Establishment Methods for Alfalfa in Irrigated Corn1

Abstract

AbstractEstablishing alfalfa (Medicago sativa L.) under irrigation is expensive and production is low during the establishment year. Our objective was to determine, in the absence of moisture stress and weed competition, which combinations of corn (Zea mays L.) types and alfalfa planting dates would be most productive during the year of planting and the year following establishment. Alfalfa was planted at corn planting time, at last corn cultivation, or after the harvesting of corn for silage. Weed control was obtained by cultivation or using 4‐(2,4‐dichlorophenoxy)butyric acid (2,4‐DB), 2,2‐dichloropropionic acid (dalapon) or S‐ethyl dipropylthiocarbamate (EPTC) without cultivation. Alfalfa stand and yield were increased 27 and 9%, respectively, when alfalfa was planted simultaneously with the corn and the corn harvested as silage; however, this planting method reduced corn silage production from 20 to nearly 50% and grain yields from 1,000 to 3,000 kg/ha compared to alfalfa planted at last cultivation or following silage harvest. Generally ‘Brachytic dwarf’ corn was a poor competitor to alfalfa. Full‐season and midseason hybrids had about the same silage yields, but the full‐season hybrid produced more corn. Under the conditions of our experiment, a midseason corn hybrid planted at 59,000 seeds/ ha, with corn and alfalfa planted at the same time and corn harvested as silage, proved to be an excellent establishment method. This combination gave high silage yields, and removing the corn crop permitted good fall growth of the alfalfa.