Utilization of alfalfa (Medicago sativa L.) as a smother crop in field corn (Zea mays L.)

Field experiments were conducted at two locations in Jordan to investigate the effects of alfalfa grown as a smother crop on corn and weeds. The two locations were characterized by semi-arid conditions. Treatments were; (1) a mixture of alfalfa-corn with alfalfa clipped once; (2) a mixture of alfalfa-corn with alfalfa clipped twice; (3) a mixture of alfalfa-corn with alfalfa clipped three times; (4) a mixture of alfalfa-corn with alfalfa clipped four times; (5) weed-free corn; (6) weedy corn; (7) weed-free alfalfa; and (8) weedy alfalfa. Results indicated that alfalfa reduced corn grain yield more than total above ground dry biomass. Grain yield reductions ranged from 23 to 53% of amounts harvested in weed-free corn plots. Yields were comparable or greater than amounts harvested from weedy check plots, indicating that alfalfa imposed equivalent or less competition on corn than the prevailing weeds of the two sites. Alfalfa harvested from frequently clipped plots was 48 to 57% of quantities harvested from weed-free alfalfa plots. Effectiveness of alfalfa in suppressing weeds was not obvious and varied between locations and cutting frequencies. Results of these experiments encourage corn producers to replace polyethylene mulches with alfalfa smother crop to maximize their utilization of scarce water resources available for Mediterranean agriculture. Possible economic advantages arise from lowering the initial costs of polyethylene mulches and additional returns from producing a high-quality forage crop, thus compensating for any reductions in corn grain yields. (C) 2004 by The Haworth Press, Inc. All rights reserved.