Modeling Yield, Soil Water Balance, and Economic Return of Soybean Under Different Water Deficit Levels

Abstract

Evaluating the impacts of water stress on crop yield allows comparing irrigation management alternatives, aiming to ensure an economic return for the irrigated farms. Thus, the main objectives of this study were to model the soil water balance, deriving the crop coefficients, grain yield prediction, and economic return of soybean grown at different levels of water deficit and price quotations. The experiment was carried out under a rainout shelter, using four irrigation water managements. Irrigations were applied when the soil available water in the root zone reached 75%, 64%, 60%, and 50% of the total available water (TAW). Crop and soil parameters were monitored throughout the crop season. The SIMDualKc model was used to simulate the soil water balance. Statistics indicators demonstrated the goodness of the simulation, with regression coefficients (b0) ranging from 0.96 and 0.99 and root mean square errors (RMSE) ≤8.4 mm. Crop coefficients for initial, intermediate, and final stages were calibrated and validated at 0.15, 1.00, and 0.10, respectively. Crop yield and economic return were higher for the treatment kept at 75% of TAW, results that should be considered in irrigation management programs.

MOISTURE LIMITS AND POTASSIUM CONCENTRATIONS IN THE SOIL SOLUTION FOR CULTIVATION OF LISIANTHUS (Eustoma grandiflorum) FERTIGATED UNDER PROTECTED ENVIRONMENT CONDITIONS

“…A probe-TDR system was set up to allow the monitoring of the volumetric content of water in the soil (θ) at 25 points, using the equation by Topp et al (1980). The system consisted of a TDR100 reflectometer (Campbell Scientific, Logan-Utah), which was driven by a Campbell Scientific CR10X datalogger, which also stored the data (Petry et al, 2020). K + concentration data were collected using solution extractors equipped with a porous capsule installed in the center of the plots.…”

“…Knowledge of lisianthus irrigation and fertigation, factors that have a high impact on the production and quality of stems and flower buds, have generally been based on empiricism, often resulting in the application of inadequate amounts of water and fertilizers. These actions have resulted in low crop yields, due to a deficit or excess soil moisture, changes in stem development due to a lack of potassium, waste of nutrients, and even soil salinization, which increase production costs (Backes et al, 2008;Petry et al, 2020).…”