Effects of Cutting Interval between Harvests on Dry Matter Yield and Nutritive Value in Alfalfa

Abstract

Understanding the relationship between dry matter yield and nutritive value throughout the growing season will help optimize the cutting intervals between harvests in alfalfa ( Medicago sativa L.). The Ogallala Aquifer is a very important water source when growing alfalfa in Southwest Kansas and unfortunately, the water level of the Ogallala Aquifer is shrinking. The objective of this study was to determine the optimum cutting interval that optimizes dry matter yield and nutritive values of alfalfa. Alfalfa was harvested with different cutting intervals, i.e. , every 28, 35, 42 and 49 day, which was equivalent of 5, 4, 4, and 3 cuttings per year, respectively in 2013 and 2014. Based on 2-yr total yield, by delaying alfalfa harvest by 21 days, i.e. , from every 28th day to 49th day, alfalfa yield increased by 2.25 Mg/ha whereas by 5.58 Mg/ha by delaying cutting intervals from every 28th day to 42nd day. Although harvesting alfalfa every 42nd day had the same cutting frequency as the 35th day treatment ( i.e. , 4 cuttings per year), the treatment harvesting every 42nd day had significantly higher alfalfa yield than 35th day cutting interval. Alfalfa yield increased by approximately 20% by delaying one week for harvesting alfalfa from 35th to 42nd day interval, based on dry matter yields of 2013 and 2014. As cutting interval increased from every 28th to 49th day, crude protein (CP) content decreased. In contrast to CP, acid detergent fiber and neutral detergent fiber increased as the cutting interval and stage of maturity increased in 2013 and 2014. The results suggest that alfalfa producers in Southwest Kansas possibly could reduce the cutting frequency from 5 to 4 per year. Cutting interval of every 42nd day between harvests appears to be the optimum when considered a dry matter yield and nutritive values in alfalfa.