Determination of optimal strip width in strip intercropping of maize (Zea mays L.) and bean (Phaseolus vulgaris L.) in Northeast Iran

Intercropping is a sustainable method for crop production used to maximize utilization of available resources. The aim of this study, conducted in 2009 and 2010, was to determine an optimal strip width in maize/bean strip intercropping. Treatments evaluated in the study were contribution of different strip width and intercrops of 2 rows bean and 2 rows maize (II), 3 rows bean and 3 rows maize (III), 4 rows bean and 4 rows maize (IV), 5 rows bean and 5 rows maize (V), maize and bean monocultures. The higher than average temperature in 2010, led to decrease crop yields in that year. The climatic conditions had more effect on reduction of bean yield than maize. Radiation absorption, radiation use efficiency, biological yield, land equivalent ratio, crowding coefficient and system productivity index were greater in 2009 than in 2010. Radiation use efficiency for maize and bean were higher in 2009 than 2010 (8.9% and 17.6% respectively). The strip intercropping system enhanced radiation absorption, radiation use efficiency, biological yield, land equivalent ratio, crowding coefficient and system productivity index compared with the monoculture system. Increasing strip width from 2 to 5 rows resulted in a decrease all the criteria measured. The best strip width was with II and III strip intercropping treatments. Although biological yield in intercropping was less than in monoculture, total land productivity was improved by greater land equivalent ratio (1.39 and 1.37). This means that 39% and 37% more land was required for monoculture than intercropping to produce the same yields in 2009 and 2010, respectively. Therefore it was demonstrated that an intercropping system is more effective than a monoculture system in resource utilization. It also appears that equivalent row numbers of 3 and 4 for each crop in a strip manner is more promising in resource use than other combination of rows.