System of Rice Intensification: does it translate into increased yield?

System of Rice Intensification (SRI) methodology exploits the inherent genetic potential of rice which has been inhibited by common management practices (flooded paddies, transplanting of mature seedlings, close spacing and use of chemical fertilizers). SRI studies in Madagascar produce high yields of over 10 t/ha. However, other rice scientists indicated that benefits of SRI over conventional rice management were likely to be small in well managed rice crops grown on fertile soils with no specific constraints such as potential Fe-toxicity. Therefore, SRI composed of using rotary weeder, organic fertilizers, wider spacing (30×30 cm), younger seedling (8-12 days old), and intermittent irrigation was compared to conventional management system such as Leaf Color Chart-based Nutrient Management (GS-NM) at the PhilRice Central Experiment Station in Nueva Ecija from 2005-2008. The Treatments were LCC-NM-N fertilizer was applied based in Leaf Color chart (LCC) readings; optimum Phosphorus (P) and Potassium (K), GS-NM = 120-40-60 kg/ha in dry season, SRI = 1 = applied 20 bags/ha of organic fertilizer (OF) 1 week before transplanting (WBT), saturated soil condition throughout the growing period, SRI-2 = applied 60 bags/ha of 1 WBT, saturated soil condition throughout the growing period, SRI-3 = applied 20 bags/ha of OF 2 WBT, irrigated when soil cracked. In 2008 dry season (DS), the lowest yield of 3.2 t/ha was obtained with SRI = 1. The yields of LCC-NM (7.3 t/ha) and GS-NM (7.9 t/ha) were higher than any of the SRI treatments by 3.1 t/ha or more. In 2008 wet season (WS), SRI-3 obtained the lowest yield of 3.1 t/ha. Consistently, GS-NM (5.4 t/ha) and LCC (5.1 t/ha) were comparable and higher than any of the SRI treatments by 1.3 t/ha or more. The previously reported high yields from SRI technology were not attained in this study. Results indicated that SRI, particularly with the use of organic fertilizers had significantly lower grain yield and return on investment than LCC-NM and GS-NM.