Effects of mixed cropping of alfalfa and three grasses species on vegetative traits, forage yield and land equivalency ratio in dryland farming systems of Northern Khorasan

Production of forage protein is limited in arid and semi-arid environments. Grass-legume intercropping could be a viable option to obtain forage with higher protein content. To study the best composition of mixed cropping of alfalfa (Medicago sativa) and three grass species (Agropyron elongatum, Agropyron desertrum and Festuca arundinacea) on vegetative characteristics and forage yield, a two-year experiment was conducted during 2009 and 2010 in Sisab station of the Natural Resources Research Station of North Khorasan province. The experimental design was a split plot based on randomized complete block design with three replications. The main factors were mix-cropping ratios and sub-factors were two methods of mixed cropping (including mixed and intercropping). Vegetative traits, forage yield, and land equivalency ratio(LER) were determined during the experiment. Data were analyzed by SAS software and means comparisons were made by Duncan's test. Results of analysis of variance showed that the effect of mixed cropping on growth characteristics of alfalfa and grass species was significant. The higher values of the leaf to stem ratio (81.66%) was obtained from mixed cropping of alfalfa 25% Festuca 75% treatment. The effects of sowing pattern (mixed and row intercropping) on vegetative traits were not significant. The effects of mixed cropping on the yield and LER of both alfalfa and grass forage were significant. The highest amount of dry matter production with average values of 2317 kgh-1 was obtained in mixed cropping of alfalfa 25% Agropyron elongatum 75%. The highest LER (1.53) was related to the treatment of Festuca 25% 75% alfalfa in intercropping patterns, representing 53% improvement in land use compared with monocultures of each of species.