Abstract
Despite numerous positive effects on the environment, increased demands, intense research, and adequate public attention, crops grown according to the principles of organic production still occupy considerably small areas. It is difficult for certified producers to decide to expand the production of certified organic vegetables. One of the reasons is the insufficiently developed growing technology of different vegetable species in accordance with the law and regulations on organic production. Intercropping, growing of subsequent crops, and application of microbiological fertilizers are considered as the most useful techniques for yield increases in sustainable growing practices. The aim of this study was to investigate the possibilities for enhancing root yield of beetroot and radish, when grown as second crops in an organic double-cropping production system. The effects of intercropping and applying microbial fertilizers on the vegetable root weights were assessed. Intercropping was with green beans, implemented by replacement series method. Two microbial fertilizers were applied, one containing selected strains of Bacillus megatherium, B. licheniformis, B. suptilis, Azotobacter chrocoocum, A. vinelandi and Derxia sp. (M1), and other with Bacillus subtilis, Azotobacter sp., Penicillium oxalicum and Fusarium sp. (M2). Intercropping and microbial fertilizers contributed to the root weight increase. The highest root weights were noted for the intercropped plants treated with M1 (beetroot, 151.8 g) and M2 (radish, 351.0 g), which was 23.5% and 15.5% higher than in the sole crop unfertilized control. The results imply combining intercropping and the appropriate microbial fertilizers as an effective strategy for increasing yields of organically grown beetroot and radish.
Highlights
As an environmentally sound method, organic plant production improves soil structure and microbial activity, enhances water quality, promotes biodiversity, and reduces human and animal exposure to potentially harmful pesticides and other chemicals
Unlike for beetroot, intercropped radish yielded significantly better than as a sole crop. This confirmed the results of our previous research on intercropping other varieties of green beans and radish, where we found significantly lower intercrop efficiency in green beans, and higher in radish (Ugrinovic et al, 2014)
Intercropping beetroot with green beans according to the replacement series method did not increase beetroot root weight
Summary
As an environmentally sound method, organic plant production improves soil structure and microbial activity, enhances water quality, promotes biodiversity, and reduces human and animal exposure to potentially harmful pesticides and other chemicals. Since the presence of macro- and microelements in the soil does not necessarily mean their immediate accessibility to plants, the fertilizers containing different strains of microorganisms that are non-pathogenic for plants, are becoming increasingly important. Plant growth promoters, such as beneficial strains of some bacterial species {Azptobacter sp, Derxia sp., Bacillus sp., Rhizobium heguminosarum etc.), contribute to the plant growth and reduce the need for additional fertilization, which refers to both organic and conventional production (Hayat et al, 2010; Sripontan et al, 2014; Ugrinovic et al 2014; Miskoska —Milevska et al 2018)
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