4 Impact of potassium application and harvest regime in alfalfa yield, forage quality and stand persistence in South Georgia. (29th July 2019)

• Record Type: Journal Article
• Authors: Thinguldstad, Britta; Tucker, Jennifer J; Baxter, Lisa; Segers, Jacob R
• Is Part Of: Journal of animal science. Volume 97(2019)Supplement 1
• Page Start: 15
• Page End: 16
• Publication Date: 2019-07-29
• Subjects: alfalfa -- harvest frequency -- potassium; Livestock -- Periodicals; Livestock; Electronic journals; Periodicals; 636.005
• DOI: 10.1093/jas/skz053.034
• Languages: English
• ISSNs: 0021-8812

Abstract

Abstract: Potassium fertilization and harvest timing can both impact stand life of alfalfa (Medicago sativa L.). In the Southeast, high temperatures and humidity often influence harvest timing and fertilization. Current nutrient management and harvest recommendations are generated from research conducted in northern climates with different varieties. The objective of this trial is to determine the impact of potassium fertilization and harvest regime on stand persistence, forage yield, and quality of 'Bulldog 805' alfalfa in the Southeast. This study was conducted at the Coastal Plain Experiment Station in Tifton, GA, on a two-year-old stand of 'Bulldog 805' alfalfa planted fall 2015. Plots were randomly assigned using a split block design. Main plots were harvest treatment: bud, and 10, 30, and 50% bloom stage. Plots were subdivided to examine K fertilization at rates: 0, 67, 101, 134, and 168 kg/ha, split 3 times throughout the season. Plots were visually assessed each harvest to determine ground cover and percent bloom. Fifty shoots were collected to evaluate leaf:stem and mass:shoot ratio, and yield was determined through harvest using a Swift forage harvester. Grab samples were collected for nutritional analysis using near-infrared reflectance spectroscopy. Data was analyzed using the PROC GLIMMIX of SAS with repeated measures analysis option at a = 0.05. Leaf:stem ratio was not significant for all main effects (P > 0.46). Harvest treatment had an effect on yield, with 10% bloom greater than bud stage (1, 321 kg/ha and 1, 104 kg/ha, respectively; P = 0.04). Crude protein levels were the greatest in bud stage and lowest with 50% bloom (22.8% and 21.2%; P < 0.01). Total digestible nutrients were greater in bud and 10% bloom compared to 30% and 50% (65% and 63%, respectively; P < 0.01). Potassium application and harvest regime can impact alfalfa growth. Funding for this project was provided by USDA-NIFA-AFRP grant #2016-70005-25653.