Stubborn facts: Still no evidence that the System of Rice Intensification out-yields best management practices (BMPs) beyond Madagascar

For more than a decade, the System of Rice Intensification (SRI) has been vigorously promoted as a method for substantially improving the yield performance of conventional rice agriculture through a set of synergistic management principles that are purported to be accessible to poorer farmers and better for the environment. To evaluate the empirical basis for claims that SRI increases the yield ceiling for rice (i.e. the physiological yield potential), McDonald et al. [McDonald, A.J., Hobbs, P.R., Riha, S.J., 2006. Does the System of Rice Intensification outperform conventional best management? A synopsis of the empirical record. Field Crops Res. 96, 31–36] conducted a retrospective analysis of field experiments that had side-by-side yield comparisons of SRI and current best management practices (BMPs). In addition to studies from Madagascar where SRI was first conceived, 35 site-years of data were compiled from nine different Asian countries. Aside from one set of experiments in Madagascar where SRI more than doubled rice grain productivity with respect to BMPs (140–245% increase), we found no evidence of a yield advantage of this magnitude elsewhere. In 24 of 35 site-years, SRI yields were less than those attained with BMPs and in no case did the SRI yield exceed BMPs by more than 22%. Uphoff et al. [Uphoff, N., Kassam, A., Stoop, W., 2008. A critical assessment of a desk study comparing crop production systems: the example of the ‘system of rice intensification’ vs. ‘best management practice.’ Field Crop Res. 108 (1), 109–114] contest these findings with criticisms of our methodology and, more importantly, contend that key evidence demonstrating yield advantages for SRI over BMPs was not considered in our analysis. The assertion of key evidence that is at odds with our conclusions is false, as we detail in this response. Beyond Madagascar, there is still no empirical evidence that SRI has a unique yield advantage over current BMPs for rice. Then and now, our original article [McDonald, A.J., Hobbs, P.R., Riha, S.J., 2006. Does the System of Rice Intensification outperform conventional best management? A synopsis of the empirical record. Field Crops Res. 96, 31–36] accurately characterizes the global experience with the System of Rice Intensification.