hour. Soil water tension is being compared to IDC visual ratings and grain yield for each cropping system to identify how soil moisture affects IDC severity.