Comparative assessment of different crop rotation schemes for organic common bean production

The aim of the current study was to contribute to the establishment of sustainable organic crop rotation schemes for common bean under mild-winter climatic conditions. Common bean was cultivated according to organic or conventional farming practices during spring-summer in two successive years with crop and treatment during the preceding winter as either: (a) organic broccoli, (b) conventional broccoli, (c) organic faba bean used as green manure, or (d) fallow. Common bean was either inoculated with Rhizobium tropici CIAT 899 or non-inoculated, while faba bean was inoculated or non-inoculated with Rhizobium laguerreae VFLE1. Inoculating faba bean with rhizobia enhanced dry biomass production and biological N-fixing ability in both experimental years. Furthermore, organic farming did not restrict the yield of broccoli compared to conventional practices during the first year, while the reverse was the case in the second year, due to reduced soil N availability. Furthermore, green manure enhanced the fresh pod yield in the following organic crop of common bean in both years. The lowest yield was recorded in organically grown common bean when the preceding winter crop was organically grown broccoli in both years. Rhizobia inoculation of the common bean during the first year slightly increased atmospheric N fixation by common bean.