Highlights: (1) Productivity of organic cropping systems cannot be inferred from yield of individual crops alone. (2) Manures for individual organic crops are provided at expense of additional land, water and nutrients. (3) Productivity of organic cropping systems must be made relative to all land and inputs for the crops produced. (4) Organic cropping systems have low productivity per total land area involved.
Reference: Connor, D. J. (2013). Organically grown crops do not a cropping system make and nor can organic agriculture nearly feed the world. Field Crops Research 144: 145-147. Available online at http://dx.doi.org/10.1016/j.fcr.2012.12.013