evaluation of legumes as substituting crops for fallow in wheat-based rotation on north khorasan province

long term use of fallow in wheat-based cropping system of dry and semi-dry lands can increase erosion and decrease soil fertility. legumes as substituting crops for fallow could improve sustainability in this area. this study was conducted to evaluate the substituting of some legumes for fallow in a 2-yr wheat rotation at research stations in north khorasan province (natural resources research station of north khorasan, sisab-bojnord) from 2002 till 2006. six cropping systems, follow-wheat, wheat-wheat, chickpea-wheat, lentil-wheat, vicia-wheat and annual medic-wheat, were used on three replications. according to the average data from biomass and yield of substituting crops, wheat biomass was more than the legumes biomass in 2002-03 and 2004-05, and among the legumes, vicia and lentil biomass was more than that from chickpea and annual medic. also, wheat yield (159.9 g.m-2) was more than lentil and chickpea yield (86.8 and 83.3 g.m-2). average wheat yield on the two rotation cycles (p<0.05) affected by previous substituting crops, significantly. the most and the least wheat yield was achieved on the fallow-wheat (180.8 g.m-2) and wheat-wheat (110.4 g.m-2) rotations. however, the wheat yield on the lentil-wheat and vicia-wheat rotations had not significantly different from wheat-wheat cropping system. according to the results, it seems that lentil and vicia could be introduced as a crop candidate for substituting for fallow at the north khorasan province.