To achieve socio-economic development, global south is extensively developing digital public infrastructures (DPI). Unlike traditional ICT4D, DPI establishes open design, protocols, and standards that can be implemented by multiple stakeholders into varied solutions. We seek to identify DPI's offered affordances and higher-order mechanisms by employing the affordance-based generative mechanism framework of critical realism. As DPI are implemented to scale, we also investigate the challenge of multifinal outcomes due to affordance actualization by different user types. Using ethnographic case study analysis and topic modelling, we retroduce mechanisms of the Government of India's agricultural DPI, the sugarcane information system (SIS). The preliminary results indicate that small farmers do not fully actualize the offered affordance and encounter further marginalization due to their current niche. The governing bodies can utilize the framework and recommendations to increase the adoption and generative outcomes of a DPI in the presence of multiple niches.