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| 05 Tuesday | The Economics of K Fertilizer Rate RecommendationsMarch 5th webinar on "The Economics of K Fertilizer Rate Recommendations"
Title: Economics of K Fertilizer Rate Recommendations
Presenter: Dr. Michael Popp, Department of Agricultural Economics and Agribusiness, University of Arkansas
Description: Potassium (K) fertilizer recommendations are often based on expected uptake, yield potential, and soil test K (STK) information for ‘build and maintain’ rate recommendations. Adding crop price and fertilizer cost for profit-maximizing rates leads to a ‘sufficiency’ recommendation. To assist with the latter, decision support software has been developed to arrive at rate recommendations that take field-specific STK, yield potential, crop price, fertilizer cost, and application charges into account. Further, the question of how many soil samples to take in a field, especially if considering variable rate technology (VRT) for fertilizer application, is important, as soil map accuracy will impact the degree of nutrient matching between existing STK, added fertilizer, and crop needs. We simulated field-level, profit-maximizing rate recommendations using VRT with different soil sampling densities to estimate profitability and yield implications in comparison to uniform rate technology (URT). In a 60-acre, irrigated soybean field with average STK of 84 ppm, we find optimum field profit using URT at the lowest soil sampling density with several caveats. Soil sampling charges, application cost differential between VRT and URT, as well as crop price and fertilizer cost play important roles for soil K fertility management.
Time: Tuesday, March 5th at 11am CST
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2024 Orange County Soil Health WorkshopOrange County Community Center, 1075 Sandy Hook Rd, Ste 2, Paoli, IN, 47454 Please contact Ophelia Davis for more information.
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| 06 Wednesday | MIami County Annual Winter MeetingMiami County 4-H Fairgrounds, 1029 W 200 N, Peru, IN, 46970 Please contact Nicholas Allen Musser for more information.
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Winter Meeting with Miami SWCD, Miami County Extension & Moss FertilizerMiami County 4-H Fairgrounds Event Center, 1029 W 200 N, Peru, IN, 46970 Please contact Courtney Schmidt for more information.
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| 20 Wednesday | Put Your Crop Top On - A Field Day Devoted to Soil HealthCross Creek Ag Solutions, 3783 South 1250 East, Greentown, IN, 46936 Please visit the website for more information.
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| 21 Thursday | Conservation Focus Workshop & PARP TrainingWayne County Fairgrounds, 861 Salisbury Road, Richmond, IN, 47374 Please view the website for more information.
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| 26 Tuesday | Correlation and Calibration of Soil-Test Phosphorus and Potassium from Different Soil Depths with Soybean YieldMarch 26th Webinar on "Correlation and Calibration of Soil-Test Phosphorus and Potassium from Different Soil Depths with Soybean Yield"
Title: Correlation and Calibration of Soil-Test Phosphorus and Potassium from Different Soil Depths with Soybean Yield
Presenter: Muhammad Rasel Parvej, PhD CCA, Assistant Professor and State Soil Fertility Specialist, Louisiana State University Agricultural Center
Description: Most land-grant universities have developed fertilizer-P and K recommendations based on soil-test P and K concentrations from 0-4, 0-6, or 0-8-inch soil depth. We evaluated soybean yield response to five different fertilizer-P or K rates (0, 40, 80, 120, and 160 lb P2O5 or K2O ac-1) and four different Mehlich-3 soil-P and K concentrations from 0-4, 0-6, 0-8, and 0-12-inch depths across 61 sites in Louisiana from 2020 to 2023. Out of 61 sites, fertilizer-P and K significantly increased soybean yield at 22 and 29 sites, respectively. Among all depths, soil-P concentration at 0-6-inch depth explained the maximum (53%) relative soybean yield variability. However, soil-K concentration explained 82-84% of the relative yield variability for all depths. Soil-P and K concentrations at 0-6-inch depth were more accurate in predicting soybean yield response to P or K fertilization than any other depths. The critical concentrations at 0-6-inch depth ranged from 22 to 28 ppm P and 102 to 130 ppm K. Below these critical concentrations, 75 and 100% of the sites responded positively to fertilizer-P and K, respectively, and above these concentrations, only 11 and 3% of the sites responded positively. Based on the sufficiency philosophy, our multiple regression model among relative yield, soil-test concentrations, and fertilizer rates showed that for maximum yield, soybean requires 90, 60, and 40 lb P2O5 ac-1 for fields with ≤10, 11-20, and 21-30 ppm P and 120, 90, and 60 lb K2O ac-1 for fields with ≤60, 61-90, and 91-130 ppm K, respectively. No fertilizer-P or K is needed for fields with >30 ppm P and >131 ppm K.
Time: Tuesday, March 26th at 11am CST
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