On the Number of Seedlings for the System of Rice Intensification: Experiment Results from Lombok Island, Indonesia

Abstract

The System of Rice Intensification (SRI) is an environmentally friendly and sustainable rice farming practice developed in the 1980 s in Madagascar. It has spread to many countries in the early years of the 21st century, with Indonesia becoming one of the early adopters of SRI practices. The authors conducted experiments on SRI plots on Lombok Island, Indonesia, measuring water consumption, rice growth, GHG emissions and other variables. The focus of the current study was on accessing the appropriate number of seedlings under different irrigation regimes. This experiment prepared 30 small plots and set 2 types of irrigation: intermittent and continuous; 3 types of seedlings by nursery age: 0, 7, and 21 days; and 3 types of seedling groups: 1, 2, and 4 seedlings. At the harvest stage, the number of tillers, number of panicles, grain weight, filled grain weight, and root weight of 5 samples were measured from each plot. In terms of the irrigation method, intermittent irrigation achieved a higher yield than continuous irrigation. 2 seedlings achieved the best yield under intermittent irrigation, regardless of nursery age, while 4 seedlings achieved the best yield under continuous irrigation for both 7 day- and 21 day-old seedling types. In Indonesia, SRI promoters including local government and NPO staff recommend farmers to transplant one 7-day seedling. However, the experiment conducted in this study demonstrated that two day-old seedlings achieved better results. The two-seedlings method costs twice as much as the one-seedling method, but is only about half the cost of the traditional method. Moreover, the two-seedlings method gives farmers peace of mind at the transplant stage. The two-seedling method can thus be considered more reasonable than the one-seedling method.