Forage Production of Sorghum and Alfalfa in Sole and Intercropping Systems

Abstract

Field experiment was carried out for three years to investigate forage production in sorghum/alfalfa intercropping starting spring 2002 in Karaj region, Iran. In this experiment 3 mixing ratios of alfalfa with sorghum (including 75/25, 50/50 and 25/75%) were compared with sorghum and alfalfa sole cropping in a randomized complete block design with three replications. The results showed that the highest amount of forage was produced in 2nd year. Intercropping alfalfa/sorghum with 3:1 row ratio offered the highest mean forage production in 3 years of experimental period. In 2nd year of experiment, alfalfa sole cropping produced more forage than other treatments, followed by 3:1 alfalfa/sorghum treatment. Sorghum monoculture had the lowest total forage yield in 3 years. According to evaluating indices of intercropping profitability, LER in the first year was less than one due to the antagonistic effects of species on each other. Definite profitability of intercropping appeared in 3rd year, in such a manner that alfalfa/sorghum with 3:1 row ratio had LER = 1.22 and the minimum competition index (CI = 0.21). Aggressivity index indicated that alfalfa and sorghum in first year were the suppressed and dominant species, respectively. In 3rd year of experiment sorghum dominance decreased as its proportion increased in intercropping system. Overall, intercropping alfalfa/sorghum with 3:1 row ratio could be suggested as the superior treatment because of its higher total and available forage production system.