Semester of Graduation
Spring, 2025
Degree
Master of Science (MS)
Department
School of Plant, Environmental, and Soil Sciences
Document Type
Thesis
Abstract
This research was driven by concerns over phosphorus (P) and potassium (K) losses from fall-applied fertilizers and the increasing marketing popularity of liquid-P and K fertilizers over traditional granular-dry forms. We evaluated corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] yield and tissue nutrient concentration responses to fertilizer-P and K application timings, methods, and sources across 9-13 site-years on silt-loam soils in Louisiana from 2020-2024. For timing and method study, five treatments were evaluated: a no fertilizer-P and/or K check, fall broadcast followed by rehipping the seedbed, spring broadcast without rehipping, spring broadcast with rehipping, and spring top-of-bed application. In P- and K-deficient soils, no significant differences in yield or leaf nutrient concentrations were measured among fertilizer-P timings and methods for corn, or fertilizer-K timings and methods for soybean. Spring broadcast-K with rehipping increased corn yield by 7.6% over fall broadcast-K with rehipping. When fertilizer-P and K were applied together in suboptimal-P and K soils, no significant yield or nutrient concentration differences were found across timings and methods for either crop. The fertilizer source study included five treatments: a no-fertilizer check, and half- and full-recommended rates of both dry and liquid fertilizers. Triple superphosphate (0-46-0) and muriate of potash (0-0-60) were used as dry-P and K sources and ammonium polyphosphate (11-37-0) and Nachurs K-fuel (0-0-24) as liquid sources. In P- and K-deficient soils, corn yield did not differ between dry and liquid sources, but full-rate applications produced 5-13%, depending on nutrients, greater corn yield than half-rate. For soybean, no significant yield differences were noted between sources or rates for either P or K. However, when both nutrients were applied together, full-rate treatments produced 9-10% greater soybean yield than half-rate. These yield differences did not consistently correlate with leaf nutrient concentrations for either crop. Overall, results suggest that fertilizer-P can be applied in either fall or spring, but fertilizer-K should be applied in spring, at or before planting, especially in coarse-textured, low cation exchange capacity (CEC) soils. Additionally, liquid-P and K sources offer no significant advantage over traditional granular-dry fertilizers, and the nutrient rates should follow soil-test-based rate recommendations.
Date
1-17-2025
Recommended Citation
Wahid, Abrar Bin, "Corn and Soybean Responses to Phosphorus and Potassium Application Timings and Methods and Fertilizer Sources" (2025). LSU Master's Theses. 6087.
https://repository.lsu.edu/gradschool_theses/6087
Committee Chair
Md Rasel Parvej